Dietary marine algae maintains egg consumer acceptability while enhancing yolk color.

A drum-dried docosahexaenoic acid (DHA; C22:6n-3) enriched marine microalgal product (MA) was investigated as a n-3 fatty acid (n-3 FA) source in laying hen diets. Hen diets were supplemented with 2.4 or 4.8% MA. Eggs were analyzed for yolk color following 4 wk of feeding as well as weekly for 4 wk. Egg flavor was evaluated by consumer panelists. Feeding MA significantly (P < 0.01) increased yolk a* values in a dose response manner as early as 1 wk post-MA feeding. Consumer panelists found n-3 FA enriched eggs as acceptable as typical eggs. These data suggest that dietary MA is useful for enhancing yolk n-3 FA and color while maintaining consumer acceptability of the resulting egg product.

Comparison of n-3 fatty acid sources in laying hen rations for improvement of whole egg nutritional quality: a review.

The nutritional manipulation of the diets of laying hens to include sources of n-3 fatty acids promotes the deposition of these nutrients into egg yolk, n-3 Fatty acid-rich eggs may provide an exciting alternative food source for enhancing consumer intake of these proposed healthful fatty acids. Care must be taken when designing n-3 fatty acid-rich poultry rations, however, to assure that the resulting egg fatty acid profile is useful for promoting consumer health yet maintaining egg sensory quality. In study 1 laying hens were fed on diets supplemented with graded levels of menhaden oil (MO), rich in both eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3), for 4 weeks to determine maximal yolk fatty acid deposition attainable without sensory compromise. Yolk fatty acids were analysed for an additional 4 weeks, post-MO removal, to investigate yolk n-3 fatty acid tenacity. Dietary MO levels between 15 and 30 g/kg yielded the greatest yolk n-3 fatty acid content; however, only eggs from birds fed with 15 g MO/kg were considered acceptable by trained flavour panelists. Evaluation of eggs from hens fed with 15 g MO/ kg during storage verified that the shelf-life of enriched eggs was comparable with that of typical eggs. In study 2, graded levels of whole or ground flaxseed were used for the deposition of linolenic acid (LNA; 18:3n-3) and to determine in vivo production of DHA from dietary LNA for yolk deposition. Flaxseed form influenced yolk n-3 fatty acids only when given at 150 g/kg diet. In vivo production of DHA, while significant, was not enhanced by increasing the level of dietary flaxseed nor by grinding the seed. In the third study, a DHA-rich natural marine alga (MA) was investigated as an n-3 fatty acid supplement. Despite similar DHA profiles, dietary MA was found to be more efficient for yolk DHA deposition than dietary MO. These studies suggest that there are numerous viable n-3 fatty acid supplements for poultry rations. It must be realized, however, that the fatty acid profile of the final product varies substantially depending on which supplement is fed.

Dietary marine algae promotes efficient deposition of n-3 fatty acids for the production of enriched shell eggs.

Two experiments were conducted to investigate the usefulness of a natural golden marine algae (MA) as a poultry ration supplement for the production of shell eggs rich in n-3 fatty acids (n-3 FA). This MA is unique due to a high concentration of docosahexaenoic acid (DHA; C22:6n-3) and the absence of other n-3 FA normally present in marine oils such as menhaden oil (MO). In the first experiment, 60 24-wk-old Single Comb White Leghorn (SCWL) hens were divided among four dietary treatments, including a typical corn-soybean control (CON); 1.5% MO, supplying 233 mg eicosapentaenoic acid (EPA) and 155 mg DHA per d; 2.4% MA, supplying 200 mg DHA/d; and 4.8% MA, supplying 400 mg DHA/d. A second experiment using 96 56-wk-old SCWL was conducted using the same diets. In both experiments, eggs were collected weekly for 4 wk for determination of egg production parameters and yolk FA content. Each week, yolk samples were extracted, methyl estered, and quantified using gas chromatography. Transient depression in egg and yolk weights were noted early in Experiment 1 in response to dietary 4.8% MA. Although egg and yolk weights were not affected in Experiment 2, egg production was significantly reduced in the 4.8% MA treatment. Egg production was unaffected due to diet or week in Experiment 1. In both experiments, yolk polyunsaturated profiles were significantly influenced by diet. Dietary n-3 FA supplementation significantly increased yolk total N-3 FA with concomitant reductions in yolk n-6 FA. Although hens fed MO were supplied predominantly EPA, the principal yolk FA deposited was DHA. Marine algae also promoted efficient yolk DHA deposition with the highest yolk DHA concentrations attained in eggs from hens fed 4.8% MA. These data indicate that utilization of MA as a direct source of dietary n-3 FA may provide an efficient alternative to current sources of n-3 FA available for the production of poultry products rich in n-3 FA.

Yolk thiobarbituric acid reactive substances and n-3 fatty acids in response to whole and ground flaxseed.

n-3 fatty acid (FA)-enriched shell eggs have been proposed as an economical source for increasing consumption of n-3 FA. As dietary n-3 FA sources vary with respect to fatty acid profile and lipid stability, the comparison of resulting egg products is warranted. This study was designed to determine yolk thiobarbituric acid reactive substances (TBARS) and n-3 FA when hens were fed whole or ground flaxseed. Gold flaxseed (whole or ground) fed at levels of 5 or 15% were compared to a 1.5% menhaden oil or a typical control layer ration. A 5-wk feeding trial was used with 21 hens per treatment. Eggs were collected and FA composition determined during Weeks 4 and 5 of the feeding trial. The TBARS content of yolk was also determined. All flaxseed treatments increased total n-3 FA (C18:3 + C20:5 + C22:6) marine n-3 FA (C20:5 + C22:6) did not increase proportionately with increasing dietary flaxseed. Seed form did not influence n-3 FA deposition at the 5% level of flaxseed; however, ground 15% flaxseed resulted in greater total n-3 FA deposition than whole 15% flaxseed. Yolk TBARS were not different due to diet, indicating that seed form did not influence the oxidative quality of these n-3 FA-rich lipids.

n-3 fatty acid enriched table eggs: a survey of consumer acceptability.

Table eggs enriched with n-3 fatty acids may provide an alternative to fish as a source of these proposed healthful fatty acids. Successful marketing of this product may be influenced, however, by consumer perceptions of the egg as an unhealthful food. Therefore, the objectives of the current study were to assess consumer perceptions of table egg health quality and to determine the potential consumer acceptability of an n-3 fatty acid-enriched table egg. A survey was conducted in five major Texas cities; over 500 consumers completed the survey. Data were analyzed using the chi-square procedure. The majority of consumers surveyed considered eggs healthful and reported purchasing eggs at least once monthly and consuming an average of three whole eggs per week, as compared with an average reported fish consumption of only one serving per week. Sixty-five percent of the consumers reported willingness to purchase an n-3 fatty acid-enriched table egg and of these, 71% were willing to pay an additional $.50 per dozen. These data indicate that n-3 fatty acid-enriched table eggs represent a viable means of incorporating n-3 fatty acids into the diet of health-conscious consumers.

Dietary menhaden oil contributes to hepatic lipidosis in laying hens.

Clinical and epidemiological investigations have indicated that there may be substantial human cardiovascular benefits associated with increased consumption of n-3 fatty acids commonly found in fish oils. Recent studies have indicated that egg yolk n-3 fatty acid content is significantly increased when hens are fed diets enriched with selected fish oils such as menhaden oil (MO). In the present study, reproductively active females but not males exhibited increased hepatic lipidosis following 6 mo of feeding 3% MO. Hens fed 3% animal-vegetable oil (AV) did not exhibit hepatic lipid accumulation. Serum triglyceride and cholesterol concentrations were reduced (P < or = .05) in hens fed MO. Subsequently, yolk and total egg weights of hens fed MO were decreased as compared with those of hens fed AV. A significant interaction of dietary MO and exogenous 17 beta-estradiol was noted among chick liver and gallbladder weights. These data suggest that dietary MO and estradiol may interact in a manner that enhances the lipogenic activity of the liver, thereby inducing hepatic lipidosis in laying hens.

Evaluation of two extraction methods for the determination of egg yolk cholesterol.

Controversy concerning egg cholesterol values exists in recent literature due to varying procedures used for cholesterol determination. The purpose of the present study was to investigate the efficacy of direct sample saponification (Method A) versus saponification of a lipid extract (Method B) for analysis of yolk cholesterol. Method A resulted in a value of 19.1 +/- .4 (SE) mg cholesterol/g of yolk for the National Institute of Standards and Technology (NIST) reference (cholesterol in whole egg powder) as compared with the NIST certified value of 19.0 +/- .2 mg/g. Method B resulted in a significantly lower value of 14.6 +/- .5 mg/g. Egg yolk cholesterol values were determined to be 196 +/- 4.2 mg per egg by Method A and 132 +/- 11 mg per egg by Method B. Various amounts (1, .5, .25 g) of yolk cholesterol assayed by either method proportionately decreased cholesterol values as yolk amount decreased; however, Method B consistently resulted in lower yolk cholesterol. These data suggest that both Methods A and B are valid for determining relative differences between treatments; however, the NIST standard data indicate that for quantification of absolute cholesterol values, direct saponification is more accurate. The NIST standard of cholesterol in whole egg powder should be used as a control for comparing cholesterol data regardless of extraction method used.

Dietary modification of yolk lipid with menhaden oil.

Due to the numerous proposed cardiovascular benefits associated with consumption of omega-3 fatty acids, marketing of an egg enriched by omega-3 fatty acid may benefit the egg producer. Effects on yolk composition of a standard laying hen diet enriched with 3% menhaden oil (test diet), versus an isocaloric (control) diet containing no added fat, were evaluated for 18 wk. Dietary menhaden oil did not alter egg production, egg weight, total yolk fat, or yolk cholesterol. However, yolk contents of omega-6 and omega-3 fatty acids were influenced by diet. Arachidonic acid decreased and eicosapentaenoic acid increased in eggs from hens fed the test diet following 1 wk of dietary treatment. Docosahexaenoic acid and linolenate increased in eggs from hens fed the test diet at 2 and 3 wk of the trial, respectively. These alterations in yolk composition resulted in a decrease in the ratio of omega-6 to omega-3 fatty acids from 18 for eggs from hens fed the control diet to 3 for eggs from hens fed the test diet. At Weeks 14 and 18, hens (n = 10 per diet) were killed and necropsied. No change in gross scoring of hepatic lipidosis was observed. Histologically, significantly greater scores for hepatocellular lipid infiltration were recorded for liver sections from hens fed menhaden oil than for control hens. Increased microscopic hepatic lipid infiltration observed with dietary omega-3 administration may have significance for flocks predisposed to fatty liver syndrome and may also provide a unique system in which to study the effects of dietary omega-3 fatty acids on liver lipid metabolism.