Effect of dietary fish meal replacement by AquPro on growth performance, body composition and total protease activity of rainbow trout (Oncorhynchus mykiss) fry

In this study, the replacement effect of dietary fish meal with AquPro (Processed soybean meal) was assessed on growth performance, body composition and total protease activity of rainbow trout (Oncorhynchus mykiss) over a period of 6 weeks. In this experimental study, at the beginning of the trial, 5 experimental diets were formulated with fish meal as control (A) and diets with 25% (B), 50% (C), 75% (D) and 100% (E) AquPro, respectively. At the end of the feeding trial, growth performance, body composition and total protease activity from pyloric caeca and intestine were measured. The results indicated that the WG, SGR and ADG in experimental diet C were the highest and showed a significant difference with other treatments (p<0.05). However, the status index in experimental diet C was lower than other treatments, but did not show significant differences (p>0.05). The moisture content, fat, and body ash were respectively, significantly higher in experimental diets A, B and E than those of other treatments (p<0.05), But the highest amount of protein was observed in the experimental diet of C, which did not show any significant difference with other treatments (p>0.05). The highest total protease activity from pyloric caeca and the intestine was observed in the fish fed with diet C which showed a significant difference with other diets (p<0.05). Based on the results of growth performance, body composition, and total protease activity was revealed that the diet containing 50% AquPro could be appropriate for rainbow trout growth.