Growth performance and haematological response of Clarias gariepinus broodstock fed diets enriched with bitter leaf meal

Inclusion of bitter leaf (Vernonia amygdalina) meal (VALM) in the diet of broodstocks of Clarias gariepinus was investigated for 24 weeks. The broodfish were fed experimental/commercial diets at 0% (control), 10%, 20% and 30% inclusion levels of VALM. The control group exhibited significantly (p > 0.05) higher growth parameters compared to the VALM-treated groups; however, fish group fed 30% VALM-treated feed displayed the highest survival. The blood parameters generally displayed a decreasing trend with higher inclusion rate of VALM. A linear relationship was established between protein synthesis or nitrogen metabolism, Nm (y) and VALM-inclusion level (x) as described by the equation: y = -27.801x + 216.46 correlation, r = -0.982. Hence, the 30% VALM diet recorded the least protein synthesis resulting in elevated ammonia excretion. Using quadratic regression analysis, a 7.2% V. amygdalina inclusion level in broodfish diet of C. gariepinus is recommended to elicit optimum growth performance and health. Intersexual variation was observed with males exhibiting significantly (p < 0.05) higher haemoglobin, packed cell volume and total white blood cell values than females. The blood reference values obtained for the broodfish were observed to be higher than those recorded for healthy European and African catfish species.