Targeted use of automated estrus detection and strategies to improve fertility outcomes in lactating dairy cows.

Reproductive performance of lactating dairy cows has improved largely over the past two decades. Such progress reflects advances in reproductive management practices, but also incorporation of fertility traits into genetic selection programs and improvements in cow comfort and health that have allowed high-producing dairy cows to better express their reproductive potential. This review summarizes recent developments in reproductive management strategies that have contributed to continued improvements in reproductive efficiency in lactating dairy cows. Increased availability of genomic data and automated monitoring technologies has created unique opportunities for the development of targeted management strategies tailored to specific cohorts of cows, which can reduce reproductive costs and allow for reorganization of routine tasks and labor utilization while maintaining reproductive performance. As the genetic makeup of high-producing dairy cows continues to evolve, understanding of the biological processes that control fertility will remain paramount so that novel technologies can be employed effectively as they become applicable to commercial farms. Strategies to improve reproductive performance of cows with inferior genetic merit for fertility and during the hot months of the year, among solutions to other physiological and environmental challenges, are expected to complement automated monitoring systems. Novel strategies for early identification and reinsemination of nonpregnant cows have allowed for the development of efficient resynchronization protocols.