Endocrine and Metabolic Status of Dairy Cows during Transition Period

Abstract

The objective of this study was to determine blood levels of cortisol, insulin, triiodothyronine (T3), thyroxine (T4), glucose, non-esterified fatty acids (NEFA), β-hydroxybutyrate (BHB), triglycerides (TG) and total cholesterol in dairy Holstein cows (n = 40) during the transition period. The test cows were classified into four groups: Group A (n = 10), clinically healthy late-pregnant cows from day 20 to day 10 before calving. Group B (n = 10), clinically healthy late-pregnant cows from day 10 to day 1 before calving. Group C (n = 10), clinically healthy puerperal cows. Group D (n = 10), puerperal ketotic cows. The blood serum of ketotic cows was found to have lower levels of T3 (p < 0.01), T4 (p < 0.05), insulin (p > 0.05), cortisol (p > 0.05), glucose (p < 0.01), TG (p <0.01) and total cholesterol (p < 0.05), and higher (p < 0.01) levels of NEFA and BHB, as compared to the blood levels in healthy pregnant and healthy puerperal cows. Results suggest that ketotic cows undergo homeorhetic adaptation of the regulation of organic nutrient metabolism being manifested through a decrease in the blood levels of the test hormones, resulting in increased lipomobilization, hypoglycemia, and intensive ketogenesis and lipogenesis in liver cells.