Dietary Lysine Requirements and Gustation of Hybrid Clariid Catfish (Heterobranchus bidorsalis ♂ x Clarias gariepinus ♀) (“Heteroclarias”)

Abstract

This study was conducted to evaluate the effects of crystalline Lysine powder on growth performance, nutrient utilization and gustation of Hybrid clariid catfish (Heterobranchus bidorsalis ♂ x Clarias gariepinus ♀) (“Heteroclarias”), fed Lysine supplemented diets. Five isonitrogenous test diets of (40% crude protein) were formulated, using groundnut cake, fishmeal and graded levels of crystalline Lysine (0.00%, 0.74%, 1.04%, 1.34%, 1.64% dry diets) with  methionine of (0.30g/100g) as (D1, D2, D3, D4 and D5), in the experimental diets , the Lysine level in the diet ranges from 0.00% (D1) to 1.64% (D2) respectively. Three hundred (300) heteroclarias fingerlings with mean body weight (7.50±0.05g) were distributed into 15 plastic tanks (65×45×45)cm³ at ten (10) per tanks. Fish were fed for 90 days at 5% body weight. The result obtained from these study shows, the weight gain, specific growth rate, the feed intake, survival rate and the protein efficiency ratio were significantly different (P<0.05) compare with those fed control diet. The best feed conversion ratio (FCR), was recorded in the (D3, 0.93±0.10) and the highest specific growth rate was also observed in D3, (0.76±0.10). There were significant differences in feed intake across the experimental tanks and the highest feed intake was recorded in D5 (72.65±1.46). Carcass protein and lipids increased significantly with increasing lysine levels while the fibre content decreasing significantly with increasing lysine levels in the diets. There was significant different (p<0.05) gustation across the diets and the lowest time of grasp (0.75sec) was recorded in D2 (0.74%). Thus, feed protein reduction to 20% with lysine supplement will reduce feed cost and support growth rate in Heteroclarias.