The effectiveness of supplemental administration of progesterone with GnRH, hCG and PGF2α on the fertility of Tuj sheep during the non-breeding season

This study investigated the effects on fertility parameters of combined administration of flugestone acetate, GnRH, hCG and PGF2α to Tuj ewes during the non-breeding season. In the study, 60 Tuj ewes were separated into four groups. Seven days before administering an intravaginal gestagen (20 mg Flugestone acetate, sponge) to the ewes in Group I (GI, n = 15), they were given an injection of GnRH (8.4 μg Buserelin acetate). Seven days after the sponge was administered, the ewes were given a second intramuscular injection of GnRH. The sponge was left in the vagina for 14 days. Immediately after removing the sponge, an intramuscular injection of PGF2α (15 mg) was administered. The ewes in Group II (GII, n = 15) were administered hCG injections at a dose of 1000 IU/ewe instead of the GnRH injection that was given to the first group. The ewes in Group III (GIII, n = 15) were only administered intravaginal sponge. The ewes in Group IV (n = 15) were kept as a control group and were not given any treatment. Immediately after the sponges were removed, rams were introduced in all groups, ensuring that ewes exhibiting estrus were mated. The percentage of ewes exhibiting estrus was found to be significantly higher in all the study groups (GI, GII and GIII) than in the control group (GIV) (P < 0.05). It was determined that the pregnancy ratio for ewe mating at the first estrus was higher in group GII than in all the other groups (46.6%) (P < 0.05). The overall pregnancy rate and lambing rate was found to be significantly higher in GII (100%) than the other study groups (GI: 66.6% and 66.6%; GIII: 66.6% and 46.6%, respectively, P < 0.05) as well as the control group (GIV: 6.6% and 0%, respectively, P < 0.01). On day 7 after the sponge was administered, the mean plasma progesterone level (3.64 ng/ml) was found to be higher in the ewes in GII, and this difference was found to be statistically significant (P < 0.01). We concluded in this study that administering hCG and vaginal sponges to Tuj ewes during the non-breeding season had a positive effect on pregnancy and lambing rates.