Benzoic acid-the cornerstone of any swine nutrition program.

Benzoic acid (BA) is an organic acid that has become a key dietary supplement in swine production, offering a comprehensive approach to improving gut health and performance while addressing challenges such as antimicrobial resistance and environmental sustainability. This review explores the existing literature on dietary BA supplementation across different physiological stages of pigs: weaned piglets, growing-finishing pigs, and sows. Although the exact mechanism of action of BA is not yet fully understood, three non-mutually exclusive mechanisms have been proposed: 1) modulation of the microbiota, which may inhibit pathogenic bacteria in both the feed and the gut; 2) a reduction in gastric pH, leading to increased pepsin activity and improved nutrient digestibility; and 3) urine acidification resulting from BA metabolism, which may limit bacterial activity in the urinary tract and lower the pH of slurry. Consequently, BA supplementation has been shown to improve growth performance, reduce the incidence of diarrhea, and enhance nutrient digestibility, thereby promoting overall pig health. Additionally, BA supplementation has been associated with a reduced risk of urinary tract infections in sows during farrowing and a decrease in ammonia emissions from slurry. This review highlights BA's potential as a viable alternative to conventional antimicrobial growth promoters. It also stresses the need for further research to optimize BA supplementation strategies and investigate its synergistic effects with other additives. Such knowledge is crucial for developing sustainable swine production systems that prioritize animal health and environmental stewardship without compromising performance or economic viability.