Supplementation with Xinjiang licorice extract in diets enhanced the growth performance and intestinal immunity of broilers.

Xinjiang is rich in high quality licorice resources. However, as a relatively new production area, the licorice resources have not been fully utilized, resulting in a certain degree of waste. To enhance the efficient use of Xinjiang licorice and explore its potential applications in veterinary medicine, this study systematically investigated the growth-promoting effects and gastrointestinal protective properties of Xinjiang licorice extract (XLE) in broiler chickens. A total of 540 one-d-old broilers (with an initial average body weight of 44.71 ± 0.40 g) were randomly assigned to five groups receiving XLE supplementation at graded levels (0, 500, 1000, 2000, and 4000 mg/kg). Each group had 6 replicates, with 18 chickens per replicate. The entire experimental period was 42 d. The findings indicated that the diet containing 1000 mg/kg XLE significantly improved the average daily weight gain (ADG) and decreased the feed conversion ratio (F:G) compared to the control group (P < 0.05), enhanced the levels of immunoglobulin (Ig) A, IgY, glutathione peroxidase (GSH-Px), and catalase (CAT) in the serum (P < 0.05). Furthermore, XLE supplementation significantly decreased the crypt depth (CD) of the duodenum (P < 0.01), increased the villus height (VH) to CD ratio of the duodenum and ileum, reduced the relative abundance of Faecalibacterium, Ruminococcus_torques_group, and Ruminococcus_gauvreauii_group at the genus level (P < 0.05), which demonstrated the benefits for the intestinal health of broiler chickens. Histomorphological analysis revealed that dietary supplementation with XLE did not adversely affect the histological architecture of visceral organs in broilers. Therefore, XLE supplementation improved intestinal immunity by regulating inflammatory factors and intestinal microbiota, providing significant benefits for the growth performance and intestinal health of broiler chickens. This study provides a novel insight into the application of Xinjiang licorice in broiler chickens.