Activity of protein and carbohydrate metabolism enzymes in black pied heifer blood in relation to subsequent reproductive intensity

Abstract

The character of metabolism in the precalving period is one of the factors determining the reproductive potential of dairy cattle. The purpose of the present investigation was a comparative analysis of the activity of a number of metabolic enzymes participating in protein and carbohydrate metabolism in Black Pied heifer blood at different stages of pregnancy in connection with further reproduction indices. Regardless of the length of the subsequent service period, the activity of aspartate aminotransferase (AST) in blood in the late stage of pregnancy was 1.7 times lower than in the middle stage. The activity of alanine aminotransferase (ALT) in blood also decreased in the late stage; however, this decrease was expressed more strongly in animals with a service period length greater than 150 days (by 1.8 times) than in animals with a service period length less than 150 days (by 1.3 times). In this case, the AST/ALT ratio decreased with progressing pregnancy in heifers with increased reproductive capacity (p < 0.05) and didn’t change in heifers with reduced reproductive capacity. In the blood of animals with a longer service period, the AST/ALT ratio was 1.3–1.7 times higher (p < 0.05) than in blood of animals with a shorter period. No significant variability was revealed in the activity of alkaline phosphatase and lactate dehydrogenase depending on progressing stages of pregnancy and on the reproductive potential of heifers.