Dietary American Cockroach (Periplaneta americana) Residue in Juvenile Black Carp (Mylopharyngodon piceus): Effects on Growth, Antioxidant Status, Metabolism, and Whole-Body Amino Acid Profile

This study evaluated the efficacy of post-extraction American cockroach (Periplaneta americana) residue (PAR) as a dietary feed ingredient on the growth performance, antioxidant defense, and whole-body amino acid profile of juvenile black carp (Mylopharyngodon piceus). A total of 300 juvenile black carp (initial weight 17.19 ± 0.20 g) were fed five isonitrogenous and isolipidic diets for 64 days. PAR was supplemented at inclusion levels of 0% (control), 5%, 10%, 15%, and 20% (corresponding to progressive reductions in dietary fishmeal). The results showed that fish fed the diet with 5% PAR inclusion maintained growth performance and feed conversion efficiency comparable to those of the control group (p > 0.05). Thus, 5% PAR did not significantly improve growth performance, but it did not impair growth under the present experimental conditions. Moreover, 5% PAR supplementation significantly increased hepatic catalase activity and was associated with numerically higher values of several other antioxidant- and immune-related indices. PAR inclusion also increased whole-body glycine deposition, whereas high inclusion levels reduced whole-body methionine content and crude protein deposition. Dietary PAR inclusion at higher levels, especially 20%, was associated with a possible reduction in feed utilization, altered organ indices, altered serum glucose levels, suppressed hepatic transaminase activities, and changes in digestive enzyme activities. However, these responses should be interpreted as the combined outcome of ingredient substitution, amino acid imbalance, altered lipid source, possible essential fatty acid changes, chitin/fiber-like fractions, and metabolic burden, rather than as effects of chitin alone. In conclusion, 5% PAR may be a suitable practical inclusion level for juvenile black carp under the present experimental conditions, whereas excessive inclusion should be used with caution and may require amino acid balancing, improved processing, and further evaluation of dietary gross energy, fatty acid profile, and chitin content.