Synchronization o f oestrus cycle in cattle with Prostaglandin F2 alfa. II. Breeding at a predetermined time following PGF2 alfa, with estrus detection

Abstract

Feasibility of breeding cattle at a predetermined time, in spite of regarding estrus detection, was investigated in nulliparous cows crossed of Zebu and Holstein or Jersey breed. Forty animals were assigned randomly to two treatments. Treatment 1 (n = 20) included animals day 5 to 16 of the oestrus cycle and was an injection of 4 mg PGF2 alfa in to the uterine horn ipsilateral to the active corpus luteum, followed by A l at 72 and 80 hs post PGF2 alfa. Treatment 2 serving as control (n=20) was Al at standing estrus during a 60-day period. PGF2 alfa (1) resulted in 70.0% of the animals in estrus within 2.5 ± 0.2 days. Percent pregnant (60 days post -AI) of those assigned to treatments 1 and 2 were 28,5% and 25,0%.respectively. Differences between treatments were not significant. The possibility of therapeutic utilization of PGF2 alfa is commented.