Association of leptin gene polymorphisms with predisposition of cattle to ketosis
Leptin is a hormone produced by adipocytes - cells of adipose tissue, involved in the regulation of eating behavior, affecting the reproductive function, as well as the growth and Constitution of animals. In certain physiological conditions in cows, intensive use of their own fat reserves leads to excessive appearance of volatile fatty acids in the blood, which, in turn, become «satiety signals» and lead to a reduction in feed consumption. At this point, the genetic characteristics of the animal associated with the regulation of metabolism, eating behavior, contributing to or preventing the possible development of ketosis become particularly important. The aim of the research is to determine the possible influence of the leptin locus genotype (y7f, a80v, R25C polymorphisms) on the frequency of ketosis in cattle. We have genotyped Holstein breeding bulls (PCR/RFLP) belonging to WWS (USA) based on the A80V, R25C, and Y7F loci of the leptin gene, which were evaluated by their daughters and «ketosis resistance coefficients» (Wellness trait index (WT$) ketosis) were determined with a high level of confidence. It was found that the group of breeding bulls with the AARRYY genotype is distinguished by a significantly higher average index of «daughters' resistance to ketosis» compared to the AARCYY and AVCCYY groups, which may indicate that the AARRYY genotype in breeding bulls is one of the genetic factors protecting their daughters from the development of ketosis. In addition, 150 Holstein cows were genotyped using the same loci, of which 50 had ketosis and 100 were healthy. In the group of healthy Holstein cows, compared with the group of animals with ketosis and hepatopathology, the AARCYY genotype was three times more common.