The 9-day CIDR-PG protocol: Incorporation of PGF2α pretreatment into a long-term progestin-based estrus synchronization protocol for postpartum beef cows.

A pilot experiment was designed to test the hypothesis that administration of PGF2α before progestin treatment would allow for a reduced duration of progestin treatment in a long-term progestin-based estrus synchronization protocol. A modified presynchronization treatment was compared with a standard long-term controlled internal drug release (CIDR) treatment, and treatments were compared on the basis of ovarian follicular dynamics, estrous response rate, synchrony of estrus expression, and pregnancy rates resulting from timed artificial insemination (TAI) in postpartum beef cows. Estrous was synchronized for 85 cows, with cows assigned to one of two treatments based on age, days postpartum, and body condition score.