Swine-Derived Probiotics and Their Metabolites as an Alternative to Veterinary Antibiotics

The intensive development of livestock and poultry farming has heavily relied on antibiotics, leading to widespread antimicrobial resistance and posing serious threats to food safety and public health. As the industry transitions towards reduced antibiotic use and sustainable animal production, probiotics and their metabolites have garnered attention as functional alternatives. Probiotics are typically administered in the form of microecological preparations by mixing them into feed or water, offering advantages in cost-effectiveness and ease of use, with demonstrated efficacy in promoting animal health. Swine-derived probiotics, in particular, demonstrate host-specific advantages due to their natural adaptation to the porcine gastrointestinal environment, which improves intestinal colonization, pathogen inhibition, and immune modulation. Their metabolites, including short-chain fatty acids, bacteriocins, and exopolysaccharides, further contribute to these benefits through antimicrobial, anti-inflammatory, and barrier-strengthening effects. Recent studies have demonstrated improvements in average daily gain (18-22%) and feed conversion ratio (12-15%), along with a reduction in diarrhea incidence (up to 40-45%) in weaned piglets supplemented with certain probiotic consortia. It should be noted, however, that part of the supporting evidence is derived from in vitro or non-porcine models, and practical outcomes in swine may vary depending on husbandry conditions, probiotic strain, and husbandry conditions. This review systematically summarizes the isolation and identification of swine-derived probiotics, the active components and functions of their metabolites, and the mechanisms of action and application effects of these metabolites as antibiotic-alternative feed additives. It primarily focuses on innovative research advances in probiotic metabolites for enhancing antibacterial activity and improving pig growth performance. Furthermore, the review discusses the prospects for commercial applications and future research directions, aiming to provide theoretical foundations and technical references for green and healthy farming practices.