Utilization of gelatinized carbohydrate in diets of Labeo rohita fry

A total of 180 Labeo rohita fry (approximate to1 g) were distributed into six treatment groups with three replicates each. Six isoenergetic (15.8 kJ g(-1) ) diets were prepared with varying levels of protein (CP) and gelatinized carbohydrate (GC), viz. D(1) : 450 g kg(-1) CP, 258 g kg(-1) GC; D(2) : 400 g kg(-1) CP, 302 g kg(-1) GC; D(3) : 350 g kg(-1) CP, 399 g kg(-1) GC; D(4) : 301 g kg(-1) CP, 447 g kg(-1) GC; D(5) : 249 g kg(-1) CP, 517 g kg(-1) GC and control diet, D(6) : 400 g kg(-1) CP, 468 g kg(-1) GC and these were fed to fish at 40 g kg(-1) wet body weight per day for 60 days. Highest growth was recorded for fish fed D(4) , decreasing for D(5) . Protein utilization, amylase activity and carbohydrate digestibility were significantly positively correlated with GC (P < 0.05) and were highest in fish fed D(5) . Hypertrophy of hepatic cells was only recorded for D(5) . Lysine, which may be affected during gelatinization, was estimated in diets and found to be above the minimum level required. Survival rate was unaffected by diet. The results of the present study indicate that a diet containing 450 g kg(-1) GC and 300 g kg(-1) CP was efficiently utilized by L. rohita fry.