Assessment of liver enzymes observed through the prism of the influence of daily cow's milk production
Objective: The aim of the study was to determine the possible impact of the total daily amount of skim milk on the level of bilirubin and liver enzymes through regression analysis. Materials and Methods: The study included 63 Holstein-Friesian cows. They were formed in 3 groups, based on the amount of daily milk production. Peripheral blood was punctured, through which the activities of total bilirubin were analyzed (μmol/L), as well as liver enzymes: alanine aminotransferase – ALT (U/L), aspartate aminotransferase – AST (U/L), lactate dehydrogenase – LDH (U/L) and alkaline phosphatase – ALP (U/L). Results: The lowest concentration of total bilirubin in blood plasma was recorded in the group of cows that have the lowest daily milk production (1.295 ± 0.255 µmol/L), and highest concentration is in cows that produce the most milk (1.855 ± 0.159 µmol/L), but intergroup differences are not significant. Regression analysis found a statistically significant relationship between the amount of produced daily milk and the concentration of total bilirubin (R2=0.132, p=0.0050.05). Conclusion: The activities of bilirubin and liver enzymes in the examined cows were in physiological balance. This indicates that the cows on the farm are raised in modern and good zootechnical and feeding conditions. In such conditions, dairy cows are able to maintain blood composition and homeostatic integrity within physiological limits and adequate reproductive and productive capacity.