Metabolic Health in the Transition Period and Fertility of Dairy Cows
Keywords:catabolism, negative nutrient balance, dry period, feed, nutrition, management
During early postpartum, high-producing dairy cows undergo a period of extensive tissue catabolism because of negative nutrient balance. Homeorrhetic controls assure that nutrients are partitioned to favor lactation at the same time that homeostasis secures survival. However, unrestrained metabolic disturbances often lead to diseases which, in turn, dramatically decrease both productive and reproductive performance. Negative nutrient balance has been associated with compromised immune and reproductive functions in dairy cows. Low circulating concentrations of glucose and insulin associated with elevated concentrations of non-esterified fatty acids and ketone bodies postpartum have detrimental effects on the function and viability of the oocyte, granulosa cells, and immune cells. Therefore, minimizing the extent and duration of negative nutrient balance in early lactation is expected to reduce morbidity and enhance fertility. Reductions in circulating concentrations of Ca, and vitamins A and E around parturition are also linked with impaired immune competence, and have to be accounted for when formulating peripartum diets. Furthermore, dietary additives that influence rumen or intermediary metabolism to favor postpartum health, and supplementation with specific fatty acids during early lactation and the breeding period, might benefit fertility of dairy cows. Finally, manipulating the length of the dry period and the caloric content of prepartum diets might have carry-over effects during the subsequent lactation that favor resumption of post-partum ovulation. Proactive management of dairy cows during the periparturient period is needed for cows to achieve high production with good fertility.