INBREEDING IN THE MIRGORODIAN PIGS
Authors: Voitenko S. L. , Vishnevsky L. V. 
Published: November 2018

The problem of inbreeding in livestock, which is directly related to breed creation, the improvement of breeding methods and the preservation of the gene pool of populations, although highlighted in the works of many researchers, has no logical conclusion to date. Biologists, geneticists and breeders cannot give an unambiguous answer to the question of the effectiveness of the use of related breeding in livestock, although it is common knowledge that inbreeding was one of the main means of breeding work for the creation of cultivars of farm animals in the world.

It is impossible to make a single conclusion about the positive or negative effects of related breeding. Probably the effect of a related breeding does not depend on the inbreeding itself but on the animal on which it is applied, and on the degree of homozygosity of inbred animals. While the growth of inbreeding did not exceed the optimal homozygosity for a certain kinds, it is possible to obtain high-yielding individuals that consistently transmit hereditary signs to offspring. Undeniable can also be considered the use of this method in the creation of new lines, types and breeds, the detection of hidden alleles, the consolidation of animals, etc. However the smaller the population in terms of the number of individuals and, first of all in the number of pedigrees, the use of related breeding will result in loss of heterozygosity and the creation of an inbred genotype. That is why the constant control of animal productivity, especially low-inheritance traits, in a small number of pedigrees in local populations and the presence of inbred animals, is an urgent problem of the present.

The purpose of our research was to determine the number of inbred sows of the mirgorodian breed in general on the breed and directly in each of the available families, the coefficients of inbreeding, as well as the effect of inbreeding on the number of emergency farms and multiplicity of the uterus.

Studies were conducted on stems of the mirgorodian breed. Our research has established that mirgorodian breed of pigs is concentrated in only one breeding plant in Ukraine. Genealogical structure of the herd consists of 11 families of sows (150 main sows) and 7 lines of boars (13 main boars). Moreover, the number of animals in the herd is constantly reduced. When breeding pigs of mirgorodian breed of this herd during the last 10–20 years, a selection of mutters and uterus belonging to different lines was used to avoid the related breeding. In order to reduce the number and probability of occurrence in the flock of inbred animals, breeders, when developing a parry plan, select the stumps and moths that are not related to each other within the first to third generation.

Our researches found that among the 165 analyzed sows of mirgorodian breed of 11 available families, the number of outbred individuals is 52%, and inbreds – 48% for the different ratio of inbred and outbred mothers within families.

Determined complex inbreeding of sows of mirgorodian breed testifies that the investigated female individuals of this population are inbred in degree 0,78–10,1%. At the same time, the vast majority of inbred mothers do not have a high homozygosity coefficient of 1.56–2.34%, and only single animals are inbred at a rate of 6.25–10.1%. Inbred sows of the mirgorodian breed, without their distribution by degree of inbreeding, had a lower number of emergency farms, as compared with outbred ones, as a whole in the group of animals, and in the context of families.

The positive aspect of the inbred sows of mirgorodian breed was also somewhat higher infertility in the average for a number of farrowing in the families – 10,2 heads, compared with outbreds, in which this figure was at 9,9 points. From what it is possible to draw a conclusion about the positive influence of inbreeding not a high degree of tightness – not higher than 10%, on indicators of reproductive ability of sows of mirgorodian breed.