Dietary African Yam Bean Meal (Sphenostylis sternocarpa) as a Complementary Substitute for Soybean Meal in African Catfish (Clarias gariepinus) Fingerlings: Effect on Intestinal Histology and Zootechnical Performance

Background: The effects of soybean meal replacement with African yam bean meal on the intestinal histology and zootechnical performance of African catfish, Clarias gariepinus fingerlings was assessed in this study. One hundred and eighty C. gariepinus fingerlings weighing 13.62±0.12g were randomly distributed into plastic tanks at ten fish per tank in triplicate and fed six rations (treatments) representing graded replacement levels of soybean with African yam bean for 70 days. Soybean meal was replaced with African yam bean (AYB) at 0, 20, 40, 60, 80 and 100% denoted as the control T1 (0%), T2 (20%), T3 (40%), T4 (60%), T5 (80%) and T6 (100%) respectively. Weekly weighing of fish was done and data collected was subjected to statistical analysis. Zootechnical performance was based on growth performance and nutrient utilization efficiency. Results: After the feeding trials, tissue samples from the intestines were removed by dissection for histological study. Tissue sections were compared after examination under the microscope for differences in the morphology of the tissues. The histology of the intestine of fish fed African yam bean meal included diets showed apparently normal intestinal villi and enterocytes in T2, T3 and T4. Histology of the intestine of C. gariepinus in T6 had disorganized enterocytes which induced enteritis in the fish. The result on growth performance and nutrient utilisation showed that body weight gain, specific growth rate and feed conversion ratio were significantly different from each other (P< 0.05). The best feed conversion ratio was recorded in the control. Conclusions: This study showed that African yam bean can replace soybean up to 60% in the diet of African catfish, Clarias gariepinus for required growth without any negative effect on the gut histology of the fish.