Predicting Predisposition to Subclinical Ketosis in Holstein Cattle Based on Polymorphism Analysis of the DGAT1, GHR and GH_2141 Genes
This article presents the results of a study investigating the genetic factors influencing the predisposition of first-lactation Holstein cows to subclinical ketosis, based on an analysis of polymorphisms in the DGAT1, GHR, and GH_2141 genes. The study involved 940 first-lactation cows housed at the "Krasnodarskoe" training and experimental farm of Kuban State Agrarian University. We analyzed the associations between the genotypes of these genes and the physicochemical milk parameters, including acetone, ß-hydroxybutyrate, fat, urea, and casein content. The polymorphism of the DGAT1 gene was found to primarily affect lipid metabolism. A moderate positive correlation was identified with fat content, along with a pronounced negative correlation with acetone levels. For the GH_2141 gene, no significant association with protein or nitrogen metabolism parameters was established; however, a moderate negative correlation with ketone body concentration was observed. Analysis of the GHR gene demonstrated a weak effect on the studied traits, although a tendency for altered acetone and ß-hydroxybutyrate levels depending on the genotype was noted. The findings indicate the complex influence of genetic factors on the metabolic status of animals and confirm that individual genetic markers do not provide high predictive accuracy without considering environmental factors. It is demonstrated that using polymorphisms of the DGAT1, GHR, and GH_2141 genes in conjunction with biochemical milk parameters improves the effectiveness of early diagnosis of subclinical ketosis. The research materials can be applied in the development of breeding programs aimed at reducing the risk of metabolic disorders and increasing the resilience of high-producing dairy herds.