Nutritional and Chemical Composition of By-Product Fractions Produced from Wet Reduction of Individual Red Salmon (Oncorhynchus nerka) Heads and Viscera

There is growing interest for fishmeals and oils made from utilizing different fish by-products (heads, viscera, frames, etc.) that come directly from the commercial processing line. The major components of fish processing waste from salmon filleting operations are heads and viscera. In order to maximize the utilization of these individual by-products, the different fractions were evaluated. Analysis of essential amino acids in fishmeal showed significant differences in all essential amino acids except lysine. Differences were also noted in the levels of minerals, fatty acid methyl esters, biogenic amines, and fat soluble vitamins. The largest difference observed was in the level of retinol in the oil extracted from heads (8.9 ± 1.0 μg/g oil) and viscera (26.9 ± 3.8 μg/g oil). Head processing resulted in more lipids and cake, while the majority of viscera became stickwater. Results suggest that the fishmeal produced from different by-product parts can result in different nutritional values for feed or food ingredients.     

CHANGING SUPPLY AND DEMAND FOR FISH OIL

Competition for fish oil from human nutritional supplements (nutraceuticals) is starting to threaten its supply for aquaculture feeds. World supply of fish oil is not increasing but is the main source of healthy omega-3 fats (n-3 LC-PUFA). Fish oil demand by nutraceuticals is a derived demand for such fats. Demand growth and insecure supply are causing price inflation of fish oil, helping to drive its substitution in aquaculture feeds by vegetable oils. This is reducing the content of n-3 LC-PUFA in aquaculture products, especially salmon, with potentially negative health implications. Given the scope for further substitution of fish oil, it is unlikely that future growth of global aquaculture will be constrained by reducing omega-3 content, although it will complicate consumer marketing of salmon. Nutraceuticals is paying more than aquaculture for fish oil based on omega-3 content, but novel sources of n-3 LC-PUFA will become available in the medium term.     

Ray Liver Oils Obtained by Different Methodologies: Characterization and Refining

Currently, the use of by-products generated from fish processing is a relevant issue for the sustainable development of the fisheries. Fins are the main commercialized product of cartilaginous species. However, the livers contain a high content of polyunsaturated fatty acids (PUFAs), mainly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). These fatty acids have been exhaustively studied due to their remarkable benefits to human health. In the present work, different methodologies were investigated to extract oil from the livers of Zearaja flavirostris and Atlantoraja castelnaui. Enzyme-assisted processes, cold extractions, and high temperatures were studied. The extraction with enzymes was the most efficient in both species. The oils obtained presented physicochemical and quality parameters suitable for its refinement and commercialization. Palmitic (C16:0) and oleic acid (C18:1) were the most abundant saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs), respectively. Both species showed similar content of DHA; however, the oil of Z. flavirostris had twice as much EPA than A. castelnaui. The results suggest that the livers of the species studied can be used as a source of valuable oils, rich in PUFAs, as a viable alternative for the integral use of these resources.     

Economic feasibility of high Omega-3 soybean oil in mariculture diets: A sustainable replacement for fish oil

ABSTRACT

The growth of global aquaculture has put intense pressure on sources of fish oil and fishmeal for aquafeeds. The nutraceuticals industry has added further pressure on fish oils with high Omega-3 fatty acids. GM soybeans could provide substitutes in high Omega-3 soybean oil (STA oil), as well as soy protein concentrate (SPC). This article examines the technological and economic feasibility of substituting STA oil for one-half the fish oil in the diet of Seriola rivoliana, a species often destined for sushi markets. Previous studies have shown that the substitution results in no change in flesh quality or consumer acceptance. We find that the two feed technologies result in essentially identical growth pattern and feed consumption. Economic feasibility depends upon the price of STA oil being lower than the price of fish oil. Based on our market analysis, we estimate that STA oil will enter the market at a price about two-thirds of the fish oil price. The estimated cost savings at these prices are small, a 2.8% reduction in feed costs and 0.9% reduction in total costs. However, the potential global market for STA oil could be as much as 252 thousand metric tons annually, which would require soybean production equivalent to that from 1.63% of current U.S. soybean area.     

Evaluation of canola oils as alternative lipid resources in diets for juvenile red seabream, Pagrus auratus

This study examined three potential oil resources, crude and refined canola oil and refined soybean oil as replacements for added dietary fish oil in diets for juvenile red seabream. These oil resources were evaluated for their potential to replace added fish oil (40 g kg^?1) in fishmeal based (600 g kg^?1) diets, with 100 g kg^?1 of total lipids. Each of the three plant oils was used to replace 25%, 50%, 75% or 100% of the added dietary fish oil. Each of the three plant oils showed potential as a replacement for dietary fish oil, although a significant reduction in growth and feed utilisation was observed with the complete (100%) replacement of added fish oil by crude canola oil. No other significant effects of oil type or inclusion level on growth were apparent. A negative control (no added fish oil or plant oil, 60 g kg^?1 of total lipid) yielded poorer growth than all treatments except the diet containing 40 g kg^?1 of added crude canola oil (100% replacement). This observation confirmed that the added oils were utilized by the fish. A positive control diet containing 80 g kg^?1 of added fish oil (140 g kg^?1 total dietary lipid) sustained the best growth in the study, confirming that the 13 experimental diets were energy limiting as planned. Notably, few effects of the alternative oils were seen on the proximate composition of the fish. However, the influence of the alternative oils on the tissue fatty acid composition was considerable, irrespective of plant oil type or processing grade. Particularly notable was the overall increase in the level of polyunsaturated fatty acids in the tissues of the fish fed the plant oil diets, with these trends becoming more apparent with the greater levels of fish oil replacement. Minimal reductions in the levels of the long‐chain polyunsaturated fatty acids of eicosapentaenoic (20:5n‐3) and docosahexaenoic (22:6n‐3) acid were observed from any of the plant oil treatments. Sensory assessment, by an Australian taste panel, of the fish fed the fish oil reference, or the 100% replacement by refined canola or refined soybean diets showed a preference in order of canola oil > soybean oil > fish oil fed fish. Clearly, both canola and soybean oils have considerable potential as replacements of fish oils in diets for this species.     

THE EFFECT OF FISH QUALITY ON THE COMPOSITION AND OXIDIZATION OF FISH OIL

本文以不同质量的鱼及生产出的鱼油为原料，研究了鱼体质量对鱼油组成及氧化特性的影响。氧化程度即鱼油的化学发光强度随鱼体质量下降而上升。化学发光强度与ＥＰＡ、ＤＨＡ含量无明显关系。随鱼体质量下降，鱼油颜色由浅而深，且共轭二烯系含量、游离脂肪酸和甘油二酯含量增加。鱼油中甘油三酯与鱼体总挥发性氨基氮呈负相关。由低质鱼生产的鱼油较易氧化。     

Oxidative stability of salmon and herring roe lipids and their dietary effect on plasma cholesterol levels of rats

ABSTRACT:   The oxidative stability of lipids from salmon roe and herring roe was compared with those of commercial fish oils originated from sardine and tuna. Both fish roe lipids contained high amounts of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Total EPA and DHA was more than 35% of total fatty acids in both roe lipids. On the basis of oxygen consumption, fish roe lipids showed the higher oxidative stability than both fish oils. This tendency in oxidative stabilities was also confirmed by the determination of propanal formation during oxidation. Analyses of lipid compositions suggested that the higher oxidative stabilities of fish roe lipids would be mainly due to the presence of phospholipids in them. Dietary effects of salmon and herring roe lipids were also determined. Little increase in total cholesterol level was observed in plasma lipids in rats fed salmon and herring roe lipids, although cholesterol content in fish roe lipids were 6.3% and 9.7% of total lipids for salmon roe and herring roe.     

Effect of dietary fatty acid composition on the growth of the tiger puffer <Emphasis Type="Italic">Takifugu rubripes</Emphasis>

Effects of dietary fatty acid composition on the growth of the tiger puffer Takifugu rubripes were examined. Eight experimental diets were formulated with fish meal and casein as the major ingredients, providing 45.0–48.2% crude protein. Pollack and squid liver oils were used for the control diet while experimental diets contained three levels of EPA-DHA concentrated (C-HUFA) oils, soybean oil, linseed oil, and combinations of them, providing 0.5–5.5% n-3 HUFA and 5.0–11.1% crude lipid. Triplicate groups of fish with a mean body weight of 18.7 g per dietary treatment were fed the diets twice daily to apparent satiation, 6 days per week for 8 weeks. The final body weight and weight gain of the fish fed the soybean oil diet without C-HUFA oils were significantly lower than those fed the control diet. Both parameters were not statistically different among the other dietary groups, although the values obtained for the linseed oil diet without C-HUFA oils were lower. Similar trends were seen for SGR and feed efficiency. However, significantly lower PER values compared to the control were observed for the lower C-HUFA and the vegetable oil without C-HUFA oil groups. These results indicate that tiger puffer can be produced successfully with diets containing more than 1.5% n-3 HUFA.     

Deposition of astaxanthin in fillets of Atlantic salmon (Salmo salar) fed diets with herring, capelin, sandeel, or Peruvian high PUFA oils

To elucidate whether absorption and deposition of dietary astaxanthin are influenced by the use of different dietary fish oils having different melting points and fatty acid profiles, triplicate groups of individually labeled Atlantic salmon (initial average weight 569 g) were reared in 2 m² tanks, supplied with saltwater. The fish were fed four different experimental diets coated with either herring oil, capelin oil, sandeel oil, or a Peruvian oil high in polyunsaturated fatty acids. Salmon fed diets containing Peruvian high PUFA oil had significantly higher (13%) fillet carotenoid content than salmon fed herring oil (P<0.05). Astaxanthin retention was significantly higher (P<0.05) in salmon fed capelin and Peruvian high PUFA oil than in the two other groups. The effects of dietary oil supplements on carotenoid deposition were rather small and require verification. Redness of fillets and blood plasma astaxanthin levels did not differ among treatments. Liver weights, body weights, as well as specific growth rates, and feed conversion ratios were unaffected by dietary oil source. Significant (P<0.05) positive linear relationships were found between final fillet idoxanthin concentration and total saturated fatty acids in supplement oils, astaxanthin and total monounsaturated fatty acids, and redness and total n−3 fatty acids, whereas the relationships between redness and total monounsaturated fatty acids and astaxanthin and total n−3 fatty acids were negative.     

Fatty Acid Composition and Oxidative Stability of Fish Oil Products in Turkish Retail Market

The fatty acid composition and oxidative stability of fish oil and syrups available in the Turkish retail market were examined in this study. The major saturated fatty acids in capsules and syrups were palmitic acid (16:0) and stearic acid (18:0). The monounsaturated fatty acid contents of fish oil products have very different results (10.71–50.46%). The results show that the label claims for total omega-3, eicosapentaenoic acid, and docosahexaenoic acid presented a reasonable accuracy for the examined products, but it was noted that some of the results showed a considerable difference with the labels.

The free fatty acid level in fish oil products was generally low (0.13–1.95% of oleic acid). Peroxide value of all examined products was below the limit of 10 meq kg^?1 oils for edible oil as indicated in Codex (1999). It was detected that the p-Anisidine value of fish oil capsules (5.36–8.90) was considerably lower than for fish oil syrups (21.86–26.74). According to our results, the totox value of fish oil capsules evaluated in this study (7.08–17.35) was within acceptable limits. However, fish oil syrups (34.72–38.06) highly exceeded the upper tolerable limit (26).     

Fish meal quality assessment for Atlantic salmon (Salmo salar L.) reared in sea water

Studies were conducted to investigate the quality of 16 fish meals for Atlantic salmon ( Salmo salar L.) reared in sea water, and to assess in vitro and in vivo methods for the measurement of the quality of the protein in fish meals. The commercial fish meals tested were Canadian-produced (herring, groundfish, and mixed meals) and were of West Coast and East Coast origin; they included silver hake (Russian origin), two mackerel meals (Chilean) and Norwegian fish meal (Norse-LT94®). In addition, five herring meals were produced in the laboratory to assess the influence of processing conditions and freshness of the raw material on fish meal quality. The dilute-pepsin digestibility was the preferred in vitro assay to evaluate the protein quality of herring meals for Atlantic salmon, but this assay correlated poorly with the results from in vivo assays when other types of fish meals (menhaden, mackerel, silver hake, groundfish) were included.     

Effects of replacing fish meal and oil with plant resources in on‐growing diets for Atlantic cod Gadus morhua L

The present paper gives an overview on the use of plant protein and plant oils as replacers for fish meal and fish oil in diets for Atlantic cod Gadus morhua L. In focus are effects on growth, feed utilization, digestibility, gut health, muscle and liver uptake and retention of nutrients, and muscle quality. Plant oil can replace fish oil without affecting growth provided that the requirement of marine long chain (LC) n‐3 fatty acids is met, but the altered dietary fatty acid profile in diet will be reflected in both muscle and liver. This can reduce the value of cod liver as an oil source for cod liver oil production. For the fish itself, there are more challenges replacing fish meal than fish oil, due to the amount of fibre and antinutrients in plant protein meals. However, A. cod seems to tolerate a wide range of plant types and their inclusion levels provided that the amino acids requirements are met. It is our view that there is sufficient knowledge to be able to design an A. cod diet based on a mixture of plant and marine ingredients and be able to predict performance such as growth, feed utilization, digestibility, liver size and fish health in general.     

Enhancing highly unsaturated ω‐3 fatty acids in phase‐fed rainbow trout (Oncorhynchus mykiss) using Alaskan fish oils

Rainbow trout, average weight 185–187 g, were fed feeds containing menhaden oil, canola oil or fish oils (pollock, pink salmon or rockfish) produced from Alaskan seafood processing waste as the added oil for 8 weeks, at which time the fish weighed 391–411 g (average 404 g, pooled SE = 5.7). The fish were previously fed from 75 g average weight fed commercial feed containing poultry oil as the added oil. No significant differences were measured in final weight or feed conversion ratio among dietary treatment groups. Significant differences were found in fillet ω‐3 fatty acid (FA) levels from fish receiving fish oil‐supplemented feeds compared to those from fish receiving feeds containing canola oil. Fillet contents of eicosapentaenoic acid (EPA; 20:5ω3) and decosahexaenoic acid (DHA; 22:6ω3) were highest in the pollock oil treatment group, although all fish oils increased highly unsaturated ω‐3 FA contents (mg 100 g^?1) of fillets. Fish oil used through the production cycle was reduced by 25% by supplementing feeds with poultry oil during the middle phase of production (75–175 g) compared to using feeds containing fish oil throughout the production cycle. Fish oils recovered from Alaskan seafood processing waste were suitable alternatives to conventional fish oil as ingredients in rainbow trout production feeds.     

Influence of partial substitution of dietary fish oil by vegetable oils on the metabolism of [1-14C] 18:3n-3 in isolated hepatocytes of European sea bass (Dicentrarchus labrax L.)

The static or declining supply of fish oil from industrial fisheries demands the search of alternatives, such as plant (vegetable) oils, for diets in expanding marine aquaculture. Vegetable oils are rich in C₁₈ polyunsaturated fatty acids but devoid of the n-3 highly unsaturated fatty acids in fish oils. Previous studies, primarily with salmonids, have shown that including vegetable oils in their diets increased hepatocyte fatty acid desaturation. In the present study, we have investigated the effects of dietary partial substitution of fish oil (FO) with rapeseed oil (RO), linseed oil (LO) and olive oil (OO) on the desaturation /elongation and, -oxidation capacities of [1-¹⁴C]18:3n-3 in isolated hepatocytes from European sea bass (Dicentrarchus labrax L.), in a simultaneous combined assay. Fish were fed during 34 weeks with diets containing 100% FO, or RO, LO and OO, each included at 60% with the balance being met by FO, with no detrimental effect upon growth or survival. The highest total desaturation rates were found in hepatocytes of fish fed FO diet (0.52±0.08 pmol/h/mg protein) and OO diet (0.43±0.09 pmol/h/mg protein), which represented 3.2% and 2.7% of total [1-¹⁴C]18:3n-3 incorporated, respectively. In contrast, lowest desaturation rates were presented by hepatocytes of fish fed LO and RO diets (0.23±0.06 and 0.14±0.05 pmol/h/mg protein, respectively) represented 1.4% and 0.9% of total [1-¹⁴C]18:3n-3 incorporated, respectively. The rates of [1-¹⁴C]18:3n-3 β-oxidized were between 11-fold and 35-fold higher than desaturation. However, no significant differences were observed among β-oxidation activities in hepatocytes of fish fed any of the diets. The present study demonstrated that the European sea bass, as a carnivorous marine fish, presented a ‘marine’ fish pattern in the metabolism of 18:3n-3 to 20:5n-3 and 22:6n-3. This species appeared to have all the enzymic activities necessary to produce 22:6n-3 but presented only extremely low rates of fatty acid bioconversion. Furthermore, nutritional regulation of hepatocyte fatty acid desaturation was minimal, and dietary vegetable oils did not increase desaturase activities, and in RO and LO treatments the activity was significantly lower. This revised version was published online in July 2006 with corrections to the Cover Date.     

Acid and Fermented Silage Characterization and Determination of Apparent Digestibility Coefficient of Crude Protein for Pacu Piaractus mesopotamicus

Three types of raw materials including commercial waste from saltwater (SW), freshwater fish (FW) and tilapia fillet residue (FR) were used to produce fish silage by either acid digestion (2% formic acid and 2% sulfuric acid) or anaerobic fermentation (5% of Lactobacillus plantarum and 15% sugar cane molasses). Six test diets were used in digestibility trials prepared with 70% reference diet and 30% of each experimental silage. These diets were fed to juvenile pacu Piaractus mesopotamicus (146 g average weight) in triplicate. Fish were kept in 500-L tanks and feces collected by manual extrusion. It was observed for both processes that SW waste always had the highest moisture content and lowest fat and ash. Highest crude protein levels were found in silages from commercial fish waste (SW and FW) made from whole fish unfit for human consumption. However, apparent digestibility coefficients did not vary among diets ( P > 0.05). Although values did not differ statistically, fermented silage consistently displayed higher digestibility coefficients compared to acid silage. The silages exhibited relatively high protein digestibility (72.5–80.0%), thus suggesting the feasibility of using fish industry by-products in aquaculture feeds.     

Effects of dietary fish oil substitution with mixed vegetable oils on growth and fillet fatty acid composition of juvenile Caspian great sturgeon (Huso huso)

The objective of this study was to determine the effects of fish oil replacement with dietary vegetable oils on growth performance, chemical composition and fatty acids profiles in fillets of farmed Caspian great sturgeon juveniles Huso huso (26.97 ± 0.49 g). Five isonitrogenous and isolipidic diets were formulated, containing 10 % of added oil. The diet with 100 % kilka fish oil (Caspian tyulka, Clupeonella caspia) was the control. Fish oil was substituted by 50 % of vegetable oils consisting of an equal share of sunflower and soybean oils (diet A), sunflower and canola oils (diet B) and soybean and canola oils (diet C). In diet D, 100 % of fish oil was replaced with vegetable oil (1:1:1 ratio of sunflower oil, soybean oil and canola oil). Significant differences (P > 0.05) were not detected during 60 days feeding trial in final body weight, weight gain, condition factor, specific growth rate, feed conversion rate, protein efficiency ratio and the chemical composition of fillet (crude protein, crude lipid, moisture and ash). Generally, the fatty acids composition of fish fillets was reflective of the dietary lipid sources. These results indicate the feasibility of substituting fish oils with the mixture of vegetable oils in diets of juvenile H. huso without negative influence on growth providing optimum ratios of n-3/n-6 and n-3/18:1n-9 is met in the diet.     

The rise of fish oil: From feed to human nutritional supplement

ABSTRACT

This article tells the story of how fish oil has gone from an inferior to a premium oil product. With the growth of aquaculture, fish oil became a valuable feed component. Its value increased further as the belief in the health benefit of Omega-3 opened the market for direct human consumption through nutritional supplements. Strong demand, limited supply growth and weaker substitution between Omega-3 and Omega-6 has led to diverging trends between fish oil and vegetable oil prices, with fish oil now a premium oil product. We also investigated how the salmon aquaculture industry has responded to the challenge of rising fish oil prices. Concerted effort in nutrition and feed research is shown to have allowed a reduction in the share of fish oil in feed from around 25% in the early 2000s to around 12% today. This substitution effort has allowed salmon production to grow without using substantially more fish oil.     

Effects of dietary lipid level and vegetable oil on fatty acid metabolism in Atlantic salmon (Salmo salar L.) over the whole production cycle

Changes in fatty acid metabolism in Atlantic salmon (Salmo salar) induced by vegetable oil (VO) replacement of fish oil (FO) and high dietary oil in aquaculture diets can have negative impacts on the nutritional quality of the product for the human consumer, including altered flesh fatty acid composition and lipid content. A dietary trial was designed to investigate the twin problems of FO replacement and high energy diets in salmon throughout the entire production cycle. Salmon were grown from first feeding to around 2 kg on diets in which FO was completely replaced by a 1:1 blend of linseed and rapeseed oils at low (14–17%) and high (25–35%) dietary oil levels. This paper reports specifically on the influence of diet on various aspects of fatty acid metabolism. Fatty acid compositions of liver, intestinal tissue and gill were altered by the diets with increased proportions of C₁₈ polyunsaturated fatty acids and decreased proportions of n-3 highly unsaturated fatty acids (HUFA) in fish fed VO compared to fish fed FO. HUFA synthesis in hepatocytes and enterocytes was significantly higher in fish fed VO, whereas β-oxidation was unaltered by either dietary oil content or type. Over the entire production cycle, HUFA synthesis in hepatocytes showed a decreasing trend with age interrupted by a large peak in activity at seawater transfer. Gill cell prostaglandin (PG) production showed a possible seasonal trend, with peak activities in winter and low activities in summer and at seawater transfer. PG production in seawater was lower in fish fed the high oil diets with the lowest PG production generally observed in fish fed high VO. The changes in fatty acid metabolism induced by high dietary oil and VO replacement contribute to altered flesh lipid content and fatty acid compositions, and so merit continued investigation to minimize any negative impacts that sustainable, environmentally-friendly and cost-effective aquaculture diets could have in the future. Abbreviations: FO - fish oil; HUFA - highly unsaturated fatty acids acids (carbon chain length ≥C ₂₀ with ≥3 double bonds); LO - linseed oil; RO - rapeseed oil; VO - vegetable oil. This revised version was published online in July 2006 with corrections to the Cover Date.     

Antioxidant and immune defences of rainbow trout (Oncorhynchus mykiss) offered plant oils differing in fatty acid profiles from early stages

The antioxidant defence and immune response of rainbow trout (Oncorhynchus mykiss) that had received plant oils, rich in either n‐3 polyunsaturated fatty acids (PUFA; linseed oil) or n‐6 PUFA (safflower oil) was evaluated upon antigen exposure. The fish employed in this study had been offered the diets for 18 months from the first feeding. Rainbow trout from each group were injected intraperitoneally with formalin‐killed bacteria (Aeromonas hydrophila) or were sham‐injected and observations were made 24 h later. Though the fish fed safflower oil seemed to be under relatively greater oxidative stress, the antioxidant defences (superoxide dismutase, catalase, glutathione peroxidase) were as effective as in those fed linseed oil. The humoral (alternate complement activity and lysozyme activity) and cellular (phagocytic activity and lymphocyte proliferation) immune responses were not significantly affected by the oil offered. With the exception of reactive oxygen production that was significantly greater in the linseed oil fed fish, both groups did not differ greatly in their immune responses after antigen exposure. Thus, fish fed safflower oil that was deficient in n‐3 PUFA was able to sustain most of the critical responses similar to those fed linseed oil suggesting that plant oils of both fatty acid categories were effective for this fresh water fish.     

Oil extraction From the Copepod Calanus finmarchicus Using Proteolytic Enzymes

The limited amount of fish oils available has led to extensive search for alternative sources of oils rich in long-chain n-3 polyunsaturated fatty acids (PUFA). The zooplankton Calanus finmarchicus is present in large amounts in the North Atlantic and have lipid-rich stages which can be harvested. The main objective of this study was to investigate if the use of food grade proteolytic enzymes, Alcalase® and Flavourzyme®, could improve oil recovery in an industrial-like process, and to characterize the oil obtained. The results showed a substantially higher oil yield with the use of proteolytic enzymes compared to standard fish oil production technology. The oil from C. finmarchicus had a high content of n-3 PUFA mainly comprised of stearidonic acid (18:4 n-3), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). Wax esters were the dominating lipid class in the oil.