Induction of Synchronized Oestrus in Akkaraman Cross-Bred Ewes Treated with Prostaglandin F2 Alpha, Norgestomet and Sponges Impregnated with Different Doses of Fluorogestene Acetate at the Beginning Transitional Period

Abstract

The efficiency of different progesterone and PGF<inf>2</inf>α treatments in the induction of ovarian activity and synchronization of oestrus was investigated the beginning transitional period in sheep. A total of 75 ewes were used in the experiment. Animals were divided into 5 groups. Vaginal sponges containing either 30 mg or 40 mg fluorogestene acetate (FGA) were inserted into the vagina of ewes in the first (FGA-30; n=15) and second (FGA-40; n=15) groups, respectively. The sponges were withdrawn after 12 day. In the third group of ewes (n=15), ear implants containing 3 mg norgestomet (N-IMPLANT) were inserted subcutaneously and removed after 9 day. In the fourth group (n=15), Tiaprost tromethamine (PGF<inf>2</inf>α; 0.294 mg) was intramuscularly injected twice at an interval of 9-d. The control (Control) group is consisted of 15 ewes. After the second PGF<inf>2</inf>α injections and the withdrawal of the sponges and implants, 600 IU PMSG was injected to all ewes in the FGA-30, FGA-40, N-Implant and PGF<inf>2</inf>α groups. After the detection of oestrus ewes, they were naturally mated. Oestrus response rates were significantly higher in the groups FGA-30 (93.3%), and N-IMPLANT (93.3%) than those in the groups PGF<inf>2</inf>α (53.3%) and Control (26.6%). However, oestrus rates in the group FGA-40 were only significantly higher (86.6%) than those in the group Control (26.6%). The pregnancy rates in the groups FGA-30 (93.3%) and N-IMPLANT (93.3%) were significantly higher than that in the group PGF<inf>2</inf>α (53.3%). No significant difference was observed among the groups FGA-30, FGA-40, N-IMPLANT and PGF<inf>2</inf>α with respect to lambing rates. Multiple birth rates were significantly higher in the group N-IMPLANT (35.7%) than in the group PGF<inf>2</inf>α (0.0%). As a conclusion, a double dosed application of PGF<inf>2</inf>α was observed to be inefficient compared to different progesterone treatments in ewes the beginning transitional period.