Efficiency of artificial insemination as a scaling tool of sheep breeding schemes

Abstract

The study investigated, for artificially-inseminated (AI) Menz ewes, the reproductive performance of prostaglandin-based treatments simultaneously to the standard “P4+eCG” protocol using progestogens priming with intravaginal devices and gonadotropin. A total of 483 non-pregnant and non-suckling Menz ewes were assigned to either the “P4+eCG” protocol, the “PGFs” treatment where sheep were synchronized with a single injection of prostaglandin or “PGF7” and “PGF11” where the sheep had their estrus and ovulation synchronized with a double injection of prostaglandin 7 or 11 days apart, respectively. The ewes were artificially inseminated with fresh semen at 55 ± 1 h after the end of the hormonal treatment. Conception rate (60.87±4.2) was highest for PGF11 ewes in comparison to sheep in all other treatment groups (P<0.05). The lowest conception rate (34.07±4.1) was recorded for the PGFs group. Location, body condition score and parity did not affect variation in conception rate (P>0.05). A higher proportion of ewes in the P4+eCG group yielded multiple births (2 and 3) compared to the 3 prostaglandin-based protocols (P<0.01). Nevertheless, a higher (P=0.02) proportion (17.11±4.3) of ewes treated with PGF11 protocol yielded twins by comparison to their counterparts in the PGF7 protocol (2.50±2.5). It is concluded that use of a prostaglandin-based protocol composed of 2 injections 11 days apart, preceded by a careful selection of non-pregnant ewes for cervical fixed-time AI with fresh semen, is a feasible reproductive management option to support sheep breeding programs in Ethiopia.