Growth, feed conversion, body composition and nutrient retention efficiencies in fingerling catfish, Heteropneustes fossilis (Bloch), fed different sources of dietary carbohydrate

Growth, conversion efficiency, body composition, nutrient retention and pla sma glucose concentration were evaluated in fingerling catfish, Heteropneus tes fossilis (Bloch), (3.25 +/- 0.1 g) fed iso-nitrogenous (40% crude prote in) and iso-caloric (4.7 kcalg(-1) gross energy) test diets containing diff erent sources of carbohydrates (i.e, glucose, fructose, maltose, sucrose, d extrin, pre-cooked corn-starch or alpha-cellulose) at the 20% level of incl usion. Each dietary treatment had three replicates of 20 fish each. The gro wth trial was conducted in 70-L high-density polyvinyl now-through (1-1.5 L min(-1)) indoor circular troughs (water volume = 55L). The catfish were fed to apparent satiation twice daily at 0800 and 1600 h for 6 days a week ove r approximate to 8 weeks. No significant (P > 0.05) differences were noted in the growth and feed conversion efficiencies when fish were fed the sucro se, dextrin and corn-starch diets, Similarly, growth and conversion efficie ncies were similar (P > 0.05) in fish fed the glucose, fructose and maltose diets. The minimum growth and conversion efficiencies were found in fish f ed the alpha-cellulose diet. Post-feeding glucose or maltose resulted in th e maximum increase in plasma glucose, followed by sucrose, dextrin, fructos e or corn-starch diets, over the 8-h sampling period, Post-feeding alpha-ce llulose produced a relatively low (P > 0.05) variation in the plasma glucos e level. Compared to the initial values, higher values of dry matter, crude protein, lipid and body energy, and lower percentages of ash were recorded in catfish fed different sources of carbo-hydrate. The maximum protein ret ention rate was seen in fish fed the dextrin diet, while a higher energy re tention rate was observed in fish fed the sucrose-based diet. Dietary alpha -cellulose produced significantly (P < 0.05) lower values of protein and en ergy retention in fish. The present study indicates that utilization of com plex carbohydrates in catfish is more successful with di- and monosaccharid es, while dietary zeta-cellulose is poorly utilized.