Dietary Lipid Sources Research Articles

Dietary oils mediate cortisol kinetics and the hepatic mRNA expression profile of stress-responsive genes in gilthead sea bream (Sparus aurata) exposed to crowding stress. Implications on energy homeostasis and stress susceptibility

Juveniles of gilthead sea bream were fed with plant protein-based diets with fish oil (FO diet) or vegetable oils (66VO diet) as dietary lipid sources. No differences in growth performance were found between both groups, and fish with an average body mass of 65–70g were crowded (90–100kg/m3) to assess the stress response within the 72h after the onset of stressor. The rise in plasma cortisol and glucose levels was higher in stressed fish of group 66VO (66VO-S) than in FO group (FO-S), but the former stressed group regained more quickly the cortisol resting values of the corresponding non-stressed diet group. The cell–tissue repair response represented by derlin-1, 75kDa glucose-regulated protein and 170kDa glucose-regulated protein was triggered at a lower level in 66VO-S than in FO-S fish. This occurred in concert with a long-lasting up-regulation of glucocorticoid receptors, antioxidant enzymes, enzyme subunits of the mitochondrial respiratory chain, and enzymes involved in tissue fatty acid uptake and β-oxidation. This gene expression pattern allows a metabolic phenotype that is prone to “high power” mitochondria, which would support the replacement of fish oil with vegetable oils when theoretical requirements in essential fatty acids for normal growth are met by diet.

Effect of dietary flaxseed oil level on the growth performance and fatty acid composition of fingerlings of rainbow trout, Oncorhynchus mykiss.

This study evaluated the suitability of flaxseed oil as a source of supplemental dietary lipid for fingerlings of rainbow trout (Oncorhynchus mykiss). Triplicate groups of the 30 fingerlings held under identical culture conditions were fed twice daily by iso-nitrogenous, iso-calorific and iso-lipidic diets for 8 weeks. Experimental diets consisted of 30.2% protein, 18.6 kJ g-1 energy and 16.5% lipid from fish oil (FO), flaxseed oil (FxO) and 1:1 blends of the oils (FFxO). Moisture, ash, protein, final body weight, specific growth rate, weight gain, feed conversion ratio, survival and hepatosomatic index were not affected by treatments but the percent of lipids was significantly highest in fish fed the flaxseed oil diet (FxOD). The condition factors of fingerlings reared on FxOD and fish and flaxseed oils diet (FFxOD) were significantly lower than those fed the fish oil diet (FOD). Protein efficiency ratio (PER) was significantly higher than those fed the FOD and FFxOD. Whole body fatty acid compositions mirrored those of diet treatments. The highest amounts of highly unsaturated fatty acids (HUFAs) were detected in fish fed 100% FO, which was significantly different from other treatments. In all treatments polyunsaturated fatty acids/saturated fatty acids (PUFAs/SFAs) and n-6/n-3 ratios were higher than 0.45 and lower than 4, respectively. Present results indicate the fingerlings can be reared on diets in which FO has been replaced with FxO, with no significant effects on fish performance.

Effects of dietary lipid sources on apoptotic and immune gene expression in head kidney of olive flounder (Paralichthys olivaceus)

It can be hypothesized that dietary fatty acids can modulate immune responses in fish by inducing apoptosis of immune cells since dietary polyunsaturated fatty acid (PUFA) increase apoptosis by oxygen radicals generated by peroxidation. Thus we examined the effects of deferent dietary lipid sources such as squid liver oil (FO), linseed oil (LO) and soybean oil (SO) on oxidation (Cytochrome C oxidase; COS), apoptosis (TNF-  Scinderin like) and immune (IL-1  and NKEF) gene expression in the main immune organ (head kidney) in olive flounder (Paralichthys olivaceus) by Q-PCR analysis after feeding diets containing each oil (5%) for 15 weeks. Linseed oil and soybean oil were chosen to compare n-3 or n-6 enriched vegetable oils, respectively. Consequently, COS, TNF-α and Scinderin like gene expression was increased in SO group, indicating the induction of oxidation and apoptosis. Meanwhile, no significant difference was found in immune gene expression. In conclusion vegetable oils containing n-3 PUFA like linseed oil seems to be more suitable lipid source than soybean oil for replacement of fish oil in flounder since n-6 PUFA in SO leads to activation of apoptosis pathways within the cellular damage in head kidney.

Predictable Effects of Dietary Lipid Sources on the Fatty Acids Compositions of Four 1-Year-Old Wild Freshwater Fish from Poyang Lake

The descriptors linking dietary and fish fatty acids (FAs) compositions in four 1-year-old wild freshwater fish, Mylopharyngodon piceus, Ctenopharyngodon idella, Hypophthalmichthys molitrix, and Hypophthalmichthys nobilis, from Poyang Lake were studied. M. piceus mainly feeding on crustaceans had the highest relation of polyunsaturated fatty acids (PUFAs; r = 0.812) and odd-branched chain fatty acids (OBCFAs; r = 0.742) with spiral shells. Correlations between C. idella (herbivore) and aquatic plants (PUFAs, r = 0.995; OBCFAs, r = 0.783) were higher than other diet sources. The strongest correlation for PUFAs (r = 0.972) between H. molitrix (filter feeder with phytoplankton-feeding preference) and phytoplanktons was observed, followed by zooplanktons, whereas H. nobilis (filter feeder with zooplankton-feeding preference) showed the highest association with zooplanktons for PUFAs (r = 0.895). The high retainment of dietary FAs in fish body highlighted the potential for tailoring cultured fish FAs. The preferential distributions of n-3 long-chain PUFAs in sn-2-triacylglycerols and sn-2-phospholipids made fish an alternative for inland people supplementing n-3 PUFAs.

The influence of dietary lipid composition on liver mitochondria from mice following 1 month of calorie restriction

To investigate the role mitochondrial membrane lipids play in the actions of CR (calorie restriction), C57BL/6 mice were assigned to four groups (control and three 40% CR groups) and the CR groups were fed diets containing soya bean oil (also in the control diet), fish oil or lard. The fatty acid composition of the major mitochondrial phospholipid classes, proton leak and H2O2 production were measured in liver mitochondria following 1 month of CR. The results indicate that mitochondrial phospholipid fatty acids reflect the PUFA (polyunsaturated fatty acid) profile of the dietary lipid sources. CR significantly decreased the capacity of ROS (reactive oxygen species) production by Complex III but did not markedly alter proton leak and ETC (electron transport chain) enzyme activities. Within the CR regimens, the CR-fish group had decreased ROS production by both Complexes I and III, and increased proton leak when compared with the other CR groups. The CR-lard group showed the lowest proton leak compared with the other CR groups. The ETC enzyme activity measurements in the CR regimens showed that Complex I activity was decreased in both the CR-fish and CR-lard groups. Moreover, the CR-fish group also had lower Complex II activity compared with the other CR groups. These results indicate that dietary lipid composition does influence liver mitochondrial phospholipid composition, ROS production, proton leak and ETC enzyme activities in CR animals.

A mixture of fish oil and soybean oil as a dietary lipid source prevents precocity and promotes growth in juvenileMacrobrachium nipponense(De Haan)

Macrobrachium nipponense is an important economic freshwater prawn in China, Japan and other South-East Asian countries (Yang, Xie, Lei, Zhu & Yang 2004). In recent years, precocity has become a serious problem in M. nipponense farming, which results a large number of prawns mature at a small size and grow slowly (Wu, Qi, Chen, Zhang, Zhang, Qin & Hu 2009). Although the mechanisms of precocity in prawn have not been fully understood, inappropriate nutrition is believed to contribute, at least partly, to the precocity during growth and development of prawn (Rowe & Thorpe 1990; Karlsen, Hemre, Tveit & Rosenlund 2006; Lu, Chang, Wu, Yang, Zhao & Cheng 2010). Thus, regulating dietary nutrient composition to promote growth, but suppress early maturation, is eagerly needed for M. nipponense. Lipids, the primary energy source as well as critical supply of essential nutrients such as essential fatty acids, phospholipids and sterols, play important roles for prawn growth and development (Deering, Fielder & Hewitt 1997). As well known, different dietary lipid sources have various effects on growth of prawn. Soybean oil containing high n-6 polyunsaturated fatty acids (PUFA) was regarded to promote growth in leader prawn and red claw crayfish (Deering et al. 1997; Li, Guo, Gan, Wang, Zhang & Zhao 2011), but in Penaeus vannamei and Litopenaeus vannamei, fish oil containing high n-3 highly unsaturated fatty acids (HUFA), such as 20:5n-3(EPA) and 22:6n-3(DHA), had better effect in promoting growth (Lim, Ako, Brown & Hahn 1997; Gonz alez-F elix, Lawrence, Gatlin & Perez-Velazquez 2002). Except improving growth, proper dietary fatty acid composition can also prevent the occurrence of precocity in crustacean (Lu et al. 2010; Wu, Wang, Cheng, Zeng, Yang & Lu 2011). In M. nipponense, the optimal dietary lipid content has been reported as 6–12% (Yu & Shen 1990), but the effects of lipid sources on growth and precocity have not been studied yet. In this study, we made four isonitrogenous and isocaloric diets with different oils, to examine the effects of lipid sources on growth, survival and precocity in this freshwater prawn. We hypothesized that there might exist an optimal lipid source, which could not only promote growth but also prevent sexual precocity for M. nipponense. The four lipid sources, which are widely used in commercial formulated diets for M. nipponense, were beef tallow (BT) containing high saturated fatty acids (SFA), soybean oil (SO) containing high n-6 PUFA, pollack fish oil (FO) containing high n-3 HUFA, and a mixture of fish oil and soybean oil (FO/SO 2:1 w/w). The formulation process was previously described (Li, Yu, Chen, Zeng, Liu & Qin 2010), and the ingredients and fatty acids composition of these diets are shown in Table 1 and 2 respectively. Healthy juvenile prawns (0.090 0.0010 g) were randomly stocked in twenty 300-L tanks

Fatty acid metabolism in European sea bass (Dicentrarchus labrax): effects of n-6 PUFA and MUFA in fish oil replaced diets

Monounsaturated fatty acids (MUFA)-rich and n-6 polyunsaturated fatty acid (n-6 PUFA)-rich vegetable oils are increasingly used as fish oil replacers for aquafeed formulation. The present study investigated the fatty acid metabolism in juvenile European sea bass (Dicentrarchus labrax, 38.4 g) fed diets containing fish oil (FO, as the control treatment) or two different vegetable oils (the MUFA-rich canola/rapeseed oil, CO; and the n-6 PUFA-rich cottonseed oil, CSO) tested individually or as a 50/50 blend (CO/CSO). The whole-body fatty acid balance method was used to deduce the apparent in vivo fatty acid metabolism. No effect on growth performance and feed utilization was recorded. However, it should be noted that the fish meal content of the experimental diets was relatively high, and thus the requirement for n-3 long-chain polyunsaturated fatty acid (n-3 LC-PUFA) may have likely been fulfilled even if dietary fish oil was fully replaced by vegetable oils. Overall, relatively little apparent in vivo fatty acid bioconversion was recorded, whilst the apparent in vivo β-oxidation of dietary fatty acid was largely affected by the dietary lipid source, with higher rate of β-oxidation for those fatty acids which were provided in dietary surplus. The deposition of 20:5n-3 and 22:6n-3, as % of the dietary intake, was greatest for the fish fed on the CSO diet. It has been shown that European sea bass seems to be able to efficiently use n-6 PUFA for energy substrate, and this may help in minimizing the β-oxidation of the health benefiting n-3 LC-PUFA and thus increase their deposition into fish tissues.

The physical and chemical structure of lipids in relation to digestion and absorption

AbstractLipids provide specific functional, nutritional and sensorial properties to foods. The main dietary source of lipids is triacylglycerols. Triacylglycerols can occur in different forms, such as free (oil), droplets (emulsions) or crystallised network (butter). Whatever the form consumed, the triacylglycerols are emulsified in the stomach, as lipolysis takes place at the oil‐water interface. If some emulsifiers are already present at the surface of the lipid droplets, they will affect the lipolysis process. Another crucial parameter is the size of the emulsified droplets, as smaller droplets, providing a larger surface area for lipase binding, will be digested faster. The chain length and degree of saturation of the fatty acids and their position on the triacylglycerol backbone influence their digestion, mode of transport and absorption. Thus the choice of emulsifiers, particle size and fatty acid composition are major factors to take into account when processing food to reduce or increase lipid digestion and absorption.

Influence of Different Sources of Dietary Lipid on the Growth, Feed Efficiency and Survival of Snakehead Channa striatus (Bloch, 1793) Grow-Out

A 84-days-long experiment was conducted with a view to observe the effects of different feeds on growth and survival of Channa striatus grow-outs to develop a rearing technique for promoting its aquaculture. There were seven treatments (L3HUF, H3HUF, MUSOL, LINOL, MIXOL, SATOL and NATFO), each having two replications, stocked with 20 grow-out having an initial average weight 27.36 ± 0.09 to 32.54 ± 0.41 g in a circular plastic pools (300 l capacity). The six feeds were formulated with basic ingredients (soybean meal, 41 %; soluble starch, 25 %; casein, 20 %; carboxy methyl cellulose, 2 %; papain, 0.5 %; vitamin and mineral mix, 3.5 %) with iso-energetic (19.3 kJ/g, F1–F6) diets and results were compared with natural food fed fishes. Each diet was hand fed two times daily for 84 days to triplicate homogenous groups of 20 fishes. The fishes fed with live tubificid worms showed significantly better results in terms of weight gain and specific growth rate (%) compared to the rest six treatments. The survival was recorded cent percent in all the treatments. Results showed that the feed efficiency and growth performance significantly (p < 0.05) changed with various types of dietary lipid. At the end of the 84 days study the weight gain was recorded as 51.65 ± 0.35, 51.15 ± 0.21, 50.95 ± 0.35, 53.20 ± 0.28, 59.15 ± 0.21, 55.53 ± 0.41 and 61.44 ± 0.24 g for L3HUF, H3HUF, MUSOL, LINOL, MIXOL, SATOL and NATFO respectively. The best growth recorded in natural food fed fishes followed by MIXOL, SATOL, H3HUF, LINOL, L3HUF and MUSOL. The hepatosomatic and viscerosomatic indices ranged between 2.1–2.5 and 3.4–4.3 respectively in F1–F7. The feed efficiency in terms of feed conversion ratio recorded as 2.02–3.04 among all the feeding trials. It could be concluded, based on the results of this trial, that a diet formulated with a gross energy of 19.3 kJ/g is sufficient to promote good feed efficiency and growth performance in C. striatus grow-out however, the best growth recorded in mixed oil (MIXOL) containing 50 % mustard oil and 50 % linseed oil.

Effects of dietary fish and vegetable oils on the growth, tissue fatty acid composition, oxidative stability and vitamin E content of red hybrid tilapia and efficacy of using fish oil finishing diets

The use of alternative lipids in tilapia feeds is becoming increasingly commonplace due to the rising cost of fish oil (FO). However, since this practice will reduce the content of heath beneficial long chain polyunsaturated fatty acids (LC-PUFA) in tilapia fillets, investigations on finishing diets to enhance their nutritional value prior to harvest are increasing. A five month grow-out trial was conducted to evaluate the replacement of dietary FO with FO+crude palm oil (CPO) (1:1), linseed oil (LO)+CPO (1:1), CPO or soybean oil (SBO) on the growth performance, feeding efficiencies, body condition, fatty acid changes of the fillet/liver, fillet vitamin E content and oxidative stability of red hybrid tilapia (Oreochromis sp.). Diets were fed to duplicate groups of 50 fingerlings (initial weight=19.84±0.02g) and after five months were switched to a FO-based finishing diet and measured for tissue oxidative stability and fatty acid composition every month for another three months of culture. Results showed that growth performance and feeding efficiencies were not significantly better (P>0.05) for tilapia fed the FO based-diet than the alternative oil-based diets while none of the body indices or carcass/fillet yield were impacted by the dietary lipid source. Fillet vitamin E content and oxidative stability of tilapia fed the CPO or SBO diet were significantly higher than all other dietary treatments. The fatty acid composition of tilapia fillet/liver generally reflected those of the diet. Within one month of tilapia fed the finishing diet, the content of eicosapentaenoic acid (EPA, 20:5n-3), docosahexaenoic acid (DHA, 22:6n-3) and n-3/n-6 ratios rapidly increased in the fillets. After three months on the FO finishing diet, fillet DHA was not significantly different among all dietary treatments, although EPA and the n-3/n-6 ratios were still significantly lower compared to fillets from fish continuously fed the FO diet throughout the eight months. Among the tested alternative oil based-diets, tilapia previously fed the FO+CPO diet followed by the finishing diet resulted in the highest EPA, DHA and n-3/n-6 ratios, which should decrease feeding costs while improving the fillet quality of tilapia.

Dietary Lipid Levels Affect Growth and Fatty Acid Profiles of Malaysian Mahseer Tor tambroides

AbstractAfter protein, the second major essential macronutrient in fish diet is lipid. This study was conducted to determine the optimum level of dietary lipid for the best growth performance of juvenile Malaysian mahseer Tor tambroides. Four isonitrogenous diets containing 40% crude protein were formulated to contain different levels of lipid (5, 10, 15, or 20% on an as‐fed basis). Cod liver oil was incorporated into the feed as the main dietary lipid source used to formulate the diets while residual oil coming from other ingredients contributed about 5% of dietary lipid. The experimental diets were labeled as L5, L10, L15, or L20 to denote the levels of dietary lipid. Fish were fed the experimental diets in triplicate groups for 63 d. Growth performance, survival rate, and daily feed intake by Malaysian mahseer significantly decreased when fed diets in which levels of dietary lipid increased from 5% to 20%. However, the growth performance did not vary significantly between fish fed the L5 and L10 diets. The increase in dietary lipid significantly increased the hepatosomatic index but did not influence the viscerosomatic index. Increasing dietary lipid levels also decreased the lipid content in the whole body composition of fish. The monounsaturated fatty acid (MUFA) and n‐3 polyunsaturated fatty acid (PUFA) contents of fish liver significantly increased with the increase of dietary lipid. The results of this study suggested that 5% dietary lipid is sufficient for the best survival rate and growth performance of juvenile Malaysian mahseer.

Effect of dietary fat source on fatty acid profile and lipid oxidation of eggs

This study investigated the effects of supplementary dietary lipid sources on the fatty acid profile and lipid oxidation of eggs. Five isoenergetic (12.6 MJ AME/kg DM) and isonitrogenous (170 g CP/kg DM) diets were formulated, using a control diet (50 : 50 blend of fish- and linseed oil), fish oil, sunflower oil, high oleic acid (HO) sunflower oil and tallow at a 30 g/kg inclusion level. Two hundred individually caged HyLine Silver-Brown hens (20 weeks of age) were randomly allocated to the five dietary treatments (n = 40 hens/treatment). Birds received the experimental diets from 20 weeks of age. At 30 weeks of age, 12 eggs per treatment were randomly selected for analyses of egg yolk fatty acid methyl esters (FAME), thiobarbituric acid reactive substances (TBARS) and peroxide values (PV). Dietary lipid sources affected FAME, TBARS and PV of egg yolk significantly. The fish oil treatment resulted in the highest TBARS (0.27 mg malonaldehyde/kg yolk) and PV (3.96 milli-equivalent peroxide/kg fat) whereas the HO sunflower oil resulted in the lowest TBARS (0.13 mg malonaldehyde/kg yolk) and PV (2.77 milli-equivalent peroxide/kg fat). Fish oil also resulted in the lowest n-6 to n-3 ratio (1.16 to 1), while sunflower oil resulted in the highest ratio (24.6 to 1). Results indicate that the fatty acid profile of eggs could be altered by means of dietary intervention. However, an improvement of omega-3 type fatty acids of eggs will result in a higher susceptibility to lipid oxidation and possibly a shorter shelf-life of stored eggs.Keywords: Fish oil, high oleic sunflower oil, linseed oil, percentage yolk fat, peroxide value, tallow

Evaluation of poultry fat and blends of poultry fat with cold-pressed flaxseed oil as supplemental dietary lipid sources for juvenile sablefish (Anoplopoma fimbria)

The objective of this study was to access the suitability of using poultry fat (PF) or blends of PF with flaxseed oil (FO) to replace 75% of the supplemental anchovy oil (AO) in the diet of juvenile sablefish (Anoplopoma fimbria), a relatively new marine species to aquaculture. Sablefish were fed one of four diets twice daily to satiation for 15 weeks. The test diets were identical in composition except for the source of supplemental lipid which was either 100% AO (100AO), or had 75% of the supplemental AO replaced with 50% FO:25% PF, 25% FO:50% PF or 75% PF. Sablefish growth parameters, whole body and fillet proximate constituent concentrations, and apparent digestibility coefficients were uninfluenced by diet treatment. There were also no adverse effects of the diet treatments on fish health, as determined from analysis of various haematological and innate immunological parameters. Terminal fillet fatty acid compositions generally reflected the dietary fatty acid compositions. Results indicated that PF or blends of PF and FO may comprise 75% of the supplemental lipid in a grower diet for sablefish and are an economic alternative to AO while still providing humans with a rich dietary source of highly unsaturated fatty acids.

Echium Oil Provides No Benefit over Linseed Oil for (n-3) Long-Chain PUFA Biosynthesis in Rainbow Trout1–3

AbstractThe implementation of alternative lipid sources for use in aquaculture is of considerable interest globally. However, the possible benefit of using stearidonic acid (SDA)–rich fish oil (FO) alternatives has led to scientific confusion. Two hundred and forty rainbow trout (Oncorhynchus mykiss) were fed 1 of 4 diets (3 replicate tanks/treatment) containing either FO,linseed oil (LO), echium oil, or mixed vegetable oil (72% LO, 23% sunflower oil, and 6% canola oil) as the dietary lipid source (16.5%) for 73 d to investigate the competition and long-chain PUFA (LC-PUFA) biosynthesis between the fatty acid substrates a-linolenic acid (ALA) and SDA. SDA was more efficiently bioconverted to LC-PUFA compared with ALA.However, when the dietary lipid sources were directly compared, the increased provision of C18 PUFA within the LO diet resulted in no significant differences in (n-3) LC-PUFA content compared with fish fed the other diets. This study therefore shows that, rather than the previously speculated substrate competition, the limiting process in the apparent in vivo (n-3)LC-PUFA biosynthesis appears to be substrate availability. Rainbow trout fed the SDA- and ALA-rich dietary lipid sourcessubsequently had similar significant reductions in (n-3) LC-PUFA compared with fish fed the FO diet, therefore providingno additional dietary benefit on (n-3) LC-PUFA concentrations.

Effects of fish meal- and fish oil-free diets on growth responses and fatty acid composition of juvenile coho salmon (Oncorhynchus kisutch)

Commercial diets fed to coho salmon (Oncorhynchus kisutch) contain high levels of fish meal and fish oil. Given concerns about future supplies and prices of these commodities, more nutritional research aimed at identifying alternative dietary ingredients for Pacific salmon is needed. Thus, utilizing a factorial design, terrestrial proteins and lipids were evaluated in practical diets fed to coho salmon. The two basal diets, containing mostly marine proteins or containing only terrestrial proteins, were extruded and top-coated with either marine fish oil or a 63:37 mixture of canola and flaxseed oils. Each of the four dietary treatments was fed to quadruplicate groups of juvenile coho salmon initially weighing 7.5g/fish. At the end of the 15-wk feeding trial, weight gain (WG), feed efficiency (FE) and survival were significantly higher in fish fed diets containing marine protein compared with fish fed diets containing terrestrial proteins. Similarly, WG and FE were significantly higher in fish fed diets containing fish oil compared with fish fed diets containing plant oils. Survival was not significantly affected by dietary lipid source. Hemoglobin, hematocrit and total protein concentrations in whole blood were significantly higher in fish fed the marine protein diets compared with fish fed the terrestrial protein diets. Hematological responses were not significantly affected by dietary lipid source. Tissue (liver, muscle and carcass) lipids in fish fed the diets with added fish oil contained significantly higher proportions of 20:5n-3 and 22:6n-3 and significantly lower 18:1n-9, 18:2n-6 and 18:3n-3 percentages compared with fish fed the diets with added plant oils. Tissue fatty acid profiles also were significantly affected by dietary protein source, as liver, muscle and whole body lipids of fish fed the terrestrial protein diets contained significantly higher percentages of 18:2n-6 and total n-6 PUFA and a significantly lower total n-3:n-6 fatty acid ratio compared with fish fed the marine protein diets. Results of this study indicate complete replacement of dietary fish meal or fish oil individually have similar inhibitory growth effects in coho salmon, but have different effects on survival, hematological responses and tissue fatty acid percentages in this species.

Plant proteins and vegetable oil do not have detrimental effects on post-mortem muscle instrumental texture, sensory properties and nutritional value of gilthead seabream

A trial was undertaken to evaluate if the concomitant replacement of fishmeal and fish oil by vegetable ingredients affects fillet quality of gilthead seabream. Fish were fed either a fishmeal/fish oil diet, a fishmeal/vegetable oil diet, a plant protein/fish oil or a plant protein/vegetable oil diet over 70days. Dietary treatments had no effect on the muscle proximate composition and free amino acid profile. The n−3/n−6 PUFA ratio in fillets was higher in seabream fed fish oil based diets. Fishmeal and fish oil replacement did not affect instrumental texture parameters, but fish fed plant protein-rich diets showed higher fibre density and lower mean fibre diameter. Dietary lipid sources had no effect on sensory attributes, while protein source affected significantly the perception of typical odour and colour (white) of the fillets and succulence in the mouth, with seabream fed plant protein-rich diets receiving the highest scores.

Lipids in the Diet and the Fatty Acid Profile in Beef: A Review and Recent Patents on the Topic

The objective of this review is to report how the use of lipid sources in diets for ruminants can affect the fatty acid profile of beef. In addition, recent patents that can be utilized to alter the fatty acid profile in the meat, or which concern the synthesis of conjugated fatty acids will be reviewed. The industrial production of conjugated linoleic acid (CLA) has already started and the commercial products present isomers cis-9, trans-11; trans-9, cis-11; and trans-10, cis-12. Patents on the biological synthesis of isomer C18:2 cis-9, trans-11 from the linoleic acid have also been published. However, the economic production of CLA in industrial scale is a difficult process. Most of the patents published for CLA production utilize bacteria of the genera Bifidobacterium sp. and Propionibacterium sp. Lipid supplementation, with the objective to improve the fatty acid profile of beef, can be done through the use of patented products, such as genetically modified oilseeds and calcium soaps of fatty acids.

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.

Effects of Dietary Lipid Source and Level on Growth Performance, Blood Parameters and Flesh Quality of Sub-adult Olive Flounder (Paralichthys olivaceus).

This study was conducted to investigate the effects of dietary lipid source and level on growth performance, blood parameters, fatty acid composition and flesh quality of sub-adult olive flounder Paralichthys olivaceus. Eight experimental diets were formulated to contain 5% squid liver oil (SLO), 5% linseed oil (LO), 5% soybean oil (SO), a mixture of 1% squid liver oil, 2% linseed oil and 2% soybean oil (MIX), no lipid supplementation with high protein level (LL-HP), 10% squid liver oil (HL-SLO), a mixture of 1% squid liver oil, 4.5% linseed oil and 4.5% soybean oil (HL-VO), and 1% squid liver oil with high starch level (LL-HC), respectively. Two replicate groups of fish (average initial weight of 296 g) were fed the diets for 17 wks. After 5 wks, 11 wks and the end of the feeding trial, five fish from each tank were randomly sampled for analysis of body composition. At the end of the feeding trial, final mean weight of fish fed the LL-HP diet was significantly (p<0.05) higher than that of fish fed the HL-VO diet, but did not differ significantly from those of fish fed the SLO, LO, SO, MIX, HL-SLO and LL-HC diets. Fish fed the LL-HP diet showed significantly higher feed efficiency than fish fed the LO, HL-SLO and HL-VO diets. Feed efficiency of fish fed the LO, SO and MIX diets were similar to those of fish fed the SLO and HL-SLO diets. Fish fed the HL-SLO diet showed significantly higher total cholesterol content in plasma compared with other diets. Fatty acid composition of tissues was reflected by dietary fatty acid composition. The highest linoleic (LA) and linolenic acid (LNA) contents in the dorsal muscle were observed in fish fed the SO and LO diets, respectively, regardless of feeding period. The highest eicosapentaenoic acid (EPA) content in the dorsal muscle was observed in fish fed the LL-HP and LL-HC diets after 11 and 17 weeks of feeding, respectively. Fish fed the SLO and HL-SLO diets showed higher docosahexaenoic acid (DHA) content than that of other treatments after 11 and 17 weeks of feeding, respectively. Dietary inclusion of vegetable oils reduced n-3 HUFA contents in the dorsal muscle and liver of fish. The n-3 HUFA contents in tissues of fish fed the SLO and HL-SLO diets were higher than those of fish fed other diets, except for the LL-HP and LL-HC diets. Hardness, gel strength, chewiness and cohesiveness values of dorsal muscle in fish were significantly affected by dietary lipid source. The results of this study indicate that fish oil in fish meal based diets for sub-adult olive flounder could be replaced by soybean oil and linseed oil without negative effects on growth and feed utilization

Long-term supplementation of dietary omega-6/omega-3 ratios alters bone marrow fatty acid and biomarkers of bone metabolism in growing rabbits

The long-term effects of different dietary lipid sources with varying ratios of omega-6/omega-3 (ω6/ω3) polyunsaturated fatty acids (PUFAs) on the bone marrow fatty acid profile, ex vivo prostaglandin E2 (PGE2) release in bone, and plasma biomarkers of bone metabolism were evaluated in rabbits. Weanling male and female New Zealand white rabbits were randomly assigned to five groups and fed ad libitum on diets containing 70g/kg of added oil for 100days as follow: soy bean oil (SBO control), sesame oil (SO), fish oil (FO), DHA algae oil (DHA), and DHA and ARA algae oils (DHA/ARA). The dietary lipid treatments were formulated to provide the following ratios of ω6/ω3 fatty acids: 8.7 (SBO), 21.8 (SO), 0.4 (FO), 0.6 (DHA), and 0.7 (DHA/ARA). The bone marrow fatty acid profile of rabbits was significantly influenced by and reflected the dietary lipid treatments. Rabbits fed the FO diet had the highest ω3 PUFA concentration, and those fed the SBO diet were highest in ω6 PUFA. Ex vivo PGE2 level declined progressively as the ω6/ω3 dietary ratio declined. Plasma alkaline phosphatase (ALP) activity was significantly higher in male and female rabbits fed the DHA/ARA diet compared with those fed the control, SO, FO, or DHA diets. These results demonstrated that the dietary ω6/ω3 ratio modulates bone PGE2 production and plasma ALP activity in growing rabbits. In addition, the significant elevation in ALP activity in the DHA/ARA fed group proved that algae oils may be promising dietary sources for promoting bone formation during the growing stage.