Effects of Probiotic Fermented Broth on Reproductive Performance and Intestinal Microbiota of Pregnant Sows

ABSTRACT In recent years, China’s comprehensive ban on antibiotics in feed has highlighted the need for safe, non-toxic, growth-promoting feed additives. As microbial products, probiotic preparations serve as ideal antibiotic alternatives, enhancing livestock and poultry growth performance, immunity, and feed utilization efficiency; regulating fecal microbial balance; and inhibiting pathogenic bacteria. These live microorganisms colonize the host’s intestines to benefit intestinal health, immune function, and development, making them a novel, widely applicable antibiotic-substituting feed additive in sow production. Forty-eight healthy pregnant sows with similar ages and parities were randomly divided into 4 groups : the control group was fed a basal diet, and three treatment groups (SPL: Lactiplantibacillus plantarum QZF; SPB: Bacillus velezensis; DP: L. plantarum QZF + B. velezensis) in which respective seed solutions were added to the basal diet for anaerobic fermentation at a 10:1 water-to-feed ratio for 24 hours. The experiment ran from day 90 of gestation to weaning, and supplementation with probiotic fermented broth significantly altered sows’ reproductive performance, anti-stress function, immune function, and fecal microbiota—specifically reducing the piglet diarrhea rate, increasing early piglet average daily gain (ADG) and milk protein content (Cpr). Compared with the control group, the SPL group had decreased serum albumin (ALB) and total protein (TP) (P < 0.05) as well as extremely significantly reduced serum IgA, IgG, and IgM (P < 0.01), while the DP group showed no significant differences in these immune indicators, consistent with its ALB results. These results show that feeding Lactiplantibacillus plantarum alone inhibits the immune performance of pregnant and lactating sows, whereas Bacillus velezensis alleviates this effect via its immune-regulatory function; combined probiotic supplementation mitigates the inhibitory impact. Additionally, the co-administration of the two strains effectively improves intestinal microbial flora and extremely significantly reduces the abundance of the intestinal pathogen Shigella, which is directly linked to the significant reduction in piglet diarrhea rate. IMPORTANCE The reproductive performance and intestinal microbiota health of sows are key factors affecting the economic benefits of breeding. As a bioactive additive, probiotics can improve animal intestinal health and enhance animal production performance. This study aimed to investigate the effects of probiotic fermented broth on the reproductive performance, antioxidant function, anti-stress function, immune function, and fecal microbiota of pregnant sows. In conclusion, compared with the single probiotic application strategy, the compound probiotic liquid fermentation technology can improve the intestinal immune function of sows, and at the same time, assist young piglets in establishing a balanced intestinal flora through mother-to-offspring transmission, reduce piglet diarrhea, and provide a new solution for antibiotic-free breeding.