Partial replacement of fishmeal with corn protein concentrate in diets for rainbow trout (Oncorhynchus mykiss): Effects on growth performance, physiometabolic responses, and fillet quality

An 8-week feeding trial was run to investigate the replacement of fishmeal with corn protein concentrate (CPC; Empyreal(R)) in rainbow trou (100.5 +/- 2.3 g) diet. Fishmeal was increasingly replaced with 0 (Control), 30 (CPC3), 60 (CPC6), 90 (CPC9) and 120 (CPC12) g/kg CPC. The results showed that the substitution of fishmeal with CPC up to 90 g/kg did not cause significant differences in the growth indices as compared to the control group, while further replacement resulted in the reduction of the growth performance. The fillet crude protein showed no significant difference between the control diet and diets containing up to 90 g/kg CPC (p > .05). Serum biochemical parameters such as albumin and glucose did not change notably, while the highest levels of alanine aminotransferase and lactate dehydrogenase were seen in the CPC(12)group (p < .05). Also, serum lysozyme activity was increased with the elevation of dietary CPC up to 90 g/kg (p < .05). The redness and yellowness of the fillet were markedly elevated with the dietary incorporation of CPC (p < .05). Taken together, the optimum range of fishmeal substitution with CPC was 81.0-82.2 g/kg CPC in rainbow diet based on the broken-line regression analysis.

Automated summary

The study found that replacing fishmeal with corn protein concentrate (CPC) up to 90 g/kg did not significantly affect the growth performance of rainbow trout, but further replacement could lead to performance reduction. Serum biochemical parameters were relatively stable except for increases in certain enzymes with higher levels of CPC in the diet. The optimal range for fishmeal substitution with CPC in rainbow trout diet was determined to be 81.0-82.2 g/kg based on the regression analysis.