Inbreeding Of Dogs And Its Use In Breeding Work

To solve certain zootechnical problems when conducting breeding work with animals, one has to resort to the use of an extreme form of homogeneous selection by origin - inbreeding (inzukhta), or related mating.

Inbreeding is considered to be a pairing in which the father and mother of the future offspring are consanguineous, that is, they have one or more common ancestors

Usually, the cases of inbreeding are established by the pedigrees of the animals. If the same animal (or several animals) is found in the pedigree on the part of the mother and father within the first five rows of ancestors, then it is considered that this animal (proband) was obtained by using inbreeding. If in the maternal and paternal parts of the pedigree of a proband in five rows there are no common ancestors, or they occur taking into account the sixth and more distant rows, then the proband is outbred.

Afghan Hound

Inbreeding for one ancestor is called simple, and for two or more ancestors - complex or complex … To account for the degrees of inbreeding, the methods proposed by Shaporuz and Wright are widely used. Shapruzha's method is that the ranks of the proband's ancestors in the pedigree, starting with the parent, are indicated by Roman numerals. Then write down the row in which the common ancestor is found in the maternal part of the pedigree, and through a dash the row in which it occurs in the paternal part of the pedigree. If an ancestor in one side of the pedigree is repeated several times, then write down all the rows in which he occurs, separating them with commas. If the ancestor is repeated only in one side of the pedigree, then from the side where it is not, they put zero and write down the rows in which it repeats after a dash, separating them with a comma. At the same time, it is believed that the proband was learned by mating unrelated animals, but one of its ancestors was inbreeding. So, Trumpeter 195 / G,whose pedigree was borrowed from the book of B. V. Dmitriev Hounds (M., Agropromizdat, 1987, p. 93) and corrected in accordance with the existing rules for recording ancestors *, obtained as a result of the use of complex inbreeding in degrees II - III on Hornist (Vlad. Sadikov) and III - IV at h. Budilo 5651 (owner Baryshnikov).

Несмотря на то, что ч. Будило в родословной встречается трижды - один раз в третьем ряду и дважды в четвертом, инбридинг на него при получении Трубача 195/Г следует записать в степени III - IV, а не III - IV, IV, ибо он как отец Горниста уже был учтен в записи инбридинга в степени II - III на Горниста. А поскольку он передает свои наследственные качества и через Тараторку 11 7369, то сочетание его как отца Горниета в материнской части родословной и отца Тараторки в отцовской части и записывается. В четвертом ряду родословной Трубача 195/Г с отцовской стороны дважды встречается Найда и Заливай. Эти случаи следует записать как 0 - IV, IV на Найду и 0 - IV, IV на Заливая. Сам Трубач 195/Г не был инбридирован ни на Найду ни на Заливяя. На них была инбридирована бабушка Трубача 195/Г Волторка, полученная в результате спаривания родных, причем полных, брата и сестры.

Based on this recording system, the following degrees of inbreeding are distinguished: inbreeding (I-II, II-I, I-III, III-I, II-II); close related mating (II-II, III-II, III-III, II-IV, IV-II, I-IV, IV-I); moderate related mating (III-IV, IV-III, IV-IV, IV, VI). More distant degrees of related mating refer to distant inbreeding, which, as a rule, is not taken into account. The closest case of incest is the mating of littermates. Mother-son mating is considered closer than father-daughter mating.

The use of the method of accounting for the degrees of inbreeding according to Shapourouge, especially with complex inbreeding, often does not make it possible to establish in which case the animals were more inbreeding, i.e. does not allow quantifying the degree of inbreeding. It does not reflect this method and the genetic essence of inbreeding, which consisted in the fact that it leads to a decrease in heterozygosity and an increase in homozygosity.

S. Wright suggested calculating its coefficient or coefficient of increase in homozygosity as a measure of inbreeding. For this purpose, Wright's formula, slightly modified by D. A. Kislovsky, is usually used.

The inbreeding coefficient is expressed as a fraction of one or as a percentage (0 to 1 or 0 to 100 percent). It does not show the absolute homozygosity of inbred individuals, but only the probable degree of its increase in them as a result of the use of inbreeding in comparison with animals obtained during outbred mating,

In the calculations, the initial homo- and heterozygosity of animals is taken as 0.5 or 50 percent, that is, it is believed that half of all genes are homozygous and half are heterozygous.