DELAYED TIME OF CONCEPTUS ATTACHMENT IS A KEY LIMITING FACTOR IN PREGNANCY SURVIVAL OF LACTATING DAIRY COWS

The PD's long-term research goals are to improve reproductive efficiency of lactating dairy cows and thereby increase profitability of dairy operations. To accomplish these goals, the PD is focused on gaining a greater understanding of fertility gaps that occur following 1stparturition.Utilization of electronic estrus detections systems are gaining in popularity and new systems are entering the marketplace at a fast pace. But a key disadvantage to these systems is poor fertility following AI especially in multiparous cows [8]. There are four key questions in this proposed work: 1) Does insufficient circulating progesterone concentrations post-AI affect timing of conceptus attachment? 2) Is the difference in fertility between heifers and cows attributable to insufficient circulating progesterone post-AI? 3) Is the gap in fertility between Double-Ovsynch and AI following detected estrus due to timing of conceptus attachment? 4) Does timing of conceptus attachment influence pregnancy losses? The following three specific aims are proposed to answer these questions.Specific Aims1)Determine the effect of reducing progesterone following AI on time to conceptus attachment in dairy heifers.2)Determine the difference in time to conceptus attachment in lactating dairy cows receiving AI following estrus vs. the fertility program Double-Ovsynch.3)Determine the effect of increased progesterone following AI after detected estrus on time to conceptus attachment and subsequent pregnancy loss in lactating dairy cows.