Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8986811 | Small Ruminant Research | 2005 | 7 Pages |
Abstract
An oestrous synchronization study was conducted on 202 Dorper ewes kept under extensive veld conditions of South Africa, during the transition period from the natural breeding to the anoestrus season. Two types of intravaginal progestagen sponges, namely MAP (60Â mg) (n=102) and FGA (40Â mg) (n=100), three times of PMSG administration relative to sponge withdrawal (24Â h before (n=59), at (n=56) or 24Â h after (n=57)) and two routes of PMSG administration (intramuscular (n=87) or subcutaneous (n=85)) were compared regarding synchronization efficiency (oestrous response, time to onset of oestrus and duration of oestrus) and fertility (pregnancy, lambing, and fecundity rates) following AI with 0.1Â ml fresh diluted semen. There were no significant differences in terms of oestrous response, time to onset of oestrus and the duration of induced oestrus due to differences in the type of progestagen sponges or time and route of PMSG administration. The overall pregnancy, lambing, and fecundity rates were 72.3, 91.1, and 126.0%, respectively. There were no significant differences in pregnancy, lambing, and fecundity rates between ewes treated with MAP and FGA sponges (70.6, 85.3, and 120.8% versus 74.0, 97.0, and 131.1%, respectively). However, within treatment, pregnancy, lambing, and fecundity rates were significantly (P<0.01) higher in ewes administered 300Â IU PMSG 24Â h prior to (78.0, 115.3, and 147.8%, respectively) or at sponge withdrawal (75.0, 94.6, and 126.2%, respectively), compared to those administered 24Â h after sponge withdrawal (70.2, 73.7, and 105.0%, respectively) or those not injected with PMSG (60.0, 70.0, and 116.7%, respectively). Both MAP and FGA sponges could be used to synchronize oestrus in Dorper ewes during the transition period from breeding to anoestrus. Administration of 300Â IU PMSG preferably 24Â h prior to or at progestagen sponge withdrawal is essential to obtain better fertility rates at the induced oestrus and following AI. The subcutaneous administration of PMSG is preferable to intramuscular administration as it resulted in higher fertility rates and litter sizes.
Related Topics
Life Sciences
Agricultural and Biological Sciences
Animal Science and Zoology
Authors
M. Zeleke, J.P.C. Greyling, L.M.J. Schwalbach, T. Muller, J.A. Erasmus,