Vinegar residue: a sustainable alternative to conventional feedstuffs for improving nutritional value and gut health in growing pigs

The global scarcity of conventional foodstuffs such as corn, soybeans, and wheat has prompted the exploration of sustainable alternatives. Vinegar residue (VR), a byproduct of the food industry, appears as a potentially economical and nutritious feed resource. This study evaluates the nutritional composition of vinegar residue and its impact on growing pigs. Among the several types of vinegar residue evaluated, vinegar residue 7 (sorghum) had the highest crude protein (15.63%), while vinegar residue 1 (rice) had the highest fiber content, and also provided the highest digestible energy (DE) and metabolizable energy (ME). In feeding trials, growing pigs were fed a basic diet supplemented with 5% vinegar residue from rice, wheat, sorghum, and wheat bran (VR-R, VR-W, VR-S, and VR-WB) over 5 weeks. The results showed that both VR-R and VR-W supplementation reduced oxidative stress by lowering plasma malondialdehyde (MDA) levels and boosting antioxidative enzymes (CAT, GSH-Px). VR-R further modulated inflammation by suppressing pro-inflammatory cytokines, inhibiting nuclear factor kappa B (NF-<italic>κ</italic>B), and activating the nuclear factor erythroid 2 (Nrf2) pathway with genes including <italic>GPX4</italic> and <italic>HO-1</italic>. It also improved gut health by enhancing microbiota diversity, increasing butyrate, and promoting the growth of beneficial bacteria such as <italic>Clostridium sensu stricto 1</italic>. These findings highlight vinegar residue's potential as a sustainable feed alternative for improving intestinal health in growing pigs.