Reproductive performance in seasonally anestrous ewes treated with exposure to ram with reference to the effects of feeding level around early mating period and PMSG-PGF2α treatment
1999 Volume 1999 Issue 36 Pages 19-26
Details
1999 Volume 1999 Issue 36 Pages 19-26
This study aims to compare the reproductive performance of seasonally anestrous ewes which were exposed to ram starting from 94 days after lambing; fed with 2 different level of TDN at early mating period; hormonally treated with PMSG and PGF2α.
Forty-five Suffolk ewes weaned at 73 days after lambing were divided into following 4 groups namely :
Group H 0 - exposed to ram for 39 days; consumed 1.15 kg TDN/day
Group H 1- exposed to ram for 39 days; consumed 1.15 kg TDN/day; hormonally treated at 13 days after exposure to ram with PMSG (500 IU) and PGF2α (15 mg)
Group M 0- exposed to ram for 30 days; consumed 0.89 kg TDN/day
Group M 1- exposed to ram for 39 days; consumed 0.89 kg TDN/day; hormonally treated at 13 days after exposure to ram with PMSG (500 IU) and PGF2α (15 mg)
All groups of ewes were maintained on natural daylength or supplemented with 20-24 hours of artificial lighting during perinatal period. Fisher's exact probability test was adopted to detect statistical difference among groups.
The incidence of estrus and pregnancy rate was higher than 92% and 50% respectively in all groups, however, there was no significant difference among treatment groups. The daylength pattern during perinatal period had also no significant effect on the incidence of estrus and pregnancy rate. Intake of 1.15 kg of TDN/day improved the daily gains of ewes in group H 0 and H 1, however, failed to show significant effect on the incidence of estrus and pregnancy rate.
In conclusion, this study was able to demonstrate that exposure of ewes to ram without hormonal treatment successfully induced fertile estrus. Moreover, exposure to ram in combination with PMSG-PGF2α treatment induced cyclic ovarian activity and synchrony of estrous time was achieved.
