Protein and nitrogen supplementation vs. reproduction of bovine females in grazing: Review

Abstract

Nutrition exerts great influence on the reproduction of animals. In this sense, this review has the proposal to present and discuss results of some studies related to the influence of protein and nitrogen nutrition on reproductive aspects in bovine females grazing. With the increase in animal performance (meat and milk production), there is an increase in the demand for nutrients. The increase in nutritional requirements associated with low nutrient intake may affect reproductive functions. Malnutrition during the dry and postpartum onset results in lipid and protein mobilization with consequent increase in the incidence of metabolic diseases, reduction in conception rate and longer period of service. However, overfeeding can increase the excretion rate of steroid hormones (progesterone or estradiol), resulting in the occurrence of sub-estrus and decreased rate of conception. The supply of degradable protein in the rumen, non-degradable protein in the rumen and non-protein nitrogen has, in several situations, resulted in an increase in reproductive indices in dairy and beef cattle.