Animal Reproduction Science 96 (2006) 323–330 Prospects for improving reproductive performance through genetic selection  Kent A. Weigel ∗ Department of Dairy Science, University of Wisconsin, 1675 Observatory Drive, Madison, WI 53706, USA Available online 3 August 2006 Abstract Prospects for improving female fertility in dairy cattle using genetic selection are reviewed. Today’s high producing cows have shorter estrous cycles, fewer standing events, shorter duration of estrus, and more frequent multiple ovulations. Although high milk production is often implicated as the cause of impaired fertility, the impact of inadequate body condition appears to be greater, as the latter has a significant impact on probability of conception, rate of embryonic loss, and proportion of anestrous animals. Genetic improvement of female fertility can be achieved by indirect selection for longevity or body condition score, or by direct selection for traits such as daughter pregnancy rate. Most leading dairy countries have implemented genetic evaluation systems for female fertility in the past decade, but refinement of these systems to account for hormonal synchronization, differences in the voluntary waiting period, exposure to natural service bulls, and other confounding factors is warranted. Recent work has focused on the development of data collection and genetic evaluation systems that will allow selection of bulls that have daughters that are resistant to common health disorders, including mastitis, lameness, ketosis, displaced abomasum, and metritis. Such systems will allow selection of animals that can remain healthy and fertile while producing large quantities of milk. © 2006 Published by Elsevier B.V. Keywords: Fertility; Dairy; Conception rate; Pregnancy; Body condition; Animal health 1. Introduction The challenges associated with achieving pregnancy in modern, high producing dairy cows have received considerable attention from scientists, veterinarians, and farmers in recent years. Today’s dairy cows tend to have lower conception rate, greater days open, and greater likelihood of  This paper is part of the special issue entitled Nutrition and Fertility in Dairy Cattle, Guest Edited by A. Evans and F.J. Mulligan. ∗ Tel.: +1 608 263 4321; fax: +1 608 263 9412. E-mail address: kweigel@wisc.edu. 0378-4320/$ – see front matter © 2006 Published by Elsevier B.V. doi:10.1016/j.anireprosci.2006.08.010