The addition of insect meal from <i>Spodoptera littoralis</i> in the diets of Nile tilapia and its effect on growth rates, digestive enzyme activity and health status

Abstract

The current study evaluated the insect meal originated from Spodoptera littoralis (SLM) at 0, 50, 100, 150 and 200 g/kg in the diets of Nile tilapia for 60 days. Fish with similar initial sizes (17.28 ± 0.03 g) were distributed into 15 glass aquaria (60 L; triplicates, 12 fish/aquarium). All aquaria provided with continuous aeration, and half of the water was replaced daily with dechlorinated freshwater. The formulated diets were nutritionally balanced in terms of crude protein, lipids, essential amino acids and gross energy. The final weight, weight gain, specific growth rate, feed intake and protein efficiency ratio were decreasing by increasing the level of SLM with the lowest value in fish fed 200 g SLM/kg while feed conversion ratio increased (p < 0.05). The intestinal lipase and amylase activities were lowered by increasing the inclusion levels of SLM (p < 0.05). The moisture, protein and ash contents were not altered by SLM (p > 0.05), while the lipid content was lowered by increasing the level of SLM in linear and quadratic trends (p < 0.05). The haematological variables, biochemical indices and immune responses did not alter by the inclusion of SLM in tilapia diets (p > 0.05) except for the alanine aminotransferase (ALT) and aspartate aminotransferase (AST) enzymes. The ALT was increased by increasing the level of SLM (p < 0.05). Interestingly, the immune and antioxidative indices were similar and did not reduce by increasing the level of SLM in the tilapia diet (p > 0.05). The replacement of FM with SLM up to 200 g SLM/kg is recommended for the profitable production of Nile tilapia.