J APPL POULT RES 2009. 18:143-150. doi:10.3382/japr.2008-00070
© 2009 Poultry Science Association
Egg quality and lipid composition of eggs from hens fed Camelina sativa
G. Cherian*,1,
A. Campbell* and
T. Parker
* Department of Animal Sciences, Oregon State University, Corvallis, OR 97331; and Willamette Biomass Processors Inc., Rickreall, OR 97371
1 Corresponding author: Gita.Cherian{at}oregonstate.edu
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SUMMARY
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The present study was conducted to investigate the effect of feeding Camelina sativa to layer birds on egg production, egg quality characteristics, egg lipids, and fatty acid and lipid oxidation products. Fifty-eight-week-old ISA Brown Leghorn laying hens (n = 48) were kept in individual cages and were fed a corn- and soybean meal-based diet with added Camelina meal at 0%, (control), 5%, (CAM5), 10% (CAM10), and 15% (CAM15). The experimental diets were fed for a period of 80 d. Hen-day egg production was lowest for CAM15 (P < 0.05). A significant reduction in yolk weight was observed for CAM10 and CAM15 eggs when compared with control eggs (P < 0.05). Yolk weight, as a percentage of egg weight, was lower for CAM10 and CAM15 eggs, whereas albumen weight, as a percentage of egg weight, was higher in CAM10 and CAM15 eggs than in control eggs (P < 0.05). The yolk:albumen ratio was higher in control eggs than in CAM10 and CAM15 eggs (P < 0.05). Egg total fat content was lowest for CAM15 eggs and was 31.5, 31.9, 30.8, and 29.5 for control, CAM5, CAM10, and CAM15 eggs, respectively (P < 0.05). Total n-3 fatty acids constituted 0.32% in control eggs compared with 2.54, 2.69, and 2.99% in CAM5, CAM10, and CAM15 eggs (P < 0.05). An 8-fold increase in docosahexaenoic acid was observed in CAM15 eggs when compared with control eggs (P < 0.05). The n-6:n-3 ratio was 14.8, 5.6, 4.6, and 4.3 for control, CAM5, CAM10, and CAM15 eggs, respectively (P < 0.05). Total saturated fats were lowest for CAM5 and CAM10 eggs. Eggs from the CAM15 regimen had higher TBA-reactive substance values (P < 0.05) than those from the CAM5, CAM10, or control regimen. Camelina meal could be incorporated into poultry rations as a source of energy, protein, and essential n-3 and n-6 fatty acids. However, inclusion of more than 10% Camelina meal in the hen diet may affect egg lipid quality aspects. Therefore, measures for minimizing lipid peroxidation should be used to enhance egg quality and lipid stability.
Key Words: egg • Camelina • n-3 fatty acid • thiobarbituric acid-reactive substance
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DESCRIPTION OF PROBLEM
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Camelina sativa or false flax ("gold-of-pleasure") is an oilseed crop of the Brassica (Cruciferae) family. The oil content of C. sativa is approximately 40%, and the crop is gaining popularity as a biofuel source [1]. Camelina oil is also rich in 
-linolenic acid (18:3n-3), an essential n-3 fatty acid. Because of the high oil content and essential -linolenic acid concentration in Camelina meal (a by-product obtained from Camelina seed after oil extraction), finding alternate uses for it in animal diets will increase the market value of the crop [1].
Increasing ethanol and biofuel production necessitates finding alternate energy and CP sources in poultry diets. Oilseeds and oilseed meals are incorporated into poultry rations as a source of CP and energy. Preliminary studies conducted in our laboratory and elsewhere on the nutrient composition of Camelina meal indicated that the meal has more than 35 to 40% CP and contains 11 to 12% fat [2, 3]. -Linolenic acid (18:3n-3) constitutes 30% of fatty acids in Camelina meal. -Linolenic acid is the precursor of long-chain n-3 fatty acids such as eicosapentaenoic acid (20:5n-3) and docosahexaenoic acid (22:6n-3), which are commonly referred to as n-3 fatty acids and have received considerable attention as functional nutrients for their several health-promoting effects [4]. Although no official dietary recommendation has been made in the United States, nutrition scientists suggest a 4- to 5-fold increase in the intake of n-3 fatty acids in the current US diet [5].
To accommodate the increased need for n-3 fatty acids in the diet, feeding strategies have been adopted to increase the n-3 fatty acid content of chicken eggs and other poultry products [6, 7]. Feeding flax and marine oils to hens has been used to enrich eggs with n-3 fatty acids [6–8]. However, availability and cost are limiting factors associated with these feed supplements. Therefore, alternate sources of n-3 fatty acid-rich feed ingredients such as Camelina may be incorporated into poultry diets as a source of CP, energy, and n-3 fatty acids. This may lead to reducing feed costs along with an enhanced lipid nutrient profile of poultry foods. Recently, Pilgeram et al. [3] reported an n-3 fatty acid-enriching effect of Camelina meal in poultry. However, very limited information is available on the feeding value of Camelina meal and on egg quality aspects and the lipid composition of eggs from hens fed Camelina meal. Consequently, the objective of this study was to determine egg production, egg quality characteristics, yolk lipid content, fatty acid incorporation, and lipid oxidation products, measured as TBA-reactive substances (TBARS) in layers fed Camelina meal.
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MATERIALS AND METHODS
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These experiments were reviewed by the Oregon State University Animal Care Committee to ensure adherence to Animal Care Guidelines.
Diets, Birds, and Housing
The Camelina meal [9] was analyzed for gross energy, CP, amino acids, minerals, and crude fat content at the University of Arkansas Poultry Science Central Analytical Laboratory (Table 1
). Fifty-eight-week-old ISA Brown Leghorn laying hens (n = 48) [10] were kept in individual cages and were fed a corn- and soybean meal-based diet with added Camelina meal at 0% (control), 5% (CAM5), 10% (CAM10), and 15% (CAM15; Table 2). The diets were prepared biweekly and kept in a cold room (4°C) in airtight containers. Hens were fed the experimental diet for a period of 80 d. Water and feed were provided ad libitum.
Production Variables and Egg Quality Characteristics
Total feed consumption and daily egg production were monitored during the trial. Egg production is expressed as average hen-day production, calculated from total eggs divided by the total number of days and hens. For egg quality characteristics and lipid analytical aspects, 12 eggs from each treatment were collected after 8 wk on the experimental diet. 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, and yolk:albumen ratio was determined. Albumen height was also documented. Yolk color was determined by comparing yolk color with the Roche color fan. Egg total lipid content, fatty acid composition, and lipid peroxidation assays, as measured by TBARS, were conducted.
Total Lipid and Fatty Acid Analysis
Total lipids were extracted from egg yolk by using chloroform:methanol (2:1) [11] and total lipids were determined gravimetrically. Fatty acid methyl esters were prepared from lipid extracts as reported previously[12], and the analysis of fatty acid composition was performed with an Agilent 6890 gas chromatograph [13] equipped with an autosampler, flame-ionization detector, and fused-silica capillary column, 30 m x 0.25 mm x 0.2 µm film thickness [14]. Each sample (1 µL) was injected onto the column with helium as a carrier gas, programmed for increased oven temperatures (initial temperature of 110°C, held for 1 min, then increased at 150°C/min to 190°C and held for 55 min, and 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 fatty acid percentages were calculated using Agilent ChemStation software [13]. Fatty acid methyl esters were identified by comparison with retention times of authentic standards [15] and were expressed as percentages of total fatty acid methyl esters.
TBARS Assay
Egg samples (2 g) were homogenized with 3.86% perchloric acid. Butylated hydroxytoluene (50 µL in 4.5% ethyl alcohol) was added to each sample during homogenization to control lipid oxidation. The homogenate was filtered and the filtrate was mixed with 20 mM TBA in distilled water and incubated. Absorbance was determined at 531 nm. Thiobarbituric acid-reactive substances were expressed as milligrams of malondialdehyde per gram of yolk [16].
Statistical Analysis
The effects of diet on egg production, egg quality, lipids, fatty acids, and TBARS were analyzed by one-way ANOVA using SAS (version 9.2) [17]. Each individual cage was considered the experimental unit. Significant differences among treatment means were analyzed by Duncan’s multiple range test at P < 0.05 [18]. Computations were done by using the GLM procedure of SAS [17]. Mean values and SEM were reported.
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RESULTS AND DISCUSSION
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The chemical composition of Camelina meal used in layer feeding is shown in Table 1
. Gross energy constituted 4,688 kcal/kg, CP constituted 37.2%, and crude fat constituted 11.9%. The protein of Camelina meal contained several essential amino acids such as threonine, glycine, methionine, valine, isoleucine, leucine, lysine, and phenylalanine. Among the minerals in Camelina meal, potassium was the major mineral, followed by sulfur, phosphorus, magnesium, and calcium. Fatty acid composition of the Camelina meal showed that the meal is rich in -linolenic acid, which constituted 29.6%. Linoleic acid (18:2n-6) constituted 23.4%. Total monounsaturated fatty acid constituted 32.7%. Oleic acid was the major monounsaturated fatty acid, followed by eicosenoic acid (20:1). Other monounsaturated fatty acids included palmitoleic (16:1) and erucic acid (22:1). Total saturated fatty acids constituted 11.5%. Palmitic acid (16:0) and stearic acid (18:0) were present at 9.0 and 2.5%, respectively, in Camelina meal (Table 1). The high protein, energy, n-3, and n-6 fatty acid content of Camelina meal makes it a potentially suitable source of plant protein and essential fatty acid source in poultry diets.
Egg Production and Feed Consumption
Hen-day egg production was lowest for CAM15 (P < 0.05). No difference was found in hen-day egg production of the control, CAM5, or CAM10 birds. Feed consumption was 106.5, 105.2, 97.7, and 98.7 g/hen per day for control, CAM5, CAM10, and CAM15 birds, respectively. In the current study, total feed consumption during the trial was conducted. Camelina belongs to the Brassica family and species of this family are high in nonstarch polysaccharides and glucosinolates, which can affect feed consumption [2]. Using Camelina sativa in the diets of young turkeys, Frame et al. [19] reported a reduction in feed consumption when the diets contained more than 5% Camelina. However, no effect on feed consumption was observed in rabbits when Camelina seed was fed at 15% [20]. No mortality was observed among the birds during the experimental period.
Egg Characteristics and Lipid Composition
A significant reduction in yolk weight, as a percentage of egg weight, was observed for CAM10 and CAM15 eggs when compared with control eggs (P < 0.05; Table 3). However, albumen weight as a percentage of egg weight was higher in CAM10 and CAM15 eggs when compared with control eggs (P < 0.05). The yolk:albumen ratio was lower in CAM10 and CAM15 eggs when compared with control eggs (P < 0.05; Table 3). It is not clear why inclusion of higher levels of Camelina led to a reduction in yolk weight. However, other researchers have reported that feeding flaxseed (10%) to layers led to smaller yolks [21, 22]. No difference was found in egg weight, shell weight, or shell thickness because of Camelina meal feeding at all levels (P > 0.05; Table 3). No difference attributable to dietary treatment was observed for albumen weight or height. Yolk color was lowest for CAM5 eggs and highest in control eggs (P < 0.05). No difference was found between the yolk color of CAM10 and CAM15 eggs. Yolk color is contributed by pigments such as carotenoids. Yolk pigments have been associated with antioxidant and visual health-promoting properties [23]. The lower yolk color score observed in the CAM5, CAM10, and CAM15 eggs in the current study may be due to the inclusion of Camelina meal, which is produced after oil extraction and could be low in fat-soluble pigments such as carotenoids.
Egg total fat content was 31.5, 31.9, 30.8, and 29.5 for control, CAM5, CAM10, and CAM15 eggs, respectively (P < 0.05; Table 4). It has been reported that addition of fish oil (source of n-3 fatty acids) to layer and breeder hen diets resulted in a reduction in yolk total lipid content [16, 24]. Yolk lipids and proteins are synthesized in the liver as lipoproteins under the influence of estrogen [25]. Triacylglycerol-rich very low density lipoprotein (VLDL) is the major lipoprotein that accounts for more than 60% of the dry yolk mass [25]. Secretion of VLDL-triacylglycerol from liver cells is highly dependent on the activity of stearoyl-coenzyme A desaturase, an enzyme converting saturated fatty acids into monounsaturated fatty acids [26]. Omega-3 fatty acids have been reported to reduce the activity of stearoyl-coenzyme A desaturase [27]. In the current study, a significant reduction in total monounsaturated fatty acids (16:1 + 18:1 + 20:1) was observed in CAM5, CAM10, and CAM15 eggs when compared with control eggs (Table 4). Therefore, it appears that high levels of n-3 fatty acids may affect the activity of stearoyl-coenzyme A desaturase in birds, thereby decreasing the synthesis of VLDL and leading to a reduction in yolk mass and lipid content.
An increased supply of -linolenic acid through Camelina in the hen diet increased the n-3 fatty acid content of CAM5, CAM10, and CAM15 eggs. Total n-3 fatty acids constituted 0.3% in control eggs as compared with 2.5, 2.7, and 3.0% in CAM5, CAM10, and CAM15 eggs (P < 0.05; Table 4). A 10-fold increase in -linolenic acid (18:3n-3) was observed in CAM15 eggs as compared with control eggs. Similarly, an 8-fold increase in docosahexaenoic acid (22:6n-3) was observed in eggs from hens fed Camelina when compared with control eggs (P < 0.05). The n-6:n-3 ratio was 14.8, 5.6, 4.6, and 4.3 for control, CAM5, CAM10, and CAM15 eggs, respectively (P < 0.05). Addition of extra Camelina meal in hen diets did not alter total n-3 fatty acids or the n-6:n-3 ratio in CAM10 and CAM15 eggs as compared with CAM5 eggs. The increases in n-3 fatty acids were associated with a concomitant decrease in arachidonic acid (20:4n-6) in CAM5, CAM10, and CAM15 eggs as compared with control eggs (P < 0.05). The Camelina meal had higher levels of linoleic acid, and this led to an increase in linoleic acid in the eggs from hens fed diets with Camelina meal as compared with control eggs. Arachidonic acid is formed from yolk linoleic acid through desaturation and elongation. However, the increase in yolk linoleic acid did not increase the arachidonic acid content in CAM5, CAM10, or CAM15 eggs. A decrease in arachidonic acid and a significant reduction in the n-6:n-3 ratio in eggs from hens fed Camelina meal corroborate our previous research on laying hens fed diets containing flax and fish oil [28, 29]. The enzyme 
6-desaturase is the rate-limiting step in the synthesis of arachidonic acid and docosahexaenoic acid from their 18-carbon precursors [30]. There is competition between n-6 and n-3 fatty acids in which n-3 fatty acids are used as the preferred substrate in the desaturation-elongation pathway, leading to a decreased n-6:n-3 ratio in the egg. Total saturated fatty acid was highest in control eggs (16:0 + 18:0) and was lowest in CAM5 and CAM10 eggs. The effects of Camelina supplementation on saturated fatty acids were varied for palmitic (16:0) and stearic (18:0) acids. No difference was found in the stearic acid content. However, palmitic acid was highest in control eggs (P < 0.05). Because of links between dietary lipids, saturated fat, cholesterol, and coronary heart disease, eggs from CAM15, with low levels of lipids and saturated fatty acids and a small yolk mass, may reduce the human dietary intake of fat, saturated fatty acids, and cholesterol while providing essential n-3 fatty acids.
Based on TBARS, the oxidative stability of fresh eggs revealed a significant effect of diet. Eggs from the CAM15 regimen had higher (P < 0.05) TBARS values than those from the CAM5, CAM10, or control regimens, suggesting that the onset of lipid oxidation may be enhanced in these eggs because of the high content of n-3 fatty acids (Figure 1). Although incorporating n-3 fatty acids into eggs through Camelina feeding has been reported before [3, 31], no published reports are available on egg quality and lipid oxidation products in eggs from hens fed Camelina meal. It is not known whether high TBARS will have any effect on the sensory aspects of eggs from CAM15. In the current study, no organoleptic attributes were assessed. Nevertheless, Rokka et al. [31] reported that Camelina seed oil had no effect on the sensory attributes of chicken eggs.
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Figure 1. Effect of dietary Camelina sativa on the TBA-reactive substances in egg yolks. Control, CAM5, CAM10, and CAM15 represent the corn-soybean meal basal diet (control), or basal diets containing 5% (CAM5), 10% (CAM10), or 15% (CAM15) Camelina meal. n = 12. a,b Means with no common letter differ (P < 0.05). Thiobarbituric acid-reactive substances are reported as milligrams of malondialdehyde (MDA) per gram of yolk.
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CONCLUSIONS AND APPLICATIONS
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- Camelina meal is rich in protein, lipids, and essential n-3 and n-6 fatty acids and could be incorporated into poultry diets as a source of energy, protein, and essential n-3 and n-6 fatty acids.
- Camelina meal at low levels (5 and 10%) did not lead to any changes in egg production or egg quality. However, the current study used only 48 birds in a short (80-d) trial. Feeding trials with larger numbers of birds or with different strains for longer periods or during the whole laying cycle would be ideal to investigate the enrichment of egg yolks with n-3 fatty acids and the subsequent health effects produced as a result of using Camelina meal in layer diets.
- Consuming 2 large eggs from hens fed Camelina meal could provide more than 300 mg of n-3 fatty acids to the human diet. However, inclusion of more than 10% Camelina meal in the hen diet may affect egg lipid quality aspects. Therefore, measures for minimizing lipid peroxidation should be used to enhance egg quality and lipid stability.
- Addition of Camelina at higher levels (15%) led to reductions in egg production, yolk fat, and yolk size without affecting egg weight. Because of links between dietary lipid, saturated fat, and cholesterol consumption and coronary heart disease, eggs from Camelina-supplemented hens with a lower level of lipids, a lower level of saturated fat, and smaller yolks may decrease the human dietary intake of total fat, saturated fats, and cholesterol while increasing essential n-3 fatty acids.
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ACKNOWLEDGMENTS
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The financial assistance from Oregon Department of Agriculture is acknowledged. The Camelina meal used in this study was kindly supplied by Willamette Biomass Processors Inc. (Rickreall, OR). The laboratory analytical assistance of Natalie Quezeda and bird care and management of the Oregon State University poultry farm staff are acknowledged.
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REFERENCES AND NOTES
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SUMMARY
DESCRIPTION OF PROBLEM
