143 SUPEROVULATORY RESPONSE AND EMBRYO PRODUCTION INFLUENCED BY THE ADDITION OF LH AND EFFECT OF THE REPEATABILITY IN SANTA INêS SHEEP

Abstract

The aim this study was to evaluate the effect of the addition of LH in superovulatory response and embryo production in Santa Inês sheep. Ten donors with 60.3 ± 10.7 kg and BCS of 3.9 ± 0.3 were superovulated in a cross-over design, with a 60-day interval. Estrus was synchronized with a progesterone-releasing intravaginal device (CIDR^™; Pfizer Animal Health, Brazil) inserted on Day 0 and replaced by a new one on Day 7, that was maintained to Day 14. Two doses of 37.5 g of D-cloprostenol (Prolise^™, Arsa, Buenos Aires, Argentina) were administered, on Days 7 and 14. Donors also receive 256 mg of pFSH (Folltropin^™, Bioniche, Belleville, ON, Canada) in 8 decreasing doses, starting on Day 12. On Day 14, all females received 200 IU of eCG (Novormon ^™, Syntex, Argentina). On Day 15, the animals were homogeneously allocated in 1 of 2 groups: Control (GC, n = 10) and treated (G-LH, n = 10). Ewes in GC did not receive exogenous LH, whereas ewes in G-LH were treated with 7.5 mg of LH (Lutropin^™, Bioniche), on Day 15. All females were inseminated by laparoscopy, with frozen–thawed semen, 42 and 48 h after CIDR removal. On Day 21, the embryos were surgically collected. The superovulatory response was classified in scores: (0) 4 or fewer CL; (1) between 5 and 10 CL, and (2) 11 or more CL. Means were compared using Kruskal-Wallis test and percentages using chi-square (P < 0.05). Most of donors (70%, 7/10) from G-LH presented a superovulatory response classified as score 2, and the remaining (30%, 3/10) as score 1, whereas, half of the controls were classified as score 2 and half as score 1. Ovulation rate tended to be greater in G-LH (135/158, 85.4% v. 105/135, 77.7%, P = 0.08). The number of CL (mean ± SD) was 10.5 ± 3.8 in GC and 13.5 ± 4.84 in G-LH, but was not statistically different. The number of anovulatory follicles (AF) did not differ between groups (GC: 3.0 ± 3.2; G-LH: 2.3 ± 1.6), but the proportion of AF tended to decrease in G-LH (30/135, 22.2% v. 23/158, 14.5%, P = 0.08). Considering embryo production, there was no difference between GC and G-LH (P > 0.05) related to number of recovered ova/embryos (6.1 ± 4.6 v. 8.4 ± 5.2), viable embryos (3.8 ± 4.3 v. 4.2 ± 5.2), unfertilized (1.7 ± 3.4 v. 2.0 ± 2.9) and degenerated embryos (0.7 ± 0.7 v. 2.2 ± 2.9), respectively. Data showed that the addition of LH tended to increase ovulation rate and to decrease the proportion of AF, but did not affect the number of viable embryos.