YEAST CULTURE ON THE GROWTH AND INTESTINAL HEALTH OF JUVENILE AMERICAN EEL (ANGUILLA ROSTRATA) FED DIETS WITH VARYING PROPORTIONS OF LOW-QUALITY BROWN FISHMEAL

This study aimed to investigate the effects of dietary yeast culture (YC) supplementation on the growth and intestinal health of juvenile American eels (Anguilla rostrata) fed with varying proportions of low-quality brown fishmeal replacing high-quality white fishmeal. The experimental diets consisted of a basal diet devoid of low-quality brown fishmeal (Grade Ⅱ) and four trial diets in which low-quality brown fishmeal (Grade Ⅱ) replaced high-quality white fishmeal (Grade Ⅰ) at levels of 0, 10%, 20%, and 30%. All trial diets containing low-quality brown fishmeal were supplemented with 0.10% YC. Over an eight-week period, American eels initial weight of (13.52±0.05) g per fish were administered the experimental diets. The results revealed that dietary YC supplementation significantly enhanced the growth performance, intestinal tissue morphology, and intestinal antioxidant capacity of juvenile American eels fed the basal diet and the diet with 10% low-quality brown fishmeal. Compared to the basal diet group, YC supplementation had no discernible impact on the growth performance, intestinal tissue morphology, and intestinal antioxidant capacity of eels fed the diet with 20% low-quality brown fishmeal. However, YC supplementation failed to mitigate the growth inhibition, intestinal injury, and disruption in intestinal flora induced by the 30% low-quality brown fishmeal diet in juvenile American eels. Furthermore, YC supplementation promoted the proliferation of probiotics and inhibited the growth of pathogenic bacteria in the intestines of eels fed the basal diet and the diet with 20% low-quality brown fishmeal. In conclusion, this study demonstrates that the inclusion of 0.1% YC in the diet promotes the growth performance and intestinal health of juvenile American eels, providing effective alternative to replacing 20% white fishmeal with low-quality red fishmeal. This research establishes a scientific foundation for reducing eel feed costs and the judicious utilization of YC in fish feed.