Pregnancy risk in beef and dairy cows after supplementing semen with transforming growth factor beta-1 at the time of artificial insemination.

Our objective was to determine if the addition of a concentrated human recombinant transforming growth factor beta-1 (TGF) to bovine semen at the time of AI would result in increased risk of pregnancy in beef and dairy cows. Suckled beef cows (n = 1,132) in 11 herds across 2 states and lactating dairy cows (n = 2,208) in one organic-certified herd were enrolled. Beef cows received fixed-time AI (FTAI) following a 7 d CO-Synch + controlled internal drug release estrous synchronization protocol.