Video: Breeding Systems For Cats
In order for selection and breeding to be carried out most effectively, it is necessary to adhere to a certain breeding system. Unfortunately, most Russian breeders do not follow this rule. Their breeding of cats in the language of such a discipline as breeding is called random breeding, or random crossing. In random breeding, there are almost no related mating, and the few closely related mates that do occur occasionally have no sign of any meaningfulness.
Outbreeding and outbred dysgenesis. Most often, inexperienced breeders tend to avoid related breeding and prefer all kinds of unrelated, distant mating options - the so-called outbreeding.
They motivate this, as a rule, by the fact that inbreeding leads to degeneration, for some reason they understand this word as the appearance of "freaks". By "freaks" in this case, mutants, and weakened, and sick animals are equally meant. In this sense, outbreeding can be no less dangerous than inbreeding, and besides, it is fraught with, though not so fatal, but unpleasant result: the simplification of the type of offspring.
Qualitative, but genetically heterogeneous sires can produce offspring of a weak breed type. This is due to the mechanism of inheritance of morphological characters. However, the consequences of outbreeding can be much more serious.
Everyone knows that hybrids between animals of different species are often sterile. It often happens that these hybrids do not reach their normal size, remaining underdeveloped. These developmental disorders, called hybrid dysgenesis, arise from the incompatibility of the genetic systems of two representatives of different species. Indeed, a living organism is an integral system, and during its development, genes must be included in the work in a certain order, and the activity of some affects the inclusion or shutdown of others. In a hybrid animal, this system is disrupted, the genes, figuratively speaking, do not fit together.
Roughly the same thing often happens when two cats of the same breed are crossed, but belonging to different populations and having no common ancestors. Usually the consequences are not as tragic as with interspecific hybridization.
Deviations are especially noticeable in those breeds, whose development is significantly different from natural. So, for example, two variants of the development of the head in Persian kittens are known: in some individuals, there is an intensive growth of the brow ridges and zygomatic bones at the age of one month and older, in others - the outstripping growth of these areas, and by the age of 1.5-2 months the growth rate the bones of the skull are aligned.
What will happen when such cats are crossed, if not a violation of the development of the skull and facial skeleton? An analysis of the pedigrees of anomalous animals showed that any displacement of the jaws and asymmetry of the structure of the head in Persians, underdevelopment of the upper jaw in Oriental and Cornish Rex, as a rule, is the result of outbred dysgenesis.
In breeds with a developmental type close to natural, a single outbreeding does not give such visible consequences. But the constant "pumping" of uncontrolled genes during regular unrelated mating leads to imbalance in the genome: animals cease to be balanced, imbalances appear in the structure of the body and head, the angles of the bony joints, the correlations of the muscular apparatus and ligaments, and the like.
This is not a call to stop unrelated crossbreeding and go exclusively to inbreeding. Reasonably reasonable outbreeding is, of course, necessary for the progress of the breed. But this type of crossing cannot be made the main, if not the only, method of breeding work.
Inbreeding. All breeding systems are based on inbreeding. Related mating is necessary in order to genetically fix the traits, that is, to achieve homozygosity for the genes that determine them. It is clear that in litters obtained from homozygous parents, splitting of kittens by external signs will not be observed.
Inbreeding is performed on a cat or a cat that is outstanding in its exterior qualities (less often - for a couple of sires), which, ideally, should have a high prepotency for a complex of significant traits.In addition, this sire should not be a carrier of recessively inherited anomalies. After all, those breeders who do not practice inbred crosses, fearing "degeneration", in fact, are afraid of splitting into a homozygous form of these mutant alleles. But there can be no real degeneration, more correctly, inbred depression, neither in the first nor in the second generation, even with the closest inbreeding.