Assessment of fermented vegetable wastes in Nile tilapia diets: impacts on fish performance, amino acids profile, health, and intestine histomorphology

This study assessed the effects of incorporating fermented vegetable wastes (FVW), with Bacillus subtilis and Saccharomyces cerevisiae, in Nile tilapia (Oreochromis niloticus) diets at 0, 10, 20, and 30% inclusion levels (FVW0, FVW1, FVW2, and FVW3, respectively) on fish growth, feed utility, amino acids profile, health, nutrient utilization and intestine histomorphology. The results indicated 100% survival rates for all experimental groups. Furthermore, based on WG and SGR recorded values, fish growth was insignificantly changed among all fish groups (P > 0.05). Feed intake was significantly higher in FVW3 and FVW2 compared to other groups, however, feed utilization efficiency was not varied among all experimental groups depending on FCR and PER values. Carcass biochemical analysis showed that only ash content was significantly different among dietary groups as it was higher in FVW1 and FVW2 compared with the other two groups. The results illustrated an increase in most of the essential amino acids (EAAs) percent in the experimental groups relative to the control. Complete blood count revealed that red blood cells count remained insignificantly different among all groups, however, FVW1 showed a significantly lower hemoglobin content compared to the control and other groups. White blood cells count was significantly the highest in FVW2. Aspartate aminotransferase (AST) concentration was significantly elevated in both FVW2 and FVW3 groups compared to control, however, alkaline phosphatase (ALP) concentration was significantly decreased in these two experimental groups. The highest alanine aminotransferase (ALT) concentration was recorded in FVW3. Total protein and globulin values were significantly increased in all tested groups relative to the control. Proteases activity was propositionally increased with increasing FVW inclusion level, however, both lipase and amylase activities were significantly decreased in the treated groups relative to the control. Histomorphological inspection of fish distal intestine revealed normal intestinal architecture with enhanced villi development and goblet cell density in FVW-fed fish, particularly at 20% inclusion. The present results indicate that FVW can be safely included in Nile tilapia diets up to 30%.