The role of <i>LEP</i> R25C polymorphism in the predisposition of cows to ketosis

Abstract

In conditions of intensification of the dairy cattle industry, persistent stress of metabolic processes in the cow's body can lead to metabolic disorders and the development of ketosis. Scientists have established the genetic susceptibility of cows to ketosis. The available data allow us to consider the leptin gene (LEP) as one of the candidate genes. The purpose of the study is to carry out an associative analysis of the predisposition to ketosis of Kostroma cows of different genotypes according to the leptin gene. The research was carried out in 2022-2023 yy on clinically healthy and highly productive fresh cows of third lactation and higher of the kostroma breed (n=167) in pedigree farms of the Kostroma region. In animals in the postpartum period, the content of ketone bodies in the blood was determined by express method and the RT-PCR genotypes were determined by the R25C locus of the LEP gene. Groups of cows were formed depending on the content of ketone bodies in the blood: 1st – 0-1.2 mmol/l (healthy), 2nd – above 1.2 mmol/l (subclinical ketosis). It was found out that among the experimental cows of the Kostroma breed, the CT genotype is characterized by the highest frequency. The almost complete absence of differences in the concentration of ketone bodies in the blood between carriers of different LEP genotypes from group 1 was determined. At the same time, among the animals of the 2nd group, the highest level of ketone bodies in the blood was observed in heterozygous animals, whereas carriers of the CC and TT genotypes did not differ from each other in this indicator. Heterozygous animals classified as subclinical ketosis had the highest average ketone concentration in the blood with the highest coefficient of variation (Cv=51.6%), which indicates a pronounced influence of other genetic factors. Thus, the role of LEP R25C polymorphism in the predisposition of cows to ketosis disease has not been established in this sample of animals, but may be supplemented by the influence of other factors, these hypotheses need to be tested in a larger sample and in other breeds of cattle. These data can be used to conduct such exploratory studies, such as the research of complex genotypes of genes that cause predisposition of cattle to ketosis.