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J APPL POULT RES 2009. 18:541-551. doi:10.3382/japr.2009-00008
© 2009 Poultry Science Association
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Research Reports

Effect of feeding flax and two types of antioxidants on egg production, egg quality, and lipid composition of eggs

Z. Hayat*,{dagger}, G. Cherian{ddagger}, T. N. Pasha*, F. M. Khattak* and M. A. Jabbar*

* University of Veterinary and Animal Sciences, Lahore-54000, Pakistan; {dagger} University College of Agriculture, University of Sargodha, Pakistan-40100; and {ddagger} Department of Animal Sciences, Oregon State University, Corvallis 97331

1 Corresponding author: Gita.Cherian{at}oregonstate.edu


   SUMMARY
TOP
 SUMMARY
DESCRIPTION OF PROBLEM
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSIONS AND APPLICATIONS
 REFERENCES AND NOTES
 
The present study was conducted to investigate the effect of feeding flaxseed and 2 types of antioxidants [{alpha}-tocopherols (Toc), butylated hydroxy toluene (BHT)] at 3 levels (50, 100, and 150 IU or mg/kg) on production performance, egg quality, fatty acid profile, Toc, and egg cholesterol content. Twenty-four 1-wk-old ISA Brown Leghorn laying hens (n = 96) were kept in cages and were fed a corn- and soybean meal-based diet for 56 d: control (no flax, no antioxidant), 10% flax with no antioxidant, or 10% flax + antioxidants. The flax-based diets had no effect on egg production, egg weight, egg mass, or feed conversion (P > 0.05) when compared with the control diet. Feed intake was reduced in hens fed the flax diets (P < 0.05, except flax + 150 mg of BHT) as compared with those fed the control diet. Egg weight, yolk weight, shell weight, albumen weight and height, Haugh units, yolk color, and shell thickness were unaffected by feeding flaxseed (P > 0.05). Lower levels of saturated fat were observed in eggs of hens fed the flax + Toc and flax + 50 mg of BHT diets when compared with hens fed the other diets (P < 0.05). Eggs from hens fed flax had increased {alpha}-linolenic (18:3n-3), eicosapentaenoic (20:5n-3), and docosahexaenoic (22:6n-3) acid levels and a decreased arachidonic acid (20:4n-6) level and total n-6:n-3 ratio when compared with control eggs (P < 0.05). Total n-6 fatty acids were lowest in eggs from hens fed flax + 50 IU of Toc, flax + 50 mg of BHT, flax + 100 mg of BHT, and flax + 150 mg of BHT. Total n-3 fatty acids were highest in eggs from hens fed flax + 50 mg of BHT. Flaxseed and antioxidant supplementation had no effect on egg cholesterol content (P > 0.05). Inclusion of Toc led to more than 4.5- to 12-fold increases in Toc in eggs from hens fed flax-based diets. These data demonstrate that eggs with increased n-3 fatty acids and Toc can be produced by minor diet modifications without affecting egg quality parameters.

Key Words: egg • flax • tocopherol • butylated hydroxy toluene • n-3 fatty acid


   DESCRIPTION OF PROBLEM
TOP
 SUMMARY
 DESCRIPTION OF PROBLEM
MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSIONS AND APPLICATIONS
 REFERENCES AND NOTES
 
Omega-3 fatty acids (FA), including {alpha}-linolenic (18:3n-3), eicosapentaenoic (EPA, 20:5n-3), docosapentaenoic (DPA, 22:5n-3), and docosahexaenoic acid (DHA, 22:6n-3) have received considerable attention in the past 2 decades for their health-promoting effects and their role in growth and development [1–3]. Dietary n-3 FA are contributed by marine products (EPA, DPA, and DHA) and plant sources such as flax, canola, and green vegetables ({alpha}-linolenic). However, dietary sources do not meet the requirements of these nutrients in the human diet; hence, feeding strategies have been adopted by the animal food industry to enhance the n-3 FA content of animal-derived foods [4–7]. Diet manipulation by incorporating marine oils or oil-seeds into the hen diet is the usual way of increasing the n-3 FA content of chicken eggs [8, 9]. In this regard, flaxseed, because of the high protein (>22%), fat (>40%), and {alpha}-linolenic acid content (>50%) and availability, is the most common and attractive feed ingredient used in the table egg industry to produce n-3 FA-modified chicken eggs.

Several authors have reported both short- and long-term feeding trials using flax in laying hen diets [10, 11], with inclusion from 5 to 30% [8]. The drawbacks of including higher levels (>8%) of flax have been associated with its various components affecting palatability, feed intake, egg production, egg quality, and organoleptic aspects [12]. Similarly, the efficacy of flax in increasing long-chain (>C20) n-3 FA content was limited after 10% inclusion. Cherian and Sim [13], who fed 8% compared with 16% flax in a hen diet, reported no increase in the content of long-chain n-3 FA in eggs. Dietary {alpha}-linolenic acid is metabolized to long-chain n-3 FA by {Delta}6-, {Delta}5-, and {Delta}4-desaturases and elongases [14]. There is competition between n-3 and n-6 FA for the enzymes, with a preference for n-3 over n-6 FA [15]. Several factors are known to influence the activities of desaturases and elongases involved in the metabolism of n-3 and n-6 FA. For example, saturated and trans fats inhibit the {Delta}6, {Delta}5 pathways, limiting long-chain FA concentrations [1]. Inclusion of vitamin E has been reported to modulate {Delta}6 activity and increase long-chain n-3 FA concentration in liver tissue in rodent models [16]. Cherian et al. [17], who fed fish oil along with tocopherols, reported a significant increase in the content of EPA and DHA in chicken eggs, indicating vitamin E had a role in modulating the desaturase and elongase enzyme pathway in laying hens.

Antioxidants such as vitamin E (natural) and butylated hydroxy toluene (BHT; synthetic) are added to poultry diets to prevent oxidative destruction of dietary fats and to provide enhanced protection for the longer chain polyunsaturated FA, and hence protect against oxidative rancidity. Synthetic antioxidants have been widely used as food or feed preservatives because of their low cost and effectiveness. Lipid oxidation, which leads to an off-flavor or "fishy" flavor and a reduction in acceptance by panelists, is a major concern with eggs from hens fed flax [5, 9, 18]. For this reason, adding vitamin E (10 vs. 100 IU) to the diet of the hen is common practice for n-3 FA-enriched egg production [5, 6, 8]. Although several studies have looked into feeding flax to laying hens, we are unaware of studies evaluating the different types of antioxidants (natural vs. synthetic) and their levels on FA incorporation, hen production, egg quality, and egg lipid components. Feeding 2 levels of vitamin E (27 vs. 50 IU), Scheideler and Froning [19] reported an improvement in egg production during an 8-wk feeding period. However, Gonzalez-Esquerra and Leeson [9] reported no effect of including 10 compared with 100 IU/kg of vitamin E in layer diets on egg production or egg weight. The objective of this study was to evaluate the effects of feeding flaxseed with 2 types of antioxidants [natural, {alpha}-tocopherols (Toc); synthetic, butylated hydroxy toluene (BHT)] at 3 levels (50, 100, and 150 IU or mg/kg) on 8-wk production performance, egg quality characteristics, and egg yolk cholesterol, egg vitamin E content, and FA profile.


   MATERIALS AND METHODS
TOP
 SUMMARY
 DESCRIPTION OF PROBLEM
 MATERIALS AND METHODS
RESULTS AND DISCUSSION
 CONCLUSIONS AND APPLICATIONS
 REFERENCES AND NOTES
 
These experiments were reviewed by the Oregon State University Animal Care Committee to ensure adherence to Animal Care Guidelines.

Birds, Diets, and Housing
A total of 120 ISA Brown layer pullets [20] were reared in floor pens to 18 wk of age. At 18 wk, 96 hens were moved to laying cages in a room maintained at 20°C, and a step-up lighting schedule was used. Hens received 15L:9D from 18 until 21 wk of age, and 16L:8D beginning at 21 wk of age, which was maintained until the end of the trial. Diets were provided as follows: commercial chick starter from 0 to 6 wk; grower diet from 16 to 23 wk; and the experimental layer diet from 24 to 32 wk. Hens were distributed randomly to the experimental diets. Two hens housed in 1 experimental cage (38 x 41 cm) were considered as 1 replicate. Six replications were made for each diet. The 8 experimental diets, formulated according to standard specifications for ISA Brown layers, were as follows: a corn- and soybean-based diet with no added antioxidants (control); flax = basal diet with 10% flax and no added antioxidants; flax + 50 IU of Toc diet = basal diet with 10% flax plus 50 IU of tocopherols; flax + 100 IU of Toc diet = basal diet with 10% flax plus 100 IU of tocopherols; flax + 150 IU of Toc diet = basal diet with 10% flax plus 150 IU of tocopherols; flax + 50 mg of BHT diet = basal diet with 10% flax plus 50 mg/kg BHT; flax + 100 mg of BHT diet = basal diet with 10% flax plus 100 mg/kg BHT; flax + 150 mg of BHT diet = basal diet with 10% flax plus 150 mg/kg of BHT. The diets were mixed every 2 wk and were stored in a cold room (4°C) in airtight containers. Each diet was randomly fed to hens in 6 replicate pens. Water and feed were provided ad libitum. The experimental diets were fed for a period of 56 d.

Production Parameters and Egg Quality Characteristics
Production performance (egg production, egg mass, feed intake, and feed conversion) was measured from 24 to 32 wk of hen age. Daily egg production per replicate was recorded, and at the end of each experimental week, the total number of eggs laid per bird per week was calculated. Eggs laid per replicate were weighed daily and at the end of each experimental week, the average weight for that particular week was calculated. The data generated (number of eggs and egg weight) were used to calculate egg mass per bird per week (weekly egg number in replicate x average egg weight). Feed intake was measured on a weekly basis (total feed offered in a week minus feed refused at the end of the week). Data on feed intake and egg mass were used to calculate feed conversion (feed intake/egg mass; g/g).

For egg quality characteristics, 2 eggs from each replicate collected at the end of every 2 wk were used to determine egg characteristics, lipid composition, and quality (n = 12, 2 per replicate). The eggs were weighed, and yolks were separated using an egg separator and weighed. Albumen weight was calculated by subtracting the yolk and shell weight from the total egg weight. Albumen height was documented at 2 different sites by using a spherometer, and Haugh units (HU) were calculated by the formula HU = 100 log(H + 7.57 – 1.7 W0.37) [21], where H is the average albumen height (mm) and W is the weight of the egg (g). Yolk color was determined by comparing yolk color with the Roche color fan. Shell thickness was measured using an electronic micrometer.

Total Lipid and FA Analysis
An aliquot of yolk sample was taken for total lipid, FA composition, cholesterol, and Toc content. Total lipids were extracted from the egg yolk sample by the method of Folch et al. [22]. One gram of sample was weighed into a screw-capped test tube with 18 mL of chloroform:methanol (2:1, vol/vol) and homogenized for 10 to 15 s at high speed. After an overnight incubation at 4°C, the homogenate was filtered through Whatman #1 filter paper into a 100-mL graduated cylinder and 4 mL of 0.88% sodium chloride solution was added and mixed. After phase separation, volume of the lipid layer was recorded, and the top layer was completely siphoned off. Total lipids were determined gravimetrically.

FA Methyl Ester Preparation and Analyses
Fatty acid methyl esters were prepared from the total lipid extract using methanolic HCl as the derivatizing agent. Approximately 2 mL of lipid extract was taken and evaporated to dryness under nitrogen at 40°C and 1 mL of anhydrous 3 N methanolic HCl was added to the dried lipid extract. Aliquots were incubated in a water bath at 60°C for 40 min, cooled to room temperature, and then extracted with hexane. Analyses of FA methyl esters were performed with an Agilent 6890 gas chromatograph [23] equipped with an autosampler, flame-ionization detector, and fused-silica capillary column, 100 m x 0.25 mm x 0.2 µm film thickness [24]. Samples (1 µL) were injected with helium as a carrier gas onto the column, which was programmed for increased oven temperatures (initial temperature was 110°C, held for 1 min, then increased at 150°C/min to 190°C and held for 55 min, then increased at 5°C/min to 230°C and held for 5 min). Inlet and detector temperatures were both 220°C. Peak areas and FA percentages were calculated using Agilent ChemStation software [23]. Fatty acid methyl esters were identified by comparison with retention times of authentic standards [25]. Fatty acid values and total lipids are expressed as percentages of total FA.

Toc Assay
Egg yolk Toc was analyzed by HPLC according to the method of Podda et al. [26]. Approximately 1 g of egg yolk was weighed and an equal amount of distilled water was added. The contents were mixed, and 1.0 mL was transferred to a screw-capped tube and mixed with 0.1 mL of the internal standard (rac-5,7-dimethyltocol), 2 mL of 1% ascorbic acid in ethanol, and 0.3 mL of saturated KOH. The samples were incubated in a 70°C water bath for 30 min and then cooled on ice. After addition of 0.1 mL of 0.25 mg of BHT/1 mL in ethanol (1% ascorbic acid in H2O) and 2.5 mL of hexane, the samples were centrifuged for 5 min at 1,500 x g. The upper hexane layer was transferred to a clean tube and evaporated under a stream of nitrogen, and the residue was dissolved in 0.2 mL of ethanol. The samples were transferred to 0.5-mL tubes and centrifuged at 8,000 x g for 5 min, after which 0.15 mL of the supernatant was taken for assay. A Shimadzu LC-2010 HT HPLC system was used with an LC2010 AHT High Speed Autosampler [27]. A Supelguard LC-18 guard column [28] was used, with 97.5% methanol as a mobile phase at a 1.0 mL/min flow rate. Detection was performed with a Shimadzu RF-535 fluorescence detector at an excitation wavelength of 295 nm. A Shimadzu EZSTART 7.3 chromatography data system [27] was used to integrate peak areas. Concentration of Toc was calculated by comparing Toc peaks with peak areas of the internal standard (rac-5,7-dimethyltocol) and was quantified using authentic standards (DL-{alpha}-tocopherol) [29].

Egg Yolk Cholesterol Quantification
Approximately 0.1 to 0.2 g of egg yolk was weighed into a 12-mL screw-capped tube, 1.0 mL of distilled water was added, and the samples were saponified with 2 mL of ethanol and 0.3 mL of saturated KOH at 70°C for 30 min. The unsaponifiable fraction was extracted with hexane, evaporated to dryness, dissolved in 0.3 mL of ethanol, and centrifuged at 8,000 x g for 5 min. Approximately 0.2 mL of the supernatant was taken for the cholesterol assay, using a Shimadzu LC-2010 HT HPLC system [27]. A Supelguard LC-18 guard column [28] and 75% acetonitrile:25% isopropyl alcohol as a mobile phase at a flow rate of 1.0 mL/min was used. Peaks were detected at 210 nm. Concentration of cholesterol was quantified using authentic standards [25]. A Shimadzu EZSTART 7.3 chromatography data system [27] was used to integrate peak areas.

Statistical Analysis
The experiment used a completely randomized design, and the experimental unit was a replicate consisting of 2 layers. Hen performance, egg characteristics, egg quality, and lipid components were analyzed by 1-way ANOVA using PROC GLM of SAS [30] for a completely randomized design in which treatments were taken as main effects and replicates within treatment were taken as the error term. The following model was used: Yij = µ + {tau}i + {varepsilon}ij, where Yij is the variable measured for the jth replicate, µ is the overall mean, {tau}i is the effect as a result of the ith treatment, and {varepsilon}ij is the error component. Mean values along with pooled SEM are reported. Values were considered significant at P ≤ 0.05. In the case of significant differences, the Duncan multiple range test was used to compare differences among means [31].


   RESULTS AND DISCUSSION
TOP
 SUMMARY
 DESCRIPTION OF PROBLEM
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
CONCLUSIONS AND APPLICATIONS
 REFERENCES AND NOTES
 
The ingredient content and FA composition of the diet are shown in Table 1Go. The laying hen diets were isocaloric and isonitrogenous and provided 2,751 kcal/kg of ME and 16.5% CP, following ISA guidelines for Brown layers. {alpha}-Linolenic acid constituted 3.0 and 32.6% and the n-6:n-3 FA composition of the diets was 19.0 and 1.1 for the control and flax-based diets, respectively. Oleic acid constituted 23.6 and 18.4%, whereas total saturated FA were 16.5 and 12.7 for the control and flax-based diets, respectively.


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  		Table 1. Ingredient content and fatty acid composition of experimental diets (%)
 
Egg Production and Feed Intake
The effects of flaxseed and antioxidant supplementation on egg production, egg weight, egg mass, feed intake, and feed conversion are presented in Table 2Go. Feeding flax-based diets with and without added antioxidants had no effect on egg production, egg weight, egg mass, or feed conversion (P > 0.05) when compared with the control diet. However, a trend for decreased egg production was observed for the flax diet with no added antioxidants. The egg production of hens fed the other flax-based diets with added antioxidants at different levels fell within very narrow ranges. Although not significant, eggs from hens fed flaxseed at 10% + 150 mg of BHT were heavier compared with eggs from hens fed the other treatments, whereas eggs from hens fed flaxseed + 50 mg/kg of BHT produced eggs with the lowest weight (Table 3Go). Egg production and egg weight had no significant effect (P > 0.05); likewise, egg mass (g/d) exhibited no significant effect. These results are in agreement with the findings of Baucells et al. [32], Bean and Leeson [10], and Mazalli et al. [33], who reported nonsignificant differences in egg production attributable to incorporation of flaxseed. However, feed intake was reduced in hens fed flaxseed (P < 0.05; Table 2Go). More than a 3 g/d per hen decrease in feed intake was noticed on all diets except flax +150 mg of BHT as compared with the control diet. The highest feed intake was observed in hens fed the control diet. A decrease in feed intake attributable to addition of flaxseed was also reported by Scheideler and Froning [19] in White Leghorn hens and by Bean and Leeson [10] in Brown egg layers. The reduction in feed intake could have been due to antinutritional factors in flaxseed affecting the palatability, in accordance with the results of Hulan et al. [34], who reported that palatability problems affected feed intake in poultry. Feed conversion was calculated using data on feed intake and egg mass (feed intake/egg mass, g/g), with no statistical differences found among the different experimental diets. However, the best feed conversion occurred in hens fed the diets containing 10% flaxseed + 150 mg/kg of BHT.


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  		Table 2. Effect of feeding flax with different antioxidants on production parameters from wk 24 through 32
 

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  		Table 3. Effect of feeding flax with different antioxidants on egg quality
 
Egg Characteristics
Egg quality aspects such as yolk weight, shell weight, albumen weight and height, HU, yolk color, and shell thickness were unaffected by feeding flaxseed (Table 3Go). A trend for lower yolk weight was observed in birds fed flax without added antioxidants, whereas the highest yolk weight percentage was recorded in birds fed 10% flaxseed + 50 mg of BHT (P > 0.05). Eggs from hens fed flax + 50 mg of BHT had the lowest shell weight percentage as compared with those from all other dietary treatments. The highest albumen weight percentage was recorded for eggs from flax-fed hens and the lowest was recorded from eggs laid by hens fed the control diet (P > 0.05). Haugh unit value based on the albumen height and egg weight is an acceptable measure of the quality and freshness of shell eggs. Eggs produced by layers fed the flaxseed + 50 IU of Toc diet had the maximum value, whereas those from flax + 100 IU of Toc had the minimum HU. However, albumen height and HU were statistically independent of dietary treatments. Yolk colors of eggs on all experimental diets were consistent within a narrow range, having a maximum value on all 3 diets containing BHT. There was no statistical difference among the different diets for yolk color. Shell thickness was also independent of dietary treatments. However, eggs from hens fed the flax + 50 IU of Toc diet had the thickest shell, whereas those obtained from the flax + 50 mg of BHT diet had the minimum shell thickness. Egg components and quality parameters were independent of dietary treatments, and the lack of effect attributable to flaxseed corroborates the results of Bean and Leeson [10] and Novak and Scheideler [11], who demonstrated nonsignificant differences in shell weight, albumen height, and shell thickness of eggs from hens fed flaxseed.

Egg Lipid Components
FA.
The FA compositions of eggs are listed in Table 4Go. Incorporating flaxseed and antioxidants imparted significant changes in the FA profile of eggs. Compared with control eggs, the lowest total SFA values were found in eggs produced from hens fed the diet containing flaxseed + Toc. The major unsaturated FA was C18:1, which constituted approximately 90% of total monounsaturated FA (MUFA). Palmitoleic (16:1) and oleic acids (18:1) were lowest in the flax + 50 mg of BHT group, leading to a significant reduction in total MUFA in eggs from hens fed flax + 50 mg of BHT. Birds that consumed flaxseed deposited higher {alpha}-linolenic acid, EPA, and DHA, resulting in an increase in total n-3 FA and a decrease in arachidonic acid (20:4n-6) and in the total n-6:n-3 FA ratio when compared with control eggs (P < 0.05). The decrease in arachidonic acid and the significant reduction in the n-6:n-3 FA ratio in eggs from hens fed the flax-based diets corroborate previously reported research on laying hens fed diets containing flax [13]. Arachidonic acid is formed from linoleic acid through desaturation and elongation in the hen liver. The enzyme {Delta}6-desaturase is the rate-limiting step in the synthesis of arachidonic acid and long-chain n-3 FA from their 18-carbon precursors [15]. There is competition between n-6 and n-3 FA in which n-3 FA are used as the preferred substrate in the desaturation-elongation pathway, leading to a decreased n-6:n-3 FA ratio in the eggs from hens fed flax. Among the eggs from hens fed flax-based diets, the concentration of arachidonic acid was lowest in the eggs from the flax + Toc- and flax + BHT-supplemented groups when compared with the flax (no antioxidant) group, suggesting a role of antioxidants in modulating the {Delta}6-desaturase pathway in a favorable way. An exception occurred with flax + 150 Toc, for which no difference in arachidonic acid was observed when compared with the flax group.


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  		Table 4. Effect of feeding flax with different antioxidants on egg fatty acids
 
Yolk-derived lipids are synthesized in the hen liver. The {Delta}9-, {Delta}6-desaturase pathway is involved in the synthesis of FA [14]. Alterations in {Delta}9-, {Delta}6-desaturase in the liver through supplemental vitamin E have been reported in animal models [16]. Addition of Toc (0.07%) to the diet of White Leghorn hens fed fish oil has been shown to increase EPA and DHA in eggs [17]. Therefore, it seems that the level of antioxidant in the diet may have an effect on {Delta}9-, {Delta}6-desaturases in laying birds, resulting in alterations of egg saturated FA, MUFA, and n-6 and n-3 polyunsaturated FA content, as observed in the current study. Total n-6 FA were lowest in eggs from hens fed flax + 50 IU of Toc, flax + 50 mg of BHT, flax + 100 mg of BHT, and flax + 150 mg of BHT, leading to a reduction in the n-6:n-3 FA ratio when compared with eggs from hens fed flax (no antioxidant; P < 0.05). In the flax-based diets, BHT was more effective than Toc in incorporating long-chain n-3 FA (DPA, DHA) into eggs. Total n-3 FA were highest in eggs from the flax + 50 mg of BHT group. To minimize lipid peroxidation, precautions such as feed mixing every other week and storage at 4°C in tightly closed containers were followed. Therefore, it is not known whether the effectiveness of BHT compared with Toc may have been due to their stability in the feed.

Total Lipids, Cholesterol, and Vitamin E.
Total lipids were highest in eggs from the flax + 50 or 100 IU of Toc group, the flax + 100 mg of BHT group, or the flax + 150 mg of BHT group (Table 5Go). Flaxseed and antioxidant supplementation had no effect (P > 0.05) on cholesterol content when expressed as milligrams per gram of yolk or on a milligrams per egg basis. Cholesterol content of egg was independent of dietary treatments, and no significant change was observed in cholesterol concentration because of either flaxseed or antioxidant supplementation. In agreement with our results, Ferrier et al. [35] and Scheideler and Froning [19] also found no effect of dietary flaxseed in the cholesterol content of eggs.


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  		Table 5. Effect of feeding flax with different antioxidants on total lipids, cholesterol, and vitamin E
 
Addition of Toc in diets resulted in a linear increase in its concentration in eggs (P < 0.05; Table 5Go). Inclusion of Toc led to more than 4.5- to 12-fold increases in Toc in eggs from the groups fed flax-based diets. According to the results from the current study, consuming 2 large eggs from hens fed flax + 150 IU of Toc could provide more than 11 mg of Toc to the human diet. Manipulation of the diet of the hen to increase the vitamin E content of chicken eggs, thus providing a natural source of health-enhancing vitamins through the diet, has been reported [36, 37] and the linear increase in egg Toc caused by manipulation of the hen’s diet is in agreement with previously reported studies [37, 38]. Located in the phospholipid-rich cellular membranes, Toc can function as an intracellular and intercellular antioxidant, thus neutralizing free radicals, preventing oxidation, and preserving the membrane integrity and structural properties. In addition, Toc has been reported to have health benefits in certain diseases, such as cancer, coronary heart disease, and immune functions [39, 40]. Inclusion of BHT in the diet of the hen had no effect on Toc content of the eggs.

Overall, in light of findings in the present study, it may be concluded that eggs enriched with n-3 FA can be produced by minor dietary modifications without affecting overall production and egg quality parameters. The production of n-3 FA- and Toc-enriched eggs may give poultry farmers an opportunity to be part of an emerging industry that can increase marketability and economic returns by offering consumers an alternate way of obtaining these health-promoting nutrients through their diet.


   CONCLUSIONS AND APPLICATIONS
TOP
 SUMMARY
 DESCRIPTION OF PROBLEM
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSIONS AND APPLICATIONS
REFERENCES AND NOTES
 

  1. Inclusion of flaxseed at 10% did not result in any changes in egg production, egg quality, or egg cholesterol.
  2. Addition of antioxidants enhanced the long-chain n-3 FA content of eggs.
  3. Supplementation with Toc increased the Toc content of eggs. Consuming 2 large eggs from hens fed 10% flax + 150 IU of Toc could provide 11 mg of Toc to the human diet, along with more than 500 mg of n-3 FA.


   ACKNOWLEDGMENTS
 
The authors acknowledge support from the Oregon State University Agriculture Research Foundation award to G. Cherian and the Higher Education Commission, Government of Pakistan, for supporting Z. Hayat under the International Research Support Initiative Program to conduct this experiment as a part of his PhD thesis. The laboratory analytical assistance of D. Goeger, and bird care and management of the poultry farm staff, Department of Animal Sciences, Oregon State University, are acknowledged.


   REFERENCES AND NOTES
TOP
 SUMMARY
 DESCRIPTION OF PROBLEM
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSIONS AND APPLICATIONS
 REFERENCES AND NOTES
 

  1. Das, U. N. 2006. Essential fatty acids: Biochemistry, physiology and pathology. Biotechnol. J. 1:420–439.[CrossRef][Medline]
  2. Simopoulos, A. P. 1991. Omega-3 fatty acids in health and disease and in growth and development. Am. J. Clin. Nutr. 54:438–463.[Abstract/Free Full Text]
  3. Carlson, S. E., and M. Neuringer. 1999. Polyunsaturated fatty acid status and neurodevelopment: A summary and critical analysis of the literature. Lipids 34:171–178.[CrossRef][Web of Science][Medline]
  4. Kris-Etherton, P. M., D. S. Taylor, S. Yu-Poth, P. Huth, K. Moriarty, V. Fishell, and R. L. Hargrove. 2000. The polyunsaturated fatty acids in the food chain in the United States. Am. J. Clin. Nutr. 71:179S–188S.[Abstract/Free Full Text]
  5. Cherian, G. 2002. Lipid modification strategies and nutritionally functional poultry foods. Pages 77–82 in Food Science and Product Technology. T. Nakano and L. Ozimek, ed. Research Sign Post, Trivandrum, India.
  6. Rymer, C., and D. I. Givens. 2005. Omega-3 fatty acids enrichment of edible tissue of poultry: A review. Lipids 40:121–130.[CrossRef][Web of Science][Medline]
  7. Whelan, J., and C. Rust. 2006. Innovative dietary sources of n-3 fatty acids. Annu. Rev. Nutr. 26:75–103.[CrossRef][Web of Science][Medline]
  8. Cherian, G. 2008. Omega-3 fatty acids: Studies in avians. Pages 169–178 in Wild-Type Food in Health Promotion and Disease Prevention: The Columbus Concept. F. De Meester and R. R. Watson, ed. Humana Press, Totowa, NJ.
  9. Gonzalez-Esquerra, R., and S. Leeson. 2001. Alternatives for enrichment of eggs and chicken meat with n-3 fatty acids. Can. J. Anim. Sci. 81:295–305.
  10. Bean, L. D., and S. Leeson. 2003. Long-term effects of feeding flax seed on performance and egg fatty acid composition of brown and white hens. Poult. Sci. 82:388–394.[Abstract/Free Full Text]
  11. Novak, C., and S. E. Scheideler. 2001. Long-term effects of feeding flax seed-based diets. 1. Egg production parameters, components, and eggshell quality in two strains of laying hens. Poult. Sci. 80:1480–1489.[Abstract/Free Full Text]
  12. Bhatty, R. S. 1995. Nutrient composition of whole flaxseed and flaxseed meal. Pages 22–42 in Flaxseed in Human Nutrition. S. C. Cunnane and L. U. Thompson, ed. Academic Press, Champaign, IL.
  13. Cherian, G., and J. S. Sim. 1991. Effect of feeding full fat flax and canola seeds to laying hens on the fatty acid composition of eggs, embryos, and newly hatched chicks. Poult. Sci. 70:917–922.[Web of Science]
  14. Cooke, H. W. 1991. Fatty acid desaturation and chain elongation in eucaryocytes. Pages 141–169 in Biochemistry of Lipids, Lipoproteins and Membranes. D. E. Vance and J. Vance, ed. Elsevier, New York, NY.
  15. Brenner, R. R. 1971. The desaturation step in the animal biosynthesis of polyunsaturated fatty acids. Lipids 6:567–575.[CrossRef][Web of Science][Medline]
  16. Özkan, Y., Ö. Yilmaz, A. Öztürk, and Y. Ersan. 2005. Effects of triple antioxidant combination (vitamin E, vitamin C and {alpha}-lipoic acid) with insulin on lipid and cholesterol levels and fatty acid composition of brain tissue in experimental diabetic and non-diabetic rats. Cell Biol. Int. 29:754–760.[CrossRef][Web of Science][Medline]
  17. Cherian, G., F. W. Wolfe, and J. S. Sim. 1996. Dietary oils with added tocopherols: Effects on egg or tissue tocopherols, fatty acids, and oxidative stability. Poult. Sci. 75:423–431.[Web of Science][Medline]
  18. Jiang, Z., D. U. Ahn, L. Ladner, and J. S. Sim. 1992. Influence of full fat flax and sunflower seeds on internal and sensory quality of yolk. Poult. Sci. 71:378–382.[Web of Science]
  19. Scheideler, S. E., and G. W. Froning. 1996. The combined influence of dietary flax seed variety, level, form, and storage conditions on egg production and composition among vitamin-E supplemented hens. Poult. Sci. 75:1221–1226.[Web of Science][Medline]
  20. ISA Babcock, Ithaca, NY.
  21. Haugh, R. R. 1937. The Haugh unit for measuring egg quality. US Egg Poult. Mag. 43:522–555.
  22. Folch, J., M. Lees, and G. H. Sloane-Stanley. 1957. A simple method for the isolation and purification of total lipids from animal tissues. J. Biol. Chem. 226:497–507.[Free Full Text]
  23. Agilent Technologies Inc., Palo Alto, CA.
  24. Sp-2560, Supelco, Bellefonte, PA.
  25. Matreya, Pleasant Gap, PA.
  26. Podda, M., C. Weber, M. G. Traber, and L. Packer. 1996. Simultaneous determination of tissue tocopherols, tocotrienols, ubiquinols and ubiquinones. J. Lipid Res. 37:893–901.[Abstract]
  27. Shimadzu, Columbia, MD.
  28. Superguard LC-18, Supelco, Bellefonte, PA.
  29. MP Biomedical, Solon, OH.
  30. SAS Institute. 2001. SAS User’s Guide. Statistics, Release 9.2. SAS Inst. Inc., Cary, NC.
  31. Duncan, D. B. 1955. Multiple range and multiple F tests. Biometrics 11:1–42.[CrossRef][Web of Science]
  32. Baucells, M. D., N. Crespo, A. C. Barroeta, S. López-Ferrer, and M. A. Grashorn. 2000. Incorporation of different polyunsaturated fatty acids into eggs. Poult. Sci. 79:51–59.[Abstract/Free Full Text]
  33. Mazalli, M. R., D. E. Faria, D. Salvador, and D. T. Ito. 2004. A comparison of the feeding value of different sources of fats for laying hens: 2. Lipid, cholesterol, and vitamin E profiles of egg yolk. J. Appl. Poult. Res. 13:280–290.[Abstract/Free Full Text]
  34. Hulan, H. W., R. G. Ackman, W. M. N. Ratnayake, and F. G. Proudfoot. 1989. Omega-3 fatty acid levels and general performance of commercial broilers fed practical levels of redfish meal. Poult. Sci. 68:153–162.[Web of Science][Medline]
  35. Ferrier, L. K., L. J. Caston, S. Leeson, J. Squires, B. J. Weaver, and B. J. Holub. 1995. {alpha}-Linolenic acid- and docosahexaenoic acid-enriched eggs from hens fed flaxseed: Influence on blood lipids and platelet phospholipid fatty acids in humans. Am. J. Clin. Nutr. 62:81–86.[Abstract/Free Full Text]
  36. Cherian, G. 2008. Eggs and health: Nutrient sources and supplement carriers. Pages 333–346 in Complementary and Alternative Therapies and the Aging Population. R. R. Watson, ed. Academic Press, San Diego, CA.
  37. Qi, G. H., and J. S. Sim. 1998. Natural tocopherol enrichment and its effect in n-3 fatty acid modified chicken eggs. J. Agric. Food Chem. 46:920–926.
  38. Meluzzi, A., F. Sirri, G. Manfreda, N. Tallarico, and A. Franchini. 2000. Effects of dietary vitamin E on the quality of table eggs enriched with n-3 long-chain fatty acids. Poult. Sci. 79:539–545.[Abstract/Free Full Text]
  39. Diplock, A. T. 1991. Antioxidant nutrients and disease prevention: An overview. Am. J. Clin. Nutr. 53:189–193.
  40. Traber, M. G. 1999. Vitamin E. Pages 347–362 in Nutrition in Health and Disease. 9th ed. M. Shils, J. A. Olson, M. Shike, and A. C. Ross, ed. Williams and Wilkins, Baltimore, MD.



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G. Cherian and Z. Hayat
Long-term effects of feeding flaxseeds on hepatic lipid characteristics and histopathology of laying hens
Poult. Sci., December 1, 2009; 88(12): 2555 - 2561.
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