Multi-omics approach to study the dual effects of novel proteins on the intestinal health of juvenile largemouth bass () under an alternate feeding strategy.

INTRODUCTION

In an effort to minimize the usage of fishmeal in aquaculture, novel protein diets, including Tenebrio molitor, cottonseed protein concentrate, , and were evaluated for their potential to replace fishmeal. Nevertheless, comprehensive examinations on the gut health of aquatic animals under an alternate feeding strategy when fed novel protein diets are vacant.

METHODS

Five isonitrogenous and isolipidic diets containing various proteins were manufactured, with a diet consisting of whole fishmeal serving as the control and diets containing novel proteins serving as the experimental diets. Largemouth bass (Micropterus salmoides) with an initial body weight of 4.73 ± 0.04g employed as an experimental animal and given these five diets for the first 29 days followed by a fishmeal diet for the next 29 days.

RESULTS

The results of this study demonstrated that the growth performance of novel protein diets in the second stage was better than in the first stage, even though only the diet increased antioxidant capacity and the cottonseed protein concentrate diet decreased it. Concerning the intestinal barriers, the diet lowered intestinal permeability and plasma IL-1β/TNF-α. In addition, the contents of intestinal immunological factors, namely LYS and sIgA-like, were greater in than in fishmeal. From the data analysis of microbiome and metabolome, the levels of short chain fatty acids (SCFAs), anaerobic bacteria, , and Firmicutes were significantly higher in the diet than in the whole fishmeal diet, while the abundance of , aerobic bacteria, , and Proteobacteria was lowest. However, no extremely large differences in microbiota or short chain fatty acids were observed between the other novel protein diets and the whole fishmeal diet. In addition, the microbiota were strongly connected with intestinal SCFAs, lipase activity, and tight junctions, as shown by the Mantel test and Pearson's correlation.

DISCUSSION

Taken together, according to Z-score, the ranking of advantageous functions among these protein diets was diet > diet > whole fishmeal diet > cottonseed protein concentrate > diet. This study provides comprehensive data illustrating a mixed blessing effect of novel protein diets on the gut health of juvenile largemouth bass under an alternate feeding strategy.