This study was carried out to investigate the effect of administration of progestagen, prostaglandin F2α, PMSG and GnRH on estrus synchronization and some reproductive and productive traits in Barki ewes. Increasing conception, lambing, fecundity and weaning rates and some other traits are the principle measurements for reproductive efficiency and the principle aim in the current study.This study was performed during the period from September 2012 till May 2013, in Siwa Oasis Research Station (Tegzerty Experimental Farm for animal production), belongs to Desert Research Center (DRC). This station is located at 330 Km southwest of the Mediterranean shoreline and at 65 Km east of the Libyan borders.
Sixty-six Barki ewes with 3-5 years old and 41.80 ± 0.559 kg average live body weight were used. Animals were randomly divided into three groups (22 ewes each). The estrous cycles of ewes in each group were synchronized using one of the following hormonal treatments: Group one (G1) received double injections of prostaglandin F2α (1 ml Synchromate) 10 days apart. Ewes of group two (G2) received double injections of prostaglandin F2α (1 ml Synchromate) 10 days apart and after 10 days intravaginal progestagen impregnated sponges (40 mg fluorogestone acetate, FGA) were inserted. Sponges remained in situ for 14 days. On the day of sponge removal, ewes received an intramuscular injection of 750 IU PMSG. Ewes of group three (G3) received the same treatment of group two, but one day before sponge removal ewes were injected with 2 ml (0.004 mg) of GnRH.
The results showed that, the percentage of estrus exhibition in G2 reached 95.45 % (P<0.05), while the lowest percentage (86.36 %) was observed in G3. The conception and lambing rates increased to 100% in G2 but there were no significant differences among experimental groups. Weaning rate was higher (P<0.05) for ewes in G2 than those of other groups. Litter size was higher (P<0.05) for ewes in G2 (1.38%) compared with other groups. The highest fecundity rate was recorded for G2 (138%) and the lowest rate was for G3 (94%). No significant differences in birth weight, weaning weight, average daily gain and mortality rate were found among groups. Gestation period was shorter (P<0.05) for ewes in G2 as compared with other groups. The percentage of ewes lambing twins was higher for ewes in G2 (28.57 %) than G1 (5.26), while G3 did not give twins. Moreover, G2 gave one triplet twins, while no other groups gave triplets. In conclusion, PGF2α with intra-vaginal FGA sponges + PMSG regime could adequately improve the estrus synchronization and some reproductive and productive traits in Barki ewes. Treatment with PGF2α-FGA-GnRH was markedly inferior to the PGF2α-FGA- PMSG protocol in Barki ewes.
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