Effect of Nutrition, Lactation and Periparturient Complications on Adrenal, Pituitary and Ovarian Function and Uterine Involution in High-Producing Dairy Cows

Abstract

Effects of body condition at parturition, purperal complications, milk yield and parity on the sequential changes in postpartum adrenocortical and pituitary functions , ovarian activity and uterine involution were investigated in 44 high-producing Holstein Friesian cows. One half of the cows had normal adrenocortical function and the other half had either enhanced or depressed adrenocortical function 8 days postpartum. The adrenocortical function was found to be normal in all cows 22 days after calving. Pituitary gland response to GnRH was low in 68.2 % of cows 7 days after parturition and 31.8 % still had low response 21 days postpartum. A significant negative correlation (P<0.05) was observed between basal and ACTH-stimulated plasma cortisol levels and GnRH-stimulated plasma luteinizing-hormone levels 7 to 8 days after calving. Multifactorial analysis of variance showed that postpartum adrenocortical function was enhanced by poor body condition at calving, high milk yield, and increased parity. In association with enhanced adrenocortical function, pituitary function tended to be depressed 7 days postpartum in cases of poor body condition, high milk yield and increased parity. Among all the various factors examined, milk yield had the most significant effect on postpartum adrenocortical and pituitary functions. Uterine involution tended to be delayed in cows with poor body condition at calving, high milk yield and increased parity. It may be concluded that undernutrition, high milk yield and increased parity are predominant factors causing enhancement of adrenocortical function which is associated with depression of pituitary function.