Enrichment of poultry products with omega3 fatty acids by dietary supplementation with the alga Nannochloropsis and mantur oil.

Experiments were conducted to evaluate the efficiency of the microalga Nannochloropsis sp. (Nanno.), as a supplement to laying hens' diet, for the production of enriched eggs and meat with omega3 fatty acids (FA). Nanno. has a unique FA composition, namely, the occurrence of a high concentration of eicosapentaenoic acid (EPA; 20:5 omega3) and the absence of other omega3 FA. The effect of supplementing diets with Nanno. on omega3 FA levels in eggs, plasma, liver, and thigh muscle was compared to that of mantur oil, high in alpha-linolenic acid (LNA; 18:3 omega3). Nanno. is rich also in carotenoids, which may be useful for egg yolk pigmentation. The observed effect of Nanno. supplementation on yolk pigmentation was dose responsive, in both the rate of coloration and the color intensity. Addition of enzyme preparations (glucanase plus cellulase or glucanase plus pectinase) slightly elevated the yolk color score. The most prominent changes in the level of omega3 FA in egg yolk were evident when the diets were supplemented with 1% Nanno. or mantur lipid extracts. Levels of dietary algal meal (0.1-1.0%) had low and inconsistent effects on the level of yolk omega3 FA. Algal EPA is not accumulated in the liver or in the egg yolk; it is apparently converted and deposited as docosahexaenoic acid (DHA). LNA from mantur oil was partially converted to DHA, and both DHA and LNA were deposited in egg yolks and livers. It is suggested that the absence of DHA and EPA from thigh muscle is due to the small amount of dietary omega3 FA used in this work, compared to other studies, and to the possibility that in laying hens the egg yolk has a priority on dietary FA over that of muscles.

Availability and antiperoxidative effects of beta-carotene from Dunaliella bardawil in alcohol-drinking rats.

The present study demonstrated the high bioavailability and antiperoxidative capacity of the natural beta-carotene isomer mixture of Dunaliella bardawil compared with synthetic beta-carotene under alcohol-induced oxidative stress. Weanling rats were adapted to ethanol by increasing ethanol levels in their drinking water to 30% at 5% intervals per week; other rats received water with no added ethanol. One water-drinking group and one alcohol-drinking group with no dietary carotene were used as controls. Two water-drinking groups were supplemented with 1 g/kg diet beta-carotene either from Dunaliella or a synthetic source, and due to reduced food intake, two ethanol-fed groups received 2 g beta-carotene per kilogram of diet from each source. Following 3 months of ethanol consumption, both carotene sources were found to prevent ethanol-induced lipid peroxidation as expressed by the hepatic conjugated oxidized dienes level. However, in the algal-fed rats, hepatic carotene and vitamin A levels were higher. In addition to a lower performance of the group fed ethanol and synthetic beta-carotene, there were three deaths in this group.

All-trans beta-carotene is absorbed preferentially to 9-cis beta-carotene, but the latter accumulates in the tissues of domestic ferrets (Mustela putorius puro).

The algae Dunaliella bardawil and Dunaliella salina naturally contain large concentrations of all-trans and 9-cis beta-carotene (betaC). The purpose of this study was to compare the relative serum and tissue accumulation of all-trans and 9-cis betaC in ferrets fed different ratios of all-trans/9-cis betaC derived from two commercial sources, D. bardawil or D. salina (Betatene). Male ferrets (7 wk old) were fed carotene-free, pelleted diets for 27 d. Beginning on d 18, groups of ferrets (n = 6 or 7) received daily, one of six oral supplements varying in ratios of 9-cis and all-trans betaC mixed with approximately 1.0mL of Ensure. Four supplements containing 5.2-8.3 micromol total betaC were prepared from a 20% Betatene preparation, D. bardawil, a high-cis Betatene preparation, and Betatene further enriched in 9-cis betaC with all-trans betaC/9-cis betaC ratios of 2.2, 1.5, 0.6 and 0.4, respectively. Two control supplements, high and low betaC, were prepared from commercial betaC beadlets. The high control supplement had an all-trans/9-cis ratio of 19.0, whereas 9-cis betaC was not detected in the low supplement. On d 27, serum and tissues were obtained for HPLC analysis of betaC and its isomers. Analysis of livers showed that all-trans betaC was the primary isomer present, but 9-cis and other isomers were also detected in all groups. The hepatic all-trans/9-cis ratios were 5.9, 4.9, 2.5, 1.4, 52.2 and47.5, respectively, for the groups listed above. Lower amounts of all-trans and 9-cis betaC were found in kidneys compared with the liver, but ratios of all-trans/9-cis were not different among groups. Only trace amounts of 9-cis betaC were found in serum. These results demonstrate that the algae D. bardawil and D. salina provide a bioavailable source of betaC isomers, but, as in humans, absorption of 9-cis betaC is poor and any 9-cis betaC absorbed is apparently cleared by the liver.

Nutritional aspects of hydrogenated and regular soybean oil added to diets of broiler chickens.

The objective of the present study was to evaluate the effect of degree of saturation of fat incorporated into broiler diets on performance and body fatty acid (FA) profile. The various degrees of saturation were achieved by using regular soybean oil (SO) and hydrogenated soybean oil (HSO), mixed at different proportions. The work was carried out on commercial broilers (Experiment 1) and on lines of chickens divergently selected for high (HF) or low (LF) abdominal fat (Experiment 2). Daily BW gain and gain:feed ratio increased and the amount of feed intake decreased as the dietary fat saturation decreased. Digestibility of total fat and of each of the FA was lowest in the HSO group and reached maximal values when 23% or more of the added oil was SO. The AMEn values of the diets were almost parallel to fat digestibility. The performance of the HF and LF chickens was affected by the degree of saturation similarly to that observed for the commercial stock. The degree of dietary fat saturation had very little effect on saturated FA (C16:0 and C18:0) in body lipids, reduced the level of monoenoic FA (C16:1 and C18:1), and raised that of polyunsaturated FA (PUFA) (C18:2, C18:3, and C20:4). Monoenoic FA were higher, whereas PUFA were lower in the HF than in the LF line. The improved AMEn in diets containing unsaturated fat is probably due to higher fat digestibility, direct deposition of PUFA in body lipids, and lower lipogenesis, associated with lower heat production.

Enhanced peroxidation of proteins of the erythrocyte membrane and of muscle tissue by dietary oxidized oil.

Male weanling rats were fed on diets containing 10% of either oxidized or fresh (control) soybean oil for periods of 4 and 7 weeks. The ingestion of oxidized oil was found to reduce the content of free thiols in the erythrocyte membrane and to increase the amount of membrane-extractable spectrin. The level of reactive carbonyl groups was higher in the proteins of the ghosts and of the muscle tissue derived from the experimental animals. These alterations which are characteristic of peroxidized proteins, suggest that oxidative stress caused by oxidized dietary lipids may damage tissue proteins.

Effect of added soyabean oil and dietary energy on metabolisable and net energy of broiler diets.

1. The 'extra caloric' effect of added soyabean oil, as reflected in improved body weight gain, food utilisation, metabolisable energy or net energy deposition in the body was determined. 2. Two diets were formulated to contain 12.1 MJ/kg, one with no added fat and the second with 30 g/kg soyabean oil. Addition of oil improved body weight gain by 6.9% (P < 0.05). Two other diets were formulated to contain 13.0 MJ/kg, one with 30 and one with 60 g/kg added soyabean oil bringing the total fat in the high energy, high fat diet to 84 g/kg. Addition of oil in this case improved weight gain by only 3.4% (ns). Addition of soyabean oil increased the apparent digestibility of total dietary fat and reduced that of starch. 3. The effect of soyabean oil supplementation on mash diets at both energy concentrations or to the pelleted diet (formulated to contain 12.1 MJ) on AMEn was consistently positive although not significant. Addition of soyabean oil improved net energy deposition in the body by 17% within the 12.1 MJ/kg diets, (30 g/kg soyabean oil addition) (P < 0.05), but was reduced by 2% (ns) within the 13.0 MJ/kg diets (60 g/kg soyabean oil addition). 4. Supplementing a pelleted diet formulated to contain 12.1 MJ/kg, with 30 g/kg soyabean oil, improved food utilisation (P < 0.05). The 'extra caloric' effect of added soyabean oil, defined as the beneficial effect of the oil above that predicted from its energy value, varied according to the parameter chosen to express this effect and was influenced by the concentration of added soyabean oil and the dietary energy.

In vivo antiperoxidative effect of 9-cis beta-carotene compared with that of the all-trans isomer.

It has been implied that the antiperoxidative activity of beta-carotene is important for its ability to prevent malignant and cardiovascular diseases. In vitro studies have shown that 9-cis beta-carotene is a better antioxidant than the all-trans isomer. In the present study the antiperoxidative biopotency of 9-cis beta-carotene was studied in vivo. For three weeks, weanling female rats were fed diets containing 10% fresh or oxidized soybean oil. The experimental diets were supplemented with beta-carotene at 1 g/kg with the synthetic all-trans isomer or with a carotene extract of Dunaliella bardawil containing 75% 9-cis beta-carotene. Both carotene sources prevented to the same extent hepatic and erythrocyte peroxidation associated with the consumption of oxidized oil. However, this beneficial effect was accompanied, in most of the groups, by a reduction in the hepatic carotene stores. Only in the animals fed Dunaliella extract combined with oxidized oil were the hepatic stores of beta-carotene and vitamin A maintained. The enhanced degradation of 9-cis beta-carotene observed in the livers of these animals might indicate that, like the effect observed under in vitro conditions, this isomer has a greater affinity toward free radicals and therefore might be a more efficient antioxidant than the all-trans form under in vivo conditions. The activity of glutathione peroxidase, glucose-6-phosphate dehydrogenase, and glutathione reductase as affected by the two carotene sources was also studied.

9-Cis beta-carotene as a precursor of retinol isomers in chicks.

The possibility that 9-cis beta-carotene serves as a precursor for retinol in general, and particularly for 9-cis retinol, was studied in chicks, in which the 9-cis beta-carotene is preferentially accumulated. One week old chicks were fed a synthetic diet supplemented with 9-cis and all-trans beta-carotene mixtures, in which the 9-cis isomer content was 9, 19.1, 31.2, 40.8, 57.7 or 77.0%. It was found that an elevation in the dietary 9-cis beta-carotene level led to a decrease in the hepatic retinol stores, despite the increased level of total and 9-cis beta-carotene in the liver. HPLC chromatography revealed the presence of all-trans, 13-cis and 9-cis retinol in the livers. A high 9-cis beta-carotene diet brought about a significant, but very small, elevation in the part of the cis retinol isomers relative to the all-trans isomer. It was concluded that 9-cis beta-carotene has a low activity as a precursor of retinol in general. This decreased activity is not due to a low availability of the isomer to the enzymatic cleavage. It seems also that 9-cis beta-carotene is not an efficient precursor of 9-cis retinol.

Dietary fish oil modulates the alkaline phosphatase activity and not the fluidity of rat intestinal microvillus membrane.

The effect of dietary fish (mackerel) oil on the function and fluidity of the intestinal microvillus membrane in 1-y-old rats was compared with that of coconut and soybean oils. The animals were fed diets containing 10% protein (derived from casein) and 15% oil. Intestinal microvillus membranes and RBC ghosts were isolated after a 6-wk feeding period and examined for fluidity by fluorescence polarization with 1,6-diphenyl-1,3,5-hexatriene. The functionality of the microvillus membrane was assessed by the activity of the intrinsic enzyme alkaline phosphatase. No differences in the fluidity were observed between the microvillus membranes or between the RBC ghosts derived from the various dietary groups. The alkaline phosphatase activity of the microvillus membrane was found to be the lowest in the membranes isolated from the fish oil-fed rats. In these membranes the contents of 20:5(n-3) and 22:6(n-3) fatty acids were higher than in the membranes derived from the coconut and soybean oil-fed animals. The cholesterol to phospholipid molar ratio was lower in the coconut oil-fed group than in the other two groups. It is suggested that the compensatory effect of the elevated cholesterol to phospholipid molar ratio on the membrane fluidity was such that no differences in the overall fluidity were detected. It is likely that the incorporation of these long chain fatty acids might have caused compositional changes in the lipid microenvironment of the enzyme. Such changes could alter the fluidity of these microdomains, thereby affecting the activity of the integral enzyme alkaline phosphatase.

Excessive dietary tryptophan enhances plasma lipid peroxidation in rats.

High plasma cholesterol levels and plasma lipid peroxidation are associated with atherosclerosis. The effect of excessive dietary tryptophan on plasma lipid peroxidation was studied in rats fed a diet containing soybean oil (control), as well as an atherogenic diet, containing coconut oil and cholesterol. Feeding the atherogenic diet resulted in a 5-fold increment in plasma cholesterol concentration with no significant effect of the tryptophan supplementation. The plasma obtained from the hypercholesterolemic rats exhibited a 67% increased lipid oxidation (measured as thiobarbituric acid reactive substances) in comparison to normocholesterolemic plasma. Dietary tryptophan supplementation increased plasma lipid peroxidation by 9 and 21% in the control and in the hypercholesterolemic animals, respectively. Similarly, the excessive dietary tryptophan enhanced macrophage cholesterol esterification rate by 40 and 38% following cell incubation with the plasma obtained from the control and from the hypercholesterolemic animals, respectively. Since tryptophan is the precursor of serotonin we have measured urine concentration of 5-hydroxyindoleacetic acid (5HIAA), the metabolite of serotonin, and found 22 and 118% elevation in 5HIAA in the tryptophan fed control and hypercholesterolemic rats, respectively. The direct effect of tryptophan and serotonin on in vitro lipid peroxidation was also studied. Low density lipoprotein (LDL) was peroxidized by incubation with copper ions in the presence of tryptophan or serotonin. Serotonin was shown to enhance LDL peroxidation whereas tryptophan had no effect on LDL peroxidation. We conclude that excessive dietary tryptophan may be atherogenic since it enhanced plasma lipid peroxidation in hypercholesterolemic rats and increased macrophage uptake of plasma cholesterol. These effects are probably associated with increased plasma concentration of serotonin following the consumption of a tryptophan supplemented diet.

Avocado oils and hepatic lipid metabolism in growing rats.

The effect of various avocado oils on liver metabolism was studied in growing female rats. The rats were fed diets containing 10% (w/w) avocado oil for 4 wk. In comparison with rats fed refined avocado oil obtained from cored fruit by centrifugal separation, rats fed unrefined avocado oil obtained by organic solvent extraction from intact fruit, or its unsaponifiable components, showed a significant increase in total liver lipogenesis as well as in phospholipid and triglceride synthesis. Rats fed avocado-seed oil exhibited enhanced [1-14C]acetate incorporation into total liver lipids but showed the same distribution of label in the three main lipid classes as that of rats fed refined avocado oil. In addition, a significant reduction of triglycerides and protein content of plasma very-low-density lipoprotein and high-density lipoprotein fractions was observed in rats fed avocado-seed oil as compared with rats fed refined oil. Electron micrographs suggested that the alterations in hepatic lipogenesis are related to the marked proliferation of the smooth endoplasmic reticulum, which is known to be associated with induction of enzymes involved with lipid biosynthesis. The differences between the animals fed seed oil and those fed the unrefined oils, in the distribution of label within the main lipid classes, indicate that more than one factor is involved in the alterations caused by these oils.

Dietary lipid level and the availability of beta-carotene of Dunaliella-bardawil in rats.

High plasma and tissue levels of beta-carotene have been implicated to be inversely related to the incidence of some types of cancer. Previous studies indicated that the availability of the natural beta-carotene isomer mixture of Dunaliella bardawil was severalfold higher than that of synthetic all-trans beta-carotene. This study illustrated that this higher availability, as expressed by hepatic and plasma beta-carotene, can be further enhanced by increased dietary lipid level. For 12 days, weanling male and female rats were fed diets containing either 0.1% all-trans beta-carotene or spray-dried Dunaliella bardawil having an equal level of the beta-carotene isomer mixture. The diets contained 5 or 15% soybean oil. The rise in dietary fat resulted in a marked increase in plasma and liver beta-carotene, with the Dunaliella isomer mixture being more effective. Higher levels were found in female than in male animals. These findings may be relevant when a high dose of beta-carotene is considered as a potential anticancer agent.

Effect of dietary avocado oils on hepatic collagen metabolism.

The effect of various avocado and soybean oils on collagen metabolism in the liver was studied in growing female rats for 8 weeks and in day-old chicks for 1 week. In comparison with rats fed either refined avocado oil, refined or unrefined soybean oils, rats fed unrefined avocado oil showed a significant decrease in total collagen solubility in the liver, while there were no changes in total collagen, protein and moisture content. Chicks fed unrefined avocado oil as compared to those fed refined avocado oil also showed a decrease in hepatic total soluble collagen while hepatic total collagen remained unaffected. Electron micrographs and light-microscope examinations of rats' liver revealed collagen accumulation in the periportal location. This is suggestive of the early stages of fibrosis.

The effect of various avocado oils on skin collagen metabolism.

The effects of various avocado oils on collagen metabolism in skin were studied in growing rats fed diets containing 10% (w/w) of the tested oils. Rats fed the unrefined avocado oil extracted with hexane from the intact fruit, its unsaponifiables or the avocado seed oil, showed significant increases in soluble collagen content in skin, though total collagen content was not affected. The increased soluble collagen content appears to be a consequence of the inhibition of lysyl oxidase activity. The active factor was found to be present in the unrefined avocado oil and probably originated from the avocado seed, since collagen metabolism was affected only by fractions which contained lipids fraction from the seed. In comparison rats fed the refined or unrefined soybean oils showed no effects.

Riboflavin deficiency and the function and fluidity of rat erythrocyte membranes.

The effect of riboflavin deficiency on the fluidity and function of the red blood cell (RBC) membrane and on the activity of some enzymes involved in antioxidant defense mechanisms was studied. Growing male rats were fed an experimental (riboflavin-deficient) or a control (riboflavin-supplemented) diet. Following 7 wk of feeding, RBC from riboflavin-deficient rats contained higher levels of peroxidation products, most likely due to decreased glutathione reductase activity. An elevation in glutathione peroxidase activity was also observed whereas the activity of catalase and superoxide dismutase was not affected. Membrane fluidity was studied by fluorescence polarization, using 1,6-diphenyl-1,3,5 hexatriene (DPH) as a probe. The fluidity of RBC membranes isolated from riboflavin-deficient rats was significantly lower than that of the controls. This decreased fluidity was accompanied by an increase in the activity of the membrane-bound enzyme acetylcholinesterase. This study demonstrated that a decrease in cells' ability to cope with peroxidative damage as a result of riboflavin deficiency may lead to changes in the fluidity and function of membranes.

Bioavailability of a natural isomer mixture as compared with synthetic all-trans-beta-carotene in rats and chicks.

The unicellular halotolerant alga Dunaliella bardawil was previously shown to contain high concentrations of beta-carotene composed of about equal amounts of the all-trans and 9-cis isomers. One-d-old chicks and 7-wk-old male rats were fed diets supplemented with synthetic all-trans-beta-carotene or dry D. bardawil at equivalent levels of beta-carotene. The chicks were fed diets containing up to 0.025% beta-carotene for 2 mo, and the rats up to 0.1% beta-carotene for 2 wk. Liver analyses at the end of these periods indicated that both species showed at least a tenfold higher accumulation of the algal beta-carotene isomer mixture than of the synthetic all-trans-beta-carotene. The ratio of 9-cis-beta-carotene to the all-trans isomer in the livers of the algae-fed rats and chicks was similar to or higher, respectively, than that present in the algae. Retinol plus retinyl ester accumulated to a similar extent in the rats and chicks fed diets supplemented with synthetic all-trans or the natural isomer mixture of beta-carotene. The preferable accumulation of the natural isomer mixture of beta-carotene suggests that attention should be paid to the different sources of beta-carotene when testing their efficacy in effects other than providing retinol, such as in their possible role in the prevention of some types of cancer.

The effect of avocado oils on some liver characteristics in growing rats.

The effects of various avocado oils on some liver characteristics were studied in growing rats. The rats were fed diets containing 10% (w/w) avocado oil for 4 wk. In comparison with rats fed refined oil obtained from cored fruit by centrifugal separation, rats fed unrefined avocado oil obtained by solvent extraction from the intact fruit, or refined avocado oil containing avocado-seed oil, showed significant growth inhibition, an increase in the amount of hepatic lipids (identified as steatosis by histopathological examination), and a decrease in levels of triglycerides in blood. Rats fed the refined oil containing unsaponifiable material prepared from unrefined oil from the intact fruit showed similar responses. Fatty livers were not induced by feeding rats unrefined avocado oil obtained from intact fruit by centrifugal separation, although a significant decrease in blood triglycerides was observed. There were no significant differences between groups in serum total protein, albumin or bilirubin content or in alanine aminotransferase activity. However, serum alkaline phosphatase activity was increased in rats fed the seed oil, the unrefined solvent-extracted oil from intact fruit, or the unsaponifiables, and aspartate aminotransferase activity was significantly increased in the group fed avocado-seed oil. These data suggest that consumption of avocado oil extracted from intact fruit may cause changes in liver metabolism.

The safety evaluation of Dunaliella bardawil as a potential food supplement.

The safety of the alga Dunaliella bardawil for food use, was evaluated in a multigeneration study with rats. Four generations were raised on diets containing 0, 5 or 10% dehydrated D. bardawil. Each experimental group comprised ten males and 20 females. No significant differences were observed between the rats consuming algae and the controls, of any generation, in general appearance, behaviour, growth, reproductive performance or gross pathology. The blood chemistry and haematology of the first generation animals, after 1 yr on the diets, showed no appreciable differences between the experimental and control animals. The only differences in histopathology observed were a decrease in some chronic inflammations and an increased frequency of focal bronchopneumonia in rats fed 10% algae compared with the controls. The latter effect may be attributed to the powdery nature of the algal diet. Considering the large amount of algae consumed by the experimental rats, and the absence of adverse effects in these animals, this multigeneration feeding study may be indicative of the safety of D. bardawil for human consumption.

The beta-carotene-rich alga Dunaliella bardawil as a source of retinol in a rat diet.

1. Dunaliella bardawil, a beta-carotene-accumulating alga, has been tested as a source of retinol and beta-carotene in a diet given to rats. The beta-carotene in this alga is composed of about equal amounts of the 9-cis and all-trans isomers. Male weanling rats were fed on a retinol-deficient diet for 60 d. Thereafter, the rats were divided into groups and fed on a diet deficient in retinol or supplemented with retinol, synthetic beta-carotene, dry alga or an algal oil-extract. Following further growth for 7 d, samples were taken for liver analyses of retinol, retinol isomers and beta-carotene. 2. Liver analyses revealed a comparable content of retinol and normal conversion rates in the rats grown on the diets supplemented with synthetic or natural beta-carotene. Rats fed on the alga and the algal-oil-supplemented diets accumulated 9-cis retinol in addition to the all-trans isomer. Rats fed on synthetic beta-carotene, alga and algal oil had a liver retinol: beta-carotene value of about 3:1. 3. These studies demonstrate the possibility of using dried D. bardawil or an oil extract of the alga as a dietary natural beta-carotene supplement which satisfies the total requirement of retinol in rats. 4. Rats fed on alga or on algal oil, accumulated in the liver 9-cis beta-carotene and all-trans beta-carotene in a ratio similar to that present in the alga.

The effect of amino-acid-supplemented wheat gluten on cholesterol metabolism in the rat.

The effect of lysine- and threonine-supplemented wheat gluten on cholesterol metabolism was studied using male weanling rats. Animals were fed on cholesterol-free diets containing 100 or 200 g gluten/kg with or without amino acid supplementation, and compared with animals given 50, 100 and 200 g casein/kg diets, for 3 weeks. A hypocholesterolaemic effect observed with the wheat gluten-fed rats, compared with the animals given 100 and 200 g casein/kg diets, was accompanied by increased turnover of cholesterol as expressed by enhanced cholesterol biosynthesis and increased faecal excretion of cholesterol and bile acids. This effect was not abolished by lysine and threonine supplementation. Low levels of blood cholesterol were also observed in the rats fed on the 50 g casein/kg diet. However, a different mechanism, related to impairment of cholesterol transport from the liver, was most likely responsible for the hypocholesterolaemia found in these protein-malnourished animals. The effect on cholesterol metabolism produced by dietary wheat gluten was independent of the low quality of the protein and of its specific deficiency in lysine and threonine.