287 Effects of Number of Sperm and Site of Uterine Semen Deposition on Conception Rate and Number of Embryos in Weaned Sows Receiving a Single Fixed Time Insemination

Abstract

Abstract Induced ovulation with single fixed time artificial insemination (SFTAI), combined with uterine (IUI) or deep uterine insemination (DUI), could improve fertility with low numbers of sperm and allow greater use of high genetic merit boars. At weaning (0 h), sows (n = 534) were assigned by parity and estrus induction method (eCG or Control) to receive 1200 × 106 sperm by IUI, 600, 300, or 150 × 106 sperm by IUI or DUI, or 75 × 106 sperm by DUI. At 80 h post weaning, sows received OvuGel and 26 h later a pooled semen SFTAI. Ultrasound was performed to determine follicle size and time of ovulation (OV). Sows were slaughtered 27 d after AI to determine pregnancy and litter traits. There was no effect (P > 0.05) of eCG on estrus (93%) within 5 d of weaning or follicle size (6.1 mm) at OvuGel, but wean-to-estrus (3.8 vs. 4.0 d,P < 0.01) and AI-to-OV (15.9 vs. 17.0 h, P = 0.04) intervals and AI-to OV were slightly reduced. eCG did not affect pregnancy rate (78.6%), number of CL (21.7), or number of viable embryos (12.2). There was no effect of number of sperm or site of insemination (P > 0.05) on pregnancy rate (range: 80.9% to 70.5%), but AI occurring after ovulation reduced pregnancy rate (P < 0.02). Total number of embryos (range: 16.5 to 10.3) increased with CL number (P < 0.001) but was not affected by number of sperm or site of insemination (P > 0.05). Higher sperm treatments (1200 and 600 x 106) had more embryos compared to lower sperm treatments (P < 0.01), suggesting that lower sperm numbers effects litter size more than the pregnancy status. Acceptable fertility can be achieved with low sperm numbers when using SFTAI and uterine deposition, but AI-to-OV interval and ovulation rate influence final fertility.