The Effects of Inulin on the Growth, Oxidative Stress, and Immune Function of Weaned Kids

Goats are important producers of meat, milk, hair, and leather. Early-weaned kids may encounter issues such as weaning stress and stress from high-density farming, which can hinder their growth and development. Therefore, exploring feed additives capable of alleviating stress in kids to enhance their growth performance is of particular importance. This experiment aims to investigate the effects of inulin on the growth performance, immune function, and intestinal health of weaned kids. Thirty healthy 60-day-old Leizhou black goat weaned kids with similar body weights (9.00 ± 0.05 kg) were selected and evenly divided into five groups by weight, with six kids in each group. The control group was fed the basal diet, while the AM HCl group received 0.05‱ aureomycin hydrochloride. The inulin groups were supplemented with 0.1%, 0.3%, and 0.5% inulin, respectively. By comparison, the results of the 0.3% inulin group in this experiment were most consistent with those of the AM HCl group, and the final weight of the kids was the highest. The 0.3% and 0.5% inulin groups had significantly enhanced immune-related indicator (such as sIgA, IgA, and IgG) concentrations and antioxidant activities (p < 0.05) in kids. Inulin significantly increased cecal total volatile fatty acids (TVFA) and the activities of jejunal α-amylase, chymotrypsin, and trypsin (p < 0.05); the activities of intestinal antioxidant enzymes, including GSH-PX, SOD, and T-AOC, were significantly increased (p < 0.05); and the intestinal anti-inflammatory factor IL-10 was significantly elevated (p < 0.05). Inulin significantly increased the mRNA expression levels of the tight junction protein genes TJP1 (ZO-1) and OCLN in the jejunum (p < 0.05). It also significantly upregulated the mRNA expression levels of anti-inflammatory factors TGF-β1 and IL-10 while significantly reducing the mRNA level of pro-inflammatory factor IL-6 in the jejunum (p < 0.05). Therefore, inulin enhanced the growth performance and antioxidant capacity of weaned kids, improved the body's immune response, and reduced inflammatory responses. Specifically, when comparing the growth status, antioxidant enzyme activity, and tight junction protein mRNA level among the groups of kids, the 0.3% inulin supplementation yielded the best results in this experiment.