Abstract
BACKGROUND: In recent years, the livestock industry has shown increasing concern regarding the need to find effective alternatives to antibiotic products while also striving to produce high-quality livestock and poultry products. Woody feed sources exhibit wide distribution and variety, containing a variety of bioactive substances such as flavonoids and alkaloids. Among these woody plants, Neolamarckia cadamba (Nc) has the characteristics of high leaf yield, fast growth rate, and rich nutritional value, which has great development potential. However, whether Nc supplementation can improve growth performance, immunity, and gut health of yellow-feathered broilers remains to be explored. In the present study, we aimed to investigate the effects of diet supplemented with dry powder or water extract of Nc on the growth performance, immunity, and intestinal health of yellow-feathered broilers. RESULTS: The results showed that, (1) There was no significant difference in Body weight (BW), Average daily gain (ADG), Average daily feed intake (ADFI), and Feed conversion ratio (FCR) between the Nc experimental groups and the control group (P > 0.05); (2) Compared to the control group, the thymus index at 63 days was significantly increased in the 1% Nc dry powder group (P < 0.05). Conversely, the bursa index of Fabricius was significantly decreased (P < 0.05) in the same group; (3) Compared to the control group and antibiotic group, there were no significant differences in the serum levels of albumin (ALB), globulin (GLB), total protein (TP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and triglycerides (TG) in each experimental group (P > 0.05); (4) Compared to the control group, serum IgG levels were significantly increased in both the 1% Nc dry powder group and the 0.05% water extract group (P < 0.05); (5) Compared to the control group, 0.05% Nc water extract could significantly increase the mRNA expression levels of ZO-1 and TGF-β4 in the jejunum, as well as claudin-1, ZO-1, and TGF-β4 mRNA in the ileum(P < 0.05). Furthermore, the use of 1% Nc dry powder also resulted in a significant increase in the mRNA expression levels of TGF-β4 in the jejunum and ZO-1 mRNA in the ileum (P < 0.05). CONCLUSIONS: These results suggest that the dietary supplementation with Nc can enhance immune function, improve small intestinal barrier integrity, and reduce intestinal inflammation to a certain extent. Among the four doses (1% dry powder, 2% dry powder, 0.05% water extract and 0.1% water extract), 1% dry powder and 0.05% water extract were more effective. These findings underscore the importance of exploring alternative feed additives in livestock production, as they may offer a viable strategy for promoting animal health and performance in the absence of traditional antibiotics.