Abstract
Weanling piglets often develop respiratory diseases such as pneumonia because they encounter substantial environmental stress. This study investigated an alternative herbal feed additive, Guizhi Li-Zhong Tang (GLZ), for preventing pneumonia in weanling piglets. An in vitro experiment demonstrated that GLZ has high antioxidant capacity and low cytotoxicity toward Kupffer cells. In addition, GLZ treatment can alleviate lipopolysaccharide (LPS)-induced damage in Kupffer cells. A total of 94 4-week-old piglets were randomly divided into three groups, which received sham treatment, 0.2% Tilmicosin antibiotic (TAB) treatment, or 0.2% GLZ treatment. Piglets receiving the GLZ treatment had a higher survival rate and higher immunoglobulin G levels but lower allergy-related eosinophil levels and cough incidence than did piglets receiving the sham or 0.2% TAB treatments. Through immunohistochemistry and Western blot analysis, we discovered that piglets receiving the 0.2% GLZ treatment had significantly higher expression of antioxidant-related SOD2 and lower expression of oxidative-stress-related 3-NT (p < 0.01), inflammation-related TNF-α (p < 0.01) and NF-κB (p < 0.05), and apoptosis-related caspase-3 (p < 0.01) in lung tissue than did piglets receiving the sham or 0.2% TAB treatment. Therefore, GLZ treatment is promising as an alternative to antibiotic medicine for weanling piglets because of its protective antioxidative, anti-inflammatory, and antiapoptotic effects in lung tissue.