Feasibility study of American cockroach residue as a dietary supplement in diets for juvenile Carassius auratus red var.

Abstract

This study evaluated the feasibility of replacing fishmeal with American cockroach residue in diets for juvenile Carassius auratus red var. and examined its effects on growth performance, nutrient utilisation, metabolic status, antioxidant capacity, immune function and intestinal morphology. Five isonitrogenous and isoenergetic diets were formulated by replacing fishmeal with American cockroach residue at 0% (Diet 1), 20% (Diet 2), 40% (Diet 3), 60% (Diet 4) and 80% (Diet 5). Juvenile fish with an average initial body weight of approximately 7 g were fed for 70 days. No significant differences in FBW, WGR or SGR were observed among dietary groups ( P > 0.05), although fish in the Diet 4 group showed numerically the highest values. Replacement levels of 20–40% increased selected hepatic and intestinal digestive enzyme activities ( ). Serum triglyceride and total cholesterol concentrations were numerically highest in the Diet 4 group, although no significant differences were detected among dietary treatments, while intestinal morphological alterations were observed when fishmeal replacement exceeded 40%. Fish fed Diet 3 showed higher total antioxidant capacity and total superoxide dismutase activity than those fed Diet 1 ( ). Hepatic ACP activity was higher in Diet 4 than in Diets 1 and 5, while intestinal ALP activity was highest in Diet 4 ( P < 0.05). American cockroach residue can partially replace fishmeal in diets for juvenile C. auratus red var. Considering growth, digestive capacity, antioxidant capacity, immune function, metabolic responses and intestinal health, a replacement level of 20–40% appears more suitable for practical application.