Protein sparing capability of carbohydrate in fringed-lipped carp Labeo fimbriatus (Bloch, 1795)

Abstract

The study was undertaken to examine the capability of carbohydrate to spare protein in the diet of fringed lipped carp, Labeo fimbriatus (2.93 g±0.15). Three semi-purified experimental diets of iso-caloric nature were formulated having three graded levels of protein (27, 23 and 19% CP) and three levels of carbohydrate (26, 31.5 and 37% CHO). Accordingly, the treatments were designated as T1 (27% CP and 26% CHO), T2 (23% CP and 31.5% CHO) and T3 (19% CP and 37% CHO), where the experimental diet T1 served as the reference diet. The fish were reared in 200 l fibre reinforced plastic (FRP) tanks under continuous aeration with one third water exchanged daily. After 90 days of feeding trial, it was noticed that the percentage weight gain and specific growth rate (SGR) of 27% protein fed group (209.5±0.74% and 1.26±0.15%) and 23% protein fed group (204.8±0.52% and 1.24±0.13%) were not significantly different (p>0.05). Similarly, the results of feed performance like feed conversion ratio (FCR) among 27% protein fed group (2.24±0.11) and 23% protein fed group (2.29±0.14) did not vary significantly (p>0.05). On the other hand, the protein efficiency ratio (PER) and protein productive value (PPV) of 23% protein fed group (1.87±0.11 and 28.34±0.36) did not vary significantly (p>0.05) with the 19% protein fed group (1.93±0.12 and 27.65±0.32). The carcass protein (CP) and lipid (as ether extract,EE) content of 27% protein fed group and 23% protein fed group were not significantly different (p>0.05). Results of this study indicate that the CP level in the diet of fringed-lipped carp L. fimbriatus can be reduced from 27 to 23% by proportionately increasing carbohydrate level from 26 to 31.5% without compromising growth and also without any adverse physiological effect.