Productivity of Cows of the Ukrainian Red-Spotted Dairy Breed with Different Genotypes According to the TLR1, SLC11A1 and CSN2 Loci

The use of methods of marker-associated selection opens up new perspectives in the context of maximum realization of the productive potential of animals, which makes the issue of the application of modern scientific approaches in animal husbandry particularly relevant. Considering this, the analysis of the productive qualities of cattle with different genotypes according to the set of candidate genes is one of the most urgent tasks of animal genetics and breeding. Therefore, the purpose of this study is to analyze the productive qualities of cows of the Ukrainian red-spotted dairy breed with different genotypes according to the TLR1, SLC11A1 and CSN2 loci. Genotyping of cattle individuals was performed using the PCR-RFLP method for TLR1 and SLC11A1 and AS-PCR for CSN2. The analysis of productive qualities of animals was carried out by comparing the parameters of three lactations for each group of animals according to the indicators of average milk yield for 305 days of lactation (kg), protein content in milk (%) and milk fat content (%). The study was carried out on the basis of previously obtained results of individual typing of individuals according to research loci. According to the results of studies conducted in the experimental population of cows for the toll-like receptor 1 (TLR1) locus for the first and third lactations, the dominant values of the yield index are characteristic of homozygotes with the GG genotype, while for the second lactation the highest values of yield are observed for homozygous individuals for allele A. At the same time, a probable difference between the indicators of individuals with different genotypes was not established.No significant difference between the groups of cows with the studied genotypes in the parameters of fat and protein content in milk by the TLR1 locus was also found. SLC11A1 is characterized by a characteristic difference from the previous gene, as two mutations forming haplotypes – CC-AA, СG-AA and CG-AT out of nine potentially possible variants were found in this locus. According to indicators of milk productivity, animals with the СG-AA haplotype had higher values of milk compared to other haplotypes during all three lactations (the difference is probable). The greatest differences were observed with the CG-AT haplotype. According to the indicators of the content of milk protein and fat, no probable differences between individuals with different haplotypes were established. The variability of signs for all lactations was at a low level. As for the beta-casein locus, according to the results of the conducted research, no significant difference in the indicators of milk productivity of cows with different genotypes was found. The highest confidence values are characteristic of individuals with the A1A1 genotype, however, the difference with individuals with other genotypes is unlikely. In any case, the A2 allele, according to the value of the indicators of homozygous individuals (genotype A2A2), does not have a negative effect on the parameters of milk productivity of animals