Can fermented soybean meal and squid by-product blend be used as fishmeal replacements for Japanese flounder (Paralichthys olivaceus)?

Abstract

AbstractAn experiment was carried out to evaluate fer-mented soybean meal and squid by-product blend(1:1) (FP) as replacement of fishmeal (FM) for Jap-anese flounder, Paralichthys olivaceus. Five isocalo-ric (19 kJ g 1 ) diets were prepared by replacing 0(FP0), 12 (FP12), 24 (FP24), 36 (FP36) and 48%(FP48) FM protein with FP. Triplicate groups ofjuveniles (mean weight of 3.9 g) were deliveredthe test diets for 8 weeks in a flow-through seawater system. The results showed that there wereno significant differences (P > 0.05) among thegrowth rates of fish fed FP0, FP12, FP24 andFP36 diets. Growth and nutrient utilizationparameters were significantly reduced in fish fedFP48 diet. Although, whole body proximate com-position of fish were not significantly affected bythe dietary treatments compared to the control;methionine and phenylalanine contents were sig-nificantly decreased in FP48 group. Protein reten-tion was also significantly decreased in the similargroup of fish. Dietary treatments did not alter mostof the plasma metabolites, while some of thehealth parameters were improved in the replace-ment groups. Results suggested that FP is a poten-tial candidate for alternative protein ingredient inaquafeed and can replace 36% FM protein in thediet of Japanese flounder.Keywords: soybean meal, squid by-product, fer-mentation, fishmeal replacement, Paralichthys oli-vaceusIntroductionAs feed is the single most important economic fac-tor governing the success of the commercial aqua-culture production and fishmeal (FM) is the mostexpensive ingredient in aquafeed; reducing theamount of FM in diet formulations, without reduc-ing fish performance, could have a positive impacton the profitability of commercial fish production(Tidwell, Coyle, Bright & Yasharian 2005). Themain scientific area in fish feed production istherefore, to find out alternative protein sources,both from plant and animal origin. In someinstances, sea food processing industries generateby-products more than 50% of the total landingwhich have great potential to use as FM substi-tute. Japanese are well known for their high con-sumption of fish and shellfish. Squid is a marinecephalopod and is one of the major seafood in Jap-anese dishes. The world total catches of cephalo-pods (squid, cuttlefish and octopuses) are 3.6–3.8millions of tons (FAO 2009) and the domestic cap-ture of squid is 0.33 millions of tons in Japan(http://www.maff.go.jp). Thus, the industry gener-ated considerably a large amount of marine wastesby-products. The main types of squid by-productsare heads, viscera, unclaimed fins, mantles, tenta-cles and pens or backbones etc. Only a small partof these by-products are utilized for animal feedproduction. Most of them treated as waste product;incinerated, dumped into the sea or deposition onland and cause a serious environmental crisis (Xu,Yu, Xue, Xue & Ren 2008). High moisture content