Use of fluorogestone acetate sponges or controlled internal drug release for estrus synchronization in ewes: Effects of hormonal profiles and reproductive performance

Abstract

This study was carried out using 300 multiparous Najdi ewes during breeding season to compare the effects of fluorogestone acetate (FGA) sponges and controlled internal drug release (CIDR) dispensers to synchronize estrus on reproductive performance and hormonal profiles. Ewes were equally and randomly allotted into group A (FGA) and group B (CIDR); intravaginal progestagen was administered for 14-day period with intramuscular administration of 600-IU eCG at withdrawal time. Estrus was detected using a vasectomized ram starting 12 hours after progestagen withdrawal and repeated every 12 hours up to 84 hours. Blood samples were collected at the time of progestagen withdrawal (0 hour), 24 hours, and 48 hours. Follicle-stimulating hormone, LH, estradiol, and progesterone serum concentrations were measured using commercial ELISA kits and microtitrimetric plates. Timed laparoscopic insemination was performed 48 hours after progestagen withdrawal. Pregnancy and the number of fetuses were diagnosed by ultrasonography on Day 23 after insemination and confirmed on Days 35 and 60. The results revealed that the retention, vaginal discharge, and drawstring breakage rates after progestagen removal were significantly (P ≤ 0.05) higher in the FGA group (94.00, 98.58, and 9.22, respectively) than those in the CIDR group. On the other hand, pregnancy, fertility, twinning rates, and fecundity were significantly (P ≤ 0.05) higher in the CIDR group (77.86, 75.57, 34.34, and 1.02, respectively) than in the FGA group. Estrus responses in FGA and CIDR groups increased gradually to attain their significantly (P ≤ 0.05) higher percentages after 48 hours of progestagen withdrawal (91.49 and 92.37, respectively); thereafter, they decreased. The overall estrus responses and prolificacy did not differ between the FGA and CIDR groups. Follicle-stimulating hormone was significantly higher in the FGA group at 24 and 48 hours after progestagen withdrawal, whereas LH was significantly higher in the CIDR group at 48 hours after progestagen withdrawal. Estradiol and progesterone were significantly higher in the CIDR group at 0, 24, and 48 hours after progestagen withdrawal. These results indicated that although FGA and CIDR devices are efficient in synchronizing estrus in ewes, CIDR provided higher pregnancy, fertility, twinning rates, and fecundity than FGA.

Keywords: Controlled internal drug release; Estrous synchronization; Fluorogestone acetate; Reproductive hormone; Sheep.