A farm-level comparison of health disorders and reproductive performance in Holstein-Gyr and Holstein dairy cows.

Holstein-Gyr crossbred dairy cows are commonly used in Central and South American countries to combine the perceived benefits of heat and health disorders tolerance of Gyr cows with the milk production of Holstein cows. The objectives of this study were to compare the incidence of health disorders and reproductive performance in Holstein-Gyr and Holstein cows managed and housed identically in a single herd. The animals were followed up to 300 days in milk, and health and reproductive data were retrieved from farm records. Among the diseases diagnosed, breed affected only metritis, with a higher incidence in Holstein cows. Cows that calved in the cool season had an increased incidence of dystocia and hyperketonemia compared to calving in the warm season. Cows calving in the warm season had a higher incidence of stillbirth, retained fetal membranes (RFM), metritis, and multimorbidity than cows calving in the cool season. Multiparous cows had a greater incidence of retained fetal membranes, uterine diseases, purulent vaginal discharge, hypocalcemia, and morbidity than primiparous cows. An interaction between breed category and calving season was present for RFM, with Holstein cows in the warm season having a higher incidence than Holstein-Gyr. Primiparous cows had a greater pregnancy rate at first service and fewer services than multiparous cows. Morbidity and multimorbidity were associated with prolonged open days, independent of breed. In summary, Holstein-Gyr and Holstein cows housed and managed similarly experienced similar incidences of health disorders and reproductive performance, with morbidity negatively impacting the interval from calving to pregnancy in both groups.