ABSTRACT
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The cow-calf producer is faced with several challenges when trying to implement estrous synchronization and artificial insemination (AI) programs. The first challenge is dealing with the large percentage of anestrous or noncycling cows at the start of the breeding season. Adequate nutrition prior to calving and during the postpartum period can increase the percentage of cattle cycling at the start of the breeding season (Short et al., 1990). However, when nutrient requirements of the lactating cow are compromised during this period, the percentage of anestrous cattle at the start of the breeding season increases dramatically. Therefore, an ideal estrous synchronization program would initiate estrus cycles in some anestrous cattle. The second challenge deals with cattle management during the implementation of the synchronization program. Producers would like to handle the cattle as few times as possible during a synchronization and AI program and eliminate estrus detection altogether by inseminating cattle at a predetermined time, also known as timed AI (TAI). Using TAI would eliminate the costly and labor-intensive process of estrous detection. Therefore, an effective estrous synchronization system would require minimal cattle handling, induce estrous cycles in a majority of the anestrous cattle, and yield consistent pregnancy rates to a TAI.
