Abstract
A 12-week feeding trial was conducted to evaluate a corn fermented protein with solubles (CFPS) as a soybean meal (SBM) replacer in the practical diets for Atlantic Salmon (Salmo salar) and the subsequent effects on growth, nutrient digestibility, gut morphology, and health performances of this fish species. A low fish meal (15%) based control diet (CFPS0) with alternative proteins (soy protein, corn protein concentrate and wheat gluten) was produced, then 25%, 50%, 75% and 100% of SBM of the control diet formulation were replaced with the CFPS product for diet groups CFPS25, CFPS50, CFPS75 and CFPS100, respectively. All experimental diets were fed to satiation twice daily to triplicate groups of Atlantic salmon juveniles (initial weight 21 g). After the feeding trial, final weight, specific growth rate, weight gain and feed utilization performances were not significantly different among the treatment groups. Significantly higher and lower whole body moisture content was observed in fish fed diet group CFPS50 and CFPS75, respectively; other groups showed intermediate values. In comparison to the control (CFPS0), increased final whole body protein content was observed in CFPS included diet groups, and it was significantly higher in CFPS50. Except for cystine, lysine, tryptophan, tyrosine, proline and taurine, all other measured amino acids were significantly influenced by dietary treatments and significantly higher and lower values were observed in fish fed CFPS50 and CFPS100, respectively; other dietary groups showed intermediate values. CFPS inclusion significantly increased the lipid digestibility and fish fed CFPS75 and CFPS100 fed fish showed significantly higher values followed by CFPS50; CFPS25 showed an intermediate value, and a significantly lower value was observed in fish in the control group. In terms of immune response and oxidative stress, CFPS inclusion increased indices of nonspecific immune response and oxidative stress tolerance. No negative effects were observed on intestinal morphological features by the dietary CFPS product. The mean score of measured histopathological characteristics indicated that replacing half of the dietary SBM with CFPS resulted in signifi-cantly lower intestinal enteritis. Based on the overall findings we can conclude that the CFPS evaluated can be effectively used as a SBM replacement in the diets of Atlantic Salmon.