The concept and genetic basis of crossbreeding in horse breeding. Types of crossing, their meaning

Savannah - a hybrid of a wild serval and a domestic cat.The servakot turned out to be a beautiful and strong animal.The unusual look became popular among breeders in the late 20th century, and in 2001 International Association Koscheck fixed it as a new registered breed. Savannahs are much more outgoing than regular house cats and are often compared to dogs due to their devotion to their owner. They can be trained to walk on a leash and even fetch items thrown by their owner.According to the standards, the servakot should have black or brown spots, silver or black. Usually these animals have high erect ears, a long thin neck and head, and a short tail. The eyes of a Servakot are blue as a child and green as an adult. These cats weigh from 6 to 14 kilograms. They are not cheap, as for pets - from $ 600 and above.

wolfdog - a hybrid of a wild wolf and a dog. A fairly common hybrid. Usually a wolf is crossed with a dog of similar appearance- German Shepherd, Husky, Malamute. However, the physical and behavioral characteristics of hybrids do not always meet expectations.

Pig from the iron age - hybriddomestic pigs of the Tamvor breed with wild boars. So it turns out a pig from the Iron Age. This hybrid is much more tame than the wild boar. However, it is not as malleable as ordinary domestic pigs. The resulting animals are raised for their meat, which is used in some specialty sausages and other products.

And now a bonus question for 11th graders:explain why interspecific hybrids of animals are sterile and how this sterility can be overcome? (in comments)

Intrabreed types

Horse families

Line breeding

The concept and genetic basis of purebred breeding

Theme 10

HORSE BREEDING METHODS: PURE BREED BREEDING, INTERBREED CROSSING, HYBRIDIZATION

1. In horse breeding, methods of purebred and purebred breeding and crossing are distinguished. The term "purebred breeding" is adopted in relation to purebred breeds - English thoroughbred riding, Arabian and Akhal-Teke.

Purebred breeding- mating of animals belonging to the same breed. This method is used to obtain animals that have the most valuable genotypic and phenotypic traits characteristic of a particular breed. For a long time, purebred breeding has been successfully used to improve the Akhal-Teke, Arabian, English thoroughbred riding, Don, Karabakh, Oryol trotter and other breeds. Thanks to purebred breeding, great success has been achieved in thoroughbred and trotting horse breeding, specific qualities of high working capacity have been accumulated, which are hereditarily fixed and steadfastly passed on from generation to generation. The value of the purebred breeding method in improving existing breeds and improving their qualities can hardly be overestimated. That is why horses of many breeds are carefully protected from crossbreeding, bred and improved only by purebred breeding.

Horses of factory breeds are improved mainly by the method of pure breeding, which is carried out along lines and families. The line breeding method was used in the practice of thoroughbred and trotting horse breeding in the 18th-19th centuries. Its theoretical substantiation began later. E.Ya. Borisenko wrote that line breeding is the highest modern form of breeding work with factory breeds. Breeding along lines is a complex method of zootechnical work with a breed, based on the use of the best male representatives, designed to turn the valuable hereditary qualities of the ancestor and his successors into the dignity of a fairly large number of animals. It includes such methods as selection, selection, related and unrelated mating, linking work with families.

According to M.M. Shchepkina is pushed forward by the breed not by an average producer, but by an outstanding specimen among relatives, beating them either with its forms and qualities, or with a special ability to give birth to animals that overtake the established average type. Lines come from such ancestors and are usually called by their name. They differ in that exceptionally successful animals are especially often found in them.

1.1 this is a method of transforming the most valuable qualities of individual breeding animals into qualities characteristic of a sufficiently large group of animals, a method of transforming individual characteristics into group ones. The main purpose of line breeding is to saturate pedigrees with the names of the most prominent ancestors, the heredity of which is crowded out by the heredity of their mediocre or unsuccessful partners. This gives greater stability to hereditary transmission and the ability of the line to progress in a certain direction. When breeding along lines, the unity of such opposite methods as homogeneous and heterogeneous selection is carried out, as a result of which it is possible not only to retain the valuable qualities of the ancestor in the offspring, but also to create animals even more valuable than the ancestor himself.

The purpose of line breeding is to preserve and strengthen the valuable qualities of the ancestors and weaken their undesirable sides, that is, approaching the type of record holders through inbreeding and selection, and not obtaining constant forms.

It is possible to switch to breeding animals along the lines only as a result of long-term breeding work, the creation of stable heredity in the breed and high individual prepotency, which is characteristic of purebred animals. According to S.A. Ruzsky, these qualities, without which neither the formation of a line nor their further cultivation, usually arise with excellent pedigrees created in a number of generations by homogeneous selection - a method consistently applied in purebred breeding.

Line- this is an objectively existing and having a certain qualitative originality, a valuable group of breeding animals, related to a certain ancestor, capable of long-term self-reproduction and spreading mainly through male descendants.

ON THE. Yurasov noted that the line is essentially a microbreed. Within the lines - its own standard, its own features of the exterior and performance, its own requirements for selection. Lines are whole groups within the breed, united by origin from one or more ancestors, possessing the valuable qualities of these ancestors and capable of constantly passing them on to offspring. However, there are many differences between the line and the breed, especially in terms of the duration of their existence. Usually lines and families in horse breeding exist within 4-5 generations. Horses of most factory breeds belong to several lines, the number of which in the breed is more than 10. The breed is incomparably more durable. For example, the age of the Arabian breed of horses is 1.5 thousand years, and the Akhal-Teke is even more.

factory lines name the most valuable lines of the breed, significantly superior to other lines in terms of the severity of economically useful qualities. These lines require rigorous testing.

Formal name the lines that stopped progressing and lost their characteristics, i.e. only the form remained without content.

false line - this is a progressive group of descendants of a mediocre ancestor. The heredity of the ancestor in such a line is continuously absorbed by the best heredity of the queens outstanding in a number of generations, from which the successors of this false line descend. In such a line, material is often created to form a factory line.

At the core of concepts progressive, stable, fading, "going into the uterus" lines lies a comparison of the productivity and development of each subsequent generation with the previous ones. At the same time, the ideal to which it is necessary to strive in working with the line is a progressive line that improves its performance in each generation. Stable lines are good because for a number of generations they allow you to save characteristics. The line “going into the uterus” is not necessarily a bad line, it just has lost its successors. Queens of such lines are often excellent and are used to reinforce budding lines, especially if the latter have not yet reached the desired standard in quality. Fading lines can also be once valuable lines, but at some stage they have lost their specific features.

line features. One of the main features of the line is its qualitative originality, which determines a special type inherent only to it. The qualitative originality of the lines is the result of the common origin of animals and a single direction of breeding work. It leads to line specialization. The line, like the breed, is not an amorphous, structureless mass, consisting of homogeneous impersonal animals. All animals within the line, apart from known community, have and should have significant individual differences. Variability allows the lines to be dynamic, gives them genetic plasticity, the ability to improve from generation to generation.

The line is dynamic, each new generation introduces its own changes into it, which are picked up by selection and developed or swept aside. Knowing and controlling the features of the breeding process, the breeder achieves the variability of the qualitative originality of the line in the direction of the same development, in which its positive features are fixed and even strengthened, while the negative ones are weakened or lost.

The main points or stages when working with the line can be considered:

■ line tab, which begins with the choice of the ancestor. At the same time, the origin of the manufacturer is carefully analyzed. Particular attention is paid to the original line and the branch in which the candidate for ancestors was obtained. They take into account the saturation of his pedigree with animals, especially valuable in breeding terms, the presence of inbreeding in the pedigrees; analyze the degree and direction of inbreeding,
if it exists; reveal the level of productivity of parents, their breeding value. Particularly important factors are the results of the assessment of the father of the alleged ancestor in terms of the quality of the offspring;

■ creating a line structure. Line differentiation into generations, branches, branches is one of the main features of working with a line. The direction of development of the line and the measure of its length depend on it. Each of the branches, in addition to general linear properties, acquires some features inherent in each of them individually;

■ purposeful selection and selection in each generation. Selection in the lines has its own characteristics. Firstly, not the ancestor and his successors are selected to the uterus, but vice versa. Secondly, both homogeneous and heterogeneous selection are used. The first of them serves to reinforce and enhance the merits
the ancestor and his successors, the second - to weaken their shortcomings, if any. Finding and using the best compatibility is the main condition for the selection of both homogeneous and heterogeneous. Absolutely homogeneous, as well as absolutely heterogeneous, selection in the practice of breeding
breeding large mammals No;

■ the use of inbreeding to consolidate the valuable qualities of the line, cross lines. The desired compatibility can be obtained by mating unrelated
to each other of the sire and the uterus, and in related and even closely related matings. In horse breeding, it is most valued as a desirable under
bora bot-cross, i.e. mating of an inbred uterus with an outbred sire, which contributes to the refreshment of the blood;

■ approbation of the line;

■ spin off from the created new, more valuable lines.

Work with the line is aimed at preserving, consolidating and improving its advantages and correcting its inherent shortcomings. Assigning horses to the line only by origin, who did not inherit its basic qualities, violates the meaning of working with the line and can lead to its disappearance, dissolution in the breed. Features of the type and development of representatives of each line should be well known to breeders. Otherwise, major errors are possible, such as underestimation or even culling at an early age of good foals of a late maturing line.

For each line of trotting, English Thoroughbred and other breeds of horses, breeders develop detailed characteristics, from which follow specific tasks for further work with a particular line.

To achieve the best results in working with each breed, it is important to know and correctly use the compatibility of lines with each other when drawing up parental pairs. It is known that some lines "match" each other and their crosses produce good horses, while others do not "match", and mating even outstanding individuals belonging to "antagonistic" lines cannot be successful. Moreover, in some cases the very existence of a line, its progress, is possible only if its males are mated with mares of a certain other line.

A striking example of this is the use of the stallion Bubenchik in our horse breeding (record - 2 min 10 s) of the Orlov trotting breed. This stallion was used for a number of years by a stud at the Tula and Khrenovsky stud farms on first-class broodstock, but did not leave outstanding offspring there. The transfer of Bubenchik to the Dubrovsky stud farm in Ukraine, where he began to select mainly the daughters of the ancestor of the Warrior line (4.36), turned out to be decisive in creating a number of wonderful horses, descendants of Bubenchik: Waltz (2.05.6), Vorgan (2.07.1), Gall (2.07.5), Skygazer (2.08), Wind (2.10.7), etc.

Experience in domestic trotting horse breeding has revealed a number of proven combinations of lines, the use of which continues to produce high-class horses.

1.2 In breeding work with horse breeds, especially with breeds that have reached a high degree of perfection, families play a huge role. They have no less influence on the progress of the breed than lines. Usually, only a part of the total number of mares of any breed belongs to uterine families. A valuable female family is, as a rule, a more faithful, stable carrier of useful breed qualities than a male line. Families express, to a certain extent, a conservative beginning, smoothing out sometimes sharp influences on the breed of individual stallions in breeding. Outstanding queens - the ancestors of families - are no less rare in the breed than outstanding sires, and they leave an indelible mark on the breed. Mothers of winners of the Derby and other major prizes in Thoroughbred horse breeding come from 90% of the cases of outstanding female families, although most of them are not major prize winners. To the same extent, this applies to mothers of the best producers. IN. Witt recommended not to exclude healthy, good-looking mares from a valuable brood nest.

For a family, as well as for a line, one formal relationship with an outstanding ancestor is not enough; a strict transfer from generation to generation of the valuable properties of the mare - the founder of the family is also necessary. Chief among these properties is the ability to produce cool offspring. Studies conducted in the United States have shown that mares with higher agility and jumps produce a greater number of classy horses than less classy mares. Families, like lines, are not fixed. They either flourish, highlighting outstanding queens in new generations, which become the ancestors of their families, or lose their significance and cease to exist.

The progress of the English Thoroughbred is closely related to the families of Selena, Lady and others. A lot of cool horses, sires and queens from England, France, the USA and other countries came out of these families. In our country, in the English thoroughbred riding breed, valuable ancestors of the families were St. Mahesa, Glorvina, and others. Gichki, Ants and others.

In addition to families, there are uterine nests, which are a group of mares descended from a prominent queen and concentrated in one stud. The uterine nests, if the mares included in them consistently pass on to the offspring the valuable qualities of the ancestor, develop into families, transferring their influence to the breed as a whole.

The recruitment of the breeding stock of the stud farm with mares belonging to valuable female families and progressive nests is the most Right way success in breeding work, if the breeder can find the best combination of queens of each family with certain stallions. Specialist horse breeders must maintain valuable features in each family, free them from undesirable traits and enrich them with new virtues.

1.3 In addition to the differentiation of the factory breed into lines and families, intrabreed types are distinguished in a number of breeds during breeding work. The distinction between the latter is necessary when working with horse breeds that are distinguished by versatile performance.

As a rule, 3-4 types of horses are distinguished in the breed with different exterior and constitutional features. One of them, characterized by the greatest degree of expression of the signs inherent in horses of this breed, is called "basic", "characteristic" or "desirable". Along with it, two diametrically opposed intrabreed types are usually distinguished, of which one most often combines horses of a more delicate, dry constitution, sometimes not massive enough and bony, and the other is coarser, massive, sometimes raw constitution.

The presence of several types in the breed makes it relatively easy to adjust the physique of horses of a given breed and their performance by means of appropriate selections, without resorting to crossing. The same intra-breed division makes it possible to regulate the production of products for one purpose or another.

For example, in the modern composition of the Oryol trotting breed, four main types of horses are distinguished: large thick, dense medium-sized, large lightweight and medium types. Representatives various types physiques are found within the same line, they can have a similar performance and an equally high assessment of the exterior.

Today, the following are widespread in the breed and promising - Khrenovsky, Perm, Dubrovsky, Novotomnikovsky and Altai.

Breeding selections, involving the mating of horses of various intrabreed types, are always mostly heterogeneous in nature and can lead to the effect of intrabreed heterosis.

When breeding horses, they are used as unrelated (outbreeding), so related (inbreeding) mating.

With unrelated mating, the following main options are distinguished:

■ both parents are outbred (outcrossing);

■ inbred father, outbred mother (topcross);

■ outbred father, inbred mother (botomcross);

■ father and mother are inbred, but on different ancestors (inbredline cross).

Inbreeding, depending on its degree, is divided into close (I-II, II-II, II-III), moderate (III-III, III-IV, IV-IV) and distant (IV-V, V-V).

When breeding along lines and in working with uterine families in horse breeding, related matings are widely used, as a rule, in moderate degrees of kinship. Moderate inbreeding is widely used as a way to increase the genetic influence of valuable ancestors with a slight increase in homozygosity. The most common inbreeding in this case is in the III-III, III-IV, IV-IV ranks of the ancestors. So, with inbreeding in degree III-III, the coefficient of increase in homozygosity is only 3.1%, and the genetic similarity of the proband with the ancestor, repeated twice in the third row of the pedigree, is 25% (assuming that the genetic similarity with the ancestor of the first row of the pedigree is 50 %, the second row - 25%, the third - 12.5%, etc.).

Inbreeding to extremely close degrees is rarely used in horse breeding due to the risk of inbreeding depression as a result of a sharp increase in homozygosity. However, when it is required to consolidate the quality of some phenomenal producer, close inbreedings in the II-III ranks of ancestors and closer are also acceptable.

Especially successful is the use of inbreeding in the mating of animals grown in different conditions of detention, with proper feeding and rearing of the young obtained from this mating.

It should be noted that not all representatives of the line of the same breed respond equally to the use of related mating. In some cases, selections with sufficiently close inbreeding are acceptable and even necessary, while in others such selections can give negative results.

A peculiar technique of breeding work, widely used in horse breeding, is selection with complex inbreeding, in which animals are mated, obtained, as a rule, by the same cross.

The mating of horses of different lines, each of which is inbred to its ancestor, is also very successful. With this pairing, the effect of heterosis is manifested.

Remote single inbreeding is not significant, and such matings practically do not differ from outbreeding in terms of their effectiveness.

The measure of homozygosity, which is the degree of inbreeding, is considered to be the coefficient of inbreeding.

2. The first definition of the concept of "crossing" was given by Ch. Darwin. In the future, it was constantly changed and supplemented. Summarizing the definitions of the leading classics of zootechnics, we can say that crossbreeding is a breeding method in which animals are mated (artificially inseminated) different breeds, species, as well as crossbreeds (including hybrids) among themselves or with animals of both the original and other classification groups.

The method of crossing, both in quantitative terms and in terms of economic effect, is prevailing. Theoretically, the popularity of this method can be justified as follows:

■ the ability to cause fundamental changes in the breed and productive qualities of animals due to intergroup migration, the manifestation of a combinative form of variability and biological enrichment;

■ creation of prerequisites for the use of heterosis. In breeding farms, crossbreeding acts as a method of breed improvement and breed formation, in commercial farms, as a source of additional effect when heterosis is used. It should always be remembered that crossing leads to a violation of the genetic system, which is the breed. Therefore, only targeted crossings lead to progress, creation, and a real increase in the efficiency of animal husbandry.

Absorption cross. In the zootechnical literature, this method has several names: absorption crossing, transformative crossing, crossbreeding, grading, etc. Absorption crossing in a broad sense should be understood as a type of crossing in which most of the traits of animals of one genetic group are replaced by traits of animals of another group. Thus, with absorptive crossing with the help of a limited number of producers of high-value breeds or types, a rapid mass improvement of broodstock and bringing their productivity potentials to the level of an improving breed is achieved. In each generation, with such mating, the influence of one of the original breeds is halved.

From a genetic point of view, absorption crosses replace most of the genes of the local (improved) breed with genes of a more valuable factory (improving) breed or type. Success is ensured not only by obtaining crossbreeds of the 3rd-5th generations and breeding them “in oneself”, but by the ability to objectively (or intuitively) identify those individuals that combine exactly those valuable qualities of both breeds that correspond to the goal of crossing.

Assessing the advantages of the absorption crossing method, the following aspects can be distinguished:

■ the relative speed of transformation of the breed composition of herds;

■ the ability to achieve this on a large scale;

■ cheapness of such transformation;

■ no risk (with the right choice of improving breed).

In addition to the indisputable advantages, absorption crossing has some disadvantages - at the initial stages

Hybrid (from lat. hybrid) - the creation of a new individual by crossing living organisms of various breeds, species, varieties. The hybridization process is applied mainly to living things (animals, plants).

The article will focus on the creation of such organisms in the animal world. These are the most difficult experiments. Also, the reader will be able to see animal hybrids, photos of which are placed in sections.

Story

The first attempts to create hybrids were carried out as early as the 17th century by the German botanist Camerarius. And in 1717, the English gardener Thomas Freidchild presented the scientific community with a successful result of hybridization - a new type of carnation.

In the animal kingdom, things were much more complicated. In the world of wildlife, it is extremely rare to find animal hybrids. Therefore, the crossing of representatives of different species occurred artificially - in laboratory conditions or in reserves.

The very first hybrid with a thousand-year history is, of course, a mule - a mixture of a donkey and a horse.

Since the middle of the 19th century, with the advent of nature reserves and zoos (in the form in which we are accustomed to seeing them in modern times), they began to cross bears - brown and white, as well as a zebra with a horse.

Since the middle of the 20th century, scientists around the world have been conducting experiments on crossing different animal species. All of them have different goals: someone breeds hybrids to improve productivity, someone - for exotics, and someone - to obtain effective drugs.

Animal hybrids: what are they?

There are more than 80 interspecific hybrids all over the world, but let's focus on the brightest and most famous representatives.

Peasley

Peasley (aknuk) - a cross between a polar bear and a grizzly bear. The first mention of an unusual animal dates back to 1864. Then in the northwestern part of North America, near Lake Rendezvous, a bear with an unusual dull white color and a golden brown muzzle was shot.

After 10 years, the first offspring from polar and brown bears were obtained in the German zoo (Halle). Babies were born white, but over time, the color changed to bluish-brown or golden-brown. Peasley showed good results in terms of reproduction: hybrid animals successfully produced offspring. Interbreeding took place both between Aknuk and with representatives of a pure line.

Often, interspecific hybrids of animals are not reproductive, but pizzles are an exception, since both bears can be attributed to the same species by biological characteristics, but, based on a number of morphological features, the bears were identified by scientists as separate species.

Even before 2006, there was an opinion that animal hybrids did not occur in the natural environment. This myth was dispelled on April 16, 2006 by American hunter Jim Martell, who shot a Peaseley on Banky Island (Canadian Arctic), which became indisputable evidence of the appearance of hybrids in the wild.

Liger and tiger

The first is a hybrid of a tigress and a lion, and the second is the offspring of a lioness and a tiger. These animal hybrids are born exclusively in artificial conditions, the reason for this is banal - different habitats (Africa and Eurasia) do not allow them to meet, this is possible only in menageries.

Outwardly, ligers look like a cave lion, which became extinct during the Pleistocene period. To date, this hybrid is considered the largest among the cats. This phenomenon is explained by growth genes: in tigers they are not as active as in lions. For the same reason, the tigrolev is smaller than the tiger.

In the amusement park "Jungle Island" (Miami, USA) contains a male liger named Hercules weighing 418 kg. For comparison: the average weight of the Amur tiger varies from 260 to 340 kg, and African lion- from 170 to 240 kg. So, Hercules absorbs up to 45 kg of food in one approach, and develops a speed of 80 km / h in 10 seconds.

The remarkable thing about ligers is that these cats love to splash in the water. Another feature: ligers are one of the few hybrids that are able to reproduce offspring. So, in the Novosibirsk Zoo on August 16, 2012, the lion Samson and the ligress Zita became parents, giving birth to the liligric Kiara.

There are just over 20 ligers in the world today.

Bester

Bester is a hybrid of two representatives of the sturgeon family - a female beluga and a male sterlet. Bester owes its appearance to the Russian scientist-biologist - Professor N. I. Nikolyukin. Since 1948, he has come to grips with the problem of sturgeon hybridization. In 1952, the wife of Nikolai Ivanovich, who, together with her husband, worked on the creation of fish hybrids, tried to artificially obtain offspring of sterlet and beluga. The Nekolyukins did not expect that this unscheduled experiment would mark the beginning of a new direction in fish farming.

During the experiments, the professor crossed different types of sturgeons, but the turn did not reach the beluga and sterlet. Perhaps he considered such an experiment initially a failure, since these sturgeons are different in size and weight (beluga - up to a ton, and sterlet - no more than 15 kg), live and spawn in different places, and their hybrids cannot produce offspring. But everything happened exactly the opposite.

Bester took fast growth from beluga, and fast puberty from sterlet, which is an important factor for industrial fish. Also, the hybrid turned out incredibly tender meat and delicious caviar.

Now in Russia besters are bred on an industrial scale.

Kama (camel)

It is a hybrid between a male Bactrian and a female llama. The first kama saw the light in 1998 at the Animal Reproduction Center in Dubai. The individual was created artificially, the main purpose of such crossing was to get an animal with the endurance of a camel and the quality of llama wool. The experiment was a success. Kama turned out to weigh up to 60 kg, with wool at least 6 cm long, with the ability to carry loads up to 30 kg. The disadvantage of the camel is the inability to reproduce. Of course, in nature, such an option would be impossible, since llamas live in South America, and Bactrians live in Asia and Africa, and the former are significantly inferior in size to the latter. Despite these data, it turned out that the camel and the llama have the same number of chromosomes.

To date, six individuals of kam have been received in the UAE.

Kosatkodelfin (wolfin, kitofin)

Kosatkodelfin - a hybrid of killer whale (small black) and bottlenose dolphins. The first wolfin appeared in a water park in Tokyo, but died at the age of six months. The second orca dolphin hybrid appeared in Hawaii at the SeaLifePark Marine Park in 1986. The female wolffin, named Kekaimalu, began breeding at the age of five, which is quite early for killer whales and dolphins. The first experience of motherhood was somewhat unsuccessful: the mother refused to feed the baby, so she was fed artificially, which made it possible to grow an absolutely tame individual, but her life was short and ended at the age of 9 years. Kekaimalu experienced the happiness of motherhood three times, but the last one turned out to be the most successful: in 2004, the female Kavili Kai was born from a male bottlenose dolphin. The baby turned out to be very playful, and a month after birth she reached the size of her father.

An interesting fact was discovered by scientists: the wolffin has 66 teeth, the bottlenose dolphin has 88, and the killer whale has 44.

Now in the world there are two individuals of the orca dolphin, which are kept in Hawaii. Sometimes information appears that wolffins have been seen in the wild, but scientists have not yet been able to confirm this data.

Other hybrids

Let's see what are the most common animal hybrids. The examples are quite interesting. These are the following hybrids:

• domestic horse and zebra - zebroid;
• donkey and zebra - zebrul;
• bison and bison - bison;
• sable and marten - kidas;
• cichlids - red parrot;
• female African lion and leopard - levopard;
• leopard and lioness - leopon;
• capercaillie and black grouse - mezhnyak;
• dromedary and bactrian - nar;
• lioness and tiger - tigon;
• hare hare and white hare - cuff;
• cows and yaks - hainak (dzo);
• ferret and mink - honorik;
• leopard and jaguar - jagopard.

But these were obtained in the course of many experiments

• horse and donkey - mule;
• donkeys and stallion - hinny;
• ram and goat;
• diamond and golden pheasants - a hybrid pheasant;
• domestic and American bison cows - bifalo;
• a hybrid obtained by crossing musky drakes with Beijing white, Rouen, Orgpington, White Allier ducks - Mullard;
• domestic pigs with wild boar - a pig from the Iron Age.

You can talk about animal hybrids for a very long time, given their number and diversity. But are there other options, such as animal-plant hybrids?

To date, there is only one known hybrid - the sea snail (Elysia chlorotica), which lives on the coast of North America from the Atlantic Ocean. These animals feed on solar energy: eating plants, they photosynthesize. The snail has been dubbed the gelatin green plant. This hybrid receives chloroplasts, which are then stored in intestinal cells. An interesting fact: a sea snail with a lifespan of no more than one year can eat only the first two weeks from the moment of birth, after which food consumption becomes a non-priority.

Plant-animal hybrids have become commonplace, but how would the public react to a human-animal hybrid? And do they exist?

There are many rumors about the existence of such hybrids, but, unfortunately, there are very few facts. However, studying the mythology of different peoples, scientists point to the presence of beastmen in almost all epics. Scientists from Australia and the USA have studied more than 5,000 rock paintings and texts. Most often there are descriptions of people whose bodies (as a rule, the lower part) consist of the body of a horse, goat, ram, dog. The names of such beastmen are well known to us from mythology. These are centaurs, minotaurs, satyrs and others.

Scientists explained the existence of such "people" by the fact that in ancient times bestiality was common, especially in the army, because herds of sheep and goats were always kept nearby. Animals were for the military not only potential food, but also objects of satisfaction of sexual needs. Many scientists of the Middle Ages mention the birth of children from animals in women and vice versa. These facts remain a big question, since from a biological point of view this is impossible due to a different set of chromosomes.

Recently, more and more new, ambiguous facts have been revealed to the public. One of these facts is the experiment on the fertilization of a woman with the sperm of a chimpanzee in fascist Germany and the USSR. According to some reports, Soviet Union after a number of attempts received a positive result. The further fate of the experiment has not yet been revealed.

A hybrid of a human and an animal is nonsense for modern society, but information about such experiments continues to appear in the media. Is this true or fiction? We will judge in 10-20 years. Time will tell how far science will go, but for now we will eat hybrid fruits and vegetables, enjoy the beauty of hybrid plants and animals and hope that humanity will not return to the Stone Age.

Absorption (transformative) crossing consists in the fact that unproductive queens of one breed are crossed in a number of generations with producers of another highly productive breed. Thus, the properties of the improved rock are absorbed or displaced by the properties of the improving rock. The absorption process is stopped if the hybrids do not differ in productivity, conformation and constitution from the animals of the improving breed. In the future, such crossbreeds are bred "in themselves."

With each new generation of crossing, the “bloodliness” 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 the improving breed and the conditions of feeding and keeping animals.

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

The offspring obtained by breeding "in itself" crossbreeds of the second generation (3/4 blood), depending on the severity of the desired type, are classified as crossbreeds of the fourth or third generation according to the improved breed. The offspring obtained as a result of breeding "in itself" crossbreeds of the third and fourth generations, depending on the severity of the desired type, are classified as crossbreeds of the fourth or third generations according to the breed being improved. The offspring obtained as a result of breeding "in itself" crossbreeds of the third and fourth generations, and the fourth generation, depending on the severity of the desired type, are classified as crossbreeds fourth generation or purebred animals. In the absence of documents on the origin of animals, but a good expression of the type of improving breed, they are referred to as crossbreeds of the first or second generations (1 / 2 - 3 / 4 bloodlines) of this breed.

Absorption crossbreeding- an important method for the transformation of unproductive animals, and it is often desirable to obtain those that, along with the improvement of 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 outperform 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 main array of the country's animal porridge.

Before embarking on absorptive crossing, one should find out the characteristics of the improving breed, its adaptability to local conditions. So, in a number of regions of the country, little suitable for natural conditions for the breeding of fine-fleeced rams, the absorption crossing of local coarse-wooled sheep with fine-fleeced rams gives poor results.

The success of absorptive crossing also depends on the quality of the producers of the improving breed, as well as on the conditions of feeding and keeping the crossbred offspring. Only by creating favorable conditions for feeding and keeping hybrids can high rates 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 traits of the improving breed.

The value of absorption crossbreeding for the rapid mass improvement of the breed composition of animals. Absorption of blood bred many breeds of animals abroad and in our country. P. N. Kuleshov in his work “Methods of Pedigree Breeding of Domestic Animals” (1932) clearly illustrated the importance of absorptive crossing, noting that when breeding the famous thoroughbred 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 horses of several eastern breeds. In the same way, Merino sheep were obtained in many states, and in the south of Russia, astra sheep (from Karakul), American trotter (from racehorses), breeds of some American and German pigs (from English breeds), many breeds of large cattle in Europe and America (from the Dutch, Simmental, Swiss, Jersey, Ayrshire and Shorthorn breeds).

On the importance of absorption crossbreeding for the transformation of animal husbandry in our country IT. D. Potemkin wrote back in 1926 in his work “Massive improvement of Russian cattle breeding (excluding Siberia and the Caucasus)”. Many tens of millions of heads of unproductive outbred cattle, sheep, pigs and other animals were transformed in our country into pedigree animals of various bloodlines in a relatively short period.

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

In those farms where the pedigree of animals is still low, it is necessary to achieve their transformation into purebreds by absorption crossing.

Introductory crossing (blood flow). They resort to it if the existing breed meets the basic requirements in terms of its qualities, but needs to improve individual features.

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

Tasks and technique of crossing. During introductory crossing, the sires of the improving breed are used once on the queens of the improved breed to obtain 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 blood infusion consists in crossing the queens of a slow-growing 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 the breed is of decisive importance, the features of which are transmitted to the queens through the manufacturer. It is also important that the improving rein goes well with the one being improved.

In order to improve, for example, in terms of milk productivity, milk fat content, precocity, exterior and constitutional indicators, it is introductory crossed with animals related to red , red swedish and some . To increase milk production, he is given the blood of animals of a related Montbeliard (from France) breed; to increase fat content - animal blood.

At the second stage, crossbreeds of the first generation 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 selectable traits.

The third stage is the transition to breeding hybrids "in itself". According to the main constitutional features, crossbred animals are very close to animals of the main (improved) breed.

Conditions for successful introductory crossing. Along with the correct choice of an improving breed and the general direction in breeding, when the qualities of animals of related breeds are used to improve the initial breeds, it is important to take into account those qualities that favor the use in animal husbandry. modern technology. In such cases, it is more expedient to resort to "blood rush" and unrelated breeds. So, in order to increase the milk production of animals of some domestic breeds, improve the shape of the udder and increase the rate of milk flow, they resort to introductory crossing with the producers of the Ayrshire breed. The results thus obtained testify to the expediency of such an approach.

The success of introductory crossing 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.

In the farm "Askania-Nova" in the Kherson region, for example, a long-term work is underway to increase productivity and give the animals of this breed a milk-meat type, for which they are "blooded" with a milk-meat type. As a result of many years of work in Askania-Nova, a herd of animals of a new milk and meat type has been created.

Crossbreeds with milk yield and fat content of milk approach cows, and surpass the latter in live weight; they differ in precocity to a higher slaughter yield with better meat quality and lower feed consumption per unit of production. Bulls of a new type are used for breeding purposes.

Positive results have also been obtained with the improvement of black-and-white cattle with jerseys. So, in the USA, as a result of crossing Holstein-Friesian cattle with Jersey bulls, crossbreeds of the second generation 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 features. When creating new breeds of hybrids that meet the requirements for them, they are bred "in themselves", that is, hybrid queens are covered by hybrid producers. Reproductive crossbreeding has created many breeds of farm animals that are distinguished by rather high productive qualities and are well adapted to their living conditions.

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

Reproductive crossing requires the involvement of a large number of animals; the eye is much more difficult than other breeding methods. In this case, not only a combination of the qualities of the original breeds in crossbreeds is achieved, but also the development of new desirable features in animals. Most often, an aboriginal breed is used as a mother, 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 animals so that they can make up for the missing qualities of the local (aboriginal) breed. The more differences in the crossed breeds, the more diverse the crossbreeds; among them it is easier to identify individuals with completely new qualities. However, it is much more difficult in such cases to fix 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.

Every breed has different variants intrabreed types, therefore, the choice for crossing the appropriate breeds also provides for a careful selection of individual individuals according to the desired characteristics. In such cases, individual selection, selection, evaluation of producers in terms of the quality of the offspring are required.

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

Methods of breeding new breeds.

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

• development of a new breed model (excellence standard). Determine the type of physique and the main economically useful features of animals of the future breed, taking into account its adaptation to climatic, economic conditions, as well as the ability to satisfy national economic needs;
• selection of source material. The initial breeds are selected (the animals of at least one of the crossed breeds must differ in the qualities that the hybrids are planned to have), the animals are evaluated and selected for crossing, and, finally, the farm is selected;
• genetic enrichment of crossbreeds according to the desired
  qualities, breeding crosses "in itself", 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 backcrosses are carried out on the improving breed or representatives of the new factory breed are used for this;
• when crossing, they necessarily resort to strict rejection of hybrids that do not meet the desired requirements, as well as to related mating of the best producers and queens.

To consolidate the desired qualities in the crossbred offspring, an individual selection of animals is used with a thorough justification of its purpose. Reliable results in such cases are given by inbreeding, which is combined with unrelated mating, for which animals are selected that are similar in type to inbred ones. To avoid too close inbreeding and to consolidate the necessary economically useful qualities in the offspring, several lines and uterine families are laid. With a strong deviation of the crosses in the undesirable direction, they are mated with animals of the desired type, and sometimes with producers of one or more original breeds. Crossbreeds "in themselves" are bred only when they meet the desired requirements.

Simple and complex reproductive crossing. Reproductive crossing can be simple or complex. In the first case, animals of two breeds participate in crossing, in the complex case - three or more breeds. Most breeds of cattle are created as a result of simple reproductive crossing using local cattle and animals of any factory breed.

With M. F. Ivanov used reproductive crossing to breed new breeds of farm animals with great efficiency. In a short time, he created a domestic Ukrainian steppe white breed pigs, a highly productive Askanian breed of fine-fleeced sheep, and began work on the creation of a mountain merino. The main stages in the breeding of new breeds of sheep by reproductive crossing are obtaining hybrids (hybrids) of a certain bloodline, their enhanced rejection, the use of inbreeding and constant selection work with animals. As a starting material, M.F. Ivanov selected, as far as possible, homogeneous animals of a strong constitution, which he crossed with highly productive producers of factory breeds also of a strong constitution. When obtaining crossbreeds of a certain bloodline, in order to consolidate desirable qualities in the offspring, he resorted to inbreeding, and in this case he used only outstanding producers. 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, backward in development, 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, it would be possible to start unrelated mating and create favorable conditions for feeding and keeping hybrid animals, especially young animals.

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

As a result of complex reproductive crossing, the Kostroma breed of cattle was also created. At the same time, purebred and crossbred bulls of the Algauz and Swiss breeds, Yaroslavl, Miskovsky and local outbred cattle were used.

When breeding Soviet merino sheep by complex reproductive crossing, local coarse-wooled sheep from various regions of the country, Merino rams and dams of the Mazaev and Novokavkaz breeds, American rambouillet rams and new domestic fine-fleeced breeds - Askanian, Caucasian, Altai, Stavropol, Grozny, etc.

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

In horse breeding, by complex reproductive crossing using mares of the Don and Black Sea breeds and thoroughbred riding stallions, the Budennovskaya 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. The involvement of several breeds in this type of crossbreeding, the selection for a combination 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 of the world with intensive animal husbandry are working to create new breeds by the method of reproductive crossing.

Industrial crossing. It is used in all branches of animal husbandry to put into practice the effect of heterosis. It is widely used in modern non-breeding farms of an industrial type. 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 user herds.

In many livestock farms, especially in European countries and America, dairy and dairy-beef cows of less value in breeding terms, the young of which are grown for meat, are inseminated with the sperm of bulls of early maturing beef breeds. At the same time, the production direction of the economy 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. Industrial crossbreeding is also widely used in pig breeding to produce first-generation crossbreeds.

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

In some countries, complex industrial crossing is carried out on farms that are not the same in terms of intensity of animal husbandry and natural and climatic conditions.

For example, in the sheep farms of England, located in the mountainous regions of extensive sheep breeding, local queens are crossed with rams of the long-haired meat-and-wool Border Leicester breed. Crossbreeds of the first generation of rams are then castrated and, after fattening, sent for slaughter, and crossbred ewes are sold to farmers in lowland areas, where forage conditions are better than in the mountains. Here, these ewes are crossed with rams of more early maturing short-haired breeds (Oxfordshire, Southdown, etc.). The offspring resulting from such crossing is completely slaughtered.

In poultry farming, industrial crossbreeding is widely used to obtain the so-called hybrid bird, which is superior in productivity to the bird of the original breeds (lines). In many countries, this breeding method is also used in horse breeding in order to obtain half-breed horses, mainly for sports purposes.

The economic efficiency of industrial crossing is obvious, since, compared with peers used in this case, mother breed hybrids are distinguished by better development and higher productivity.

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

A great economic effect in pig and poultry production is provided by the interline hybridization method, which is a high form of industrial crossing and is widely used during the transition to the production of livestock products on an industrial basis. Interline hybridization may include forms when animals of two matching lines of one or more breeds are crossed. Other forms of interline hybridization are also known.

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

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

Interline hybridization is also used in sheep breeding.

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

Heterosis effect- a complex biological phenomenon, depending 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 parents.

The higher the productivity of animals of the original breeds, the higher the productivity of hybrids obtained as a result of industrial crossing. Therefore, the choice of breeds for crossing is crucial. 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 breeds and double productivity with meat, as well as beef breeds among themselves, have been studied. Similar studies have been carried out in other branches of animal husbandry. The most promising combinations of breeds for industrial crossing have been developed, which are being introduced into production. In beef cattle breeding, it is recommended, for example, to use: producers of the Hereford breed and cows of the Red Steppe, Simmental and Black-and-White; breeders of Aberdeen Angus (large type), Santa Gertrude, Charolais and Red Steppe cows; bulls of gray Ukrainian, Simmental breeds and black-and-white cows; shorthorn producers (large meat and milk-meat type) and red steppe cows.

Crossbred young animals of the farm are sold for meat at the age of 15-18 months after intensive rearing and fattening.

A distinction is made between simple industrial crossing, in which animals of two breeds are used (Fig. 16), and complex, when individuals of three breeds are mated sequentially. Complex industrial crossbreeding, shown in the second scheme, is used, in particular, in the GDR in order to improve the milk and milk fat content of Black-and-White breed animals. With this combination of breeds, hybrids are obtained that are distinguished by the best indicators of udder development, fertility and productivity.

The uterine composition for industrial crossing is used, as a rule, of the breed that is well adapted to local conditions. Manufacturers are selected taking into account previously identified compatibility, and they are subject to higher requirements than queens. It is desirable that both queens and sires be purebred. In simple industrial crossbreeding, crossbreeds of the first generation are used to obtain products, while in complex crossbreeding, they are crossed with animals of another or several breeds. Only after that, complex crossbreeds are obtained that meet the goals of user animal husbandry.

Industrial crossing on farms is organized on separate farms, in herds, isolated from breeding material. At the same time, they create good conditions for feeding and keeping and keep a thorough zootechnical record. Crossbreeds obtained as a result of industrial crossing for breeding purposes are usually not used.

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

It is more difficult to organize rotational crossing than industrial crossing, but its economic effect is higher.

Sometimes the use of variable crossbreeding ends with the breeding of a new breed.

In particular, in France, crossbreeds of English riding and Norman draft horses were crossed alternately with English and Norman stallions. At a certain stage, they switched to breeding hybrids “in themselves”. As a result, the work ended with the breeding 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 the experiment. When animals of two breeds are used for mating, variable crossing is called simple, and three or more breeds is called complex. Crossbreeds of the first generation, obtained as a result of two-breed crossing, are mated with producers of one of the original breeds, crossbreeds of the second generation - with producers of another original breed; in the next generation, backcrossing is carried out, etc.

In a three-breed alternating crossing, hybrid queens obtained as a result of mating animals of two breeds (AxB) are covered by producers of a third breed (C). Their offspring are bred to breed A sires, the next generation offspring to breed B sires, and their offspring to breed C sires, and so on. In the case of using four breeds, the crossbred breeding stock is mated alternately with sires of each of the four breeds.

The use of several breeds in rotational crossing 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 the crossing of hybrids with hybrids of different and identical origin. The main task of this very difficult method of crossing is the involvement of new valuable wild and semi-wild forms of animals into the material culture of man. 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, mules in the past), and hybridization, which is used to create new breeds and types of animals. In this regard, four types of animal hybridization are distinguished: industrial, absorption, introductory and reproductive. The most widespread industrial (user) hybridization and reproductive, or breed-forming.

It should be noted that the wild fauna (huge natural wealth) is unreasonably, and sometimes predatory, exterminated. In the last 50 years alone, more than 40 animal species have been destroyed. Species such as zebra quagas in Africa, American bison, tour, tarpan, arctic penguins, giant flightless geese, dodos - fat big island birds, moa ostriches, whose weight was 300 kg, height 4 m, died out or exterminated. To prevent the extinction of wild animals, special measures are now being taken to protect nature. In 1948, the International Union for Conservation of Nature was created. In the USSR in 1978 a special Law of the USSR on Nature Protection was issued. More than 350 species of animals and 650 species of birds live on the territory of our country. Among the many nature reserves of the country there are such large scientific centers as Askania-Nova, Astrakhan, Belovezhskaya Pushcha, Laplandsky, Caucasian, Issyk-Kulsky, etc. They do a lot of work on animal hybridization 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 non-crossing 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, to penetrate into it. If a hybrid zygote is formed, then due to embryonic pathology, either the resorption of the fetus occurs on early stages formation, or its death. This is explained by the fact that the body's immune protective bodies fight the penetrating foreign protein, destroying it. Due to the genetic differences of the parents in hybrids, the formation of male and female germ cells is disrupted and they become infertile. The sterility of the hybrids is caused by abnormalities in the development of the gonads and mitosis.

The rapid development of cytogenetics in our 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 the gene composition that does not affect the behavior of chromosomes, their morphology.

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

It has been established that in cases where there are gender 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 in the selection of pairs for crossing, taking into account the sex of the parents (reciprocal selection). We have indicated only the main methods and means of overcoming the non-crossing of distant species and the infertility of hybrids. The rapid development of genetics, molecular biology, biotechnology, genetic and cell engineering in our days, apparently, will allow in the near future to completely solve the problem of infertility in the 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. Hybridization of cells is practically done as follows: unrelated cells of two organisms, the useful qualities of which it is desirable to combine when crossing, are cultivated on an artificial nutrient medium, then the culture is mixed. Under certain conditions, some of the cells merge. So far, the process of formation of hybrid systems from cells is chaotic. However, with the improvement of this method, it should be expected that somatic hybridization of cells in tissue culture will be used as an experimental model of interspecific hybridization of animals.

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

The most ancient form of hybridization is crossing horses with donkey and getting mule. Even in ancient Rome, mule breeding was widely developed. The mule is an excellent pack animal, unrivaled in endurance, longevity and efficiency. It is obtained by crossing a donkey and a horse; when a donkey is mated with a stallion, a hinny will be born. The mule is larger and more valuable than the horse, but is generally sterile. Breeding these animals "in itself" is impossible.

In our country, in Askania-Nova, great work Of some interest is the hybridization of a horse with zebras and the production of strong hardy zebroids, as well as the crossing of a domestic horse and its wild ancestor, the Przewalski horse. Males from such crossing are sterile, and females are fertile. According to E. P. Steklenev, these species show differences in the karyotype (the number of chromosomes in the domestic horse is 64, in the Przewalski's horse 66), as well as features of gametogenesis. In hybrid infertile males, despite the completeness 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. In many farms, such issues as the selection and selection of pairs, the biological characteristics of zebu-like cattle, their adaptability to local conditions, etc. have been studied. It has been established that hybrids are resistant to piroplasmosis, inherit increased milk fat and protein from zebu, and are responsive to improved feeding and keeping conditions. , pay well for food, have excellent meat qualities. The meat contains an increased amount of fat and protein, the slaughter yield reaches 60%. Less frequently, there is a disease of the udder, gastrointestinal tract, and hooves. It is also important that hybrids obtained by crossing cattle with zebu are fertile.

Due to the concentration and intensification of animal husbandry in all climatic zones In the USSR, the hybridization of factory breed cattle with zebu makes it possible to create dairy and beef cattle breeds that meet the requirements of the new (industrial) technology of the industry. Of great interest are the works carried out in the scientific and experimental farm "Snigiri". 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 bred on the basis of 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.

Of great interest are the works on hybridization of cattle with banteng, carried out in Askania-Nova. Hybrids from crossing banteng with red steppe cattle are characterized by excellent meat qualities, pronounced heterosis. 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. Buina on three-breed crossing (Santa Gertrude x Webu x Red Steppe breed; Shorthorn Zebu x Red Steppe breed). Availability
zebu blood in both variants of crossing gave excellent results. Created new type beef cattle.

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

For hybridization, bison are also used, of which there are only a few hundred worldwide. Now the number of bison is being restored. Of considerable economic interest are hybrids of cattle and bison. 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 named bifalo. The hybrid offspring, which has 3/8 of the blood of a wild bison, 3/8 of the Charolais and 3/4 of the blood of the Herefords, is characterized by high precocity (weighs 400 kg at 10 months of age), well-developed meat forms. Data from laboratory studies have shown that the meat of such hybrids contains 18-20 protein and only 7 fat. The main type of food for bifalo hybrid animals, according to D. Bissolo, is pasture grass. They are hardy, have a high resistance 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 large view antelope: males weigh 700 kg, females - 540-500 kg. Females give milk well, milk yield per lactation does not exceed 700 kg, but the fat content of milk reaches 10-14. The milk of eland antelopes has healing and bactericidal properties. Yogurt from this milk does not spoil for many years under normal conditions. Now methods have been developed for obtaining sperm from eland males on the vagina and artificial insemination of cows is being carried out in order to obtain hybrid forms.

A lot of work is being done in Askania-Nova and in a number of other reserves of the country to create new breeds of deer. As a result of long-term complex intraspecific hybridization, the Ascanian deer breed was bred. European maral deer, Crimean and Caucasian deer and wapiti (the largest steppe deer) participated 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 the creation of fine-fleeced breeds of sheep. crossed wild sheep mouflon with a fine-fleeced sheep, he received a new breed of fine-fleeced sheep - mountain merino. Animals of this breed inherited from the wild mouflon the ability to move quickly, overcoming long distances, live in high mountains, to use alpine pastures, and from rambouillet - valuable productive qualities of fine-fleeced sheep. By the method of distant hybridization in the mountains of Kazakhstan, Soviet scientists have bred the fine-wooled breed of archaromerinos.

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

Remote hybridization in poultry farming gained wide scope, 96 species of birds belonging to 13 orders produced fertile offspring. Of greatest interest are hybrids of an ordinary pheasant with a wild Caucasian (Askanian pheasant), hybrids of a domestic duck with musky ducks (mulards), chicken and peacock, guinea fowl and pheasant, turkey and guinea fowl, and many others that have excellent fattening qualities. Work on remote hybridization of poultry is being successfully carried out both in the Astrakhan 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 distant hybridization, the use of the gene pool of wild forms. At present, only the use of hybrids can provide an accelerated growth in the productivity of industrial pig breeding. Taking into account this situation, 19 hybrid pig breeding centers are being created in the country. Hybridization ensures the manifestation of the heterotic effect.

In the context of the intensification of pig breeding, a new direction in hybridization has appeared. The scientific substantiation of hybridization in pig breeding is based on the relatively independent inheritance of reproductive, fattening and meat qualities in pigs. This allows you 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 breeding, 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 Greek heteroiosis - change, transformation). Heterosis is understood as the superiority of the offspring of the first generation over the parental forms in terms of viability, endurance, growth energy, fertility, constitutional strength, resistance to diseases, which occurs when different races, animal breeds, and zonal types are crossed.

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

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

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

• hybrids (or crossbreeds of the 1st generation surpass their parents in live weight and viability;
• crossbreeds of the first generation surpass their parents in constitutional strength, longevity, physical performance with complete or partial loss of fertility;
• crossbreeds of the 1st generation in terms of live weight occupy an intermediate position, noticeably surpass their parents in terms of multiple pregnancies and viability;
• each individual feature behaves according to an intermediate type
  inheritance, and in relation to the final product there is an increased
  heterosis;
• crossbreeds, or hybrids, do not exceed the best parental form in terms of productivity, but have a higher level of productivity compared to the arithmetic mean of both parents.

The 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 parental 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 action leads to the heterosis effect. This explanation is called balance heterosis. Subsequently, Lerner and Turbin continued to develop this provision.

According to them, heterosis is caused by the action of many genes mutually balanced in the genome in 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 a combination of genomes, which leads to the appearance of heterosis. Consequently, heterozygosity accompanying crossing undergoes the pressure of various factors and thus creates a balanced interaction of genes in the genome.

In the practice of livestock breeding, the so-called negative heterosis is sometimes observed, when the offspring have a trait level below the average of the parents, but slightly higher than the level of the trait of the parent in which 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 in inheritance was described by Ya.L. The wool shearing of the first generation crossbreeds was somewhat greater than that of the Angora goats, in which it was 4-5 times greater than that of the coarse-haired and local goats.

Modern animal husbandry 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: the breeding of hybrid bird lines using different types imbreeding and crossing (crossing) lines to obtain the so-called hybrid bird, which manifests heterosis. For example, in the Netherlands, Eurybrid works with two crosses of egg-oriented chickens: Highsex White (white shell based on leghorn) and Highsex Brown (with the participation of Rhode Island and Newhamshire with brown shells. These two crosses occupy a leading position in the global poultry industry.

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

The use of the effect of heterosis is also used in work with other animal species, especially in beef cattle breeding, sheep breeding, camel breeding, and fish farming. Methods for obtaining the effect of heterosis are varied. Heterosis is manifested 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, haupgamitin - in Jamaica). In our country, distant hybridization was carried out between fine-fleeced sheep and argali and bred new breed- archaromerinos. In Kyrgyzstan and Altai, hybrids of yak with Simmental cattle have been obtained. Heterosis in 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 surpass 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 in terms of milk yield are given by N.F. Rostovtsev from the experience of crossing Ostofrisian cows with bulls of the Red Gorbatov breed. In dairy cattle, the effect of heterosis is observed more often in terms of the total amount of milk fat per lactation, especially when crossing cows of different breeds with bulls of the Jere breed.

In pig breeding, interbreeding industrial crossbreeding is used more widely. Scientific institutions of our country have experimentally tested more than 100 variants of industrial crossbreeding of pigs. In many cases, the effect of heterosis has been established. Basically, it manifested itself in an increase in fertility, the viability of the offspring, and an improvement in its fattening qualities. In the experiments of M.A. Selekh crosses from crossing queens of large white breed with Berkshire boars spent feed per 1 kg of live weight gain per 0.5 -1 feed. units less than the original purebred animals.

According to M.A. Zhabaliev hybrids (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, crossbreeds from crossing pigs of Large White and Estonian breeds gave 600 g of average daily gain in live weight when fed, and the original breeds, respectively, 548 and 560 g. According to V.O. Chetyrkin, higher gains and better feed payment compared to the original breeds the crosses differed from the crossing of the queens of the large white breed and the boars of the Moldavian black breed group. The average daily gain in live weight was 598 g, the cost of feed per 1 kg of gain was 4.0 cor.un. Moldovan - 394 and 4.3%.

In addition to egg production, when interbreeding chickens, heterosis is expressed in increased embryonic and postembryonic viability, in growth energy, improved meat quality and feed payment.

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

Heterosis using heterogeneous selection in intrabreed mating. The use in purebred breeding of crosses of lines, lines of producers and families, as well as the mating of animals belonging to the same breed, grown in different conditions, are also options for heterogeneous selection. Heterosis using heterogeneous selection during intrabreed mating, in which the mated animals are in the same household, do not have a clear 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 conformation-constitutional features.

The problem of obtaining and enhancing the effect of heterosis has not been fully resolved. The main indefinite obstacle is the loss of the heterosis 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 you to maintain heterosis in several generations. One of the most accessible and effective methods is variable crossing, which is used in commercial (commercial) animal husbandry. At the same time, from the crossbreeds of the first generation obtained from crossing the queens of breed A with the producers of breed B, the best part of the queens is isolated and crossed with the producer of breed C, a crossbreed of the second generation is obtained, with the manifestation of heterosis when three breeds are combined (A, B, C) Further crossbreeds of the second generation can be crossed with the producer of the breed D and get more complex crossbreeds in which the heredity of the original maternal breed A and the heredity of the paternal breeds B, c and D are presented. Other methods to preserve the effect of heterosis have not been developed in animal husbandry.

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 postembryonic viability, a decrease in feed costs per unit of production; increase in precocity, fertility, productivity; manifestation of broader opportunities for adaptation to changing conditions and new elements of technology. The wide range of the heterosis effect, which manifests itself in a variety of reacting traits, is a reflection of the physiological and biochemical processes determined by the peculiarities of the genetic apparatus of heterotic animals.