The effects of short-medium and long-term applications of fluorogestone acetate (FGA) on reproductive performance of Kıvırcık ewes at the onset of the breeding season

Abstract

The aim of the present study was to investigate the efficiency of different treatments of progestogen with Pregnant Mare Serum Gonadotropin (PMSG) in Kıvırcık ewes at the onset of the breeding season. A total of 111 ewes, 3 to 5 years old, weighing on average 47.7 kg and with a body condition score of 3.5 to 4.0 were used in this study. The ewes were randomly divided into 3 equal groups (n= 37 per group). Intravaginal progestogen sponges containing 30 mg FGA were inserted intravaginally in the ewes and left for a different number of days; 7 days for the short-term treatment, 10 days for the medium-term treatment and 14 days for the long-term treatment. Additionally, 500 IU of PMSG was injected administered intramuscularly when the sponges were removed. The estrous response, lambing rate, rate of multiple births, fecundity and litter size were 81.8 %, 70.3 %, 19.2 %, 0.86 and 1.23 in the short-term group; 89.2 %, 83.8 %, 12.0 %, 1.24 and 1.48 in the medium-term group; and 94.6 %, 91.2 %, 35.3 %, 1.30 and 1.41 in the long-term group, respectively. The duration of sponge treatment had a significant effect on estrous response, lambing rate, fecundity, litter size (P<0.05), and the rate of multiple births (P<0.01). Occurrences of oestrous response, lambing rate, fecundity, litter size were significantly higher in the medium-term and long-term groups than in the short-term group; on the other hand, the rate of multiple births was significantly (p<0.01) higher in the long-term group than in the medium-term and short-term groups. No difference in the fertility parameters in the medium (10 days) or long (14 days) term application were detected. Short term (7 days) application were not found as successful other two practice.