Organic acid-preserved grain improves growth and gut health in weanling pigs fed zinc oxide free diets
Kathryn Ruth Connolly, Torres Sweeney, Marion T. Ryan, Vivian Gath, Shane Maher, Stafford Vigors, J.V. O’Doherty
Abstract
The effects of organic acid (OA)-preserved grain and zinc oxide (ZnO) supplementation on post-weaning (PW) piglet performance and intestinal health were evaluated in a 2 × 2 factorial study. Ninety-six piglets (28 days old) were allocated to four diets: dried grain, OA-preserved grain, dried grain + ZnO, and OA-preserved grain + ZnO, for 35 days. Diets contained 600 g/kg grain (450 g/kg wheat, 150 g/kg barley). On day 10 PW, 28 piglets (n = 7/treatment) were euthanised for small intestinal morphology, gene expression, microbial, and volatile fatty acid (VFA) analyses. OA-preserved grain reduced dietary Ochratoxin A and Deoxynivalenol concentrations and increased average daily gain (P < 0.05), but provided no additional growth benefit when combined with ZnO. ZnO increased feed intake, body weight, colonic Lactobacillus abundance, and villus height-to-crypt depth ratio, while reducing faecal scores and colonic branched-chain fatty acids (P < 0.05). OA-preserved grain increased ileal Faecalibacterium and reduced Escherichia populations, and downregulated duodenal IL17 and ileal FOXP3 expression (P < 0.05). ZnO broadly suppressed pro-inflammatory cytokines and upregulated nutrient transporter genes (SLC15A1, SLC16A1). These findings indicate that OA-preserved grain improves growth and gut health but does not fully replace ZnO in mitigating PW diarrhoea.