Growth and energy budget of juvenile lenok Brachymystax lenok in relation to ration level

Abstract

We evaluated the effect of ration level (RL) on the growth and energy budget of lenok Brachymystax lenok . Juvenile lenok (initial mean body weight 3.06±0.13 g) were fed for 21 d at fi ve different ration levels: starvation, 2%, 3%, 4% bwd (body weight per day, based on initial mean values), and apparent satiation. Feed consumption, apparent digestibility, and growth were directly measured. Specifi c growth rates in terms of wet weight, dry weight, protein, and energy increased logarithmically with an increase in ration levels. The relationship between specifi c growth rate in terms of wet weight (SGR w , %/d) and RL (%) was characterized by a decelerating curve: SGR w =-1.417+3.166ln(RL+1). The apparent digestibility coeffi cients of energy exhibited a decreasing pattern with increasing ration level, and there was a signifi cant difference among different RLs. Body composition was signifi cantly affected by ration size. The relationship between feed effi ciency rate in terms of energy (FERe) and RL was: FERe=-14.167+23.793RL-3.367(RL) 2 , and the maximum FERe was observed at a 3.53% ration. The maintenance requirement for energy of juvenile lenok was 105.39 kJ BW (kg) -0.80 /d , the utilization effi ciency of DE for growth was 0.496. The energy budget equation at satiation was: 100IE=29.03FE+5.78(ZE+UE)+39.56 HE+25.63 RE, where IE is feed energy, FE is fecal energy, ZE+UE is excretory energy, HE is heat production, and RE is recovered energy. Our results suggest that the most suitable feeding rate for juvenile lenok aquaculture for wet weight growth is 2.89% bwd, whereas for energy growth, the suggested rate is 3.53% bwd at this growth stage.