Antioxidant status, hormone levels and immunity in crossbred cows of different levels of production

Twelve crossbred (KF) cows were selected 60 days before expected date of calving for experiment. The animals were grouped on the basis of their milk production as high (> 15 kg/day) and low (< 10 kg/day) producers based on their previous milk yield. Blood samples were collected at days 60, 45, 30, 15 and 7 before calving, on day of calving and 7, 15, 30, 45 and 60 days after calving. Hormones, leptin, insulin and growth hormone have been estimated in plasma samples. Plasma leptin and insulin levels were lower and growth hormone was found to be higher in high yielding cows as compared to low yielding cows. There was significant variation in leptin, insulin and growth hormone levels between groups (P< 0.01) and between days (P< 0.01). Plasma glucose level was lower and plasma NEFA was found to be significantly higher (P< 0.01) in high yielding cows as compared to low yielding cows. Lymphocyte proliferation index was 1.33± 0.11 and 1.45± 0.15 in high and low yielding cows, respectively. Average value of total plasma antioxidant activity was 1377.39± 23.00 and 1313.09± 14.99 FRAP value (μM/L) in high and low yielding cows, respectively. The study shows that changes in leptin, insulin, growth hormone, glucose and NEFA play important roles in metabolic adaptation of cows to changes around calving and the levels of these hormones and metabolites vary with level of milk production.