Protein-sparing effect of carbohydrate in silver barb, Puntius gonionotus fry

Abstract

A 30-day study was undertaken to examine the protein-sparing effect of carbohydrate in diets for silver barb, Puntius gonionotus fry. Six semi-purified experimental diets were formulated with two levels of protein (200 and 250 g kg−1 diet) and three levels of carbohydrate (300, 340 and 380 g kg−1 diet). In addition to the six experimental diets, a diet containing the protein and carbohydrate requirement levels of 300 and 260 g kg−1 diet, respectively, as reported earlier for this species, was used as a reference diet. For each dietary treatment, 30 healthy fry of 20 days age (0.12 ± 0.01 g) were stocked in triplicate tanks using a flow-through system. The fish were fed ad libitum four times a day to a level close to apparent satiation. Batch weighing of fish was done after 15 days of stocking to measure growth and general health status of the fish. The fish fed 250 g protein and 340 g carbohydrate kg−1 diet with a protein to energy ratio of 17.86 g protein MJ−1 performed equally well in terms of growth and nutrient utilization as the reference diet group. The study indicates that dietary protein can be reduced from 300 to 250 g kg−1 diet by increasing carbohydrate from 260 to 340 g kg−1 diet without sacrificing the growth of silver barb fry.