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Gallic acid (GA) is a tannin hydrolysis product, common in plants such as knotgrass or bilberry. Its antioxidant activity is comparable to that of ascorbic acid. However, little research has been done describing its effects in pig production. Therefore, the aim of the present study was to evaluate the effects of different dietary levels of GA on growth performance, diarrhea incidence, intestinal morphology, plasma antioxidant indices, and immune response in weaned piglets. For that purpose, a total of 96 male weaned piglets (25 ± 1 days of age) with an initial body weight of 8.40 kg were randomly allotted into one of four treatments, which consisted of dietary supplementation with 0, 100, 200, or 400 mg GA /kg feed compared to a basal diet containing 3000 mg ZnO /kg. Moreover, on day 21, 24 piglets (1 piglet/pen) received an intraperitoneal lipopolysaccharide (LPS) injection. Blood samples were collected before (0 h) and 4 h after LPS challenge, and the piglets were sacrificed 4h post-challenge to collect small intestinal samples.
As a result, GA supplementation did not affect the growth performance of piglets. Piglets administered 400 mg/kg showed reduced incidence of diarrhea compared to piglets fed a control diet. In the jejunum, dietary GA at 100–400 mg/kg increased the villus height to crypt depth ratio, while dietary GA at 200 and 400 mg/kg reduced crypt depth, and dietary GA at 100 mg/kg increased jejunum villus height. LPS injection reduced catalase, glutathione peroxidase, and superoxide dismutase activity and increased the production of malondialdehyde and levels of immunoglobulin A (Ig A), Ig M, tumor necrosis factor α (TNF-α), and interleukin 8 (IL-8) in the plasma of piglets. However, there was no effect of diet on plasma antioxidant and immune status. Dietary GA linearly increased ileal secretory IgA content and showed a linear down-regulating effect on the expression TNF-α in the ileal mucosa.
In conclusion, dietary supplementation with gallic acid lessened postweaning diarrhea and protected intestinal integrity, which may be attributed to the modulation of the intestinal local immune response.
Cai, L., Li, Y. P., Wei, Z. X., Li, X. L., & Jiang, X. R. (2020). Effects of dietary gallic acid on growth performance, diarrhea incidence, intestinal morphology, plasma antioxidant indices, and immune response in weaned piglets. Animal Feed Science and Technology, 114391. https://doi.org/10.1016/j.anifeedsci.2020.114391