Effect of adlay (Coix lachryma-jobi L.) on growth, antioxidation, immune modulation, and intestinal health of crucian carp (Carassius auratus)

Abstract

In the field of aquatic feed, the search for efficient and safe feed additives to enhance aquaculture efficiency and improve the quality of aquatic products is crucial. Adlay, being rich in nutrition and bioactive substances, has garnered significant interest for feed application. However, its impact on fish has not been studied. In the current study, we evaluate the potential role of different levels of adlay on the performance of crucian carp (Carassius auratus) in terms of growth, antioxidation, immunomodulation, and intestinal health. Four groups fed diets containing 0% (control group, Con), 5.0%, 10.0%, and 14.0% adlay were separated for 8 weeks. The results showed that there was no significant difference in the growth performance of crucian carp among the experimental groups. However, in terms of antioxidant, the 10.0% and 14.0% adlay groups showed a significant reduction in MDA levels, and the levels of GSH-Px and CAT were increased in the 5.0% adlay group and/or 10.0% adlay group. In terms of immune regulation, the mRNA expression of IL-10 and Mcl-1 were increased in the 10.0% and 14.0% adlay groups. Furthermore, it showed a decreased trend of mRNA expressions of IL-1β, TNF-α, NF-κB and Bax, caspase 3, caspase 8, and caspase 9 among adlay groups. After injecting with the pathogen Aeromonas veronii, all three treatments showed lower mortality rates, with the 10.0% adlay group exhibiting the lowest mortality. The activities of amylase and lipase were increased in the 10.0% and 14.0% adlay groups, and the intestinal villus width and crypt depth showed favorable changes in adlay groups. Additionally, dietary adlay increased potential probiotics like Cetobacterium and decreased potential pathogens, such as Aeromonas and Pelomonas. Overall, dietary adlay can enhance antioxidant capacity and immunity and promote intestinal health. According to the regression equation of immunity and antioxidant-related indexes, the optimal adlay for crucian carp was estimated to be 8.87–10.25%. This study provides a scientific basis for the application of adlay in the field of aquatic feed.