200 THE USE OF LONG-ACTING FSH-MAP5 IN SHEEP SUPEROVULATION PROGRAMS

Abstract

The administration of sustained-release FSH-MAP5 in a 2-injection protocol has been shown to be as effective as a multiple-FSH injection protocol in inducing superovulation in cattle (Bo and Mapletoft 2014 Theriogenology 81, 38) and in sheep (Fry et al. 2016 Reprod. Fertil. Dev. 28, 250); however, the effect on embryo quality in the latter experiment was unclear. The following experiment further investigated the effect of FSH-MAP5 on ovulation rate and embryo quality in a sheep multiple-ovulation embryo transfer (MOET) program conducted in the breeding season. Two hundred sixteen Dohne merino ewes received a 12-day CIDR-S device containing 0.33 g of progesterone (Zoetis, Florham Park, NJ, USA) plus 200 mg of FSH IM (Folltropin-V; Vetoquinol, Belleville, Canada) and 400 IU of eCG IM (Pregnecol: Vetoquinol) in 4 treatment groups. Group 1 (n = 51) received 7 injections (a.m., p.m.) of FSH in saline (2.5, 2.0, 1.5, 1.5, 1.0, 1.0, and 0.5 mL) starting 2.5 days before CIDR withdrawal and 400 IU of eCG in saline at the time of the first FSH injection. Group 2 (n = 53) received 6 injections (a.m., p.m.) of FSH in saline (3.0, 2.0, 1.5, 1.5, 1.0, and 1.0 mL) starting 2.5 days before CIDR withdrawal and 400 IU of eCG in saline at CIDR withdrawal. Group 3 (n = 56) received 3.3 mL of FSH in hyaluronan (50 mg of MAP5, Vetoquinol) and 400 IU of eCG in saline 2.5 days before CIDR withdrawal and 1.7 mL of FSH-MAP5 at 0.5 days before CIDR withdrawal. Group 4 (n = 56) received 3.3 mL of FSH-MAP5 at 2.5 days before CIDR withdrawal, 1.7 mL of FSH-MAP5 at 0.5 days before CIDR withdrawal, and 400 IU of eCG in saline at CIDR withdrawal. Ewes were inseminated with semen collected and pooled from 5 rams at 36 to 40 h after CIDR withdrawal. Donor ewes were slaughtered 6 days after AI, corpora lutea were counted on the ovary, and ova/embryos were collected. Data for corpora lutea, total ova/embryo, and transferable embryo was analysed by the Kruskal–Wallis test and differences between groups were determined by the Dunn’s test. Results are shown in Table 1. There were no differences in the mean number of ovulations or total ova/embryo collected between any group (P > 0.05); however, those receiving eCG at the time of CIDR withdrawal (Groups 2 and 4) had significantly more transferable embryos than those receiving eCG at the time of the first FSH injection (Groups 1 and 3). In conclusion, the administration of the sustained-release FSH-MAP5 in a 2-injection protocol in sheep was as effective as a multiple-FSH injection protocol in inducing multiple ovulations and yielded similar number of transferable embryos, whereas the administration of eCG at the time of CIDR withdrawal resulted in more transferable embryos, possibly by improving fertilisation rates.

Table 1.  Results¹