Lanari D ; D'Agaro ED ; Ballestrazzi R ;

Aquaculture Nutrition vol. 1 (2)   pp. 105-110, 1995

Dip. Produzione Anim., Pagnacco (UD), Italy

The effect of DP/DE ratio in diets for rainbow trout, Oncorhynchus mykiss (Walbaum), was investigated. To evaluate growth and body composition, groups of trout were fed three experimental diets with a constant level of gross energy (25.4 plus or minus 0.12 MJ kg super(-1) dry matter (DM)) and different digestible protein/digestible energy (DP/DE) ratios (diet A, 16.35; diet B, 17.21; diet C, 18.23 g MJ super(-1)). Fat, protein and energy digestibility coefficients were not affected by the DP/DE ratio of the diets. Growth and feed utilization improved markedly as dietary DP/DE ratio increased (P < .01). The efficiency of fat, protein and energy utilization tended to increase with increasing DP/DE ratio of the diets. Nitrogen discharge in effluent water per kg of weight gain was not affected by dietary treatments (mean values for: diet A, 29.9; diet B, 29.8; diet C, 29.1 g N kg super(-1) weight gain) while phosphorus discharge in effluent water fell using diets with a higher DP/DE ratio (mean values for: diet A, 7.3; diet B, 6.7; diet C, 5.9 g P kg super(-1) weight gain)

Digestibility ;  Growth ;  Feeding experiments ;  Feed composition ;  Diets ;  Aquaculture effluents ;  Water pollution ;  Pollution control ;  Oncorhynchus mykiss ;