Research Article: Optimum dietary protein requirement for maximum growth performance of Caspian kutum (Rutilus frisii kutum) juveniles

A ۱۲-weeks feeding trial was conducted to estimate the optimum dietary protein level of Caspian white fish as one of the highly important commercial species in the south of the Caspian Sea. The fish juveniles (۰.۵۹±۰.۰۵g body weight) were randomly distributed into ۲۱ aquariums (۳۰ fish per aquarium). The fish were fed with seven experimental diets containing ۲۸, ۳۲, ۳۶, ۴۰, ۴۴, ۴۸, and ۵۲ % crude protein (CP). Results showed that dietary protein levels significantly (p<۰.۰۵) affected growth performance and feed utilization of Caspian white fish juveniles. The fish fed a diet with ۴۰% CP showed higher survival rate (p<۰.۰۵) than other groups. Feeding the fish with diets at ۴۰-۴۴% CP improved the weight gain (WG) and specific growth rate compared to ۲۸%, ۳۲%, and ۵۲% CP diets. The feed conversion ratio and protein productive value were promoted by increasing the dietary CP level, while the protein efficiency ratio was decreased in diets containing high CP levels (۴۴-۵۲%). The fish receiving the protein supplemented diets showed higher protein and lipid content than the initial fish population. The results indicated that dietary CP level only affected the body protein content of the Caspian white fish juveniles (p<۰.۰۵). A broken-line regression calculated the protein requirement at ۴۲.۸۵-۴۳.۲۳ % based on the WG and PPV (protein productive value).

کلیدواژه ها:

Body composition ، Caspian kutum ، Dietary crude protein ، Growth ، Feed efficiency