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Biochemical structure of protein (reactive SH content, content ratio of SH/SÐS and concentration of D-Asp as % of total (D L)-Asp) indicating digestibility of dietary protein was changed under different processing conditions. Based on ®sh crude enzyme extract, in vitro digestibility of different ®sh materials processed under different conditions correlated positively with reactive SH content and content ratio of SH/SÐS and negatively with D-Asp concentration. In vitro digestion of different experimental feeds, based on Atlantic salmon crude enzyme extracts, was studied in association with growth trials in order to investigate its value as a criterion for industrial strategy in predicting feed quality. Crude enzymes were extracted from the pyloric caeca before feeding. Signi®cant differences in in vitro digestibility between the experimental feeds were observed whereby there would be differences in feed conversion ef®ciency within 3 months of feeding. There were associations between the in vitro digestibility and other parameters for dietary quality, such as mink digestibility and the biochemical structure parameters of the dietary protein due to different processing conditions. Crude enzyme extracts from rainbow trout and European seabass were also used for in vitro digestibility study of different experimental feeds by standardising trypsin activity to that of Atlantic salmon crude enzyme extract. The results indicated that different ®sh species have different digestion ability to the same feed types, and the effective time for feed utilisation and growth is dependent on ®sh sensitivity and the extent of difference in digestibility between the feeds consumed as observed in the Atlantic salmon trials. For the species investigated, sensitivity ranking of the enzymes to feed quality under the condition studied was Atlantic salmon > rainbow trout > European seabass. The results indicated that in vitro digestibility study of experimental feeds using pyloric caecal crude enzyme extract from a speci®c species at an age of interest could be a practical, quick and reliable method for testing feed quality in growth trials. By standardising the crude enzyme extract with regards to trypsin activity, the in vitro digestibility values could be comparable not only within the same species but also between different species.

The effect of processing conditions on protein digestibility and fluorodinitrobenzene (FDNB)-reactive (available) lysine in the production of fish meal and extruded fish feed has been studied under pilot and commercial conditions using mink as model animals. Fish meal produced under pilot-plant conditions at processing temperatures below 70-80 • C (FM1) had protein digestibility of 929 (grams of protein digested per 1000 g protein consumed) compared with 905 when processed at temperatures above 100 • C (FM2). A low-temperature-processed commercial fish meal (CFM1) had protein digestibility of 940 compared with 888 for a standard commercial fish meal (CFM2). Pilot-produced extruded fish feed had protein digestibility of 913 when based on FM1 as the main protein source (95% of total protein) compared with 892 when based on FM2. Commercial extruded fish feed had protein digestibility of 912 when based on CFM1 compared with 871 when based on CFM2. Varying extrusion conditions at the pilot scale, ie temperatures from 100 to 126 • C and moisture contents from 21 to 12%, did not affect protein digestibility. Similarly, under commercial conditions, variation in temperature from 89 to 110 • C and moisture from 24.5 to 19.5% did not affect FDNB-reactive lysine and protein digestibility. The FDNBreactive lysine content and protein digestibility of the extruded feed were less than the values calculated from the ingredient mixture before extrusion. Thus, despite different extrusion conditions not giving different FDNB-reactive lysine and protein digestibility, the total process, ie extrusion, drying and oil coating, caused a reduction.

The aim of this review is to provide an update of Seriola spp. farming in the world, excluding yellowtail (S. quinqueradiata), and to identify strengths and weaknesses of these species as candidates for aquaculture diversification in different areas of the world. Farmed Seriola species other than yellowtail are yellowtail kingfish (S. lalandi) in Japan and Australia, longfin yellowtail (S. rivoliana) in the United States, greater amberjack (S. dumerili) in Japan, the Mediterranean and more recently Vietnam, and Pacific yellowtail (S. mazatlana) in North and Central America. Candidate countries for Seriola spp. farming development are China (although there are no published production statistics to date), New Zealand and the Canary Islands. The main bottlenecks for further expansion of Seriola spp. farming appear to be disease impact, lack of genetic improvement programs and incomplete knowledge of nutrient requirements.Extensive experience from Japan, where the success of Seriola spp. farming has been based on an integrated system between producer associations, research institutes and central government, it is clear that the aforementioned technical bottlenecks need to be addressed within a framework of medium-term public policies supporting aquaculture development.Key words: Aquaculture diversification, Amberjack, Carangids, Seriola dumerili, Seriola lalandi, yellowtail Page 2 of 38 URL: http://mc.manuscriptcentral.com/brfs Email: sandra.shumway@uconn.edu 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 Reviews in Fisheries Science IntroductionDiversification is an urgent need for aquaculture (Teletchea and Fontaine, 2014) and new candidate species must be highly appreciated by consumers so to get high prices on the market. Seriola spp., belonging to the Carangidae family, are one such group of fish with exceptional consumer acceptance. The species within this family with the longest history of commercial farming is yellowtail (Seriola quinqueradiata Temminck & Schegel, 1844) which has been farmed in Japan since the 1960's (Masumoto, 2002). Seriola spp. farming in Japan initially relied on collection of wild juveniles, caught in Spring and grown until they reached market size (2-5 kg) (Masumoto, 2002). lalandi) has the second highest production volume within Seriola species, with an annual production estimated at 4558 tonnes in Japan in 2013 and 3000-4000 tonnes (expected to increase in the near future to ≥5000 t) in South Australia (Miller et al., 2011) (Fig. 1).Yellowtail kingfish is a temperate and subtropical epipelagic species naturally occurring in the Australasian region, Southern Japan and East China Sea. It has a good adaptability to cage culture conditions. Seriola lalandi is currently farmed in Japan (Nakada, 2008; Shiraishi et al., 2010), New Zealand (Kolkovski and Sakakura, 2004, Camara and Symonds, 2014 Symond...

The presence of carotenoids in animal tissue reflects their sources along the food chain. Astaxanthin, the main carotenoid used for salmonid pigmentation, is usually included in the feed as a synthetic product. However, other dietary sources of astaxanthin such as shrimp or krill wastes, algae meal or yeasts are also available on the market. Astaxanthin possesses two identical asymmetric atoms at C-3 and C-3' making possible three optical isomers with all-trans configuration of the chain: 3S,3'S, 3R,3'S, and 3R,3'R. The distribution of the isomers in natural astaxanthin differs from that of the synthetic product. This latter is a racemic mixture, with a typical ratio of 1:2:1 (3S,3'S:3R,3'S:3R,3'R), while astaxanthin from natural sources has a variable distribution of the isomers deriving from the different biological organism that synthesized it. The high-performance liquid chromatographic (HPLC) analysis of all-trans isomers of astaxanthin was performed in different pigment sources, such as red yeast Phaffia rhodozyma, alga meal Haematococcus pluvialis, krill meal and oil, and shrimp meal. With the aim to investigate astaxanthin isomer ratios in flesh of fish fed different carotenoid sources, three groups of rainbow trout were fed for 60 days diets containing astaxanthin from synthetic source, H. pluvialis algae meal and P. rhodozyma red yeast. Moreover, the distribution of optical isomers of astaxanthin in trout purchased on the Italian market was investigated. A characteristic distribution of astaxanthin stereoisomers was detected for each pigment sources and such distribution was reproduced in the flesh of trout fed with that source. Colour values measured in different sites of fillet of rainbow trout fed with different pigment sources showed no significant differences. Similarly, different sources of pigment (natural or synthetic) produced colour values of fresh fillet with no relevant or significant differences. The coefficient of distance computed amongst the feed ingredient and the trout fillet astaxanthin stereoisomers was a useful tool to identify the origin of the pigment used on farm.