Effects of long and short-term progestagen treatments combined with PMSG on oestrus synchronization and fertility in Awassi ewes during the breeding season
2007
Ustuner, B.,Uludag Univ., Bursa (Turkey). Dept. of Reproduction and Artificial Insemination | Gunay, U.,Uludag Univ., Bursa (Turkey). Dept. of Reproduction and Artificial Insemination | Nur, Z.,Uludag Univ., Bursa (Turkey). Dept. of Reproduction and Artificial Insemination | Ustuner, H.,Uludag Univ., Bursa (Turkey). Dept. of Animal Science
The aim of the present study was to compare the effect of the length of a progestagen treatment (12 d vs. 6 d) on synchronization efficiency (oestrus response, time to onset of oestrus and duration of oestrus) and fertility rate using fluorogestone acetate (FGA) progestagen sponge treatment with pregnant mare serum gonadotropin (PMSG) administration applied at different times of sponge removal (SR). Ewes were divided into two groups as follows: long term (LT, n=33) and short term (ST, n=35) groups treated with FGA progestagen sponges. At the end of the intravaginal sponge treatment the animals of both groups were divided into 3 subgroups in relation to the time of PMSG (300 IU) treatment as follows: 24 h before SR, at SR and 24 h after SR for LT1 and ST1, LT2 and ST2, and LT3 and ST3, respectively. Each ewe was inseminated intra-cervically twice (40 h and 60 h after SR). Non-return rates (NRR-30) were monitored from 12 to 30 days after SR with the aid of teaser rams. Onsets of oestrus response and oestrus cessation were significantly different between ST and LT groups. Synchronization of oestrus was tighter in LT than in ST group. Oestrus cessation was the shortest in ST1 (88.7+/-15.4 h), it differed significantly from ST3 (120.0+/-14.2 h). Concerning the other studied indicators within the group ST and all the indicators within the group LT, no significant differences were observed among the subgroups. The NRR-30 and lambing rate of the ST and LT ewes after timed insemination were 35.7% and 31.0%, and 32.1% and 28.6%, respectively.
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