A retrospective study investigating the association of parity, breed, calving month and year, and previous parity milk yield and calving interval with twin births in US dairy cows

Twinning costs the dairy industry an estimated $96 million each year. Twin pregnancy occurrence in high-producing cows is primarily a result of multiple ovulations associated with low circulating concentrations progesterone due to high milk production. The present retrospective observational study aimed identify associations between (1) previous parity yield and subsequent twin birth prevalence, (2) same production calving interval (CInt), (3) calving. final data set included almost 2.9 US records 2001 2020. Variables considered were parity, breed, production, CInt, month, Logistic linear regression modeling used assess effects predictors on outcomes. Herd within state was as random effect for all models. probability increased independent breed or parity. Third greater (3+) compared second breeds Jerseys probability. Calving April September that corresponded conceiving July through December births decreased following event Holsteins 2 months June September. Surprisingly, 3+ 305-d yield. Cows had more likely calve twins risk having CInt 413 600 d. hazard after single births. These can be instrumental guiding research focus reducing twinning lactating cows.