Compound organic acid could improve the growth performance, immunity and antioxidant properties, and intestinal health by altering the microbiota profile of weaned piglets

This study aimed to investigate the impact of compound organic acid (COA) and chlortetracycline (CTC) on serum biochemical parameters, intestinal health, and growth performance of weaned piglets. Twenty-four piglets (24 d of age) were randomly allocated into three treatments with eight replicate pens (one piglet per pen). Feed the basal diet or a diet containing 3,000 mg/kg COA or 75 mg/kg CTC, respectively. Results showed that both COA and CTC significantly increased average daily gain and reduced diarrhea rates (P < 0.05). They also upregulated serum total antioxidant capacity and downregulated serum interleukin (IL-10) levels (P < 0.05), increased crude protein digestibility and propionic acid concentration in the colon, and decreased spermidine and putrescine contents (P < 0.05). Intestinal microbiota analysis revealed that both COA and CTC increased the Shannon and Chao1 index and decreased the relative abundance of Blautia and Roseburia, but increased the relative abundance of Clostridium-sensu-stricto-1. Correlation analysis indicated that Clostridium-sensu-stricto-1 may be closely related to inflammation levels and microbial metabolites in piglets. Based on the results, COA may be a potential substitute for CTC to reduce antibiotic use and biogenic amine emission while improving piglet growth and intestinal health. Lay Summary Weaned piglets face challenges due to their underdeveloped digestive system, resulting in high gastrointestinal tract pH and insufficient enzyme secretion. To address this issue, we found supplementing piglet diets with 3,000 mg/kg of compound organic acid positively impacted the immune and antioxidant levels of piglets, promoted their intestinal health, improved nutrient digestibility, and enhanced their overall growth performance. These benefits were attributed to the regulation of intestinal microbiota by the compound organic acid. By improving piglet health and growth, this research offers a potential solution to the challenges of piglet weaning stress. Piglet weaning stress can significantly impact intestinal health and growth performance. However, supplementing piglet diets with compound organic acid can regulate microbiota, promote antioxidant capacity, enhance intestinal health, and improve nutrient digestibility. These positive effects contribute to better piglet growth performance, providing a promising solution to the challenges of piglet weaning stress.