Endocrine and reproductive parameters in sick and healthy primiparous and multiparous dairy cows

To investigate the association of health status and parity with hormone profiles during the transition period and reproductive parameters in Holstein dairy cows, a prospective observational cohort study was carried out including only healthy primiparous (PP, n = 116) and multiparous (MP, n = 172) cows at the beginning of the study. A subset of 120 healthy and sick cows was randomly selected for insulin, IGF-I, leptin and adiponectin determination. Primiparous cows had greater IGF-I and adiponectin concentrations (P < 0.05) and tended (P=0.07) to have greater insulin concentrations than MP cows. While healthy and sick MP and sick PP cows presented a sharp decrease in IGF-I concentrations after calving, healthy PP cows maintained them. Postpartum adiponectin concentrations were lower in sick than in healthy MP cows. A greater percentage of healthy cows ovulated during the first 7 weeks after calving when compared to sick cows (67.9% vs 50%, P=0.002) and a similar trend was found for MP vs PP cows (64% vs 53%, P=0.01). More healthy cows were inseminated in comparison to sick cows (94% vs 76.5%, P < 0.01) and more PP than MP cows (90.4% vs 82.7%, P < 0.05). Similarly, healthy cows presented a greater proportion of pregnancy than sick cows (75% vs 54%, P < 0.01) and the proportion of pregnancy was higher in PP than in MP cows (74% vs 56%, P=0.04). Health status interacting with parity yielded different endocrine profiles, which may partially explain the differences in reproductive performance.