Abstract
Decreasing fertility in dairy cows, especially in the highest yielders, may be due to excessive metabolic burdens placed on their bodies. Many authors attribute decreasing reproductive efficiency in high-yielding cows to energy deficiencies in early lactation and to associated metabolic and hormonal disorders. The complexity of the issues involved in the efficient reproductive management of cows and the scientifically and practically important understanding of factors affecting fertility in high-producing cows mandate continuous updating of existing knowledge. The aim of this study was to present the effect of postpartum endocrine function, metabolism, and mastitis on fertility in high-yielding cows. Gaining insight into these mechanisms and their relationships with factors such as nutrition and milk yield appears to be crucial for improving dairy cow fertility.