The Agricultural Institute, Ballinrobe, Co. Mayo, Ireland
(Received 5th October 1974)
An experiment was conducted to determine whether gonadotrophin-releasing hormone (Gn-RH) or HCG would reduce the proportion of unruptured follicles in the Galway ewe following a high superovulating dose of PMSG given in conjunction with a progestagen to synchronize oestrus.
Forty-four Galway ewes aged 1½ to 5 years (average wt 64·7 kg) were treated with intravaginal pessaries impregnated with 30 mg 'cronolone' (Synchromate: G. D. Searle) for 14 days in early October 1973. All ewes were given 2000 i.u. PMSG (Folligon: Intervet) intramuscularly in 5 ml water at the time of withdrawal of the pessaries and were placed with raddled fertile rams. At 24 hr after removal of the pessary, the ewes were assigned to three groups and were treated as follows: Group 1—50 μg Gn-RH intramuscularly in 1 ml water; Group 2—750 i.u. HCG intramuscularly in 1 ml water