Protein sparing effect of carbohydrates in the diet of Cirrhinus mrigala (Hamilton, 1822) fry

A series of experiments were conducted to ascertain the protein sparing effect of dietary carbohydrate in diets of Cirrhinus mrigala fry by using nine iso-energetic test diets. C. mrigala fry (0.751 ± 0.01 g) were fed with the diets containing three levels of crude protein (40%, 35%, 30%) and three levels (30%, 35%, 40%) of different carbohydrate sources (glucose, sucrose, dextrin) for 60 days. Highest weight gain was recorded in the fry fed with 40% dextrin as a source of dietary carbohydrate and 30% crude protein level. FCR (1.28 ± 0.45), specific growth rate (2.20 ± 0.1) and protein efficiency ratio (2.60 ± 0.25) were significantly (P < 0.05) improved with the decrease in protein content from 40% to 30% and with the increase in dextrin from 30% to 40%. Poor growth was recorded in the fry fed with glucose-containing diets as a source of carbohydrate while intermediate growth was observed when fed with sucrose-containing diet. The analysis of body composition of C. mrigala fry indicated significant differences (P < 0.05) in various test diets. It can be concluded that the diet containing 40% dextrin with 30% protein level achieved the highest growth by sparing of protein in C. mrigala fry.