What is New in Dairy Reproduction?

Has the reproductive performance in your herd improved, remained the same or declined over time? If your herd is typical for the Southeast, reproductive performance has declined over time. A study that evaluated reproductive performance from 1976 to 2002, in Florida and Georgia dairy herds, showed that days to first service, days to conception, and calving interval increased significantly over time (de Vries and Risco, 2006). Further, average pregnancy rates decreased from 22% to 11%. Although, causes for this decline is multifactorial, attenuation of estrus expression in high producing cows, embryonic mortality, energy metabolism early postpartum and its interactions with immune function play a major role (Wiltbank et al., 2006; Santos et al, 2007; Hammon et al., 2006). Further, the trend for larger herds has resulted in new challenges with compliance of reproductive programs, namely inseminating cows on a timely basis at the end of the voluntary waiting period (VWP).