Preliminary evaluation of the nutritive value of the variegated grasshopper (Zonocerus variegatus L.) for African catfish Clarias gariepinus (Burchell. 1822) fingerlings

摘要

A preliminary feeding trial was conducted to evaluate the nutritive value of adult variegated grasshopper (Zonocerus variegatus) meal (VGM) as a replacement for fish meal in the diets of Clarias gariepinus fingerlings. Proximate analysis result showed that VGM had 61.50% crude protein, 6.87% crude lipid, 27.33 NFE and 9.35% chitin. Five isonitrogenous (30%) and isoenergetic (18.42?MJ?kg?1) diets were formulated in which VGM progressively replaced fishmeal at five inclusion levels (0%, 25%, 50%, 75% and 100%). The best performance in terms of % weight gain was observed in the group of fish fed ED₁ (25% inclusion level) and was not significantly different (P>0.05) from the groups fed the control diet. Weight gain and specific growth rate were significantly lower (P<0.05) in the group fed ED₄ (100%VGM). Feed conversion ratio and protein efficiency ratio were numerically but not significantly different (P>0.05) among the different groups. The results indicate that apparent protein and lipid digestibility were high at all levels, although there were decreases with an increase in the inclusion levels. Carcass lipid decreased with an increase in the inclusion level of VGM. The VGM can replace fish meal up to 25% in the diets of C. gariepinus fingerlings without any adverse effect on growth and nutrient utilization.