An 8-week feeding trial was conducted in flow through system to examine the effects of dietary supplementation of lysine and methionine on growth, nutrient utilization, haemato-biochemical status and carcass compositions in Indian major carp, rohu, Labeo rohita fingerlings (average weight 6.32 ± 0.06 g). Four experimental soy proteinbased diets D 0 (without lysine or methionine supplementation), D 1 (lysine supplementation alone), D 2 (methionine supplementation alone) and D 3 (both lysine and methionine supplementation) were fed to triplicate groups. L L-Lysine and DL DL-methionine were added to the diets containing 550 g kg )1 soybean meals at 4 and 7 g kg )1 of dry diet respectively. Significant higher weight gain, specific growth rate (SGR), protein efficiency ratio (PER), dry matter retention, nitrogen retention, total ash retention, whole carcass protein, haemoglobin concentration, haematocrit value, total erythrocytic count, total leucocytic count, plasma glucose and plasma total protein and lower FCR, per cent lipid retention and whole body moisture content were observed in fish fed soya protein-based diet supplemented with both lysine and methionine than that of fish of other dietary groups at the end of 8 weeks feeding trial. Although fish fed diet supplemented with either methionine or lysine did not show any significant differences of growth performances, feed utilization, carcass composition and haemato-biochemical status, fish of both of these dietary groups showed significantly better growth performances, feed utilization, carcass composition and haemato-biochemical status than that of fish fed diet without lysine and methionine supplementation. KEY WORDS

An 8-week feeding trial was conducted in flow through system to examine the effects of dietary supplementation of microbial phytase on growth, nutrient utilization, haematobiochemical status and body compositions in common carp, Cyprinus carpio (L.) fingerlings (average weight 6.66 ± 0.08 g). The aim of experiment was also to determine whether dicalcium phosphates (DCP), tracemineral premix and lysine and methionine supplemental levels in carp diet could be reduced if microbial phytase was supplemented. Control diet (diet 1) supplemented with DCP, tracemineral premix and lysine and methionine without microbial phytase supplementation. Four experimental diets were formulated with reduction of either dietary DCP or trace minerals or lysine and methionine or all four supplementation levels by 100% of control diet without microbial phytase supplementation (diet 2, 3, 4 and 5 respectively). Another two experimental diets were formulated with reduction of all dietary DCP, trace minerals, lysine and methionine supplementation levels by 0 and 100% of control diet with dietary microbial phytase supplementation at 500 FTU kg )1 diet (diet 6 and 7 respectively). After acclimation of fish for 2 weeks, 20 fish were randomly stocked into triplicate tanks for each of seven treatments (T 0 , T 1 , T 2 , T 3 , T 4 , T 5 and T 6 for diet 1, 2, 3, 4, 5, 6 and 7 respectively) and fed with respective diet to apparent satiation. Results indicated that phytase was effective in releasing most of the phytate bound proteins, amino acids and minerals for optimum utilization and performance. Results also suggested that DCP, trace minerals and lysine and methionine supplementation level could be replaced by microbial phytase supplementation at 500 FTU kg )1 in soybean-based common carp diets without altering the optimum performance of fish. Optimum replacement level of dietary DCP, trace minerals and lysine and methionine with phytase supplementation at 500 FTU kg )1 soybean-based carp diet needs to be standardized in further investigations. KEY WORDS