Five trials were conducted with 958 virgin beef heifers to evaluate the effects of various breeding management methods on pregnancy rate at synchronized estrus and during a 45-day artificial insemination (AI) season. Synchronization was achieved with the progestin treatment regimen Syncro-Mate-B (SMB). Pregnancy rate at first service and cumulative pregnancy rate were affected (P less than .01)...

Progesterone, or progesterone like compounds, (progestins) have been investigated and used for estrous synchronization for several decades. However, the success rates of programs that use progestins have varied considerably. A primary challenge to the use of this hormone for synchronization was the repeated observation in the past of reduced fertility at the synchronized estrus. Perhaps of even...