Replacement of Fish Meal With Blends of Chicken By-Product Meal or Tuna By-Product Meal and Corn Protein Sources in Diets Supplemented With Jack Mackerel Meal: Impacts on Growth Performance, Feed Utilization, and Biochemical Composition of Olive Flounder (Paralichthys olivaceus).

This experiment evaluates impacts of substituting different levels of fish meal (FM) with combinations of animal by-product and plant protein sources in diets supplemented with jack mackerel meal (JMM) on the growth, feed utilization, and biochemical composition of olive flounder (P. olivaceus). A three-way ANOVA (two animal by-product sources [chicken by-product meal (CBM) or tuna by-product meal (TBM)] × 2 plant protein sources [corn gluten meal (CGM) or corn protein concentrate (CPC)] × 2 levels of FM replacement [25% and 50%]) model was employed. The control (Con) diet included 60% FM. In the Con diet, 25% and 50% of FM were replaced with combinations of animal by-product (CBM or TBM) and plant (CGM or CPC) protein sources, and then 12% JMM was included as feed enhancer at the expense of FM. These experimental diets were named as the CBCG25, CBCG50, TBCG25, TBCG50, CBCP25, CBCP50, TBCP25, and TBCP50 dies, respectively. All diets were assigned to triplicate groups of fish. Six hundred and seventy-five juvenile (initial body weight of 4.25 g) were dispersed into 27 of 50 L tanks. Fish were hand-fed to satiation twice daily for 8 weeks. The TBM-containing diets exhibited significantly (p < 0.001, p < 0.006, and p < 0.005, respectively) higher weight gain (WG), specific growth rate (SGR), and feed consumption (FC) of fish than the CBM-containing diets. Dietary higher (50%) FM replacement levels led to significantly (p < 0.001 for all) lower WG, SGR, and FC than dietary lower (25%) FM replacement levels. WG of fish fed the TBCG25 and TBCP25 diets was significantly (p < 0.001) higher than that of fish fed the CBCG50, TBCG50, CBCP50, and TBCP50 diets. SGR of fish fed the TBCG25 diet was significantly (p < 0.001) higher than that of fish fed the CBCG50, TBCG50, CBCP50, and TBCP50 diets. Fish fed the TBCG25 and TBCP25 diets led to significantly (p < 0.002) higher FC than those fed the CBCG50 and CBCP50 diets. Feed utilization, blood chemistry, and biochemical composition of fish, with exception of fatty acid (FA) profiles, were unaffected by dietary treatments. Conclusively, the TBCG25 and TBCP25 diets seems to be most viable option for optimizing WG, SGR, and FC.