Effects of replacing antibiotics with Bacillus-based probiotics in the diet of lactating sows on reproductive performance, feed intake, serum immunoglobulin levels, milk production, oxidative stress markers, fecal short-chain fatty acids, and piglet

This clinical trial investigated the effects of adding a Bacillus-based probiotic to the lactation diet of sows (without in-feed antibiotics) on maternal and piglet outcomes. A total of 109 Landrace × Yorkshire sows (parity 1–7) were assigned to either a control group (n = 61) or a treatment group (n = 48) receiving Bacillus subtilis – 541 and Bacillus amyloliquefaciens – 516. Piglets in the treatment group also received the probiotics via creep feed from day 3 until weaning. Blood samples were collected within 12 h after farrowing to assess serum immunoglobulins (IgG, IgA, and IgM) and malondialdehyde (MDA) in sows, while piglet fecal short-chain fatty acids (SCFAs) were analyzed on days 3, 7, and 21. On average, sows were fed either a standard or probiotic-supplemented lactation diet for 5.9 ± 1.8 days before farrowing and for 21 days postpartum, resulting in a total feeding duration of 26.9 ± 1.8 days. The average daily feed intake was 3.7 ± 1.0 kg/day before farrowing and 6.2 ± 0.7 kg/day during lactation. During the first, second, and third weeks of lactation, average feed intake was 5.4 ± 1.1, 6.4 ± 0.9, and 6.7 ± 0.7 kg/day, respectively. Sows lost 14.5% of their backfat during lactation and produced an average of 8.2 ± 1.3 kg/day of milk from days 3–10 and 10.0 ± 2.1 kg/day from days 10–17. Probiotic supplementation had no effect on reproductive traits, milk yield, or piglet growth (P > 0.05), but it increased sow feed intake before farrowing (P = 0.025) and serum IgM levels (P = 0.031). Piglet IgM concentrations were lower on day 7 (P = 0.002), while fecal SCFAs were higher on day 7. In conclusion, probiotic supplementation increased sow feed intake before farrowing and elevated serum IgM levels, while transiently enhancing piglet fecal SCFAs, without affecting other performance parameters.