Postpartum blood biochemical profile in heifers in connection with polymorphic variants of the SCD1 gene and reproductive ability

Abstract

Abstract. The purpose of this study was to compare the biochemical profile of blood in the first two months of lactation in first-calf cows with polymorphic variants of the stearoyl-CoA-desaturase gene (SCD1) and its relationship with reproductive parameters. Methods. The work was carried out in one of the breeding factories of the Leningrad Region on first-calf cows of the Holstein breed with an average milk yield of 9073 ± 263 kg for 305 days of lactation. Animal genotypes were determined by PCR-RFLP. Serum samples were used to determine the content of total protein, albumin, urea, glucose, triglycerides, cholesterol, the activity of the enzymes AST (aspartate aminotransferase), ALT (alanine aminotransferase), alkaline phosphatase (alkaline phosphatase), GGT (γ-glutamyl transferase). Laboratory studies of blood serum were performed on a RX Daytona biochemical analyzer (Randox Laboratories, UK) using reagents from Cormay, Poland. The results of the study. Of the 20 individuals, 12 animals were carriers of the CT genotype, the remaining first-calf cows had the CC (n = 6) and TT (n = 2) genotypes. Blood biochemical parameters were determined in animals with CT and SS genotypes. On the 44-50th day of lactation in animals with CT genotype, the urea concentration and AST activity decreased by 1.2–1.3 times (p ≤ 0.001). In individuals with the SS genotype, no change in these indicators was found. As a result, at the end of the second month of lactation in cows with the SS genotype, blood urea and AST activity were 1.2 times higher than in animals with the CT genotype. The content of total cholesterol increased 1.3–1.4 times (p < 0.01) by the 6–7th week of lactation in cows of both genotypes (SS and CT). The remaining biochemical parameters did not differ between time intervals within the same genotype, and between groups of animals with different genotypes. When distributing the examined cows into groups depending on the genotype and service period, it was found that the duration of the service period of more than 150 days is twice as common in individuals with the CC genotype. In cows with the heterozygous ST genotype of the SCD1 gene, biochemical profile indicators are more optimal, which may be associated with an increased frequency of occurrence of individuals with a shorter service period.