Nutritional evaluation of poultry offal meal as a substitute for fishmeal in diets of Heterobranchus longifilis Fingerlings
A study was carried out to evaluate the effect of complete replacement of fishmeal (FM) with poultry offal meal (POM) in diets fed to Heterobranchus longifilis fingerlings. FM and POM were separately used to prepare diets containing 30%, 35% and 40% crude protein (CP). Diets were fed to fish (body weight 3.11„b0.56 to 8.48„b1.70 g, total length 73.07„b4.99 to 98.69„b7.64 mm for FM; weight 4.27„b0.55 to 5.71„b0.54 g, length 81.98„b3.85 to 90.39„b3.80 mm for POM) at 5% body weight for 10 weeks. Weight gain (6.99„b1.70 g), percent weight gain (82.43%) and specific growth rate (4.05„b0.19% day-1) in 40% CP fishmeal diet were higher than POM diets (P<0.05). Feed conversion ratio, protein efficiency ratio and apparent net protein utilization were also better (P<0.05) for 40% CP fishmeal diets. Poultry offal meal had greater body lipid 5.76 to 6.11% than FM fed fish (2.18 to 2.72%). Fish survival ranged from 96.0„b0.66 to 100% for all diets and values for water quality parameters were within tolerable limits. POM at dietary 35% CP exhibited appreciable performance and was the most economical with N4.09/g.wt. gain. Fishmeal diets performed better but costlier to produce than POM diets which had economic gains and probably with potentials for higher biological performance at lower inclusion levels.
Key Words: Heterobranchus longifilis, protein sources, substitution, diets, growth.