Reducing number of sperm needed to produce a litter with AI allows greater use of higher genetic merit boars. 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. The objectives of the study were to determine the fertility effects of sperm numbers and site of insemination. At weaning (0 h), sows (n = 534) were assigned by parity and estrus induction method (eCG or Control) to receive 1200 × 10 ⁶ sperm by IUI, 600, 300, or 150 × 10 ⁶ sperm by IUI or DUI, or 75 × 10 ⁶ sperm by DUI. At 80 h post weaning, sows received OvuGel and 26 h later a SFTAI using pooled semen. Sows were exposed to boars once daily and ultrasound was performed to determine follicle size and time of ovulation. Following SFTAI, sows were slaughtered 27 d after AI to determine pregnancy and litter traits. Data were analyzed using different models to test for effects of estrus induction, interaction of three levels of sperm (600 to 150) with two levels for site (IUI vs DUI), and for overall effects of AI method (8 treatments). There was no effect (P > 0.05) of estrus induction on estrus (93%) within 5 d of weaning or on follicle size (6.1 mm) at OvuGel, but wean-to-estrus interval (3.8 vs. 4.0 d) was slightly reduced (P < 0.01) as was AI-to-ovulation interval (15.9 vs. 17.0 h, P = 0.04) for eCG and Control, respectively. There was no effect (P > 0.05) of estrus induction on 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 and no interaction (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) was not affected by estrus induction, number of sperm or site of insemination (P > 0.05), but was influenced by AI treatment (P < 0.01). Treatments with a higher number of sperm (1200 and 600) had more embryos compared to those with a lower number of sperm (300 to 75).Numbers of embryos also increased with number of CL (P < 0.0001). These results suggest that the lower number of sperm affects litter size more than the pregnancy status.. Acceptable fertility can be achieved with low numbers of sperm when using a SFTAI and uterine deposition, but AI-to-ovulation interval and ovulation rate influence final fecundity.

中文翻译：

---

精子数量和子宫精液沉积部位对断奶母猪单次定时授精受孕率和胚胎数量的影响。

通过人工智能减少生产一窝仔猪所需的精子数量，可以更多地利用遗传价值更高的公猪。单次固定时间人工授精 (SFTAI) 诱导排卵，结合宫内人工授精 (IUI) 或深部子宫授精 (DUI)，可以提高精子数量较少的生育能力。该研究的目的是确定精子数量和授精部位对生育力的影响。断奶时（0 小时），母猪 (n = 534) 通过胎次和发情诱导方法（心电图或对照）分配通过 IUI 接收 1200 × 10 ⁶精子，通过 IUI 或 DUI 接收600、300 或 150 × 10 ⁶精子，或 DUI 检测 75 × 10 ⁶精子。断奶后 80 小时，母猪接受 OvuGel，26 小时后使用混合精液接受 SFTAI。母猪每天与公猪接触一次，并进行超声波以确定卵泡大小和排卵时间。SFTAI 后，AI 后 27 天屠宰母猪以确定妊娠和窝仔性状。使用不同的模型对数据进行分析，以测试发情诱导的效果、三个水平的精子（600 至 150 个）与两个水平的位点（IUI 与 DUI）的相互作用，以及 AI 方法的总体效果（8 次治疗）。发情诱导对断奶 5 天内的发情 (93%) 或 OvuGel 的卵泡大小 (6.1 毫米) 没有影响 (P > 0.05)，但断奶到发情间隔 (3.8 与 4.0 d) 略有影响心电图和对照组的 AI 至排卵间隔（15.9 小时与 17.0 小时，P = 0.04）分别减少（P < 0.01）。引情对妊娠率（78.6%）、CL数量（21.7）或存活胚胎数量（12.2）没有影响（P>0.05）。精子数量或授精部位对妊娠率没有影响（P > 0.05）（范围：80.9%至70.5%），但排卵后发生AI会降低妊娠率（P < 0.02）。胚胎总数（范围：16.5至10.3）不受发情诱导、精子数量或授精部位的影响（P > 0.05），但受AI处理的影响（P < 0.01）。与精子数量较少（300 至 75）的治疗相比，精子数量较多（1200 和 600）的治疗具有更多胚胎。胚胎数量也随着 CL 数量的增加而增加（P < 0.0001）。这些结果表明，精子数量较少对窝产仔数的影响大于妊娠状况。当使用 SFTAI 和子宫沉积时，精子数量较少即可达到可接受的生育力，但 AI 至排卵间隔和排卵率影响最终生育力。