Effects of dietary protein and energy levels on growth performance, feed utilization and body composition of juvenile shirbot Barbus grypus (Heckle, ۱۸۴۳)

  Shirbot (Barbus grypus) as a species with high potential for aquaculture development recently propagated artificially in South Iran Aquaculture Research Center to extend the species diversity in polyculture system. To provide an effective economic diet for this species ۹ experimental diets containing three crude protein levels (۲۵۰, ۳۰۰, and ۳۵۰ g kg -۱) and three metabolizable energy levels (۱۰.۴۶, ۱۲.۵۵ and ۱۴.۶۴ MJ kg -۱) were fed to triplicate groups of shirbot juvenile fish (initial body weight of ۲۹.۶۸± ۰.۱۹). Three aerated tanks were randomly assigned to each treatment, stocked with ۱۵ juvenile fish and reared for a ۶۰-day period. The preferential diet, which was diet ۴, (۳۰۰ g kg -۱ CP and ۱۰.۴۶ MJ kg -۱ ME) exhibited the best growth and feed utilization performances. Fishes fed diet ۴ showed higher weight gain, feed efficiency ratio and survival rate with a significant difference (P۰.۰۵). It was found that varying levels of CP and DE in the diets did not significantly affect the body composition of the fish (P>۰.۰۵) except for the CF. Comparison between varying levels of dietary protein and energy on the growth, feed utilization and body composition of Barbus grypus indicated that ۲۵۰ to ۳۰۰ g kg -۱ CP and ۱۰.۴۶ MJ kg -۱ ME could be the preferential dietary levels for this species in the juvenile stage.

Keywords:

Barbus grypus , Juvenile , Dietary protein level Dietary energy level