Estresse calórico materno em diferentes fases da gestação de vacas Holandesas sobre o desempenho reprodutivo e contagem de folículos antrais da progênie

Abstract

Maternal heat stress can impair placental function, fetal development and subsequent performance of bovine offspring. The number of follicles present in the ovary is determined during fetal life and can be influenced by the mother's nutrition and health during gestation. The amount of antral follicles is associated with fertility in cows. However, information on the impact of heat stress during gestation on fertility and antral follicle count on offspring is still limited. Thus, the objective of the study was to evaluate the effect of maternal exposure to heat stress conditions in different phases of gestation on reproductive performance and antral follicle count of offspring. For this, retrospective data on the reproductive indexes of daughters of Holstein cows who were exposed to heat stress conditions in the first, second or third trimester of gestation and daughters of cows not exposed to heat stress conditions were analyzed. Conception dates for inclusion of the animals in the different groups were estimated subtracting 280 days from the date of birth. In a subgroup of animals transrectal ultrasonography was performed for antral follicle count and ovarian size measurement. The number of services per conception was lower in the daughters of cows not exposed to heat stress conditions than those exposed in the different trimesters of gestation. The interval between calving was higher for the daughters of cows exposed to heat stress conditions in the second and third trimester of gestation compared to those not exposed. In addition, pregnancy rate at the first service and antral follicle count were higher in the daughters of cows not exposed to heat stress conditions compared to those exposed in different phases of the gestational period. It is concluded that the condition of maternal heat stress in the different phases of gestation interferes negatively in the future fertility and in the antral follicle count of the bovine offspring.