Authors: Ali AYAR, Erol ALAÇAM
Abstract: The present study was carried out on a total of 80 ewes, 40 Merino, 40 Akkaraman and 12 intact rams. Both group of ewes belong to Merino and Akkaraman breeds were divided in to two groups as treatment and control. In the breeding season, 500 IU PMSG (Choronogest PMSG - intervet) were injected to the treatment groups on the day 13 of their sexual cycle. All ewes detected into oestrus in treatment and the control groups were allowed for mating. Treatment and control groups of the two breeds of ewes were compaired for their pregnancy rates in first service, pregnancy periods, pregnancy problems, lambing types, incidence of retained placenta, birth weights and survival rates of lambs in end of the first month. Pregnancy rates in the treatment groups after first service increased at a rate of 20 and 25 percent for the Akkaraman and Merino ewes, respectively. Lambing rates (lambs/100 lambing ewes) also increase at a rate of 50 and 52.7 percent for the same groups. Although toxemia and abortion rate were in the acceptable limits, retained placenta cases were 15 percent higher than controls. The ewes suffering from retained placenta were observed during the next season and all of them concevied after first service. Average duration pregnancy was noted approximately a week shorter than controls in Merino treatment group. Some of the lambs which are twin or triplets needed to additional feed. As as results; pregnancy rates after first service and lambing percentages can be increased by PMSG injection on the day 13 of the sexual cycle without pregnancy problems and postpartum disorders expect from retained placenta.
Keywords: Sheep, Induction of Twinning, PMSG