Does a single fixed-time insemination in weaned sows affect gestation and lactation length, and piglet performance during lactation compared with multiple insemination protocols in a commercial production setting?

This study evaluated the effect of different single fixed-time artificial insemination (FTAI) protocols on gestation length, farrowing distribution (synchrony), and piglet performance. In Study 1, 866 sows were assigned to two groups: Multiple AI (n = 484) - multiple artificial insemination (AI) at 24 h intervals during estrus; and FTAI+MultAI (n = 382) - OvuGel® 96 h post-weaning and single FTAI 22-24 h later. In Study 2, FTAI protocols were retrospectively analyzed: pLH - sows received 2.5 mg (Exp.1, n = 184) or 5 mg (Exp.2, n = 362) of porcine luteinizing hormone (pLH) at estrus onset, and single FTAI 24 h later. The FTAI+MultAI resulted in shorter gestation length (P < 0.01) and greater synchrony of farrowing on days 114-115 of gestation (P < 0.01) than Multiple AI. Longer lactation length (21.2 vs. 20.9 d; P = 0.02) and greater piglet weaning weight (5378.9 ± 73.1 vs. 5153.2 ± 74.4 g; P = 0.03) for FTAI+MultAI compared to Multiple AI were observed. In Study 2, the gestation length based on the first AI record was shorter for FTAI and resulted in greater synchrony of farrowing on days 114-115 of gestation, compared with Multiple AI (P ≤ 0.05). Gestation length did not differ between groups (P > 0.05) when measured based on most probable AI responsible for fertilization (ultrasound evaluation). In conclusion, FTAI resulted in shorter gestation length and greater farrowing synchrony compared with Multiple AI. Longer lactation length and greater piglet weaning weight were observed for FTAI compared with multiple insemination protocols.