Synchronization of oestrus in goats: dose effect of progestagen

A trial was conducted to test the efficiency of different doses of intravag inal progestagen in the synchronization of different goat breeds, in the br eeding season. Sixty Multiparous Boer and 60 Indigenous feral does were all ocated to three treatment groups. The groups consisted of a control group ( natural oestrus) (n=20/breed); 60 mg MAP sponge groups inserted for 14 days plus 300 IU PMSG at sponge withdrawal (n=20/breed) and halved 60 mg MAP (/-30 mg) sponges inserted for 14 days plus 300 TU PMSG at withdrawal (n=20/ breed). The time from sponge withdrawal to oestrus was not significantly di fferent in the treatment groups (whole and halved sponges), irrespective of breed. The duration of the oestrous period was significantly (p<0.01) shor ter in the control group (29.3+/-14.9 h versus 28.0+/-15.7 h for the Indige nous and Boer goats, respectively), compared to the induced period for the 60 mg (31.1+/-14.7 and 31.5+/-15.9 h) or 30 mg (40.0+/-22.0 h versus 34.3+/ -21.7 h) for the Boer and Indigenous goats, respectively. No significant di fference in pregnancy rate following AT was recorded (mean 74.2%). The mean serum progesterone concentration for the observation period varied between 0.01 and 6.19 ng/ml for Indigenous and 0.01 and 9.05 ng/ml for Boer goat d oes. No significant correlation was recorded between the does pregnant and serum progesterone levels. Mean serum LH concentration of the 60 mg MAP gro ups (0.59+/-0.22 ng/ml) was significantly (p<0.05) lower than the control ( 0.84+/-0.66 ng/ml) and the halved sponge (1.9+/-0.49 ng/ml) groups. Dose of progestagen played no role in the efficiency of synchronization, regardles s of the breed. The mean pregnancy rate achieved, is acceptable following f ixed-time AI in both breeds and at both doses progestagen. (C) 2000 Elsevie r Science B.V. All rights reserved.