Field Investigation of Whether Corpus Luteum Formation During Weeks 3–5 Postpartum is Related to Subsequent Reproductive Performance of Dairy Cows

Abstract

This study analyzed the effect of corpus luteum (CL) formation during weeks 3-5 postpartum on the subsequent reproductive performance of dairy cows. Factors contributing to CL formation during the postpartum period were also determined. Data were collected from 1524 Holstein dairy cows on 18 farms using a single ultrasonographic examination to determine the presence or absence of a CL during weeks 3-5 postpartum. The dates of calving, AI, conception and cow parity were also collected. Data were acquired for a subset of 475 cows on five farms related to peripartum reproductive events and the body condition score (BCS) during weeks 3-5 postpartum. The hazard of first postpartum insemination by 150 days in milk (DIM) was higher for cows with a CL compared with herd mates without a CL during week 3 (hazard ratio [HR]: 1.40, P=0.007), week 4 (HR: 1.28, P=0.004) and week 5 postpartum (HR: 1.43, P<0.0001). Furthermore, the pregnancy hazard was also higher by 210 DIM for cows with a CL compared with cows without a CL during week 3 (HR: 1.56, P=0.0009), week 4 (HR: 1.28, P=0.006) and week 5 postpartum (HR: 1.20, P=0.04). Cows calved during autumn were more likely to have a CL than cows calved during spring (odds ratio [OR] =2.32, P=0.003). Primiparous cows were less likely to have a CL than multiparous cows (OR=0.63, P=0.03). Cows with a BCS < 3.00 were less likely to have a CL than cows with a BCS ≥ 3.00 (OR=0.51, P=0.0013). In conclusion, CL formation during weeks 3-5 postpartum was related to subsequent improved reproductive performance when compared with herd mates without a CL.