Synchronization of oestrus in goats: dose effect of progestagen

A trial was conducted to test the efficiency of different doses of intravaginal progestagen in the synchronization of different goat breeds, in the breeding season. Sixty Multiparous Boer and 60 Indigenous feral does were allocated to three treatment groups. The groups consisted of a control group (natural oestrus) (n=20/breed); 60mg MAP sponge groups inserted for 14 days plus 300IU PMSG at sponge withdrawal (n=20/breed) and halved 60mg MAP (+/-30mg) sponges inserted for 14 days plus 300IU PMSG at withdrawal (n=20/breed). The time from sponge withdrawal to oestrus was not significantly different in the treatment groups (whole and halved sponges), irrespective of breed. The duration of the oestrous period was significantly (p<0.01) shorter in the control group (29.3+/-14.9h versus 28.0+/-15.7h for the Indigenous and Boer goats, respectively), compared to the induced period for the 60mg (31.1+/-14.7 and 31.5+/-15.9h) or 30mg (40.0+/-22.0h versus 34.3+/-21.7h) for the Boer and Indigenous goats, respectively. No significant difference in pregnancy rate following AI was recorded (mean 74.2%). The mean serum progesterone concentration for the observation period varied between 0.01 and 6.19ng/ml for Indigenous and 0.01 and 9.05ng/ml for Boer goat does. No significant correlation was recorded between the does pregnant and serum progesterone levels. Mean serum LH concentration of the 60mg MAP groups (0.59+/-0.22ng/ml) was significantly (p<0.05) lower than the control (0.84+/-0.66ng/ml) and the halved sponge (1.9+/-0.49ng/ml) groups. Dose of progestagen played no role in the efficiency of synchronization, regardless of the breed. The mean pregnancy rate achieved, is acceptable following fixed-time AI in both breeds and at both doses progestagen.