Effects of dietary propyl gallate and Lactobacillus plantarum addition on growth, intestinal morphology, antioxidant capacity, and immune functions of Pekin ducks

The interaction between probiotic bacteria and polyphenol antioxidants can potentially enhance animal health. The present study examined the effects of propyl gallate and Lactobacillus plantarum supplementation on the growth, intestinal morphology, antioxidant capacity, and immune functions of Pekin ducks. A total of 128 male Pekin ducks (7-day-old) were allocated to four treatment groups with four replicates of eight birds each. The ducks were fed the corn-soybean based diet (the control), supplemented with either propyl gallate (100 mg/kg), Lactobacillus plantarum (4 × 10⁹ CFU/kg), or both, for 5 weeks. Dietary supplementation with propyl gallate and Lactobacillus plantarum had no significant effect on feed intake (P > 0.05), but increased average daily gain (P < 0.05). Lactobacillus plantarum also reduced the feed/gain ratio (P < 0.05). Villus height (VH) in the duodenum and ileum was increased by supplementation, while only propyl gallate supplement increased VH in the jejunum (P < 0.05). Supplementation had no effect on small intestine crypt depth (P > 0.05). Enhanced total superoxide dismutase activity was observed with supplementation (P < 0.05), but no effects were seen on catalase, malondialdehyde, total antioxidant capacity, and glutathione peroxidase values (P > 0.05). Serum immunoglobulin G was increased with Lactobacillus plantarum (P < 0.05), but not with propyl gallate (P > 0.05). No change in IgA and IgM concentrations was observed with supplementation. In conclusion, dietary supplementation with propyl gallate, Lactobacillus plantarum, or both, enhanced the villus height of the small intestines, improving the growth rate of Pekin ducks. The synergistic effects of both propyl gallate and Lactobacillus plantarum on the villus height and serum total superoxide dismutase activity surpassed the individual effects of each supplement in Pekin ducks.