This study examined the effects of replacing fish meal (FM) with soybean husk (SBH), palm kernel meal (PKM), and cowpea husk (CPH) on growth performance, feed utilization, and intestinal histology of catfish. Four experimental diets were formulated with different proportions of PKM, CPH, and SBH to partially replace fish meal. Juvenile catfish (Clarias gariepinus) were fed these diets for ten weeks. The results indicated that inclusion of these alternative protein sources had significant effects on growth performance and feed utilization compared to FM diet. The weight gain recorded in this study was as follows: SBH (119.5±68.02) > CPH (113.2±53.14) > FM (104.3±56.82) > PKM (86.73±31.51). Feed conversion ratio ranged from 1.25±0.57 (SBH) to 1.52±0.56 (PKM). C. gariepinus fed the diet PKM had the lowest protein efficiency ratio (2.09±0.76), followed by those fed the FM (2.57±1.40) and the CPH diet (2.74±1.28). To a larger extent, the dietary protein sources significantly influenced serum hematology parameters. C. gariepinus fed the FM diet had the highest white blood cells count (133.0±2.51), which was significantly higher than all other groups (p < 0.0001). The range of red blood cell values observed in this study was 2.08±0.13 to 2.62±0.13. Histological examination indicated modifications in intestinal morphology, suggesting possible metabolic adjustments to the experimental diets. Fish fed the FM had the highest villus height (441.2±22.6), followed by SBH (398.3±7.51), PKM (279.2±15.65), and CPH (142.3±10.84). Villus width and muscular thickness also followed this pattern, with fish fed the FM diet having the largest villus width (153.7±9.06), significantly greater than all other groups (p<0.0001). Overall, incorporating CPH, and SBH into catfish diets appears to be a viable replacement for conventional fishmeal-based diets; however, further studies are required to determine optimal inclusion levels for achieving maximum growth and well-being.
Keywords: Alternative protein, Agricultural by-products, Intestinal morphology, Blood biochemistry, Growth.