Abstract

Two experiments involving 715 suckling beef cows were conducted to determine the effects of oestrogen treatment at the time of PRID insertion on the synchronisation of oestrus and conception rate to timed AI. Experiment 1 examined the route of administration and dose level of oestrogen while Experiment 2 studied the effect of oestrogen treatment at PRID insertion and/or an injection of prostaglandin at the time of PRID removal. Treatment with oestrogen resulted in an 18% improvement in synchrony and a 9% increase in conception rate. A dose level of oestrogen 4 times that given by intramuscular injection was required to achieve similar results when it was administered via a gelatine capsule attached to the PRID.

DC, Smeaton, TK Wadams, and H-UP Hockey

Proceedings of the New Zealand Society of Animal Production, Volume 42, , 79-82, 1982