Restricted vs. <i>ad libitum</i> feeding during sow gestation affects piglet performance, behavior, and fecal microbiota composition

This study investigated how the nutrition of gestating sows affects piglet performance, behavior, and fecal microbiota. Twenty-four sows were divided into 2 feeding groups: those on a restricted diet (once a day) and those fed ad libitum (as much as they wanted), with all receiving the same diet during lactation. The piglets were categorized based on their feeding groups; RG-RL: Piglets born and nursed by restricted-fed sows with restricted feeding, AG-AL: Piglets born and nursed by ad lib-fed sows, RG-AL: Piglets born by restricted-fed sows and nursed by ad lib-fed sows, and AG-RL: Piglets born by ad lib-fed sows and nursed by restricted-fed sows. Performance traits were analyzed using the model including treatment, switching piglets, and room effects. Piglet behavior was evaluated with a generalized linear mixed model (GLMM) using binomial distribution, testing interactions of treatment, switching, gender, and other factors while accounting for random effects related to room, pen, and sow. Results showed that ad lib-fed sows had higher feed intake (P < 0.001), weight gain (P = 0.04), and backfat gain (P = 0.01) compared to restricted-fed sows. They also had lower cortisol levels during gestation (P = 0.02) and lactation (P = 0.04). Restricted-fed sows displayed more air-chewing behavior (P = 0.002), while ad lib-fed sows were more active (P = 0.03) and engaged in eating (P < 0.001). Birth weights and the number of piglets were similar across groups. During lactation, backfat loss varied among piglet groups, with the highest loss in AG-RL (P < 0.01). Piglets from ad lib-fed sows performed better overall, regardless of nursing source. At weaning, piglet weights (P = 0.01) were highest in AG-AL, followed by RG-AL, RG-RL, and AG-RL (interaction effect P = 0.006). Switching piglets initially reduced their playtime but later increased it (P = 0.04). The novel object test indicated that gilts became more active, resembling boars. Additionally, gut microbiota composition varied among sow groups during gestation (P = 0.04) and lactation (P = 0.02), suggesting that maternal diet influences piglet gut health. Overall, these findings highlight the potential role of epigenetic mechanisms in shaping these traits.