What is the cause of infertility in interspecific hybrids? Examples of interspecific hybrids. Hybrids of animals and plants: examples, photos. Human-animal hybrid Traces of unseen beasts

Since ancient times, people have been fascinated by the beauty and diversity of the surrounding plants, especially flowers. Their aroma and tenderness in all centuries have been the personification of love, purity, and expression of feelings. Gradually, man realized that he could not only enjoy the existing species of these beautiful creatures, but also take part in their formation. Thus began the era of plant selection, leading to the production of new species with more necessary and important traits in geno- and phenotype. Two sciences working together on this issue have now managed to achieve simply fantastic results - and botany.

Subject of study of botany

Botany is the science that studies everything related to plants. That is, them:

• morphology;
• genetics;
• physiology;
• anatomy;
• taxonomy.

This discipline covers all aspects of life of flora representatives, from the internal processes of respiration, reproduction and photosynthesis to the external diversity of phenotypic characteristics.

This is one of the most ancient sciences that appeared along with human development. Man has always had an interest in the creatures growing around him, which so decorate the surrounding space. Moreover, in addition to beauty, it has always been a powerful source of food, medicinal components, and building material. Therefore, botany is a science that studies the most ancient, important, diverse and complex organisms on our planet - plants.

Plant breeding

With the passage of time and the accumulation of theoretical knowledge about the structure of these creatures from the inside, their way of life and the processes occurring in them, an understanding of how their growth and development can be manipulated has become available. The science of genetics was gaining momentum, which made it possible to study different objects at the chromosomal level, cross them with each other, obtain good and bad results, and select profitable and necessary ones. This became possible thanks to the following discoveries.

1. in plants.
2. Discovery of the processes of mitosis and meiosis.
3. Development of crossing methods.
4. The phenomena of heterosis, outbreeding and inbreeding.
5. Decoding the genetic code of plants.
6. Biomolecular studies of cell and tissue composition.
7. Discoveries in the field of cytology and histology.

Of course, these are not all the prerequisites that served as the beginning of a powerful movement and the development of breeding methods for working on plants.

Crossing and its characteristics

Another name for the crossing process is hybridization. The method of using this phenomenon is called hybridological. Gregor Mendel was the first to use it for his experiments. Every schoolchild knows his famous experiments on peas.

The essence of the whole process is to cross parental forms with each other in order to obtain offspring that are heterozygous for traits, which will be called a hybrid. At the same time, different types of crossing have been developed. They are selected taking into account the individual characteristics of the variety, species or genus. There are two main types of such processes.

1. Outbreeding, or unrelated crossing. Implies that the initial parent forms do not belong to the same species, genus or variety. That is, they have no family ties. This crossing is one of the most popular and most often leads to heterosis when breeding pure lines.
2. Inbreeding or inbreeding- closely related hybridization of individuals belonging to the same species or genus, variety. This method is used to consolidate a useful trait, including a phenotypic one, in a population. With repeated, correctly carried out incubation, it is possible to obtain genetically pure plant lines.

These types of crossings also have narrower varieties within them. Thus, one of the forms of outbreeding is crossbreeding - hybridization between varieties.

In addition to types, there are also different types of crossing. They were described and studied in detail by Mendel, Thomas Morgan and other geneticists of past centuries.

Types of crossing

There are several main types of hybridization of individuals.

1. Monohybrid, or simple. It involves crossing parental forms to produce the first offspring, and is carried out once.
2. Dihybrid - based on parents that differ in two pairs of characteristics.
3. Reverse - a hybrid from the first generation is crossed with the original parent.
4. Polyhybrid, or double - individuals of the first generation are then crossed with each other, and subsequent ones with other varieties and species.

All designated varieties have meaning in each specific situation. That is, for some plants, simple crossing is enough to get the desired result. And for others, complex step-by-step polyhybrid hybridization is required to obtain the desired trait and consolidate it in the entire population.

Hybrids of different generations

As a result of any crossing, one or another offspring is formed. The traits it takes from its parents can manifest themselves to varying degrees.

Thus, the characteristics of first-generation hybrids are always phenotypically uniform, which is confirmed by (the first) and his experiments on peas. Therefore, to obtain the same result, which is required only once, the monohybrid type of hybridization is often used.

Further, all subsequent individuals already combine properties in themselves, so splitting appears in certain proportions. Recessives appear and interfere. Therefore, the most important thing for human industrial activity, his agriculture, is precisely the first generation of plants obtained.

A typical example: if the goal is to obtain only yellow tomatoes in one season, then a yellow and a red tomato should be crossed, but the red one should be obtained earlier from the yellow parent. In this case, the first generation will certainly be uniform - yellow tomato fruits.

Interspecific hybrids: characteristics

Interspecific are those hybrids that are obtained as a result of outbreeding or distant crossing. That is, this is the result of mating individuals belonging to different species in order to obtain a new one with predetermined characteristics and properties.

In this way, many important agricultural and ornamental plants were obtained by people in industry, and many new species of individuals were bred in animal breeding.

Examples of similar organisms

Examples of interspecific hybrids among plants:

• grain feed wheat;
• triticale - wheat and rye;
• rye-wheatgrass forms;
• wheat-elimus;
• several types of tobacco and others.

If we talk about animals, then many representatives can also be cited as examples:

The main problem with such hybridizations is that the offspring are either infertile or nonviable. That is why people have created and developed a lot of ways to eliminate these factors. After all, if the desired result is obtained, then it is very important not only to consolidate it, but also to introduce the production of similar organisms into the system.

What is the cause of infertility in interspecific hybrids?

The causes of such problems lie in processes, namely anaphase, when chromosomes move towards the poles of the cell. At this moment, each of them is looking for its homologous pair. This is how whole chromosomes are formed from chromatids and the general karyotype of the organism is formed.

But for those individuals in which the fusion occurred from different parental forms, the possibility of meeting such structures is minimal or impossible. This is why a random combination of traits occurs and, as a result, individuals become infertile or nonviable. That is, the genes essentially become incompatible.

If we turn to the molecular level and find out what is the reason for the infertility of interspecific hybrids, the answer will be this: it is the incompatibility of DNA sections from the cell nucleus and mitochondria. As a result, there is no conjugation of chromosomes in the meiotic process.

This leads to disastrous results both in crossing and breeding breeds and new species of animals. This happens especially often among representatives of the flora. Therefore, it is possible to obtain a harvest of hybrid plants only once, which is extremely inconvenient for the development of agriculture.

After scientists became clear about the cause of infertility in interspecific hybrids, active work began to find a way to eliminate these causes. This led to the creation of several methods for eliminating the sterility of individuals.

Ways to overcome infertility

The main path that biologists have chosen to solve this problem is as follows. At the stage of meiosis, when chromosomes diverge to the poles of the cell, a special substance - colchicine - is introduced into it. It promotes the dissolution of the filaments of the spindle (cell center). As a result, all chromosomes remain in one cell, and do not end up in different ones. Now free conjugation between homologous pairs is possible, which means that the process of meiosis will be completely normal in the future.

Thus, the offspring become fertile and easily bear fruit in the future when crossed with in different forms. Most often, this method is used in plant breeding; it is called polyploidy. It was first used by our scientist Karpechenkov. This is how he obtained the first fertile hybrid of cabbage and radish.

We have already found out what is the reason for the infertility of interspecific hybrids. Knowing the nature of the problem, it was possible to create two more ways to solve it.

1. Plants are pollinated by pollen from only one parent. This method allows you to obtain several generations of fertile hybrid individuals. However, then the trait still returns, and the individuals become sterile again.
2. Pollination of hybrids in the first generation with pollen from the parents.

To date, no more control methods have been created, but work in this direction is underway.

Lilies and their hybrids

A symbol of purity and innocence, flowers of sadness and grief for the departed, gentle and subtle representatives of the lily family - lilies. These plants have been valued by humans for many centuries in a row. During this time, what varieties were not created! Naturally, interspecific crossings affected them too.

The result was the development of nine groups of hybrid varieties that simply amaze with the beauty of their phenotypic characteristics! Among them, a special place is occupied by two of the most unusual and sought-after representatives:

• oriental hybrids;
• OT hybrid lilies.

Let's look at the characteristics of both groups and give them characteristics.

Oriental hybrids

This is the largest hybrid in terms of flower formation. Their biology is practically no different from that of other representatives. The size of the growing calyx can reach 31 cm in diameter, and the color can be different. The Nippon variety is very beautiful, having white large flowers with pink border. Their petals are corrugated.

The height of these plants varies up to 1.2 m. This allows them to be planted at a distance of 20-25 cm from each other and form beautiful flowering ridges. All representatives of this group emit a very strong aroma.

Orienpits

These are OT-hybrid lilies, the abbreviation of which is derived from the full name: oriental-tubular forms. They are also called for their very tall plant size and large flowers. On one stem up to 2.5 meters high, over 25 large (up to 30 cm) flowers can be formed, which are very fragrant and brightly colored.

This allows this group of hybrids to be in great demand among gardeners, although not everyone can cope with their breeding. Very careful care and proper planting are required so that such forms can take root and produce offspring.

Sunflower and its hybrid forms

Sunflower hybrids differ from each other in terms of seed ripening. So, they distinguish:

• early ripening (up to 90 days);
• early ripening (up to 100 days);
• mid-season (up to 110 days).

Hybrids also produce different seeds. Oil content and yield are different and depend on the timing of ripening. The longer the plant is in the ground, the higher the quality of the harvest. We can name several of the most common hybrids of this plant in the world, most in demand in agriculture.

1. Tunka.
2. Bosphorus.
3. Rocky.
4. PR64A15.
5. Jason.
6. Forward.

Among their main advantages:

• drought resistance;
• diseases and pests;
• productivity;
• high quality seeds;
• good fruiting.

Ligers, tigons, pizzlies... Ancient mythology different cultures abound with strange hybrid creatures such as centaurs, harpies and sirens, and even today graphic designers and Photoshop lovers create modern hybrids, combining different types of animals.

However, the animal hybrids that we will discuss below are real, living creatures. They could have appeared by chance (when two similar species of animals are crossed) or were obtained through in vitro fertilization ("test tube") or somatic hybridization. In this list of 25 amazing animal hybrids, you will see all forms of hybrid creatures.

In addition to the hybrid animals themselves, their names are also very interesting, which, it must be said, depend on the gender and variety of the parents. For example, males usually give the first half of the species name, and females the second. Thus, an interspecific hybrid called "pisley" (polar bear + grizzly) was the result of crossing a male polar bear and a female grizzly, while a hybrid animal called "grolar" - on the contrary, was the result of crossing a male grizzly and a female polar bear . Considering the above, you can now understand how the liger (one of the most famous hybrid animals in the world) got its name, born from the crossing of a male lion and a female tiger.

Are you ready to learn about the coolest hybrid animals that exist? From yagles and coywolves to zebroids and wolffins, here are 25 amazing hybrid animals worth seeing:

25. Liger

Let's start the list with the most famous hybrid animal. Born as a cross between a male lion and a tigress, the liger can only exist in captivity, since the habitats of the parent species in the wild do not overlap. Ligers, which can weigh up to 400 kilograms, are the largest felines known to exist.

24. Tigon, or tiger lion (tigon)


Another cross between the two largest species of the cat family is the tigon, which is a hybrid of a male tiger and a lioness. Not as common as reverse hybrids (ligers), tigons usually do not exceed the size of the parent species because they inherit growth-slowing genes from the female lioness. Tigons typically weigh about 180 kilograms.

23. Jaglev (Jaglion)


Yaglev is the result of crossing a male jaguar and a female lion. This mounted specimen is on display at the Walter Rothschild Zoological Museum in Hertfordshire, England. Yaglev has the powerful physique of a jaguar, and the color of his coat has adopted the characteristics of both species: the color of the coat, like that of a lion, and the brown rosettes, like that of a jaguar.

22. Savannah cat

One of the hybrids that form naturally in the wild, the Savannah is a cross between a serval (a medium-sized African wild cat) and a domestic cat. Savannahs are commonly compared to dogs for their loyalty. They can even be leash trained and taught to fetch killed game.

21. Bengal cat (domestic)


This breed was the result of selection of domestic cats, crossed, then backcrossed and backcrossed again with a hybrid of a Bengal cat and a domestic cat (backcrossing is a sexual crossing of a first generation hybrid with one of its parents). The goal was to create a strong, healthy and friendly cat with bright and contrasting colors. These cats typically have fur that is bright orange or light brown in color.

20. Coywolf


A coywolf is a hybrid of a coyote and a female three types North American canid families: gray, eastern or red wolf. Coyotes are closely related to eastern and red wolves, diverging from them in the development of the species only 150,000-300,000 years ago and developing side by side with them in North America.

19. Mule


Mules are born from the mating of a male donkey and a mare. Mules are more patient, resilient and hardy than horses, and also live longer than horses. They are considered less stubborn, faster and smarter than donkeys. Valued for their advanced packing ability, mules typically weigh 370-460 km.

18. Hinny (Hinny)


A reverse hybrid of a donkey and a horse, the hinny is the result of crossing a stallion and a donkey. Hinnies are much less common than mules, as they are inferior to them in endurance and performance. In addition, male hinnies are always infertile, while females are infertile in most cases.

17. Beefalo


Sometimes referred to as the cattalo or American hybrid, the beefalo is a cross between a livestock (predominantly male) and an American bison (predominantly female). Beefalo is externally and genetically primarily similar to a domestic bull, only 3/8 adopting the genetics of the American bison.

16. Zebroid


Known by many other names such as zedonk, zorse, zebrul, zonkey and zemul, a zebroid is a cross between a zebra and any other member of the equine family (horse, donkey, etc.). Bred since the 19th century, zebroids have a physical resemblance to their non-zebra parent but are striped like zebras, although the stripes do not usually cover the animal's entire body.

15. Dzo


Dzo, also known as "hainak" or "hainyk", is a hybrid of yak and livestock. Technically, the word "zo" refers to male hybrids, while the word "zomo" is used to refer to females. Unlike the fertile dzomo, the dzo are sterile. Because these animals are the product of a hybrid genetic phenomenon called "heterosis" (increased viability of hybrids in subsequent generations), these animals are larger and tougher than yaks and livestock, living in the same region.

14. Grolar


Grolar is a rare hybrid of a grizzly bear and a polar bear. Although the two species are genetically similar and often found in the same areas, they generally avoid each other and have different breeding habits. Grizzlies live and breed on land, while polar bears prefer to do this on the ice. Grolars can exist both in captivity and in the wild.

13. Kama


Cama is a cross between a male dromedary and a female llama, bred through artificial insemination at the Camel Reproduction Center in Dubai. The first kama was born on January 14, 1998. The purpose of the crossing was to create an animal that would be similar to a llama in its coat, but similar in size, strength and responsive disposition to a camel.

12. Wolfdog


Today, the Wolfdog (full name "Czechoslovakian Wolfdog") is a new, officially recognized breed of dog that arose as a result of an experiment conducted in 1955 in Czechoslovakia. Wolfdog is a hybrid of a German shepherd and a Carpathian wolf. The purpose of crossing species was to create a breed with the temperament, herd sense and trainability of the German Shepherd and the strength, physical structure and endurance of the wolf.

11. Wolfin, or orca dolphin (Wholphin)

Wolfin is an extremely rare hybrid of a male killer whale (black killer whale) and a female bottlenose dolphin. The first recorded wolffin was born at the Tokyo SeaWorld theme park, but he died 200 days later. The first wolffin in the United States and the first to survive was a female named Kekaimalu, born at Sea Life Park in Hawaii in 1985. Wolffins are reported to exist in the wild, but are extremely rare.

10. Narluha


The narluha is another very rare hybrid created by crossing the narwhal, a medium-sized mammal with a tusk, and the beluga whale, an Arctic and subarctic toothed whale from the narwhal family. Narluhi are extremely rare, but in recent years there has been an interesting trend of increasing sightings of these hybrid animals in the North Atlantic.

9. Zubron


Bisons, hybrids of domestic cattle and bison, are heavy and strong animals, with males weighing up to 1.2 tons. The name "Zubron" was chosen from hundreds of proposals sent to the Polish weekly Przekroj during a competition organized in 1969. Male bison are sterile in the first generation, while females are fertile and can be bred to either species as a parent.

8. Red Parrot Cichlid (Blood parrot cichlid)


The Redhead Cichlid is a hybrid of a male Midas cichlid, endemic to Costa Rica and Nicaragua, and a female Redhead Cichlid. Because the hybrid has various anatomical deformities, including a small, curved mouth that barely closes, making it difficult for the fish to feed, there is controversy about the morality of breeding these fish.

7. Mulard duck


Mulard (sometimes mullard) is a cross between the Muscovy duck and the domestic Peking white duck. Raised commercially for meat and foie gras, mulards are hybrids not only between different species, but also between different genera. These hybrid ducks can be created by crossing a Muscovy duck drake and a Peking white duck, but in most cases they are produced through artificial insemination.

6. Sheep goat (Geep)


Sheep and goats are born as a result of crossing a ram with a goat or a goat with a sheep. Although the two species appear similar and can mate, they belong to different genera of the goat subfamily of the bovid family. Despite the widespread grazing of goats and sheep, hybrids are very rare, and the offspring of mating are usually stillborn.

5. Black-tip hybrid shark


The first shark hybrid was discovered in Australian waters just a few years ago. The result of crossing an Australian blacktip shark and a common blacktip shark, the hybrid has greater endurance and aggressiveness. Scientists speculate that the two species deliberately crossed to increase their endurance and adaptation skills.

4. Rhino hybrid


Interspecific hybridization has been confirmed between black and white rhinos. New research suggests that this is possible because the two species are separated from each other by geographic boundaries rather than genetic differences. Native to Africa, black rhinoceroses are classified as critically endangered, with one subspecies now considered extinct.

3. Giant red kangaroo (Red-grey kangaroo)


Kangaroo hybrids between similar species have been developed by introducing males of one species and females of another to limit the choice of mating partner. To create a natural kangaroo hybrid, a baby of one species was placed in the pouch of a female of another species. The hybrid was created by mixing a large red kangaroo and a giant kangaroo.

2. Africanized bee, or killer bee (Killer bee)


Killer bees were created in an attempt to develop domesticated and more manageable bees. This was done by crossing the European honey bee and the African bee, but the offspring, which turned out to be more aggressive and more viable, were mistakenly released into the wild in 1957. Since then, Africanized bees have spread throughout South, Central and North America.

1. Hybrid iguana


A hybrid iguana is the result of the natural crossing of a male marine iguana with a female conolophus (or drushead). The marine iguana, which lives exclusively in the Galapagos Islands, has the ability, unique among modern lizards, to feed in water and generally spend most of its time in water, making it the only marine reptile that has survived to this day.

Interspecific crosses are used to enrich the genetic basis of the resistance of varieties.

There are at least two categories of interspecific hybrids - hybrids between varieties of already cultivated species and hybrids between a variety of the same species and plants belonging to a wild species.

Hybridization between different cultivated and wild species is more easily accomplished if they belong to the same ploidy group. Such hybridization is carried out, for example, between different types of wheat. Thus, from crossing wheat line No. 5129, isolated from the hybrid Triticum turgidum x Tr. dicoccum with Volga steppe durum wheat environmental group, a highly resistant to Hessian and Swedish flies variety of durum wheat, Kharkovskaya 46, was obtained. This outstanding variety quickly gained wide recognition.

In cases where hybridization of species that differ in ploidy levels is necessary, more significant difficulties arise associated with various barriers that prevent their crossing. These barriers are of a different nature and manifest themselves in a variety of forms, from the inability of pollen to germinate on the stigma of a foreign host to the degeneration of hybrid plants in the second generation. Plants of the first generation of distant hybrids, as a rule, exhibit one degree or another of sterility. To overcome these negative phenomena, developed special methods. Uncrossability is most effectively overcome by transferring one or both parental forms to more high level ploidy. To intensify pollen germination and pollen tube growth, growth hormones (indoles, gibberellins, etc.) are used. In some cases, the method of preliminary vegetative rapprochement of plants, developed by I. V. Michurin, is used.

Interspecific hybridization using various methods of overcoming barriers between species is widely used in modern plant breeding for resistance. Thus, when creating resistant forms of cotton, various species of the genus Gossypium are attracted to the bollworm and other pests. To reduce the attractiveness of plants to butterflies, so-called nectary-free forms were created. This was accomplished by hybridizing some species of G. hirsutum and G. tomentosum. Despite the recessiveness of this trait, it was possible to create various shapes cotton:

1. having no nectaries at all;
2. nectaries are located only on leaves;
3. nectar is released periodically;
4. nectaries do not function at all. All new forms have no nectaries on the bracts.

To obtain hairless forms, hybridization of some varieties of G. hirsutum with the wild Mexican species G. armourianum, whose plants lack epidermal hairs, was used. This trait turned out to be dominant and easily transferred to hybrids.

M, E. Teriovsky and A.I. Terentyeva created tobacco varieties resistant to thrips and a number of pathogens based on crossing cultivated tobacco with wild species. The hybridization was preceded by testing of 38 species of the genus Nicotiana, one synthetic species obtained by crossing N. debneyi with N. didebia and petunia.

It turns out that thrips resistance is common among wild Nicotiana species. The group undamaged by this pest included 16 types of tobacco.

Intergeneric crossings play an outstanding role in creating plant forms that are resistant not only to individual types of pests, but also to their extensive complexes. Intergeneric hybridization makes it possible to transfer to a new variety wider ecological plasticity, resistance to adverse environmental factors, including resistance to pests and other valuable properties. Distant hybridization allows you to obtain new forms of plants as a result of combining organisms with different heredity. The more distantly related the parental forms are, the more intense the results of crossings are.

With the help of distant sequential multi-stage hybridization, reliable transmission of genetic material that determines the development of the selected trait is ensured. Subsequent selection allows you to eliminate undesirable characteristics. A significant obstacle to the use of intergeneric hybridization (even greater than that which occurs with interspecific hybridization) is overcoming the uncrossability of pairs and the sterility of the resulting hybrids. Among the founders of distant hybridization methods should be named I.V. Michurin and L.L. Burbank, V.E. Pisarev and N.V. Tsitsin. The most widely distant (intergeneric) hybridization is used in the selection of grain, fruit and berry crops.

In the Main Botanical Garden of the USSR Academy of Sciences, under the leadership of Academician N.V. Tsitsin, methods for remote hybridization of cereals belonging to different genera (Triticum X Agropyron, Tr. X Elymus, Secale X Agropyron) were developed. New species, forms and varieties of hybrid crops of agricultural plants were obtained: perennial and grain fodder wheat, wheat-elimus, rye-wheatgrass hybrids. Most varieties of these crops are characterized by higher resistance to pests and pathogens. These are the varieties of winter and spring wheat-wheatgrass hybrids.

In recent years, work on the selection of a new cereal crop - triticale - a hybrid of wheat and rye - has acquired a large scale in many countries.

The founder of the creation of triticale in our country is V. E. Pisarev. The greatest prospects for obtaining highly productive complex-resistant forms of triticale have hexaploid forms (2n = 42). Such forms of winter triticale were created by A.F. Shulyndin by crossing varieties of winter durum wheat with cultivated rye. The parental forms of wheat were obtained from interspecific crosses of spring durum wheat with winter soft wheat. The resulting three-species triticale combined a whole rye kernel (14 chromosomes), one third of a soft wheat kernel (14 chromosomes) and half of a durum wheat kernel.

Three-species triticale, unlike two-species triticale, ear 3-5 days earlier than wheat variety Mironovskaya 808 and ripen simultaneously with it. Two-species plants usually ear at the same time as the standard or 1-3 days later than it.

Triticale, especially hexaploid forms, is characterized by complex resistance to fungal and viral diseases and secretive stem pests.

Absorption (transformative) crossing consists in the fact that low-productive queens of one breed are crossed in a number of generations with producers of another highly productive breed. Thus, the properties of the improved breed are absorbed or replaced by the properties of the improving breed. The absorption process is stopped if the crossbreeds do not differ in productivity, appearance and constitution from the animals of the improving breed. In the future, such crossbreeds are bred “inside”.

With each new generation of crossbreeding, the “bloodiness” of the original (maternal) breed is reduced by half compared to the previous generation.

Transformative crossbreeding- one of the most common; its effectiveness largely depends on the crossing technique, the choice of improving breed and the conditions of feeding and keeping the animals.

The purpose of absorption crossbreeding is to radically improve animals of an unproductive breed. The resulting crossbreeds are brought to a high degree of resemblance to animals of the improving breed through successive matings over several generations with purebred sires of the improving breed.

The offspring obtained by breeding “inside” crosses of the second generation (3/4 blood), depending on the severity of the desired type, are classified as crosses of the fourth or third generations according to the breed being improved. The offspring obtained as a result of breeding crosses of the third and fourth generations, depending on the severity of the desired type, are classified as crosses of the fourth or third generations according to the breed being improved. The offspring obtained as a result of breeding “inside” crosses of the third and fourth generations, and fourth generations, depending on the severity of the desired type, are classified as fourth generation crosses or purebred animals. If there are no documents about the origin of the animals, but the type of improving breed is well expressed, they are classified as crosses of the first or second generations (1/2 - 3/4 blood) of this breed.

Absorptive crossbreeding- an important method for transforming unproductive animals, and it is often desirable to obtain ones that, along with improving economically useful qualities, would not lose some of the properties of local improved livestock.

When choosing an improving breed, it is important that the representatives of the latter significantly surpass the animals of the improved breed in terms of economically useful traits and, in addition, adapt well to local conditions.

As a result of the widespread use of transformative crossbreeding, the number of purebred animals in our country is increasing every year. The use of purebred producers of improving domestic and imported breeds has made it possible over the past 35-40 years to dramatically transform the bulk of the country's porridge animals.

Before proceeding with absorption crossing, it is necessary to find out the characteristics of the improving breed and its adaptability to local conditions. Thus, in a number of areas of the country, which due to natural conditions are not very suitable for breeding fine-wool sheep, absorption crossing of local coarse-wool sheep with rams of fine-fleece breeds gives poor results.

The success of absorptive crossbreeding depends on the quality of the producers of the improving breed, as well as on the feeding conditions and maintenance of the crossbred offspring. Only by creating favorable feeding and housing conditions for crossbreds can high performance be achieved.

The successful application of this method is facilitated by the strict selection of crossbreeds, the speed of generational change and the hereditary stability of the characteristics of the improving breed.

The importance of absorption crossbreeding for the rapid mass improvement of the breed composition of animals. Many breeds of animals have been bred abroad and in our country by absorption of blood. P. N. Kuleshov in his work “Methods of breeding domestic animals” (1932) clearly illustrated the importance of absorption crossing, noting that when breeding the famous purebred riding breed of horses, in the first stages of work they resorted to absorbing the blood of a local English horse with the blood of several eastern horses breeds In the same way, merino sheep, and in the south of Russia also smooshka sheep (from Karakul), American trotter (from racing horses), breeds of some American and German pigs (from English breeds), and many breeds of cattle in Europe were obtained in many countries. and America (from the Dutch, Simmental, Swiss, Jersey, Ayrshire and Shorthorn breeds).

On the importance of absorptive crossbreeding for the transformation of livestock farming in our country IT. D. Potemkin wrote back in 1926 in his work “Massive improvement of Russian cattle breeding (without Siberia and the Caucasus).” Many tens of millions of heads of unproductive outbred cattle, sheep, pigs and other animals in a relatively short period were transformed in our country into pedigree animals of various bloods.

A well-organized system of breeding work in our country serves as a solid basis for the massive improvement of the breed composition of animals.

In those farms where the breed of animals is still low, efforts should be made to transform them into purebreds through absorption crossing.

Introductory crossing (infusion of blood). They resort to it if the existing breed meets the basic requirements in its qualities, but needs to improve certain characteristics.

The breed of animals in such crossing is determined by the breed being improved as follows: the first generation includes the offspring obtained by crossing the original animals with the sires of the breed chosen as the improving one; to the second - the offspring obtained by crossing crosses of the first generation with purebred animals of the improved breed (backcrossing); to purebred animals - offspring obtained as a result of crossing second-generation crosses with sires of an improving breed, subject to the expression of the desired type.

Tasks and techniques of crossing. During introductory crossbreeding, sires of the improving breed are used once on the uterus of the improved breed to produce first-generation crossbreeds, which are mated with the best animals of the improved breed. Thus, the basic qualities of the animals of the original breed are preserved.

The main stages of introductory crossing. The first stage of infusion of blood consists of crossing the ewes of a slow-moving breed with sires of another breed, the qualities of which the breeder must “infuse” into the animals of the improved breed. In this case, the correct choice of breed, the characteristics of which are transmitted through the manufacturer to the queens, is of decisive importance. It is also important that the reinforcing rein matches well with the one being improved.

In order to improve, for example, milk productivity, milk fat content, precocity, exterior and constitutional indicators, introductory crossings are carried out with animals related to the red , red Swedish and some. To increase milk production, he is infused with the blood of animals of a related Montbeliard (from France) breed; to increase milk fat content - animal blood.

At the second stage, first-generation crossbreeds are crossed with purebred animals of the original (improved) breed. The main task during this period is to select for further breeding animals of the most desirable type with well-defined breeding characteristics.

The third stage is the transition to breeding crosses “inside”. According to the main constitutional characteristics, crossbred animals are very close to animals of the main (improved) breed.

Conditions for the success of introductory crosses. Along with the correct choice of an improving breed and the general direction in selection, when the qualities of animals of related breeds are used to improve the original breeds, it is important to take into account those qualities that favor the use of modern technology in animal husbandry. In such cases, it is more advisable to resort to the “infusion of blood” from unrelated breeds. Thus, to increase the milk production of animals of some domestic breeds, improve the shape of the udder and increase the rate of milk production, they resort to introductory crossing with sires of the Ayrshire breed. The results obtained indicate the feasibility of such a technique.

The success of introductory crossbreeding also depends on the provision of farms with feed, as well as on the conditions of keeping animals and the organization of zootechnical accounting.

The experience of our country and foreign countries confirms the high efficiency of introductory crossing. It is used to increase the milk fat content of cows, improve the meat qualities of animals of various species, and in other cases.

At the Askania-Nova farm in the Kherson region, for example, long-term work is being carried out to increase productivity and give the animals of this breed a milk-meat type, for which they are “infused with blood” of the milk-meat type. As a result of many years of work, Askania-Nova has created a herd of animals of a new dairy and meat type.

Crossbreeds with milk yield and milk fat content are close to cows, and surpass the latter in live weight; they are distinguished by their early maturity, higher slaughter yield, better meat quality and lower feed consumption per unit of production. The new type of bulls are used for breeding purposes.

Positive results were also obtained with the improvement of black-and-white cattle with Jerseys. Thus, in the USA, as a result of crossing Holstein-Friesian cattle with Jersey bulls, second-generation crosses of the Jersey breed were obtained, the milk fat content of which is 4.12-4.4% .

Currently, introductory crossing is quite widely used in breeding work.

Reproductive (factory) crossing. With this breeding method, animals of two (simple) or more (complex) breeds are used to produce offspring that combine their positive characteristics. When creating new breeds, crossbreds that meet the requirements for them are bred “in themselves,” that is, crossbred queens are covered with crossbred sires. Reproductive crossbreeding has created many breeds of farm animals that are distinguished by fairly high productive qualities and are well adapted to their living conditions.

Yes, sheep Altai breed, slightly inferior in productivity Askanian, superior to them in greater compliance of their constitution with the natural conditions of the Altai Territory.

Reproductive crossing requires involvement in work large number animals; oko is much more complex than other breeding methods. In this case, not only a combination of the qualities of the original breeds is achieved in the crossbreeds, but also the development of new desirable characteristics in the animals. Most often, an aboriginal breed is used as a mother breed, the animals of which are well adapted to local conditions; other breeds (one or more) are selected taking into account the individual and breed characteristics of the animals so that they can fill the missing qualities of the local (aboriginal) breed. The greater the differences in the breeds being crossed, the more diverse the crossbreeds; among them it is easier to identify individuals with completely new qualities. However, in such cases it is much more difficult to consolidate the desired qualities in the offspring. On the contrary, the greater the similarity between the crossed breeds, the relatively easier it is to consolidate similar qualities in the offspring.

In each breed there are different variants of intra-breed types, so the choice for crossing the corresponding breeds also involves careful selection of individual individuals according to the desired characteristics. In such cases, individual selection, selection, and assessment of sires based on the quality of the offspring are mandatory.

On final stage work on breeding, by reproductive crossing, a new breed of crossbred queens that meet the desired requirements and combine the valuable qualities of the original breeds, are mated with crossbred sires of the same quality and origin, i.e., they resort to breeding them “in themselves.” If necessary, the blood of animals of other or original breeds can be “infused” into the crossbreeds, which is called corrective crossing.

Methods for breeding new breeds.

A.I. Ovsyannikov, summarizing the methods of breeding new breeds by reproductive crossing, gives the following sequence of work:

• development of a new breed model (standard of excellence). The body type and the main economically useful characteristics of animals of the future breed are determined, taking into account its adaptation to climatic and economic conditions, as well as the ability to satisfy national economic needs;
• selection of source material. The original breeds are selected (the animals of at least one of the breeds being crossed must differ in the qualities that the crossbreeds are planned to have), the animals are evaluated and selected for crossing, and, finally, a farm is selected;
• genetic enrichment of crossbreeds according to the desired
  qualities, breeding crosses “inside”, for which it is important to create favorable conditions for feeding and keeping. If the animals obtained during the first crossing do not satisfy the breeder, one or two return crosses are carried out to an improving breed or representatives of a new factory breed are used for this;
• When crossing, they necessarily resort to strict rejection of crosses that do not meet the desired requirements, as well as to inbreeding of the best sires and queens.

To consolidate the desired qualities in the crossbred offspring, individual selection of animals is used with careful justification for its purpose. Reliable results in such cases are obtained by inbreeding, which is combined with unrelated mating, for which animals that are similar in type to inbred ones are selected. To avoid too close inbreeding and to consolidate the necessary economically useful qualities in the offspring, several lines and brood families are established. If the crossbreeds strongly deviate in an undesirable direction, they are mated with animals of the desired type, and sometimes with sires of one or more original breeds. They begin breeding crossbreds “inside” only when they meet the desired requirements.

Simple and complex reproductive crossing. Reproductive crossbreeding can be simple or complex. In the first case, animals of two breeds are involved in crossing, in a complex one - three or more breeds. Most cattle breeds are created through simple reproductive crossbreeding using local cattle and animals of some factory breed.

WITH M. F. Ivanov used reproductive crossing with great efficiency to breed new breeds of farm animals. IN short time he created a domestic one using this method Ukrainian steppe white breed pigs, a highly productive Askanian breed of fine-wool sheep and began work on creating a mountain merino The main stages in breeding new breeds of sheep by reproductive crossbreeding are obtaining crossbreds (hybrids) of a certain blood, their intensive culling, the use of inbreeding and constant selection work with animals. As source material, M.F. Ivanov selected, if possible, homogeneous animals of strong constitution, which he crossed with highly productive producers of factory breeds also of strong constitution. When obtaining crossbreeds of a certain blood, in order to consolidate the desired qualities in the offspring, he resorted to inbreeding, and in this case he used only outstanding sires. In addition, M. F. Ivanov used a very strict culling of animals that did not meet the desired requirements, as well as weak, sick, pampered, retarded, with deformities and other defects. He paid great attention to the formation of several unrelated lines, so that after obtaining more or less homogeneous genotypes, he could begin unrelated mating and create favorable conditions for feeding and keeping crossbred animals, especially young animals.

Similar methods were used when breeding the Ukrainian steppe white breed of pigs.

As a result of complex reproductive crossing, the Kostroma breed of cattle was also created. In this case, purebred and crossbred bulls of the Algauz and Schwyz breeds, Yaroslavl, Miskovsky and local mongrel cattle were used.

When breeding the Soviet Merino sheep breed through complex reproductive crossbreeding, local coarse-wool sheep from various regions of the country, Merino rams and ewes of the Mazaevskaya and New Caucasus breeds, American Ramboulier rams and new domestic fine-fleece breeds - Askanian, Caucasian, Altai, Stavropol, Grozny, etc. were used.

By crossing local Kuban pigs with large white, Berkshire and white short-eared breeds on collective farms and state farms in the Rostov region and Krasnodar region, the North Caucasian breed of pigs was created.

In horse breeding, through complex reproductive crossbreeding using mares of the Don and Black Sea breeds and purebred riding stallions, the Budennovsky breed of horses was created, combining the best qualities of the Don and thoroughbred riding breeds.

The value of reproductive crossing lies in the fact that it allows you to create completely new breeds with predetermined parameters of economically useful and biological qualities. Involving in this type of crossing of several breeds, selection for the combinational relationship of desirable traits, makes it possible to sharply increase the economic value of new breeds and adapt them to the technology of industrial animal husbandry.

All countries in the world with intensive livestock farming are working to create new breeds using reproductive crossbreeding.

Industrial crossing. It is used in all sectors of livestock farming to put the heterosis effect into practice. It is widely used in modern non-breeding industrial farms. When using animals of two breeds, crossing will be simple, and three or more breeds will be difficult. The main purpose of industrial crossbreeding is to create highly productive commercial herds.

In many livestock farms, especially in European countries and America, less valuable dairy and dairy-meat cows, the young of which are raised for meat, are inseminated with the sperm of bulls of early maturing meat breeds. At the same time, the production direction of the farm does not change, since cows are used to produce milk, and non-breeding crossbred young animals serve as material for the production of high-quality meat. In pig breeding, industrial crossbreeding is also widely used to produce first-generation crossbreeds.

An important conditional application of this breeding method in all sectors of animal husbandry is the presence of not only sires, but also purebred queens of a certain breed. The use of crosses of unknown origin in such crossings does not always provide the expected effect. In a number of branches of livestock farming, in particular in sheep breeding, the effect of heterosis during industrial crossing is achieved with a more complex combination of breeds.

In some countries, complex industrial crossing is carried out on farms that differ in the level of intensity of livestock farming and natural and climatic conditions.

For example, in sheep farms in England located in the mountainous areas of extensive sheep breeding, local queens are crossed with rams of the long-haired Border Leicester meat and wool breed. The first-generation crossbred rams are then castrated and, after fattening, sent for slaughter, while the crossbred rams are sold to farmers in lowland areas, where feeding conditions are better than in the mountains. Here, these bright lambs are crossed with rams of faster-ripening short-haired breeds (Oxfordshire, Southdown, etc.). The offspring obtained as a result of such crossing are completely slaughtered.

In poultry farming, industrial crossing is widely used to produce so-called hybrid birds, which are superior in productivity to birds of the original breeds (lines). In many countries, this breeding method is also used in horse breeding to produce half-bred horses primarily for sporting purposes.

The economic efficiency of industrial crossbreeding is obvious, since, compared with peers of the maternal breed used, the crossbreeds are characterized by better development and higher productivity.

The use of industrial crossbreeding in beef cattle breeding provides a rapid increase in the production of high-quality beef. Good results are obtained when using bulls of the breed Charolais And Kian.

Big economic effect in pig and poultry farming, the method of interline hybridization is used, which is a high form of industrial crossing and is becoming widespread during the transition to the production of livestock products on an industrial basis. Interline hybridization can include forms where animals from two combined lines of one or more breeds are crossed. Other forms of interline hybridization are also known.

The efficiency of production of interline hybrids can be judged from the following data. In international markets, hybrid pigs fastback, saike, Cotswold (Great Britain), spurs (Holland), animals bred by Farmer Hybrid (USA), etc. are widely used. Hybrid Cotswold pigs are very fertile: under average conditions they produce 21 pig. Young animals weigh 20 kg at 8 weeks of age, and 90 kg at 160 days of age; feed costs per 1 kg of live weight gain - 2.62 kg.

In Canadian poultry farming, the best egg hybrid crosses were recognized in 1973 as the Shaver 288 crosses (average egg production 249.5 eggs, feed cost per 1 kg of egg mass 2.47 kg). “Babcock 305” (277.4 eggs and 2.51 kg, respectively), “Babcock 300” (240.6 eggs and 2.48 kg). Hybrids are also widely used in the production of broilers.

Interline hybridization is also used in sheep breeding.

In Great Britain, for example, hybrid sheep Improver Kadzova were created on the basis of the Dorsethorn and Finnish Landrace breeds. From every 100 queens - crosses of Scottish black-faced sheep with these hybrids - 222 lambs are obtained per year, and from every 100 crosses of Nmproper X Dorset Horn - 233 lambs.

Heterosis effect- a complex biological phenomenon that depends on the genetic capabilities of the original breeds or lines, the heterozygous structure of the genotype, the maternal effect and the living conditions of both the offspring and the parents.

The higher the productivity of animals of the original breeds, the higher the productivity of crosses obtained as a result of industrial crossing. Therefore, the choice of breeds to cross is critical. Many experiments have been carried out to determine the best combinations of different breeds. In beef cattle breeding, more than 50 variants of various combinations of dairy and double-productivity breeds with meat, as well as meat breeds with each other, have been studied. Similar studies have been carried out in other livestock sectors. The most promising combinations of breeds for industrial crossing have been developed and are being introduced into production. In beef cattle breeding it is recommended, for example, to use: Hereford breeders and Red Steppe, Simmental and Black-and-White cows; producers of Aberdeen Angus (large type), Santa Gertrude, Charolais and Red Prairie cows; bulls of gray Ukrainian, Simmental breeds and black-and-white cows; Shorthorn sires (large beef and dairy-meat types) and red prairie cows.

The farm's crossbred young animals are sold for meat at 15-18 months of age after intensive rearing and fattening.

There are simple industrial crossings, in which animals of two breeds are used (Fig. 16), and complex ones, when individuals of three breeds are mated in succession. Complex industrial crossbreeding, shown in the second diagram, is used, in particular, in the GDR to improve the milk and fat content of black-and-white animals. With this combination of breeds, crosses are obtained that are distinguished by the best indicators of udder development, fertility and productivity.

The breeding stock for industrial crossing is usually used from a breed that is well adapted to local conditions. Producers are selected taking into account previously identified compatibility, and higher requirements are placed on them than on queens. It is desirable that both queens and sires are purebred. In simple industrial crossing, first-generation crossbreeds are used to obtain products; in complex industrial crossing, they are crossed with animals of one or more other breeds. Only after this are complex crossbreds that meet the goals of commercial livestock farming obtained.

Industrial crossbreeding on farms is organized on separate farms, in herds separated from the breeding material. At the same time, good feeding and housing conditions are created and careful zootechnical records are maintained. Crossbreeds obtained through industrial crossbreeding are not usually used for breeding purposes.

A type of industrial crossing includes variable (rotational) crossing , in which the queens of the original (then cross-bred) group are mated alternately with sires of two or more breeds. As a result of rotational crossing, the effect of heterosis is continuously maintained, which ensures efficient use crossbreeds for the production of milk, meat, eggs and other livestock products. Variable crossbreeding is especially effective in pig farming, beef cattle breeding and poultry farming.

Organizing rotational crossing is more difficult than industrial crossing, but its economic effect is higher.

Sometimes the use of variable crossbreeding results in the development of a new breed.

In particular, in France, crossbreds of English riding and Norman draft horses were crossed alternately with English and Norman stallions. At a certain stage, we switched to breeding crossbreeds “on our own.” As a result, the work culminated in the development of the Anglo-Norman breed of horses.

When choosing breeds for crossing and determining the degree of use of each of them, they proceed from the goals set. The selection of breeds and the sequence of their crossing must be previously studied in an experiment. When two breeds of animals are used for mating, alternating crossing is called simple, and three or more breeds are called complex. First-generation crossbreeds obtained as a result of two-breed crossing are mated with sires of one of the original breeds, second-generation crossbreeds are mated with sires of another original breed; in the next generation, backcrossing is carried out, etc.

In three-breed alternating crossing, crossbred queens obtained as a result of mating animals of two breeds (AxB) are covered with sires of a third breed (C). Their descendants are mated with sires of breed A, the descendants of the next generation with sires of breed B, and the individuals obtained from them are mated with sires of breed C, etc. In the case of four breeds, the crossbred breeding stock is alternately mated with sires of each of the four breeds.

The use of rotational crossbreeding of several breeds makes it possible to obtain a combinative combination of traits in crossbred animals.

Hybridization

Hybridization is the crossing of animals belonging to different species. The resulting offspring are called hybrids. Hybridization as a breeding method also includes crossing hybrids with hybrids of different and identical origins. The main task of this very difficult method of crossing is to involve new valuable wild and semi-wild forms of animals into human material culture. Depending on the ability or inability of hybrids to produce offspring, a distinction is made between hybridization, which is widespread and produces useful animals (for example, in the past, mules), and hybridization, which is used to create new breeds and species of animals. In this regard, four types of animal hybridization are distinguished: industrial, absorptive, introductory and reproductive. The most widespread are industrial (user) hybridization and reproductive, or breed-forming.

It should be noted that wild fauna (a huge natural wealth) is unreasonably, and sometimes predatorily, exterminated. Over the past 50 years alone, more than 40 species of animals have been destroyed. Species such as zebra quags in Africa, American bison, tur, tarpan, Arctic penguins, gigantic wingless geese, dodos - fat large island birds, moa ostriches, whose mass was 300 kg, height 4 m, became extinct or exterminated. To prevent the extinction of wild animals, special measures are being taken to protect nature. In 1948, the International Union for Conservation of Nature was created. In the USSR, in 1978, a special USSR Law on Nature Protection was published. Our country is home to more than 350 species of animals and 650 species of birds. Among the many reserves of the country there are such large scientific centers as Askania-Nova, Astrakhan, Belovezhskaya Pushcha, Lapland, Caucasus, Issyk-Kul, etc. They do a lot of work on the hybridization of animals and the conservation of valuable species of wild fauna.

When hybridizing animals, they face great difficulties. The main ones are the following:

1) non-crossing of species among themselves;

2) partial or complete sterility of hybrids.

The main reasons for the uncrossability of distant species and the infertility of hybrids are genetic factors: a different set and structure of chromosomes in gametes, their inability to form a viable zygote, sperm, due to its morphological and biochemical characteristics, is not able to lyse the shell of a foreign egg and penetrate it. If a hybrid zygote is formed, then due to embryonic pathology either the fetus is reabsorbed early stages formation, or its death. This is explained by the fact that the body’s immune defense bodies fight the penetrating foreign protein, destroying it. Due to genetic differences between the parents of hybrids, the process of formation of male and female reproductive cells is disrupted and they become infertile. The sterility of hybrids is caused by abnormalities in gonadal development and mitosis.

The rapid development of cytogenetics these days has made it possible to study in more detail the cytogenetic causes of infertility in hybrids. They can be divided into three groups:

a) discrepancy in the number of chromosomes in the karyotype;

b) morphological structural differences in the structure of chromosomes;

c) a change in gene composition that does not affect the behavior of chromosomes or their morphology.

Currently, scientists have developed a number of methods to overcome the uncrossability of individual species. These include: blood transfusion of animals of one species to another, mixing of sperm of individuals different types, the use of reciprocal (back) crossing, hormonal drugs, the use of special sperm diluents, gonad transplantation, creating the necessary conditions for obtaining and raising offspring. Experiments have shown that young females more often give rise to hybrid offspring: a greater ability for hybridization and the birth of fertile offspring is observed in those individuals who themselves were obtained as a result of crossing.

It has been established that in cases where there are sexual differences in the manifestation of sterility or viability of hybrids, they appear more often in the heterogametic sex of hybrid males (y) than in the homogametic female (xx) sex. Obviously, this phenomenon is affected by cytoplasmic heredity and the maternal effect in the inheritance of traits, which can be used when selecting pairs for crossing, taking into account the sex of the parents (reciprocal selection). We have indicated only the basic methods and means of overcoming the uncrossability of distant species and the infertility of hybrids. The rapid development of genetics, molecular biology, biotechnology, genetic and cellular engineering today will apparently make it possible in the near future to completely solve the problem of infertility during distant hybridization of animals.

The most promising methods for solving this problem can be considered genetic and cellular engineering, hybridization of somatic cells (ultrahybridization), experimental polyploidy, etc. By hybridization of somatic cells in tissue culture, it was possible to transplant embryonic somatic cells of cattle and northern mink. Cell hybridization is practically done like this: unrelated cells of two organisms, the beneficial qualities of which it is desirable to combine during crossing, are cultivated on an artificial nutrient medium, then the culture is mixed. Under certain conditions, some cells merge. The process of formation of hybrid systems from cells is still chaotic. However, as this method is improved, it should be expected that somatic cell hybridization in tissue culture will be used as an experimental model for interspecies hybridization in animals.

Promising new methods for overcoming infertility during animal hybridization include damage to chromosomes by physical and chemical mutagens, as well as the use of microdoses of biologically active compounds of supermutagens. Biotechnology methods, production of transgenic animals, chimeras, and cloning of the genotype of valuable animals are of particular importance.

The most ancient form of hybridization is crossing horses With donkey and receiving mule. Also in Ancient Rome mule breeding was widely developed. The mule is an excellent beast of burden; it has no equal in terms of endurance, longevity and performance. It is obtained by crossing a donkey and a horse; when a donkey mates with a stallion, a hinny will be born. A mule is larger and more valuable than a horse, but is usually sterile. Breeding these animals “inside” is impossible.

In our country, in Askania-Nova, great work In the distant future, the hybridization of horses with zebras and the production of strong, hardy zebroids, as well as the crossing of a domestic horse and its wild ancestor- Przewalski's horses. The males from such crossings are sterile, and the females are fertile. According to E.P. Steklenev, these species have differences in the karyotype (the number of chromosomes in the domestic horse is 64, in the Przewalski horse 66), as well as features of gametogenesis. In hybrid infertile males, despite the completion of gametogenesis, there is a difference in the size of germ cells, their degeneration, rejection at different stages of formation, as well as asymmetry in the location of the testes, their underdevelopment. In hybrid females aged from one to 10 years, generative processes, sexual cyclicity, conception and fetal development occur normally.

Hybridization is also used to create new breeds of farm animals. Many farms have studied such issues as the selection and selection of pairs, the biological characteristics of zebu cattle, its adaptability to local conditions, etc. It has been established that hybrids are resistant to piroplasmosis, inherit increased fat and milk content and protein content from zebu, and are responsive to improved feeding and housing conditions , pay well for food, have excellent meat qualities. The meat contains an increased amount of fat and protein, the slaughter yield reaches 60%. Diseases of the udder, gastrointestinal tract, and hooves are less common. Important It also has the fact that hybrids obtained by crossing cattle with zebu are fertile.

Due to the concentration and intensification of livestock farming in all climatic zones In the USSR, hybridization of factory breed cattle with zebu makes it possible to create dairy and beef cattle breeds that meet the requirements of new (industrial) industry technology. The work carried out at the Snigiri scientific and experimental farm is of great interest. Here the zebu was crossed with black-and-white cattle, which made it possible to obtain highly productive hybrids with a milk yield of 3997 kg and a milk fat content of 4.27%. In the Central Asian republics there are breed groups developed by crossing zebu with Swiss and East Frisian cattle. The milk yield of such hybrids is 10-15%, and the fat content of milk is 20-25% higher than that of purebred animals.

The work on hybridization of cattle with banteng carried out in Askania-Nova is of great interest. Hybrids from crossing banteng with red steppe cattle are characterized by excellent meat qualities and pronounced heterosis. The milk yield of hybrid cows was 1500-2200 kg, milk fat content was 6.1%. Rich material has been accumulated in the works of A.E. Mokeev and P.N. Buynaya on three-breed crossing (Santa Gertrude x Webu x Red Steppe breed; Shorthorn Zebu x Red Steppe breed). Availability
Zebu blood in both crossing options gave excellent results. A new type of beef cattle has been created.

The hybridization of yak with Simmental cattle in the high mountainous regions of Altai and the Kirghiz SSR is of great economic importance. Hybrids of yak with Simmental cattle are distinguished by good milk production, high milk fat content (5.5-7), and adaptability to breeding on high alpine pastures. Thanks to these hybrid forms, cattle breeding is becoming widespread in the mountainous regions of the country.

Bison are also used for hybridization, of which there are only a few hundred in the world. Now the bison population is recovering. Hybrids of cattle and bison are of significant economic interest. As a result of 15 years of work, cattle breeder D. Bissolo from California managed to cross Charolais and Hereford cows with wild American bison. The new breed group was called beefalo. The hybrid offspring, which has 3/8 of wild bison blood, 3/8 of Charolais and 3/4 of Hereford blood, is characterized by high precocity (at 10 months of age it weighs 400 kg) and well-developed meat forms. Laboratory research data have shown that the meat of such hybrids contains 18-20 proteins and only 7 fats. The main type of food for hybrid beefalo animals, as D. Bissolo reports, is pasture grass. They are hardy and highly resistant to many diseases common in hot climates.

Hybrids have also been obtained from crossing cattle with gayals and African Watusi cattle. A very promising species for distant hybridization is the African eland. This is very close-up view antelopes: males weigh 700 kg, females - 540-500 kg. Females milk well, milk yield per lactation does not exceed 700 kg, but the fat content of milk reaches 10-14. Canna antelope milk has healing and bactericidal properties. Curdled milk from this milk does not spoil under normal conditions for many years. Methods have now been developed for obtaining sperm from eland males onto the vagina, and artificial insemination of cows is being carried out in order to obtain hybrid forms.

Much work is being done in Askania-Nova and in a number of other reserves in the country to create new breeds of deer. As a result of long-term complex intraspecific hybridization, the Ascanian deer breed was developed. European deer, Crimean and Caucasian deer and wapiti (steppe, the largest deer) took part in its creation. Much has already been done to domesticate antler deer and elk.

M. F. Ivanov developed and was the first to apply the method of distant hybridization in creating fine-wool sheep breeds. By crossing a wild mouflon ram with a fine-wool sheep, he got a new breed of fine-wool sheep - mountain merino. Animals of this breed inherited from the wild mouflon the ability to move quickly, covering long distances, to live in high mountains, to use alpine pastures, and from the Ramboulier - the valuable productive qualities of fine-wool sheep. Using the method of distant hybridization in the mountains of Kazakhstan, Soviet scientists bred the fine-wool breed Archaromerinos.

Of great scientific and practical interest are the works of N. Gigineishvili on the breeding of gray Karakul sheep by hybridization with wild and mountain sheep, on the hybridization of sheep and goats, rabbits and hares, llamas and camels.

Distant hybridization has become widespread in poultry farming; 96 species of birds belonging to 13 orders have produced fertile offspring. Of greatest interest are hybrids of common pheasant with wild Caucasian pheasant (Ascanian pheasant), hybrids of domestic duck with musk ducks (mulards), chicken and peacock, guinea fowl and pheasant, turkey and guinea fowl and many others, which have excellent fattening qualities. Work on remote hybridization of birds is being successfully carried out both in the Astrakhan Nature Reserve and in other scientific institutions of the country.

An important direction in increasing the genetic potential of pigs when transferring the industry to industrial technology is remote hybridization, the use of the gene pool of wild forms. Currently, only the use of hybrids can ensure accelerated growth in the productivity of industrial pig breeding. Taking this situation into account, 19 hybrid pig breeding centers are being created in the country. Hybridization ensures the manifestation of the heterotic effect.

With the intensification of pig production, a new direction in hybridization has emerged. The scientific basis for hybridization in pig breeding is based on the relatively independent inheritance of reproductive, fattening and meat qualities in pigs. This makes it possible to create specialized paternal and maternal forms that are successfully used in parent and grandparent herds for crossing.

In most countries of the world, in order to intensify pig production and create new highly productive types and breeds, long-term programs for hybridization in pig breeding have been developed and are being implemented.

Heterosis and its importance in animal husbandry

Heterosis (from the Greek heteroiosis - change, transformation). Heterosis is understood as the superiority of the first generation offspring over the parental forms in viability, endurance, growth energy, fertility, constitutional strength, resistance to diseases, which occurs when crossing different races, animal breeds, and zonal types.

The term “heterosis” was introduced by G. Schell (1914), who explained the presence of “hybrid vigor” by the state of heterozygosity in the genotype of an organism, formed as a result of crossing. The heterosis hypothesis, formulated by G. Schell, E. East, H. Hayes, explains the phenomenon of heterosis by the presence of heterozygosity of various loci and the resulting overdomaining, that is, when the effect of heterozygote Aa on the manifestation of the phenotype is stronger than the homozygous dominant genotype AA (that is effect of Aa more action AA).

Another explanation of heterosis, formulated by Kijbl and Pellew (1910), is based on the fact that when crossing organisms carrying different homozygous genes in the genotype, for example AAbb and aaBB, in the crossbred offspring, recessive alleles pass into the heterozygous form of the AaBB genotype, in which the harmful effect is eliminated recessive genes. The influence of dominant genes on the manifestation of heterosis can be explained by the simple cumulative effect of a large number of dominant genes, that is, there is an additive effect.

A. Schell and O. East proposed a hypothesis of overdominance, which is close to the hypothesis of obligate heterozygosity put forward by D.A. Kislovsky. Its essence lies in the fact that high heterozygosity provides diversity and enhancement of the physiological functions of the body better than homozygosity. H.F. Based on a large number of experiments, Kushner identified five forms of manifestation of heterosis used in animal husbandry:

• hybrids (or crosses of the first generation exceed their parents in live weight and viability;
• crossbreeds of the first generation are superior to their parents in constitutional strength, longevity, physical performance with complete or partial loss of fertility;
• crossbreeds of the first generation occupy an intermediate position in live weight and are noticeably superior to their parents in terms of fertility and viability;
• each individual trait behaves according to an intermediate type
  inheritance, and in relation to final products there is an increased
  heterosis;
• crosses, or hybrids, do not exceed the best parental form in productivity, but have a higher level compared to the arithmetic average of both parents.

A classic example of heterosis is the mule, a hybrid between a donkey and a horse. These are strong, hardy animals that can be used in much more difficult conditions than their parent forms.

Modern ideas about the causes of heterosis are based on the fact that heterosis is the result of the interaction of many genes. Their multiple actions lead to the heterosis effect. This explanation is called balance heterosis. Subsequently, Lerner and Turbin continued to develop this position.

According to them, heterosis is caused by the action of many genes, mutually balanced in the genome during the process of evolution, which determines the optimal development and adaptability of the organism to environmental conditions.

If, during crossing, the optimal genomes of both parents are combined, then the descendants of the first generation have the most favorable situation in the combination of genomes, which leads to the appearance of heterosis. Consequently, the heterozygosity that accompanies crossing undergoes pressure from various factors and thereby creates a balanced interaction of genes in the genome.

In the practice of animal husbandry, so-called negative heterosis is sometimes observed, when the offspring have a level of a trait below the average of the parents, but is slightly higher than the level of the trait of the parent in whom it is less developed. The higher the differences in the trait level of the parental forms, the more the average trait level of the descendants approaches the trait level of the worst parent. This feature of inheritance was described by Ya.L. Glembotsky in relation to the cutting of wool in crosses obtained from crossing Angora goats with coarse-haired goats. The wool shearing of the first generation crossbreeds was somewhat greater than that of Angora goats, in which it was 4-5 times greater compared to coarse-haired and local goats.

Modern livestock farming is characterized by the use of crossbreeding, accompanied by a heterotic effect, especially for egg and broiler poultry farming. This system includes two main stages: breeding imbrid poultry lines using different types inbreeding and crossing (crossing) lines to obtain a so-called hybrid bird that exhibits heterosis. For example, in the Netherlands, the Eurybrid company works with two crosses of egg-laying chickens: “Hisex White” (white shell based on Leghorns) and “Hisex Brown” (with the participation of Rhode Island and Newhamshire with a brown shell. These two crosses occupy a leading position in the global poultry egg industry.

Work on creating hybrid egg and meat poultry is being carried out in our country. To carry out selection for heterosis, imbred lines are bred by mating according to the “brother x sister” type for 3-4 generations or more, combining this with strict culling of unwanted individuals. Of the larger number of established lines, about 10-15% of lines remain by the end, with an inbreeding coefficient on average of 37.5% (mating of full sibs for three generations). Next, the remaining lines are crossed with each other to check their compatibility, then the most successful combinations are left for production crossing and 2-, 3-, 4-line hybrids are obtained.

The use of the heterosis effect is also used in working with other types of animals, especially in beef cattle breeding, sheep farming, camel farming, and fish farming. Methods for obtaining the effect of heterosis are varied. Heterosis manifests itself during interspecific crossing of animals: obtaining mules from crossing a donkey with a mare, breeding new heterotic breeds by obtaining hybrids from crossing cattle with zebu (Santa Gertrude, Beefmaster, Charbray, Bridford in the USA; Sao Paulo - Brazil, Hauphamitin - in Jamaica). In our country, distant hybridization was carried out between fine-wool sheep and argali and a new breed was developed - arharomerinos. In Kyrgyzstan and Altai, hybrids of yak and Simmental cattle were obtained. Heterosis during interbreeding. In the zootechnical literature, there are most examples of the appearance of heterosis in animals of different species when interbreeding is not used.

In beef cattle breeding, when crossing some breeds, crossbreeds of the first generation are superior to the original breeds in terms of fattening quality in live weight at different age periods.

In dairy cattle breeding, heterosis in terms of milk yield and fat content in milk during interbreeding is rarely observed. Data on heterosis based on milk yield are given by N.F. Rostov residents from the experience of crossing Ostofriesian cows with bulls of the Red Gorbatov breed. In dairy cattle, the effect of heterosis is observed more often total number milk fat during lactation, especially when crossing cows of different breeds with bulls of the Dzherei breed.

In pig breeding, industrial interbreeding is used more widely. Scientific institutions in our country have experimentally tested more than 100 variants of industrial crossing of pigs. In many cases, the effect of heterosis has been established. It was mainly manifested in increasing fertility, viability of the offspring, and improving its fattening qualities. In the experiments of M.A. The crossbreeds from crossing queens of the Large White breed with Berkshire boars consumed 0.5 -1 feed per 1 kg of live weight gain. units less than the original purebred animals.

According to M.A. Zhabali crosses (Landrace x Large Black) consumed 4.1 feed units per 1 kg of growth, while purebred Landrace and Large Black pigs consumed 4.2 and 5.08 feed units, respectively. units In the experiments of I.E. Zhirnov's crosses from crossing large white and Estonian pigs gave 600 g of average daily live weight gain when fed, and the original breeds - 548 and 560 g, respectively. According to V.O. Chetyrkin, higher gains and better feed costs compared to the original breeds The crossbreeds differed from the crossing of large white breed dams and boars of the Moldavian black breed group. The average daily gain in live weight was 598 g, feed costs per 1 kg of gain were 4.0 core units, and for their purebred peers, these figures were respectively equal in the group of large white pigs 465 g and 4.4% in the group Moldovans - 394 and 4.3%.

In addition to egg production, when interbreeding chickens, heterosis is expressed in increased embryonic and post-embryonic viability, growth energy, improved meat qualities and feed costs.

To obtain heterosis during interbreeding, the correct selection of paternal and maternal breeds, as well as the choice of breed representatives, is of great importance. In poultry farming, as N.F. points out. Rostovtsy, where there is a rapid change of generations and there is a great possibility of selection, methods have been developed for the directed formation of heredity of the original crossed forms, ensuring the appearance of heterosis in their crossbred offspring.

Heterosis using heterogeneous selection during intrabreed mating. The use of cross lines, lines of sires and families in purebred breeding, as well as the mating of animals belonging to the same breed but raised in different conditions, are also variants of heterogeneous selection. Heterosis using heterogeneous selection during intrabreed mating, in which the mated animals are in the same household, do not have an obvious linear affiliation or belong to the same related group and therefore are related to each other to one degree or another. Such heterogeneity is most often expressed in the difference between mated individuals only in certain characteristics, in particular in exterior and constitutional features.

The problem of obtaining and enhancing the effect of heterosis has not been fully resolved. The main unknown obstacle is the loss of the heterotic effect in the second generation, that is, the heterosis obtained in the first generation is not fixed, but is lost in subsequent generations when breeding crosses “in itself.” Some methods allow heterosis to be maintained over several generations. One of the most accessible and effective methods is variable crossing, used in commercial livestock farming. At the same time, from the first generation crosses obtained from crossing queens of breed A with sires of breed B, the best part of the queens is isolated and crossed with a sire of breed C, a cross of the second generation is obtained, with the manifestation of heterosis when three breeds are combined (A, B, C) Next crosses of the second generation can be crossed with the sire of breed D and obtain more complex crosses in which the heredity of the original maternal breed A and the heredity of the paternal breeds B, C and D are represented. No other methods have been developed in animal husbandry to preserve the effect of heterosis.

In the practice of modern animal husbandry, it has been proven that the effect of heterosis is diverse and is expressed in the improvement of valuable economic traits. The main indicators of heterosis are an increase in embryonic and post-embryonic viability, a decrease in feed costs per unit of production; increasing early maturity, fertility, productivity; manifestation of greater opportunities for adaptation to changing conditions and new elements of technology. The wide range of heterotic effect, manifested in a variety of reacting characteristics, is a reflection of physiological and biochemical processes caused by the peculiarities of the genetic apparatus of heterotic animals.

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MINISTRY OF AGRICULTURE

RUSSIAN FEDERATION

DEPARTMENT OF SCIENTIFIC AND TECHNOLOGICAL POLICY AND EDUCATION

Federal state budget educational institution higher professional education

ST. PETERSBURG STATE

ACADEMY OF VETERINARY MEDICINE

Department of Genetics and Animal Husbandry

ABSTRACT ON THE TOPIC:

"Interspecific hybridization"

Completed by: 2nd year student, 5th group

FVM full-time training

Fadeeva Anna Vitalievna

Introduction

Hybridization is the crossing of organisms that differ in heredity, i.e. one or a large number pairs of alleles (gene states), and, consequently, one or more pairs of traits and properties. The crossing of individuals belonging to different species or even less related taxonomic categories is called distant hybridization. Hybridization is also divided into natural and artificial. Natural things have been observed for a long time; for example, mules existed already two thousand years BC. e. The artificial production of hybrids was first proposed by the German scientist R. Camerarius (1694), and the first artificial hybridization was carried out by the English gardener T. Fairchild, who crossed different types of carnations in 1717. Koelreuther is considered the founder of the doctrine of hybridization in plants; he obtained hybrids of two types of tobacco (1760). Gregor Mendel laid the scientific foundations of genetics through his experiments in hybridizing peas. Charles Darwin also conducted a huge number of experiments on hybridization.

Hybridization itself involves the fusion of genotypically different germ cells during fertilization and the development of a new organism from the zygote, which combines the hereditary inclinations of the parents. The first generation of hybrids is characterized by heterosis, which is expressed in better adaptability, greater fertility and viability of individuals.

Intraspecific hybridization in livestock farming serves as a method of industrial breeding, in which individuals of different breeds and lines are mated. Distant hybridization in animals - obtaining hybrids between varieties, species and genera (fine-wool sheep and argali; cattle and zebu) is carried out with difficulty and their hybrids are, as a rule, infertile. Industrial crossing pursues the goal of obtaining custom animals, i.e. such as can be used in their own right by their work, but they cannot serve for breeding purposes. Example: in Moravia, pointers were mated with German pointers; their goal was to obtain dogs that were balanced in temperament and suitable for working in local conditions.

1. Interbreed hybridization

hybridization genetic intraspecific

Interbreeding of dogs, the offspring of which, in contrast to hybrid ones, are called crossbred or mestizo. Crossbreeds easily interbreed and produce offspring. Depending on the goal, different crossing methods are used. As a result of crossing, the heterozygosity of the resulting animals sharply increases, which often leads to heterosis, i.e. the powerful development of crossbreds, which sometimes have superiority over the best of the original breeds. The formation of the heredity of crossbreeds is influenced not only by the characteristics inherent in the breeds, but also by the characteristics characteristic of individuals, lines and offspring. Producers who produce good offspring when purebred are usually good when crossed. In crossbreeds, heterosis disappears from crossbreeds, characteristics split, the appearance of undesirable qualities is observed, and the correlations that have developed in the original breeds are broken. Interbreeding most often occurs because the breeder is trying to improve a certain breed of working or hunting dog, adding endurance, sensitivity, etc. Let's consider interbreeding using the example of huskies. Interbreeding of huskies is often observed in areas where these dogs are used for their intended purpose and where the culture of dog breeding is low. There are frequent cases of mating of huskies of different breeds in those areas where there is a system of pedigree records. And very often, documents of origin are issued for crossbreeds. There are known cases of Russian-European huskies mating with West Siberian ones (the puppies were black and white in color) and in the pedigrees they were considered Russian-European huskies. Growing up, such crosses often have good shape. In the first generation, they are often very good workers, so hunters mate their huskies with huskies of other breeds. However, indiscriminate crossing does not bring anything good (especially if these dogs are also given pedigrees). And, of course, this has nothing in common with those methods of interbreeding, which, depending on specific conditions, can not only be justified, but also necessary in selection and breeding work. In reproductive (factory) crossing, an attempt is made to create a new breed from two or more breeds. When breeding huskies, reproductive crossing is not used. Although the Russian-European Laika was, to a certain extent, bred by reproductive crossbreeding. For this purpose, sires of two breeds were used, and their descendants were bred in “themselves”. Reproductive crossing itself is one of the most complex types of crossing. From the point of view of the genotype, it is not difficult to indicate the way to work with this crossing, but from a purely livestock point of view, various problems and difficulties in crossing arise here. Reproductive crossing can be divided into two types, although this division is purely formal. The first type is a simple crossing, which consists in the fact that no more than two breeds are involved in the creation of a new genotype. The second type is precisely a complex crossing, i.e. More than two breeds are the original breeds, and a certain sequence is used when crossing. But for more accurate reproduction, we need to keep in mind what we want to get in the end and therefore we must outline a genetic plan for working with these breeds.

Absorption crossbreeding is a crossbreeding method that is used very widely and its essence is that an inferior breed is improved by using another, better breed for this purpose. Absorptive crossbreeding, carried out over a number of generations, can ultimately produce such a large modification in the phenotype and genotype of a given group of animals that they practically come close to the given improved group. The breed to be improved is called improved, and the one with the help of which improvement is carried out is called improving. The method of absorption crossing is very often and in a primitive form used by hunters to improve their different types of huskies. The essence of this method is that crosses obtained from the mating of local dogs and good imported pedigree sires are again mated with pedigree sires until the crossbreeds, in their external shape and working qualities, approach those of the improving breed. It turns out that the improving breed, as it were, absorbs the being improved. For convenience and general characteristics The breeds of local offspring, albeit conditionally, began to be divided: 1/2 - half-breeds; 3/4 - blood; 7/8 - blood and 15/16 blood. The absorption crossbreeding method itself requires a certain planning of breeding work, strict rejection of crosses of undesirable types, very careful selection and selection of sires, both from the improving breed and among crosses.

Introductory crossing is often called the infusion of a “drop of blood”. This crossing is used in cases where you are generally satisfied with the existing breed and you would like to preserve its basic qualities, but it needs to correct some shortcomings, as well as to strengthen its valuable properties. This can be achieved by choosing an improving breed, which in character, working qualities and body type is close to the one being improved, but is distinguished by well-defined characteristics that are poorly developed in the improved breed. In order not to change the type of the breed being improved, it is necessary to limit oneself to obtaining crosses of the first generation, which are then mated with the sires of the main breed being improved. Introductory crossbreeding is a slight deviation from purebred breeding, in which there is a kind of “influx of fresh blood” into the improving breed. In selection and breeding work with Karelian-Finnish huskies, introductory crossing was necessary: ​​the breed as a whole suited hunters, but due to systematic inbreeding it had some disadvantages. To improve the Karelian-Finnish Laika, there was a Finnish Laika, which was very similar both in type and in working qualities. The blood of Finnish huskies was carefully added to the Karelian-Finnish husky, and the resulting crossbreeds were crossed with Karelian-Finnish ones. In other places, mainly absorption crossbreeding was carried out, during which the Korelo-Finnish husky disappeared and was replaced by the Finnish one.

Nowadays, another crossbreed has appeared. This is a fashion fad, and dogs obtained from two completely unsuitable breeds are called designer. The first to cross a poodle with a labrador. The result was a shaggy dog ​​with wavy hair and long tail, extremely kind and playful. Another big plus of this breed is that the Labrapoodle’s fur does not cause allergies. Designer breeds are gaining popularity and people can order whatever they want (a smooth-haired lapdog or a shaggy Doberman). It is often not possible to determine what breed the parents of these dogs were. Let's take a couple more examples of experimental breeders. In America, a newfangled dog breed called “PUGGLE” is gaining momentum. The result of crossing two very popular dog breeds: the bulldog and the beagle. The result was a miniature, unpretentious dog with a typical bulldog face, expressive eyes characteristic of beagles and huge flapping ears. Puggle fur is hypoallergenic. The idea of ​​breeding a new type of dog originated in America 7 years ago. As David Barber (co-developer of the breed and owner of Dog Paradise in Brooklyn) says, it's like crossing a Versace bag with a training bag. You get the best of both breeds in one package. In Japan, as a counterbalance to the puggle, a poodle and a Maltese were crossed, and the new breed was called the “panda dog.” The puppies' fur is dyed to look like a panda with a special coat dye. The idea to paint the dog this way arose because the tear tracks near the eyes were very visible on the white fur, so Panda Dog’s owners decided to hide the imperfections and give the dog a spectacular look. The paint lasts for several months, and then the dog needs to be repainted. These mestizos are gaining popularity. Hollywood stars buy them, paying a lot of money for them. I would call this “trade-commercial crossing for one day.” These breeds are needed while there is a demand for them, and until some breeder brings out a prettier dog and they forget about the old ones. A lot of people don't approve of the idea of ​​genetically designing dogs. “Modified dogs will never have the same characteristics as purebreds,” said Lisa Peterson of the American Kennel Club. We are forced to seriously warn buyers who impose on their clients a unique combination of the best qualities of both of its prototypes in a new design.”

Interline crossing. Interline crossing can also be classified as hybridization. But to understand this, you must first understand what a pure line or purebred breeding is. Reproduction of many breeds is carried out almost exclusively by pure breeding. This method involves pairing dogs belonging to the same breed. The pure breeding method makes it possible to obtain offspring similar to their parents in appearance, working qualities, hereditary and breeding values. With purebred breeding, genotypic properties become more stable, which increases the likelihood of producing offspring with desirable qualities. The most important thing with pure breeding is preserving the valuable properties of the breed for its further improvement. Improvement of the breed can continue for a long time, because... Absolute homogeneity of rocks does not exist. A pure line is usually maintained through consanguineous mating (inbreeding). In inbreeding, individuals that are related to one degree or another mate. Highest form purebred breeding - breeding along lines - is impossible without the use of inbreeding. Inbreeding can have both positive and negative effects. Using inbreeding, we concentrate hereditary inclinations and obtain dogs that are homozygous for a number of traits - this allows us to quickly consolidate valuable properties in the breed and create a homogeneous population. At the same time, related breeding contributes to the depletion of the genotype, a decrease in fertility and productivity, the appearance of deformities, and a decrease in resistance to disease. But inbreeding affects different dogs differently. ON THE. Iln and I.F. Antipin cites facts where, for a number of generations, closely related breeding of dogs was carried out and no negative phenomena were noted. And in modern dog breeding practice there are many undesirable consequences of close inbreeding. Line breeding involves the creation within a breed of a hereditarily stable group of pedigree dogs descended from outstanding sires and possessing valuable qualities similar to them. The line is part of the breed, so it is similar to it and at the same time different from it. Qualitative originality lies in the type inherent only to this line, which may differ from the type of breed. In dogs, this can be expressed in exterior features (color, head shape, etc.), special working qualities, etc. The outstanding sire from which the line originated is called the ancestor or founder, and the line is often called his nickname. The creation and maintenance of breeding lines is not only the production of a group of valuable animals, but, first of all, a system of zootechnical work in which descendants are obtained from outstanding producers who are similar to each other in a number of generations, both in phenotype and genotype. It is also important to remember that at all stages of working with a line, the decisive role is played not so much by related matings as by selection and selection. Thanks to an outstanding manufacturer, a line is created, but it is still not durable and persists for two or three generations. The preservation and isolation of qualitative differences is greatly influenced by their branching and merging with other valuable lines, as a result of which new lines can arise. This merging of lines and their branching can also be attributed to one of the types of hybridization.

Interspecific crossing. Interspecific crossing refers to the crossing of individuals belonging to different species of animals. Animals of different species often have difficulty mating with each other - this is caused by many factors: 1) differences in the structure of the genital organs in different species; 2) the absence of a sexual reflex in a male towards a female of another species; 3) death of sperm in the genital tract of females of another species; 4) the lack of reaction of sperm to the egg of females of another species, making fertilization impossible; 5) death of the zygote; 6) impaired fetal development; 7) complete or partial infertility of hybrids, etc. When using artificial insemination, the first two factors are excluded, and as for the non-crossbreeding of different species caused by other reasons, only isolated experiments are known that are not fully tested and have methodological errors. With complete infertility, both sexes of hybrids do not produce offspring, with partial infertility, one sex is infertile in one of the original species, which often leads to the loss of valuable features of hybrids. Hybrid offspring often develop heterosis (increased life force ), which is more pronounced than in crossbreeds. The most ancient in the practice of animal husbandry are the hybrids of a horse with a donkey and a mare with a male - a donkey (mule, hinny), a horse with a zebra (zebroid), a one-humped camel with a two-humped camel (nar), a yak and a zebu with cattle. Hybrids, as a rule, are superior to their parents in many respects: performance, endurance, productivity, etc. Dogs are also crossed with wolves (wolfdog) and jackals (Srbaka Sulimova). The German scientist Gilzheimer obtained a triple hybrid: wolf - jackal - dog. And what’s interesting is that a fox and a dog don’t give birth to offspring. N.I. Ilyin in his book “Genetics and Dog Breeding” states that the described “fox-dogs” are the product of an error or delusion; even artificial insemination between a fox and a dog remains without consequences. And we can dwell on wolf dogs in more detail, since work in this direction has been going on for a very long time. The creation of dog-wolf hybrids has its roots in the distant past. The Roman historian Pliny the Elder wrote that the Gauls tied their female dogs in the forests so that they could mate with wolves. Charles Darwin, citing many researchers, wrote that the North American Indians, in order to improve the breed of their dogs, crossed them with wolves. Professor S.A. Gruner argued that the peoples of North-Eastern Siberia and Kamchatka deliberately infused wolf blood into their huskies. The resulting hybrids were valued for their agility, endurance, ability to endure hunger for a long time and run long distances, which is important for these peoples. The wolf acted to a greater extent as an improver of sled dogs, although there are many examples of improving the hunting qualities of dogs. L.A. Sabaneev, in the notes to the second chapter of his work dedicated to the wolf, writes: “In Lithuania, the admixture of wolf blood produces excellent (hound) dogs. This circumstance was well known to ancient canine hunters, and it has been used to this day. Thus, according to legend, the Timashev greyhounds in the Ufa province are famous for their viciousness; they descended from a hybrid of greyhounds and wolves. Recently, the wolf breed of dogs was bred by the famous Tver hunter P.I. Belovensky.” This information is very interesting. But there is a problem. On the one hand, crossing a dog with a wolf to get a hybrid with a more valuable property is not difficult for an experienced dog breeder. But on the other hand, such hybridization is not a very common occurrence. Let's try to understand this in more detail. Careful studies of wolf-dog hybrids conducted by German scientists indicate that in the first generation hybrids the behavioral traits of the wolf are clearly dominant: they are all timid, cautious and fearful. The second generation hybrids were distinguished by great diversity in external characteristics. Some of them looked like a wolf, and some like a dog. But almost everyone was characterized by timidity. Based on the results of crossing a dog with a wolf, German scientists deny the possibility of improving the qualities of dogs, stating: “Crossing a dog with a wolf does not give the desired results. The wolf is a timid, extremely cautious and distrustful animal. And this property, being dominant, when crossed with a dog, is firmly transmitted to the offspring.” But at the same time, Professor N.A. Ilyin wrote that wolf-dog hybrids of the first and second generation can be trained like ordinary dogs. Voilochnikov A.T. came to a similar conclusion as German scientists. and Voilochnikov S.D., who conducted the hybridological experiment at the Kirov VNIIOZ. And at the Perm Military Institute of the Ministry of Internal Affairs of Russia, an experiment was carried out in breeding wolf-dog hybrids. The experience was successful. Hybrids were prepared for mine-hunting service, on the border, etc. At this institute, for the first time in world practice, contrary to all previous experience, first-generation wolf-dog hybrids were obtained that do not show pathological fearfulness, including towards humans, and this does not depend on their cultivation and upbringing. And this proves that wolves actually have both genes that determine fearfulness towards humans, and genes that determine loyalty towards him. They acquired a two-year-old she-wolf, who was mated to a male German Shepherd at the age of three. At the next heat she was mated to the same male. The third heat was not mated. Fourth heat - was mated to a male from her second litter. Fifth heat - re-mating with a male from her second litter, but there was an empty nest that ended in a false pregnancy. It is also important to note that the first two litters of hybrids had 50% wolf blood, and the fourth - 75%. Having analyzed the result obtained, paying special attention to the behavioral sign - loyalty, tolerance towards a person, we came to certain results. The reaction of hybrids of the first litter to strangers is distrust, keeping a distance, but without panic. All hybrids of this litter are characterized by neophobia. Skis, bicycles, strollers, umbrellas, cameras in the hands cause an avoidance reaction, mainly in individuals with a black color, and what is most interesting is that in two hybrids with a zonal color, neophobia was practically not detected, they were more collected and quickly adapted to the new environment. But there were problems when changing trainers. In the second litter, only one puppy had some self-doubt and timidity. The rest of the hybrids were more relaxed, did not hesitate in a new environment, and were not afraid of strangers. Puppies of the third litter from three to four weeks of age, unlike previous litters, ran up to the enclosure bars very actively and with curiosity when people appeared, but at the age of 7 weeks only one puppy passed the Campbell test, and for the rest, the test result predicted serious problems in socialization. The following conclusions were made: hybrids are very restrained emotionally; have significantly greater physical strength and endurance than dogs; gunshots and explosions are not a problem for them; training is very quickly understood and learned; operant skills are easily developed using clicker training; have a higher sense of smell than a dog (the search for an offender in caches during a search of an object does not exceed one minute, in dogs from one and a half to four minutes, with a standard of six minutes); characterized by rationalism. Hybrids participated in sporting events through the Perm Regional Service Dog Club and took prizes.

Recently, three breeds of service dogs have been developed based on the German Shepherd crossed with a wolf. Saarloos Wolfdog: was bred in the Netherlands by Leendert Saarloos. In 1975, the Dutch club recognized the breed, which in 1981 was registered with the FCI under the name Saarloos Wolfdog (Sarloos Wolfhond). Currently, Sarloos are widely used in Holland as guides for the blind, as well as in the rescue service, for searching for people in rubble and for rescuing drowning people. The second carrier of about 25% of the wolf genotype was bred in Czechoslovakia and was named “Volchak”. The third dog was bred in Italy. All these dogs retained wolf-like behavioral traits that are unusual for dog breeders dealing with ordinary German shepherds. Many dog ​​breeds do not lack the presence of wolf genes in their genotype. Even in the time of A. Brem, Arctic sled dogs resembled local wolves.

In addition to wolves, dogs also interbred with jackals. These hybrids amaze with their strength and keen sense of smell. Wolf-dog hybrids are inferior to the wolf in size and strength, while jackal-dog hybrids, on the contrary, are superior to the jackal in size and strength. Criminologists show particular interest in jackal-dog hybrids. Their sense of smell is so strong that they can distinguish the gender of a person by smell, and they could differentiate male and female scent traces with a half-hour difference. Jackal-dog hybrids also exhibit qualities that are not characteristic of either a jackal or a dog. For example: jackal dogs from the first to the third generation were distinguished by their exceptional climbing ability. However, half-blooded hybrids, when reproducing in “themselves,” with each new generation moved away from the original forms, showing more and more new characteristics that were not present in either jackals or dogs. Some individuals were larger than their parents, while others, on the contrary, were very small. Some, regardless of size, were aggressive and constantly attacked their relatives, displaying the techniques of wolves and jackals in fights, which did not allow them to be used either for work or for reproduction, while others, on the contrary, were so loyal to their partners and people that with them There was no problem with anything. Thus, we can draw a conclusion from all of the above. It is possible to use wolf and jackal with a dog in hybridization, but it is better to use them as dog breed improvers. Since this is a very labor-intensive work, it should be carried out by research centers and institutions designed for such work. After all, breeding hybrids is a complex matter that requires appropriate conditions and a long time.

Interspecific animal hybrids are usually unable to produce offspring, since the process of formation of germ cells is disrupted. But they themselves, in addition to their unusual appearance, sometimes exhibit qualities superior to their parent species (larger, more hardy, etc.). This phenomenon is called heterosis.

Bazzle is a hybrid of a ram and a goat. In 2000, a ram and a goat were accidentally crossed in Botswana. The animals were simply kept together. The new animal is called "Toast of Botswana". The ram and the goat different quantities chromosomes - 54 and 60. Therefore, their offspring are usually stillborn. But the surviving hybrid was able to inherit the characteristics of both of its parents at once. It has long wool like a sheep and the legs of a goat. The outer hair was rough, but the inner part of the coat was soft. The animal turned out to have the heavy body of a lamb. At 5 years old it weighed 93 kilograms. The animal had 57 chromosomes, which turned out to be average between the number of its parents. The hybrid turned out to be very active, with increased libido, although sterile. That is why he was castrated at 10 months. Cases of obtaining such a hybrid have been reported in New Zealand and Russia.

Bison is a hybrid of bison and American bison. The breed was created to combine the characteristics of both animals and to increase beef production. Bison produce fertile offspring both when crossed with each other and with representatives of the original species.

The creation of bison has proven to be a major conservation problem for the wild American bison population. Most modern bison are genetically already bison, as they appeared as a result of crossing two species.

Beefalo is a hybrid of a cow and an American bison. The breed was bred to provide a better source of meat. Beefalo has it bright red, which is important, because This meat contains less cholesterol than traditional beef. Breeders also claim that beefalo meat has a more delicate and subtle taste and aroma, but the general public has not yet had a chance to evaluate it - the meat is sold only in a few stores in the USA.

Grolar (polar grizzly) is a hybrid of a grizzly bear and a polar bear. Found in captivity and in the wild. It is distinguished by thick creamy white fur, long claws, a humped back, and dark spots near the eyes and nose.

The killer whale is a hybrid of a bottlenose dolphin and a small black killer whale. A fairly rare hybrid, only two specimens currently live at a marine amusement park in Hawaii. The size of the hybrid is average between a killer whale and a dolphin; The difference in the number of teeth is interesting: the dolphin has 88, the killer whale has 44, and the hybrid has 66.

Liger and tiger lion. A liger is a hybrid of a lion and a tigress, and a tigress is a hybrid of a tiger and a lioness. Ligers are very large, know how and love to swim, and are sociable. Their males are sterile, but females can bear offspring. Tigers are smaller in size.

2. Hybrids of hybrids

We are talking about crosses between a male tiger and a female liger/tiger lion or a male lion and a female liger/tiger lion. Female ligers and tigers can give birth. Such second-level hybrids are extremely rare and are mostly privately owned.

Levopard is a hybrid of a lioness and a leopard. The body resembles a leopard print, and there is a characteristic color. The spots are not black, but brown. But the head looks more like a lion's. The new hybrid is larger than a leopard. Leopard loves to climb trees and swim in water. The first documented mention of this animal was found in 1910 in India. The most successful experiments in breeding leopard were carried out in Japan. The lioness Sonoko gave birth to two cubs from the leopard Kaneo in 1959, and three years later three more. The male hybrids were infertile, the last of them died in 1985. But one of the females was able to give birth to offspring from a hybrid of a lion and a jaguar.

Savannah is a hybrid of a wild serval and a domestic cat. Servakot turned out to be a beautiful and strong animal. The unusual species became popular among breeders in the late 20th century, and in 2001 the International Cat Association designated it as a new registered breed. Savannahs are much more sociable than the average domestic cat and are often compared to dogs due to their loyalty to their owners. They can be trained to walk on a leash and even fetch objects thrown by their owner. According to standards, servacotta must have black or brown spots, silver or black. Typically these animals have high erect ears, a long thin neck and head, and a short tail. The servacot's eyes are blue in childhood and green in adulthood. These cats weigh from 6 to 14 kilograms. They are not cheap, as for pets - from $600 and above.

The Iron Age pig is a cross between domestic Tamworth pigs and wild boars. This is how you get a pig from the Iron Age. This hybrid is much more tame than a wild hog. However, it is not as pliable as ordinary domestic pigs. The resulting animals are raised for their meat, which is used in some specialty sausages and other products.

Red parrot fish. In Asia they adore aquarium fish, constantly creating new species. This species was released in Taiwan in 1986. How this mutation was obtained is still kept secret. After all, this allows local breeders to continue to maintain a monopoly on these fish. Rumor has it that a midas cichlid was crossed with a red cichlid. Their fry are gray-black, but by 5 months they become bright orange or pink. We learned this fish in the 90s; they bring it here from Singapore and other countries in Southeast Asia. If a red parrot is placed in an aquarium, the fish can grow there up to 10-15 centimeters. The color can vary greatly; in addition to orange, yellow is also possible. At some point in their lives, parrots can be crimson, lilac or bright red. However, over time they all acquire an orange color. Experts advise feeding this fish with special food containing carotene, this will help enhance the bright red color of their body. The resulting hybrid also has some pronounced anatomical deformations. For example, the mouth looks like a narrow vertical slit. Because of this, it is very difficult to feed such fish, which is why many of them die prematurely. Bester is a hybrid of beluga and sterlet, fish of the Sturgeon family. First received in the USSR in 1952. The hybrid combines the rapid growth of beluga with the early maturation of sterlet. Length up to 2 meters, weight up to 30 kg. The hybrid is fertile. In aquaculture, first generation hybrids grow to a weight of 1 kg or more in 2 years.

The hybrid pheasant is a cross between the golden pheasant and the diamond pheasant. As a result, the new bird received a unique coloring of its plumage

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