Comparative characteristics of polymorphisms of melanocortin 4 and ryanodine 1 receptor genes of Myrhorod pigs before and after the African swine fever outbreak

Abstract

One of the global problems that are anthropogenic in nature is the sharp decline in biodiversity, a special case of which is the reduction in the number of species of wild animals and the number of breeds of farm animals. The Myrhorod pig breed, due to its genetic and biological characteristics, is of great importance for the process of preserving the biodiversity of agricultural animals. The study’s object was Myrhorod breed pigs, the study focused on the variations in the allele frequency of the RYR1 / SNP g.1843 C>T and MC4R / SNP c.1426 G>A genes that occurred in the Myrhorod breed as it recovered from the African swine fever epidemic. The age at which one pig reaches 100 kg (days); the average daily weight gain from 90 days to slaughter (g); the thickness of the backfat (mm); the length of the carcass (cm); the cross-sectional area of the longest back muscle at the level of the 6th and 7th thoracic vertebrae (cm2); the slaughter output (%); and the yield of meat, fat, and bones from the carcass (%) are other quantitative changes in indicators of fattening and meat productivity. Significant alterations in the SNP marker MC4R polymorphism were observed during the restoration of the Myrhorod pig breed after the African swine fever epidemic. The frequency of the A allele dropped by 2.79 times to just 26.9% from 75.0%, which was 3.17 times higher than the frequency of the G allele until 2019. These alterations resulted from the forced crossing of the Myrhorod breed with the Pietrain breed, which has a high frequency of the G gene (83.0%), during the early phase of the breed's restoration in order to prevent close inbreeding. It is suggested that animals with the AA genotype should be preferred during further restoration in order to restore the Myrhorod breed to its original state. If crossbreeding becomes necessary again (to prevent excessive inbreeding), only breeds related to the Myrhorod (Berkshire, Poltava meat, Large White) should be used. The allele frequency in 2023 did not differ substantially from 2015 or 2019, based on the RYR1 DNA marker. The recessive T gene at the RYR1 g.1843 C>T locus was absent in 2023, confirming the stress resistance of the Myrhorod breed. When compared to the same indicator in the population of 2019, the average daily gain in the live weight of pigs belonging to the restored Myrhorod breed in 2023 was higher. Although this is a good development in terms of making profits by producing this breed of pig, these notable variations might point to important shifts in the polymorphism of genetic markers linked to growth rate. To determine the extent to which restoration has altered DNA markers linked to this productive attribute, more research is required to examine the frequency of alleles of genes linked to growth intensity.