High Levels Of Unsaturated Fatty Acids Research Articles

Enrichment strategies for Artemia using emulsions providing different levels of n−3 highly unsaturated fatty acids

Three separate enrichment trials compared the n−3 highly unsaturated fatty acid (HUFA) levels in Artemia franciscana nauplii (Great Salt Lake, USA) as a function of the n−3 HUFA level in the emulsion (30% and 50%), the enrichment dose (0.05, 0.1, 0.2, 0.3 and 0.4 g l −1) and the degree of dilution of a high HUFA emulsion with an n−3 HUFA-free emulsion (100/0, 50/50, 25/75, 12.5/87.5 and 0/100, HUFA-rich/HUFA-free, w/w). The standard emulsions were distributed by the International Council for the Exploration of the Sea, Working Group on the Mass Rearing of Juvenile Fish (ICES). After the 48-h enrichment, the content of docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA) and total n−3 HUFA increased to 23.1, 46.4 and 74.3 mg g −1 DW, respectively, in Artemia enriched with ICES 50 (50% n−3 HUFA) and to 14, 41.4, 59.9 mg g −1 DW in nauplii enriched with ICES 30 (30% n−3 HUFA). After the 12-h enrichment, the highest enrichment level of DHA, EPA and total n−3 HUFA was observed at the 0.4 g l −1 dose (12.7, 30.2 and 45.3 mg g −1 DW, respectively). After the 24-h enrichment, the highest enrichment levels were, however, found at the 0.3 g l −1 dose, i.e., respectively, 28.9, 53.2 and 85.6 mg g −1 DW as compared to 21.7, 51.1 and 75.9 mg g −1 DW at the 0.4 g l −1 dose. After 12 h enrichment, no significant difference in n−3 HUFA levels was found among the 100/0, the 50/50 and the 25/75 treatments. After 24 h enrichment, the content of DHA in nauplii of the 100/0 treatment was twice that of the 50/50 treatment (20.2 vs. 9.3 mg g −1 DW), which was in turn five times higher than in the 12.5/87.5 treatment.

Phospholipases as candidate genes in schizophrenia

Several studies have investigated the effect of nematodes on microbial degradation of macrophyte detritus, but little is known about the potential effect of bacterivorous nematodes on productivity of macrofaunal detritivores. We investigated the influence of the bacterivorous nematode Rhabditis (Pellioditis) mediterranea on the incorporation rate of isotopically-labelled macroalgal detritus by the amphipod Paramoera chevreuxi in a laboratory microcosm. The fatty acid composition of amphipods, nematodes, and macroalgal detritus was characterized to help determine the pathway of detritus incorporation by amphipods. The potential importance of R. mediterranea as a source of highly unsaturated fatty acids (HUFAs) to higher trophic levels was also investigated.We found no clear evidence for an effect of nematodes on the incorporation rate of fresh macroalgal detritus by amphipods, although there was some indication that the type of detritus (i.e. the green Chaetomorpha sp. vs the red Polysiphonia sp.) is important in determining the nature and extent of the relationship between nematodes and macrofaunal detritivores. Fatty acid data indicated that nematodes did not contribute significantly to the diet of amphipods when detritus was present, and there was no evidence that nematodes affected the pathway of detritus incorporation by amphipods. Amphipods incorporated Chaetomorpha sp. detritus about 10 times faster than Polysiphonia sp. detritus despite the higher C/N ratio and lower HUFA content of the former. This suggests that other factors, such as the presence of grazer deterrent compounds, are important in determining the palatability of macroalgal detritus. Amphipods fed exclusively on nematodes retained high HUFA levels but suffered high mortality. The burrowing behaviour of nematodes is suggested as the most likely factor limiting their availability to predators.Results suggest a limited interaction between amphipods and bacterivorous nematodes in detrital food webs. Further experiments are needed to test the wider applicability of these findings to different nematode and macrofaunal taxa, and for different types of detritus.

Performance of Macrobrachium rosenbergii broodstock fed diets with different fatty acid composition

The effect of linoleic acid (18:2 n−6) and n−3 highly unsaturated fatty acids (HUFA) on the reproductive performance and offspring quality of the freshwater prawn Macrobrachium rosenbergii was evaluated in a 180-day trial. Three isonitrogenous and isolipidic diets containing different levels of fatty acids, high 18:2 n−6 and n−3 HUFA concentrations, high 18:2 n−6 and low n−3 HUFA, and low 18:2 n−6 and n−3 HUFA, were fed ad libitum to three groups of six females. Fecundity was improved by the addition of higher amounts of 18:2 n−6 (from 3 to 13 mg g −1 DW). As a consequence of higher fecundity, smaller eggs were obtained most likely because the number of oocytes competing for a limited amount of yolk was higher. The higher gonado-somatic index of females fed diets with high levels of 18:2 n−6 and n−3 HUFA levels further supports this hypothesis. The fatty acid composition of the eggs reflected to some extent the composition of the diets. Eggs of females fed high levels of 18:2 n−6 and n−3 HUFA had the highest n−3 HUFA content and had increased hatchability. Eight-day-old larvae from females fed high levels of 18:2 n−6 and n−3 HUFA tended to present a better stress tolerance when exposed to 100 mg l −1 total ammonia for 24 h. No other differences were detected among larval characteristics from the different offspring groups. Results demonstrate that feeding M. rosenbergii broodstock with high levels of 18:2 n−6 and n−3 HUFA (13 and 15 mg g −1 DW, respectively) improved fecundity, egg hatchability, and the overall quality of the larvae.

Effect of different dietary polar lipid levels and different n−3 HUFA content in polar lipids on gut and liver histological structure of gilthead seabream ( Sparus aurata) larvae

In a previous study feeding larval gilthead seabream on microdiets, an improved growth rate was observed when dietary n−3 HUFA ( n−3 highly unsaturated fatty acids) were contained in the polar lipid fraction. A beneficial effect of dietary lecithin on n−3 HUFA incorporation to the larval polar lipids was also observed. To confirm those results and in order to obtain additional information on larval gut and liver histological structure, 11-day-old larvae were fed 4 microdiets differing in lipid composition. In diets N′ and NL′, the main sources of n−3 HUFA were neutral lipids, and polar lipids in diets P′ and PL′. Three lecithin levels were tested, being the highest in diet NL′ and the lowest in diet P′. The total n−3 HUFA level in diets N′ and NL′ was enough to meet the essential fatty acid requirement of larval gilthead seabream obtained in a previous study with a triacylglyceride based diet, while diets P′ and PL′ had a total n−3 HUFA level lower than the minimum determined. A reduction in the larval essential fatty acid requirement to 1.5% d.w. was obtained by feeding dietary n−3 HUFA present in the polar lipid fraction. Feeding larvae with microdiets with low polar lipid levels produced an accumulation of lipid droplets in the enterocytes and a high number of lipid vacuoles in the hepatocytes producing nuclear migration and suggesting a need of dietary polar lipid for lipid transport.

The n−3 highly unsaturated fatty acids requirements of gilthead seabream ( Sparus aurata L.) larvae when using an appropriate DHA/EPA ratio in the diet

Three day-old Sparus aurata larvae were fed rotifers ( Brachionus plicatilis) previously enriched with four lipid emulsions containing different percentages (10–30%) of n−3 highly unsaturated fatty acids (HUFA) but a fixed docosahexaenoic (DHA; 22:6 n−3) to eicosapentaenoic acid (EPA; 20:5 n−3) ratio of about 2/1. The n−3 HUFA content of the enriched rotifers varied from 0.9 to 3.0% on a dry weight basis (DWB). In addition, the four groups of rotifers displayed a constant DHA/EPA ratio of around 1.4/1. After 7 days of feeding, no significant differences in larval growth were observed among the treatments. One week later, larval total length was significantly improved by the elevation of the n−3 HUFA level in the diet from 0.9 to 1.5% DWB, with further increment not exerting any apparent effect on larval development. There was some loss of total lipids in the larvae during the first week of feeding which particularly affected the levels of n−3 HUFA in the polar lipid fraction. These losses were clearly restored from day 7 to 14 of feeding. At the end of the experimental period, larvae fed rotifers contributing less n−3 HUFA, contained lower levels of total and polar lipids, as well as lower levels of n−3 HUFA in the polar lipids. In conclusion, under our experimental conditions, the minimum requirement for n−3 HUFA of 17 day-old S. aurata larvae appears to be met by 1.5% in rotifers DWB, almost four times less than the value previously reported by our group when using rotifers with DHA/EPA ratios 2–3 times less favourable to DHA than to EPA.

Effects of two Avtemia diets with different contents of polyunsaturated fatty acids on the lipid composition of larvae of Atlantic herring (Clupea harengus

Atlantic herring larvae (Clupea harengus) were fed two enriched Artemia diets with different contents of (n‐3) highly unsaturated fatty acids (HUFA), one containing low levels of 20: 5(n‐3) and no 22: 6(n‐3), the other containing substantial levels of both 20: 5(n‐3) and 22: 6(n‐3). After 30 days of culture, fatty acid compositions of lipid classes in the heads, bodies and eyes of the larvae were analysed. Fish fed Artemia with the low (n‐3) HUFA diet lacking 22: 6(n‐3) had lower amounts of total (n‐3)HUFA and, in particular, of 22:6(n‐3) in individual phospholipids and total neutral lipids of heads, bodies and eyes as compared to fish fed Artemia with high levels of (n‐3)HUFA. The amount of 22: 6(n‐3) in the fatty acids of phosphatidyl‐ethanolamine of eyes was particularly susceptible to dietary depletion. The implications of these findings are discussed, particularly in relation to dietary requirements for 22: 6(n‐3) during development of neural tissue in predatory fish iarvae.

Essential fatty acid requirement of juvenile red drum (Sciaenops ocellatus)

Feeding experiments and laboratory analyses were conducted to establish the essential fatty acid (EFA) requirement of red drum (Sciaenops ocellatus). Juvenile red drum were maintained in aquaria containing brackish water (5 ± 2‰ total dissolved solids) for two 6-week experiments. Semipurified diets contained a total of 70% lipid consisting of different combinations of tristearin [predominantly 18:0] and the following fatty acid ethyl esters: oleate, linoleate, linolenate, and a mixture of highly unsaturated fatty acids (HUFA) containing approximately 60% eicosapentaenoate plus docosahexaenoate. EFA-deficient diets (containing only tristearin or oleate) rapidly reduced fish growth and feed efficiency, and increased mortality. Fin erosion and a "shock syndrome" also occurred in association with EFA deficiency. Of the diets containing fatty acid ethyl esters, those with 0.5-1% (n-3) HUFA (0.3-0.6% eicosapentaenoate plus docosahexaenoate) promoted the best growth, survival, and feed efficiency; however, the control diet containing 7% menhaden fish oil provided the best performance. Excess (n-3) HUFA suppressed fish weight gain; suppression became evident at 1.5% (n-3) HUFA, and was pronounced at 2.5%. Fatty acid compositions of whole-body, muscle and liver tissues from red drum fed the various diets generally reflected dietary fatty acids, but modifications of these patterns also were evident. Levels of saturated fatty acids appeared to be regulated independent of diet. In fish fed EFA-deficient diets (containing only tristearin or oleate), monoenes increased and (n-3) HUFA were preferentially conserved in polar lipid fractions. Eicosatrienoic acid [20:3(n-9)] was not elevated in EFA-deficient red drum, apparently due to their limited ability to transform fatty acids. Red drum exhibited some limited ability to elongate and desaturate linoleic acid [18:2(n-6)] and linolenic acid [18:3(n-3)]; however, metabolism of 18:3(n-3) did not generally result in increased tissue levels of (n-3) HUFA. Based on these responses, the red drum required approximately 0.5% (n-3) HUFA in the diet (approximately 7% of dietary lipid) for proper growth and health.

Requirement of Hybrid Striped Bass for Dietary (n-3) Highly Unsaturated Fatty Acids

A feeding trial was conducted to quantify the requirement of hybrid striped bass (Morone chrysops female x M. saxatilis male) for dietary (n-3) highly unsaturated fatty acids (HUFA), specifically eicosapentaenoic [20:5(n-3)] and docosahexaenoic [22:6(n-3)] acids. Graded levels of (n-3) HUFA as ethyl esters were substituted for part or all of the 5 g olive oil/100 g diet in the semipurified basal diet. Total amount of 20:5(n-3) plus 22:6(n-3) in the experimental diets was 0.5, 1.1, 1.5, 2.0 or 3.2 g/100 g dry wt. Control fish received a diet containing menhaden fish oil at 5 g/100 g. Each diet was fed to triplicate groups of hybrids (with an initial average weight of 13.0 g/fish) in aquaria for 10 wk. Significantly (P < 0.05) higher relative weight gain as well as more efficient food and protein utilization were observed for fish fed the diets with 0.5, 1.1, 1.5 or 2.0% (n-3) HUFA or 5% menhaden fish oil as compared with those fed the basal diet. These responses generally reached a plateau between 1.1 and 1.5% (n-3) HUFA, but the lowest values were observed for fish fed the diet with 3.2% (n-3) HUFA. Fatty acid composition of body lipids (total lipid of intraperitoneal fat and polar lipids of muscle and liver) was affected by diet and indicated some elongation and desaturation of octadecatetraenoic acid [18:4(n-3)] and 20:5 (n-3) to 22:6(n-3). These data indicated that 20:5(n-3) and 22:6(n-3) are essential for hybrid striped bass, and the minimum requirement is approximately 1% of diet or 20% of dietary lipid.

Role of dietary lipids and butylated hydroxy anisol (BHA) administration on albino rats. Part I. Serum unsaturated fatty acids.

Adult male albino rats were supplemented with edible plant oils, corn maize and cotton seed oils and their semihydrogenated forms (Heliopolis and Sultan cooking fats) for a period of 3 months. In general, the supplementation of tested oils produced increasing effect on the serum levels of total C18:1, C18:2 and C20:4 unsaturated fatty acids (UFA). The increases were significant in case of feeding corn maize oil and Sultan cooking fat for total and C18:1 and C18:2 UFA. However, the degree of significance was intensified by the feeding of cotton seed oil and Heliopolis cooking fat. Supplementation of Sultan cooking fat showed a significant increase in serum level of C20:4, while the other tested oils and Heliopolis cooking fat produced very highly significant increase. Butylated hydroxy anisol (BHA) produced no effect on the level of UFA when administered with dietary tested edible lipid but its role revealed by maintaining the higher level of UFA due to administration of oils and its semihydrogenated analogous.

The effect of enrichment diets on the fatty acid composition of the rotifer Brachionus plicatilis

Cultures of the rotifer Brachionus plicatilis (200 ind./ml, 0.5 μg dry weight/ind.) pre-fed on yeast and capelin oil (10:1 w/w) were given different enriched diets and harvested after 24 h. The fatty acid composition of the rotifers was affected by that of the feed. The highest level of n−3 highly unsaturated fatty acids (HUFA) 38%) and 22:6 n−3 (19%) was obtained after enrichment of the rotifers fed with squid meal. A positive relation was found between the n−3 HUFA in the enrichment diet and that of the rotifers ( P < 0.05, t-test). The cultivation feed of the rotifers may nevertheless be more important for the n−3 HUFA level than the enrichment feed. Starvation for 49 h did not change the fatty acid composition of the rotifers.

Trans Fatty acids in milkfat

AbstractMilkfat is extremely complex, with ca. 500 different fatty acids reported in the triglycerides. Seasonal feed variation results in higher unsaturated fatty acid levels in summer than in winter. Rumen microbes hydrogenate unsaturated feed lipids to yield a mixture of geometrical and positional isomers which are transmitted to the milk. Total isolatedtrans fatty acids in milkfat reported in the literature range from 2 to 11% with maximal values in summer and minimal values in winter. A study was undertaken about the use of AOCS Method Cd 14‐61 for the determination of isolatedtrans levels in milkfat. The triglycerides of milkfat were analyzed using trielaidin as a standard and milkfat methyl esters were analyzed using methyl elaidate as a standard. Corrections were made, for the loss of the methyl esters of the short‐chain fatty acids. The apparent levels oftrans found by using the triglycerides were considerably higher than by using the methyl esters. Infrared spectra of pure triglycerides of saturated fatty acids showed measurable absorption at 10.36 μm, whereas methyl esters of saturated andcis unsaturated fatty acids did not.