Agricultural Institute, Grange, Dunsany, Co. Meath, Ireland
(Received 2nd May 1974)
To be ultimately successful, techniques used to control the oestrous cycle of the cow will have to embody methods which allow the time of insemination to be arranged without reference to behavioural oestrus. This is particularly important in the case of beef suckler cows as it is difficult to detect heat in these animals probably owing to the suckling stimulus. This means that treatments used to synchronize the oestrous cycle willa lso have to give precise control of the time of ovulation or that other hormones will have to be given to control ovulation time. The aim of the experiment described in this paper was to obtain hormonal control of the time of ovulation following synchronization of oestrus with implants of progesterone (Roche, 1974a). This would allow all animals to be inseminated on a fixed time basis.