Synergistic Benefits of Butyric Acid and Resistant Potato Starch on Growth and Gut Health in Weaned Pigs

Newly-weaned piglets face challenges such as reduced feed intake, impaired gut function, and susceptibility to post-weaning diarrhoea, increasing the need for dietary strategies that support gut health and growth. This study investigated the effects of dietary supplementation with butyric acid (BA), resistant potato starch (PS), and their combination on faecal markers of intestinal health and growth performance in weaned piglets. It was hypothesised that BA and PS would exert beneficial effects, and that their co-supplementation would yield complementary effects on gut function and growth. In a 2 × 2 factorial design, 96 piglets (28 days of age) were assigned to one of four treatments: (1) control, (2) control +15 g/kg BA, (3) control + 10 g/kg PS, or (4) control +15 g/kg BA and 10 g/kg PS (combination). Growth performance was assessed over 35 days, and faecal samples were collected on Day 8 post-weaning for microbiota and volatile fatty acid profiling. All supplemented diets improved faecal scores compared to the control (p < 0.05), with the combination diet producing the highest average daily feed intake (ADFI), average daily gain (ADG), and final body weight (BW) among treatments, significantly higher than the BA-only and PS-only diets (p < 0.05), and numerically superior over the control (p < 0.10). Moreover, the combination diet had the highest faecal Faecalibacterium abundance of all treatments, significantly higher than the BA-only diet (p < 0.05) and numerically superior to the control and PS-only diet (p < 0.10). The BA-only diet increased faecal Ruminococcaceae and reduced Enterobacteriaceae abundance, but reduced ADG and BW (p < 0.05), and tended to reduce ADFI (p < 0.10). The PS-only diet increased faecal Prevotella and butyrate levels, and reduced Proteobacteria and isobutyrate levels but reduced ADFI (p < 0.05). While BA and PS individually improved faecal microbial and metabolic markers without enhancing growth, their combined supplementation improved both gut health and growth, suggesting a synergistic interaction and a promising nutritional strategy to mitigate the negative effects of weaning.