Growth performance and nutrient utilization of African Catfish Clarias gariepinus fed diets containing mixture of processed moringa Moringa oleifera leaf and kernel meal

Fish meal is the most utilised animal dietary protein ingredient in aquaculture diets because of its high protein content, balanced amino acid profile, high digestibility and palatability. However, inconsistent supply of fish meal, greater demand, and constant rising prices have been driving the search for substitutes for decades. Moringa oleifera is one of the most useful tropical trees belonging to the Moringaceae family. M. oleifera kernel, though a good source of protein, is deficient in some key amino acids. These limiting amino acids are in excess in the leaf meal. Combination of moringa kernel and leaf meals in desired proportions might result in obtaining a properly balanced plant-based protein that would favourably replace fishmeal in fish feeds. Glucosinolates, lectins and alkaloids which form the major anti-nutrient substances in moringa kernel meal could be removed by water extraction or solid state fermentation. The present investigation was carried out to determine the optimum level of supplementation of fish meal by mixture of soaked moringa leaf meal and fermented kernel cake in the diets of Clarias gariepinus juveniles.

The leaves were soaked overnight and oil was extracted from the seed kernel using n-hexane. The defatted kernel was fermented using Rhizopus stolonifer (1.20 x 10³ cfu/g). Graded levels (0, 80.2, 179.2 and 305.4 gkg^-1) of mixture (1:1) of soaked leaf and fermented kernel of moringa were incorporated in an isonitrogenous (40% crude protein) diets and fed to triplicates group of Clarias gariepinus (average weight  8.87g ±0.02) for a 56-day period.

Growth performance in terms of weight gain, average daily gain, specific growth rate in the group that received control diet was significantly (P<0.05) higher than those that were reared on diets containing 179.2 and 305.4 gkg^-1  mixture of soaked moringa leaf and fermented kernel but statistically (P>0.05) similar to the group fed with 80.2 gkg^-1  of the mixture. The results of the present investigation demonstrated that despite processing mixture of moringa leaf and kernel can replace 80.2 gkg^-1 of fish meal in the diet of Clarias gariepinus without markedly reducing growth performance and nutrient utilization.