Milk productivity and the concentration of ketones in the blood of Kostroma cows of different LEP genotypes

Abstract

Relevance. Currently, scientists are searching for genes associated not only with an increased level of dairy productivity, but also with the preservation of functional longevity and health of cows, with a high level of realization of their genetic potential, as well as with the distinctive quality of dairy products. The available data allow us to consider the leptin gene (LEP) as one of the candidate genes of milk productivity.Methods. The research was conducted in 2022–2023 on cows of the Kostroma breed (n = 107) bred in the Kostroma region. In cows in the postpartum period, the content of ketone bodies in the blood and genotypes were determined by the R25C locus of the LEP gene. The animals were divided into groups depending on the concentration of ketone bodies in the blood: 1st – 0–1.2 mmol/l, 2nd – above 1.2 mmol/l.Results. The presence of a predisposition of highly productive cows to ketosis (р < 0.05) was established. The largest number of ketone bodies in the blood was determined in animals of the 2nd group with the LEPCT genotype. However, despite such a small difference, the difference in the frequency distribution of LEP alleles in groups 1 and 2 turned out to be statistically significant (χ2 = 63.48, р < 0.001). When testing the hypothesis of a significant dependence of the level of milk productivity on the concentration of ketone bodies in the blood of carriers of the CC genotype, a statistically significant rho value was obtained among cows with the CC genotype, at the level of 0.37 (р = 0.038). The rank correlation between milk yield and ketone body content in carriers of LEPCT and LEPTT genotypes was low and unreliable (р > 0.05). The tendency towards a close relationship between the level of ketone bodies and the fat content in the milk of cows of the TT genotype due to its low concentration in the sample requires further confirmation in a larger sample of cows with this genotype of the leptin gene.