Fish meal replacement by Brachytrupes portentosusas for Oreochromis niloticus: Effect on growth, feed utilization, fatty acid profiles, hematology, and histological changes

Abstract

In the aquaculture section, the scarcity of sustainable feed components is the major challenge. Insects may become an important, sustainable resource for expanding the raw material repertoire. Herein, this study evaluated the effects of fish meal (FM) replacement with giant cricket meal (GCM) on growth, feed utilization, fatty acids profiles, hematology, and histological changes of Nile tilapia. Five isonitrogenous and isolipidic diets were formulated with a FM-based diet (without GCM or GCM0), the other four diets were prepared to replace FM with 55, 111, 164, and 217 g/kg of GCM (referred to as GCM55 - GCM217). A total of 300 fish (approximately 7.27 ± 0.01 g/fish) were randomly allocated to triplicate groups with 20 fish per tank and fed until satiation twice daily. The results showed a linear and quadratic relationship were observed between growth parameters and dietary replacement of GCM levels. Although the total replacement of FM by GCM217 significantly diminished, but GCM55 – GCM164 replacement was higher than a control group and improved the feed conversion ratio. The condition factor was similar among dietary treatments, but the hepatosomatic index and viscerosomatic index were affected by GCM inclusion levels (P < 0.05). Whole-body dry matter and ash were linearly and quadratically increased up to GCM164, and slightly decreased in the GCM217 group. Dietary GCM inclusion regulated whole-body composition in a dose-dependent manner. Muscle fatty acids were affected by dietary GCM replacement with a linearly decreased in 18:3n-3, 20:5n-3, and 22:6n-3, and the quadratic effect was observed for 22:6n-3. Dietary inclusion of GCM quadratically increased hemoglobin, total protein, albumin, and globulin, and linearly improved red blood cell and hemoglobin levels. However, GCM inclusions higher than 164 g/kg were linearly and quadratically increased aspartate aminotransferase and alanine aminotransferase compared to a control group. A mild degree of vacuole enlargement was found in GCM164, while a high degree of irregular shape, cytoplasm vacuolization, and swelling was found in GCM217 group. In addition, intestinal morphometrics of GCM217 group detected a significantly linear and quadratic decrease in villi height. Results of the present study suggested that the dietary replacement of FM by GCM could replace up to 164 g/kg without negatively affecting growth, feed utilization, and improved blood hematology and serum proteins of Nile tilapia, even if mild histomorphological changes of hepatocytes were observed. In addition, replacing FM with GCM111 obtained the highest growth performance without any negative effects to Nile tilapia.