Effects of Chinese herbal mixture extract on growth, immunity, antioxidant status, and modulates rumen microbiota in weaned lambs

The weaning process in lambs induces physiological stress that heightens susceptibility to pathogens and environmental challenges. This study investigated the effects of a Chinese Herbal Mixture Extract (CHE) comprising honeysuckle, astragalus, M. officinalis and tangerine peel as a dietary supplement in weaned lambs. Forty-eight 60-day-old lambs were randomly assigned to four groups: control (CON, basal diet), and basal diet supplemented with 0.1% (LCHE), 0.2% (MCHE), or 0.4% CHE (HCHE) for 56 days. Growth performance, immunity, antioxidant status, biochemical parameters, organ histology and rumen microbiota were evaluated. Data were analyzed by one-way ANOVA. Compared with CON, MCHE and HCHE significantly increased average daily gain (ADG) and decreased the feed-to-gain ratio (F/G) (P < 0.05). In addition, apparent digestibility of crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF) was improved (P < 0.05). These groups showed growth hormone (GH) and insulin-like growth factor-1 (IGF-1) levels (P < 0.05), increased immunoglobulin (IgA, IgG) concentrations and superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) activities (P < 0.05), and reduced malondialdehyde (MDA) (P < 0.05). The HCHE increased serum total protein (TP) and calcium (Ca) at day 56 (P < 0.05). Dietary CHE supplementation (0.1% - 0.4%) increased the villus height-to-crypt depth ratio (P < 0.05), with no significant pathological lesions observed in major organs upon histological examination. Microbiota analysis showed that CHE reshaped rumen microbiota, increased the relative abundance of Euryarchaeota (P < 0.05), which have a positive effect on enhancing carbohydrate and lipid metabolic pathways based on inferred functional potential. Dietary CHE supplementation alleviated weaning stress and enhanced growth performance in lambs by improving immune function, antioxidant capacity and rumen microbiota composition.