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Strain and age effects on egg composition from hens fed diets rich in n-3 fatty acids
EDUCATION AND PRODUCTION Strain and Age Effects on Egg Composition from Hens Fed Diets Rich in n-3 Fatty Acids S. E. SCHEIDELER,1 D. JARONI, and G. FRONING Department of Animal Science, and Department of Food Science and Technology, University of Nebraska, Lincoln, Nebraska 68583-0919
(Key words: layer, flax, oats, fatty acids, yolk lipids) 1998 Poultry Science 77:192–196
although considerable amounts of docosapantoenoic and docosahexaenoic acids are also deposited (Aymond and Van Elswyk, 1995; Scheideler and Froning, 1996). Dietary fat has long been known to enhance egg weight (Jensen et al., 1958; Shutze et al., 1958), although the mechanism has remained obscure. It has been suggested that linoleic acid enhances synthesis of lipoproteins taken up by the developing yolk (March and MacMillan, 1990). Dietary oats have also been reported to increase egg weight and potential nutrient digestibility in laying hens (Scheideler et al., 1994). Dietary oats contain a substantial amount of oleic and stearic acids (NRC, 1994), which can potentially affect fatty acid utilization and yolk fatty acid deposition as documented by Sell et al. (1968). Dietary oats also contain an insoluble fiber hull compared to a more soluble type of fiber-mucilage in flax. It is hypothesized in this study that the insoluble fiber in whole oats would increase gizzard grinding and thereby enhance the flax fiber solubilization and early lipid and protein digestion. With the more recent advances in genetic selection, the
INTRODUCTION Flax is one of the most concentrated sources of unsaturated fatty acids available in natural feedstuffs for poultry (Caston and Leeson, 1990; Jiang et al., 1991). Common varieties of flax seed have very high concentrations of polyunsaturated fatty acids, especially alinolenic acid (Genser, 1994). Hens have a unique ability to deposit dietary lipid into the egg yolk, which makes the egg a potential source of unsaturated fatty acids (Huang et al., 1990; Jiang et al., 1991; Ferrier et al., 1992; Scheideler and Froning, 1996), and it is possible to modify the fatty acid composition of eggs through dietary manipulation (Caston and Leeson, 1990). n-3 fatty acid content of eggs can be significantly increased by feeding flax to laying hens (Caston and Lesson, 1990; Aymond and Van Elswyk, 1995). Studies show that the major n-3 polyunsaturated fatty acid deposited into egg yolks is linolenic acid, in the yolk triglyceride fraction,
Received for publication March 25, 1997. Accepted for publication October 7, 1997. 1To whom correspondence should [email protected]
be
addressed:
Abbreviation Key: B = Babcock B300 hens; D = DeKalb Delta hens; and H = Hy-Line W-36 hens.
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percentage albumin, which was greatest for D (61.2%) vs H (59.5%) and B (59.4%). Strain D had significantly lower total and percentage yolk lipids than the other two strains. Strain B eggs had more C16:0, but less C18:0 and C18:1 than D and H. No significant effect of strain on C18:2, C18:3, and C22:6 deposition was observed. Percentage C18:0 and C18:1 in the yolk was significantly affected by strain, diet, and strain × diet interaction. Dietary flax + oats increased C18:0 and C18:1 in all strains except H. A significant diet by strain interaction effect occurred such that C18:3 increased in D yolk but decreased in B yolk when flax + oats were fed. Deposition of C18:3 was greater at 58 wk (5.61%) than at 36 wk (2.52%) of age across all strains. Results from these trials indicate that strain, diet ,and age can affect yolk lipids and composition.
ABSTRACT A trial was conducted to study the effects of strain, age, and diet on egg production, egg composition, and yolk fatty acid incorporation. Three strains (six pens of eight hens per strain), [DeKalb Delta (D); Babcock B 300 (B); and Hy-Line W-36 (H)], were subjected to a 10% flax diet + oats from 30 to 50 wk of age. At 50 wk, hens were divided into two groups and one half were kept on flax + oats diets (three pens) or assigned to a second diet of flax – oats (three pens) to 60 wk of age. Eggs were collected at 36 and 58 wk of age for fatty acid and lipid analysis. Strain had an early effect (30 to 50 wk) on egg production with B (85.3) exceeding the other two strains D (81.0) and H (79.1). Strain D had greater feed consumption and egg weight than either B or H. Flax – oats increased percentage shell compared to flax + oats. Strain effect was significant for
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STRAIN, AGE, AND DIETARY n-3 FATTY ACIDS AFFECTS EGG COMPOSITION TABLE 2. Strain effects on production variables (30 to 50 wk of age)
TABLE 1. Dietary composition and calculated analyses, Trial 2 Ingredients and nutrients
Diet 1
Diet 2 (%)
53.8 18.6 10.0 7.4 5.0 2.0 1.5 0.92 0.25 0.23 0.10 0.10 0.05 0.05
59.4 18.8 10.0 7.4 . . . 2.0 1.5 0.04 0.25 0.24 0.09 0.10 0.05 0.05
Babcock B300 DeKalb Delta Hy-Line W-36 SEM Probability Strain
Egg production
Feed consumption
Egg weight
Specific gravity
(%) 85.3a 81.1b 79.1b 2.52
(g/hen/d) 91.4a 99.1b 94.0a 1.53
(g) 57.0a 63.1b 56.8a 1.88
1.089 1.088 1.087 0.0008
0.05
0.05
0.05
NS
a,bMeans
within a column with no common superscript differ significantly (P < 0.05).
objective of these trials was to study fatty acid utilization by current popular White Leghorn layer strains.
weighed back daily. Feed wastage was accounted for by daily weighbacks and by not allowing excessive feed buildup in the troughs. Egg weight and specific gravity were determined each week on 1 d of egg production. Egg collection for fatty acid analysis was conducted at 35 (10 eggs per strain) and 58 wk of age (12 eggs per strain with 6 eggs per diet). Fatty acid composition of the eggs was determined by gas liquid chromatography (Froning et al., 1990). Egg components and total egg lipids (solvent extraction) were measured at the 58 wk of age on six eggs per treatment. All data were analyzed by ANOVA using the SAS General Linear Models procedures (SAS Institute, 1989) testing for main (strain, age, and diet) and interaction (strain by diet and age by strain) effects. Weekly data (egg production, feed consumption, egg weight, and specific gravity) were analyzed as repeated measures by the General Linear Models procedure (SAS Institute, 1989).
MATERIALS AND METHODS
RESULTS
A total of 144 hens from three strains (48 per strain), Babcock B300 (B), DeKalb Delta (D), and Hy-Line W-36 (H), were fed a diet containing 10% flax with dietary oats (Diet 1) (Table 1) beginning at 30 wk of age. The birds were randomly assigned to six pens per strain with eight birds in each pen (387 cm2 per bird). The pens were 60 × 52 cm with 60 cm linear feeding space, allowing 7.5 cm trough space per hen. The dietary treatment was fed for 20 wk. At 50 wk of age, the same three strains of hens were divided into two groups (three pens per diet) with one group staying on Diet 1 (flax + oats) and the other group fed Diet 2 (flax – oats) to 60 wk of age. Hens were reassigned to smaller pens (562 cm2 per bird) that were 45 × 50 cm with 45 cm linear feeding space, allowing 11.3 cm trough space per hen. Diet compositions are shown in Table 1. Hens were given ad libitum access to feed and one nipple drinker per pen. Eggs were collected daily and the egg production calculated on a hen-day basis. Hens were given access to 115 g feed per bird per d and unconsumed feed was
Egg production (Table 2) was significantly higher for the B strain than for the H and D strains during the first 20 wk of the trial. At 50 wk of age, when the hens went on the two different diets, egg production was significantly less (P < 0.05) for hens on flax + oats than for those on flax – oats (Table 3), however the strain effect was no longer significant. At 50 wk of age, hens were transferred to different cages allowing more floor space per hen (562 cm2 compared to 387 cm2) and trough space (11.3 cm compared to 7.5 cm). Strain effect was significant (P < 0.01) for feed consumption (Tables 2 and 3) throughout the trial and was higher for D hens than for B and H hens. There was a significant diet by strain interaction for feed consumption, in which D hens decreased consumption rate when fed flax + oats compared to flax – oats; whereas B hens consumed less feed when oats were taken out of the ration. Egg weights were significantly different for the three strains (P < 0.05 and P < 0.01) throughout the trial, (Tables 2 and 3) with D hens producing heavier eggs than H and B hens. A significant strain by diet interaction for egg weight showed improvements in B and D but not in H
16.00 0.70 0.92 2,850 6.95 1.18 0.04 0.70 3.99 2.67 1.68
16.00 0.70 0.92 2,850 6.07 0.95 0.0034 0.54 3.57 2.67 1.68
1Vitamin
E premix provided an additional 50 IU/kg a-tocopherol. premix provided Mn, 88 mg; Cu, 6.6 mg; Fe, 8.5 mg; Zn, 88 mg; Se, 0.30 mg; vitamin A, 6,600 IU; cholecalciferol, 2,805 IU; vitamin E, 10 IU; vitamin K, 2.0 mg; riboflavin, 4.4 mg; pantothenic acid, 6.6 mg; niacin, 24.2 mg; choline, 110 mg; vitamin B12, 8.8 mg; ethoxyquin, 1.1 mg/kg. 2Vitamin/mineral
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Corn Soybean meal Flax Limestone Oats Oyster shell Dicalcium phosphate Tallow Vitamin E premix1 Salt Methionine Vitamin/mineral premix2 Choline chloride Grit Nutrients Protein Methionine + cystine Lysine ME, kcal/kg Ether extract C16:0 C16:1 C18:0 C18:1 C18:2 C18:3
Strain
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SCHEIDELER ET AL. TABLE 3. Strain effects on production variables (50 to 60 wk of age)
Strain
Diet
Babcock B300
Flax Flax Flax Flax Flax Flax
DeKalb Delta Hy-Line W-36
+ – + – + –
oats oats oats oats oats oats
SEM Probabilities Strain Diet Strain × diet
Egg production
Feed consumption
Egg weight
Specific gravity
(%) 75.6 80.5 79.6 85.6 79.3 87.0 2.45
(g/hen/d) 101.6 94.9 104.3 107.2 99.8 100.7 0.88
(g) 59.5 58.2 66.2 64.0 58.8 60.8 0.39
1.087 1.089 1.086 1.087 1.086 1.087 0.0005
NS 0.05 NS
0.01 NS 0.01
0.01 NS 0.05
NS 0.05 NS
5). Palmitic acid was higher in the B strain than in D and H strains, only at 36 wk of age. Stearic acid (C18:0) deposition was lower in B and D strains than in the H strain at 36 wk of age but this effect changed at 58 wk of age, when H eggs were low in C18:0. Deposition of oleic acid (C18:1) in the egg yolk was significantly affected by age, strain, diet, and diet by strain (P < 0.01). Oleic acid decreased from 36 to 58 wk of age and was greater in the H strain than in the D and B strains at 36 and 58 wk of age. There was a diet by strain effect on oleic acid in which there were significant decreases in B and D strains when fed flax + oats but no change in the H strain. Stearic acid (C18:0) also showed a significant diet by strain interaction, with D having increased levels when fed flax – oats compared to B and D strains. Neither strain nor diet had significant effects on linoleic and linolenic acid; however, age did show a positive effect on both linoleic and linolenic acid deposition in the egg. There was also a diet by strain interaction (P < 0.05) on linolenic acid; flax + oats improved linolenic acid deposition in D, compared to a negative effect in B and no change in H. There were no significant effects of diet or strain on linoleic acid, arachidonic acid, or docosahexaeonic acid in the egg. Age did significantly
TABLE 4. Effects on egg composition
Strain
Diet
Babcock B300
Flax Flax Flax Flax Flax Flax
Egg albumen
Egg yolk
Eggshell
Egg yolk lipids
Total yolk lipids
59.2 59.7 61.7 60.6 59.6 59.4 0.84
28.0 28.0 26.0 27.1 28.3 27.7 0.78
11.3 11.3 10.5 11.2 10.8 11.5 0.25
32.0 31.2 30.2 31.6 32.9 31.6 0.24
(g) 5.89 5.46 4.79 5.27 5.52 5.10 0.10
0.06 NS NS
NS NS NS
NS 0.05 NS
0.01 NS 0.01
0.01 NS 0.01
(%)
DeKalb Delta Hy-Line W-36 SEM Probabilities Strain Diet Strain × diet
+ – + – + –
oats oats oats oats oats oats
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hens when fed flax + oats compared to flax – oats (Table 3). Specific gravity significantly (P < 0.05) improved in eggs from hens fed flax – oats compared to flax + oats. There was no strain effect on egg specific gravity. Diet had no effect on percentage albumen or yolk (Table 4). Strain had a marked effect on percentage albumen, which was greater (P < 0.06) in strain D (61.2%) than in strain B (59.4%) or H (59.5%). Percentage eggshell was decreased in the D and H strains when oats were included in the flax diet compared to flax diets without oats. Deposition of total and percentage lipids in the yolk showed significant strain and strain by diet effects (Table 4). Percentage of yolk fat and total grams of yolk lipid were lower in eggs from the D strain than in those from the H or B strains (P < 0.05). Egg yolk lipids and percentage showed significant strain by diet interaction effects (P < 0.01). Egg yolk lipids increased in B and H when fed flax + oats compared to flax – oats, whereas in the D strain, the opposite effect of feeding flax + oats occurred, resulting in a reduction of yolk lipid. The strain effect on egg yolk fatty acid composition was significant for C16:0 (palmitic), C18:0 (stearic), and C18:1 (oleic) (P < 0.05) acids at both age intervals (Table
STRAIN, AGE, AND DIETARY n-3 FATTY ACIDS AFFECTS EGG COMPOSITION
195
increase the level of docosahexaeonic acid in the egg at 58 wk compared to 36 wk with no strain or diet effects. Eicosapentaenoic acid (C20:5) levels averaged less than 0.10% of the yolk fatty acids for all strains and diets and are therefore not reported in Table 4.
DISCUSSION
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The strain effect on feed consumption and egg weight is not unprecedented. Anderson (1994) reported, in the results of the 30th North Carolina Layer Performance and Management Test, increased feed consumption and egg mass production in the D strain compared to the H strain from 133 to 441 d of age. The findings in that study also showed that the B hens consumed more feed and produced more egg mass than the H or D hens, which was not consistent with the findings of this report. Anderson (1994) also reported an improved rate of lay in the B strain compared to D or H strain. In this research, an advantage for the B strain did occur to 50 wk of age only. After 50 wk of age, the eight hens were split into two groups and given more floor and feeder space per hen, which may have reduced stress and improved overall flock performance. Strain had a significant effect on percentage egg albumen, percentage egg yolk lipids, and total yolk lipid in this study with the D strain eggs having a larger proportion of white and less percentage yolk lipid and total lipids than eggs from the H or B strains. It appears that genetic selection for increased feed consumption and larger egg size in the D strain has resulted in more egg albumen and less yolk lipid compared to B and H at the same age. This difference provides an opportunity for the commercial egg producer to minimize egg yolk and associated lipids if desired in a designer egg. Diet significantly affected percentage eggshell, and egg specific gravity. Flax + oats caused a decline in shell quality, as measured by percentage eggshell and specific gravity. The negative effect of flax + oats compared to flax – oats on shell quality may be a result of the higher dietary fiber in these rations and potential interactions with calcium availability for shell formation. The effect of strain on yolk fatty acid profile has been previously demonstrated (Sell et al., 1968; Ahn et al., 1995) but not in today’s prolific strains of White Leghorns. As found almost 30 yr ago (Sell et al., 1968), strain of White Leghorn significantly affected proportion of palmitic, oleic, and stearic acids in the egg yolk. Significant strain effects were found in the present study for yolk palmitic, oleic, and stearic acids with B having more palmitic acid than the other two strains and H having more oleic and stearic acids than B and D strains at 36 wk. These strain results indicate genetic differences in dietary feed consumption and utilization and storage of dietary fats, with the H strain having perhaps more efficient utilization of dietary fat (oleic and stearic acids) than the B and D strains. The high level of palmitic acid in the B strain indicates more dependence on body lipid stores for egg yolk fatty acid deposition. Sell et al. (1968) also noted diet by strain interactions for fatty acid deposition, which was confirmed by the interactions in
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SCHEIDELER ET AL.
ACKNOWLEDGMENTS The authors would like to thank Lyle Robeson and Lynn Niemann for their technical support, and Minnie Stephens for preparing this manuscript.
REFERENCES Ahn, D. U., H. H. Sunwoo, F. H. Wolfe, and J. S. Sim, 1995. Effects of dietary a-linolenic acid and strain of hen on the fatty acid composition, storage stability and flavor characteristics of chicken eggs. Poultry Sci. 74:1540–1547. Anderson, K. E., 1994. Final Report of the 30th North Carolina Layer Performance and Management Test. North Carolina. Cooperative Extension Service, Department of Poultry Science, University of North Carolina, Raleigh, NC. Aymond, W. M., and M. E. Van Elswyk, 1995. Yolk thiobarbituric acid reactive substances and n-3 fatty acids
in response to whole and ground flaxseed. Poultry Sci. 74: 1358–1394. Caston, L., and S. Leeson, 1990. Dietary flax and egg composition. Poultry Sci. 69:1617–1620. Ferrier, L. K., L. Caston, S. Lesson, E. J. Squires, B. Celi, L. Thomas, and B. J. Holub, 1992. Changes in serum lipids and platelet fatty acid composition following consumption of eggs enriched in alpha-linolenic acid. Food Res. Int. 25(4):263–268. Froning, G. W., R. L. Wehling, S. L. Cuppett, M. M. Pierce, L. Niemann, and S. K. Siekman, 1990. Extraction of cholesterol and other lipids from dried yolk using supercritical carbon dioxide. J. Food Sci. 55:95–98. Genser, M. V., 1994. Description and composition of flaxseed. Pages 9–14 in: Flax Seed, Health, Nutrition and Functionality. The Flax Council of Canada. Winnipeg, MB, Canada. Hargis, P. S., and M. E. Van Elswyk, 1993. Manipulating the fatty acid composition of poultry meat and eggs for the health conscious consumer. World’s Poult Sci. J. 48: 251–264. Huang, Z. B., H. Leibovitz, C. M. Lee, and R. Millar, 1990. Effect of dietary fish oil on omega-3 fatty acid levels in chicken eggs and thigh flesh. J. Agric. Food Chem. 38: 743–747. Jensen, L. S., J. B. Allred, R. E. Fry, and J. McGinnis, 1958. Evidence for an unidentified factor necessary for maximum egg weight in chickens. J. Nutr. 65:219–223. Jiang, Z., D. U. Ahn, and J. S. Sim, 1991. Effects of feeding flax and two types of sunflower seeds on fatty acid composition of yolk lipid classes. Poultry Sci. 70:2467–2475. March, B. E., and C. MacMillan, 1990. Linolenic acid as a mediator of egg size. Poultry Sci. 69:634–639. National Research Council, 1994. Nutrient Requirements of Poultry. 9th rev. ed. National Academy Press, Washington, DC. SAS Institute, 1989. SAS/STAT Users Guide. Version 6, 4th ed. Vol. 1. SAS Institute Inc., Cary, NC. Scheideler, S. E., M. Beck, T. Brown, K. Mahmoud, and J. Douglas, 1994. Beneficial effects of dietary oats on layer production. Page 18 in: Nebraska Poultry Report. 94-259-A. Lincoln, NE. Scheideler, S. E., and G. W. Froning, 1996. The combined influence of dietary flaxseed variety, level, form, and storage conditions on egg production and composition among vitamin E-supplemented hens. Poultry Sci. 75: 1221–1226. Sell, J. L., S. H. Choo, and P. A. Kondra, 1968. Fatty acid composition of egg yolk and adipose tissue as influenced by dietary fat and strain of hen. Poultry Sci. 47:1296–1302. Shutze, J. V., L. S. Jensen, and J. McGinnis, 1958. Effect of different dietary lipids on egg size. Poultry Sci. 37:1242. (Abstr.)
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this study. When strains were given a more insoluble fiber source (oats), D strain hens responded to flax + oats diet with decreased yolk stearic acid and increased linolenic and oleic acids. The B strain showed an increase in yolk oleic acid and a decrease in linolenic acid on the flax + oats, whereas H strain hens showed no change in yolk fatty acid composition with either dietary treatment. The different strain responses to flax + oats on egg fatty acid profile indicates genetic difference in utilizing dietary fat sources and a potential fiber interaction with fat utilization. In the D strain, a combination of soluble fiber from flax mucilage and insoluble fiber from whole oats improved utilization of dietary fat and deposition of C18:3 in the egg. This result could have been due to improved gizzard and digestive function with added insoluble fiber. This interaction effect was not observed in the H strain and was the reverse in the B strain. Strain by diet interactions for egg yolk lipids and composition could be important in the construction of a modified fat egg. Certain strain and diet effects could be utilized to create a low lipid egg for the health-conscious consumer (Hargis and Van Elswyk, 1993). By feeding the D strain a high fiber diet (flax + oats), percentage yolk and total yolk lipids can be substantially reduced to produce a lower fat n-3 fatty acid enriched egg. Strain effects on yolk composition also indicate varying efficiencies of fatty acid metabolism and lipid store turnovers in the hens fed different types of diets.
(Key words: layer, flax, oats, fatty acids, yolk lipids) 1998 Poultry Science 77:192–196
although considerable amounts of docosapantoenoic and docosahexaenoic acids are also deposited (Aymond and Van Elswyk, 1995; Scheideler and Froning, 1996). Dietary fat has long been known to enhance egg weight (Jensen et al., 1958; Shutze et al., 1958), although the mechanism has remained obscure. It has been suggested that linoleic acid enhances synthesis of lipoproteins taken up by the developing yolk (March and MacMillan, 1990). Dietary oats have also been reported to increase egg weight and potential nutrient digestibility in laying hens (Scheideler et al., 1994). Dietary oats contain a substantial amount of oleic and stearic acids (NRC, 1994), which can potentially affect fatty acid utilization and yolk fatty acid deposition as documented by Sell et al. (1968). Dietary oats also contain an insoluble fiber hull compared to a more soluble type of fiber-mucilage in flax. It is hypothesized in this study that the insoluble fiber in whole oats would increase gizzard grinding and thereby enhance the flax fiber solubilization and early lipid and protein digestion. With the more recent advances in genetic selection, the
INTRODUCTION Flax is one of the most concentrated sources of unsaturated fatty acids available in natural feedstuffs for poultry (Caston and Leeson, 1990; Jiang et al., 1991). Common varieties of flax seed have very high concentrations of polyunsaturated fatty acids, especially alinolenic acid (Genser, 1994). Hens have a unique ability to deposit dietary lipid into the egg yolk, which makes the egg a potential source of unsaturated fatty acids (Huang et al., 1990; Jiang et al., 1991; Ferrier et al., 1992; Scheideler and Froning, 1996), and it is possible to modify the fatty acid composition of eggs through dietary manipulation (Caston and Leeson, 1990). n-3 fatty acid content of eggs can be significantly increased by feeding flax to laying hens (Caston and Lesson, 1990; Aymond and Van Elswyk, 1995). Studies show that the major n-3 polyunsaturated fatty acid deposited into egg yolks is linolenic acid, in the yolk triglyceride fraction,
Received for publication March 25, 1997. Accepted for publication October 7, 1997. 1To whom correspondence should [email protected]
be
addressed:
Abbreviation Key: B = Babcock B300 hens; D = DeKalb Delta hens; and H = Hy-Line W-36 hens.
192
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percentage albumin, which was greatest for D (61.2%) vs H (59.5%) and B (59.4%). Strain D had significantly lower total and percentage yolk lipids than the other two strains. Strain B eggs had more C16:0, but less C18:0 and C18:1 than D and H. No significant effect of strain on C18:2, C18:3, and C22:6 deposition was observed. Percentage C18:0 and C18:1 in the yolk was significantly affected by strain, diet, and strain × diet interaction. Dietary flax + oats increased C18:0 and C18:1 in all strains except H. A significant diet by strain interaction effect occurred such that C18:3 increased in D yolk but decreased in B yolk when flax + oats were fed. Deposition of C18:3 was greater at 58 wk (5.61%) than at 36 wk (2.52%) of age across all strains. Results from these trials indicate that strain, diet ,and age can affect yolk lipids and composition.
ABSTRACT A trial was conducted to study the effects of strain, age, and diet on egg production, egg composition, and yolk fatty acid incorporation. Three strains (six pens of eight hens per strain), [DeKalb Delta (D); Babcock B 300 (B); and Hy-Line W-36 (H)], were subjected to a 10% flax diet + oats from 30 to 50 wk of age. At 50 wk, hens were divided into two groups and one half were kept on flax + oats diets (three pens) or assigned to a second diet of flax – oats (three pens) to 60 wk of age. Eggs were collected at 36 and 58 wk of age for fatty acid and lipid analysis. Strain had an early effect (30 to 50 wk) on egg production with B (85.3) exceeding the other two strains D (81.0) and H (79.1). Strain D had greater feed consumption and egg weight than either B or H. Flax – oats increased percentage shell compared to flax + oats. Strain effect was significant for
193
STRAIN, AGE, AND DIETARY n-3 FATTY ACIDS AFFECTS EGG COMPOSITION TABLE 2. Strain effects on production variables (30 to 50 wk of age)
TABLE 1. Dietary composition and calculated analyses, Trial 2 Ingredients and nutrients
Diet 1
Diet 2 (%)
53.8 18.6 10.0 7.4 5.0 2.0 1.5 0.92 0.25 0.23 0.10 0.10 0.05 0.05
59.4 18.8 10.0 7.4 . . . 2.0 1.5 0.04 0.25 0.24 0.09 0.10 0.05 0.05
Babcock B300 DeKalb Delta Hy-Line W-36 SEM Probability Strain
Egg production
Feed consumption
Egg weight
Specific gravity
(%) 85.3a 81.1b 79.1b 2.52
(g/hen/d) 91.4a 99.1b 94.0a 1.53
(g) 57.0a 63.1b 56.8a 1.88
1.089 1.088 1.087 0.0008
0.05
0.05
0.05
NS
a,bMeans
within a column with no common superscript differ significantly (P < 0.05).
objective of these trials was to study fatty acid utilization by current popular White Leghorn layer strains.
weighed back daily. Feed wastage was accounted for by daily weighbacks and by not allowing excessive feed buildup in the troughs. Egg weight and specific gravity were determined each week on 1 d of egg production. Egg collection for fatty acid analysis was conducted at 35 (10 eggs per strain) and 58 wk of age (12 eggs per strain with 6 eggs per diet). Fatty acid composition of the eggs was determined by gas liquid chromatography (Froning et al., 1990). Egg components and total egg lipids (solvent extraction) were measured at the 58 wk of age on six eggs per treatment. All data were analyzed by ANOVA using the SAS General Linear Models procedures (SAS Institute, 1989) testing for main (strain, age, and diet) and interaction (strain by diet and age by strain) effects. Weekly data (egg production, feed consumption, egg weight, and specific gravity) were analyzed as repeated measures by the General Linear Models procedure (SAS Institute, 1989).
MATERIALS AND METHODS
RESULTS
A total of 144 hens from three strains (48 per strain), Babcock B300 (B), DeKalb Delta (D), and Hy-Line W-36 (H), were fed a diet containing 10% flax with dietary oats (Diet 1) (Table 1) beginning at 30 wk of age. The birds were randomly assigned to six pens per strain with eight birds in each pen (387 cm2 per bird). The pens were 60 × 52 cm with 60 cm linear feeding space, allowing 7.5 cm trough space per hen. The dietary treatment was fed for 20 wk. At 50 wk of age, the same three strains of hens were divided into two groups (three pens per diet) with one group staying on Diet 1 (flax + oats) and the other group fed Diet 2 (flax – oats) to 60 wk of age. Hens were reassigned to smaller pens (562 cm2 per bird) that were 45 × 50 cm with 45 cm linear feeding space, allowing 11.3 cm trough space per hen. Diet compositions are shown in Table 1. Hens were given ad libitum access to feed and one nipple drinker per pen. Eggs were collected daily and the egg production calculated on a hen-day basis. Hens were given access to 115 g feed per bird per d and unconsumed feed was
Egg production (Table 2) was significantly higher for the B strain than for the H and D strains during the first 20 wk of the trial. At 50 wk of age, when the hens went on the two different diets, egg production was significantly less (P < 0.05) for hens on flax + oats than for those on flax – oats (Table 3), however the strain effect was no longer significant. At 50 wk of age, hens were transferred to different cages allowing more floor space per hen (562 cm2 compared to 387 cm2) and trough space (11.3 cm compared to 7.5 cm). Strain effect was significant (P < 0.01) for feed consumption (Tables 2 and 3) throughout the trial and was higher for D hens than for B and H hens. There was a significant diet by strain interaction for feed consumption, in which D hens decreased consumption rate when fed flax + oats compared to flax – oats; whereas B hens consumed less feed when oats were taken out of the ration. Egg weights were significantly different for the three strains (P < 0.05 and P < 0.01) throughout the trial, (Tables 2 and 3) with D hens producing heavier eggs than H and B hens. A significant strain by diet interaction for egg weight showed improvements in B and D but not in H
16.00 0.70 0.92 2,850 6.95 1.18 0.04 0.70 3.99 2.67 1.68
16.00 0.70 0.92 2,850 6.07 0.95 0.0034 0.54 3.57 2.67 1.68
1Vitamin
E premix provided an additional 50 IU/kg a-tocopherol. premix provided Mn, 88 mg; Cu, 6.6 mg; Fe, 8.5 mg; Zn, 88 mg; Se, 0.30 mg; vitamin A, 6,600 IU; cholecalciferol, 2,805 IU; vitamin E, 10 IU; vitamin K, 2.0 mg; riboflavin, 4.4 mg; pantothenic acid, 6.6 mg; niacin, 24.2 mg; choline, 110 mg; vitamin B12, 8.8 mg; ethoxyquin, 1.1 mg/kg. 2Vitamin/mineral
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Corn Soybean meal Flax Limestone Oats Oyster shell Dicalcium phosphate Tallow Vitamin E premix1 Salt Methionine Vitamin/mineral premix2 Choline chloride Grit Nutrients Protein Methionine + cystine Lysine ME, kcal/kg Ether extract C16:0 C16:1 C18:0 C18:1 C18:2 C18:3
Strain
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SCHEIDELER ET AL. TABLE 3. Strain effects on production variables (50 to 60 wk of age)
Strain
Diet
Babcock B300
Flax Flax Flax Flax Flax Flax
DeKalb Delta Hy-Line W-36
+ – + – + –
oats oats oats oats oats oats
SEM Probabilities Strain Diet Strain × diet
Egg production
Feed consumption
Egg weight
Specific gravity
(%) 75.6 80.5 79.6 85.6 79.3 87.0 2.45
(g/hen/d) 101.6 94.9 104.3 107.2 99.8 100.7 0.88
(g) 59.5 58.2 66.2 64.0 58.8 60.8 0.39
1.087 1.089 1.086 1.087 1.086 1.087 0.0005
NS 0.05 NS
0.01 NS 0.01
0.01 NS 0.05
NS 0.05 NS
5). Palmitic acid was higher in the B strain than in D and H strains, only at 36 wk of age. Stearic acid (C18:0) deposition was lower in B and D strains than in the H strain at 36 wk of age but this effect changed at 58 wk of age, when H eggs were low in C18:0. Deposition of oleic acid (C18:1) in the egg yolk was significantly affected by age, strain, diet, and diet by strain (P < 0.01). Oleic acid decreased from 36 to 58 wk of age and was greater in the H strain than in the D and B strains at 36 and 58 wk of age. There was a diet by strain effect on oleic acid in which there were significant decreases in B and D strains when fed flax + oats but no change in the H strain. Stearic acid (C18:0) also showed a significant diet by strain interaction, with D having increased levels when fed flax – oats compared to B and D strains. Neither strain nor diet had significant effects on linoleic and linolenic acid; however, age did show a positive effect on both linoleic and linolenic acid deposition in the egg. There was also a diet by strain interaction (P < 0.05) on linolenic acid; flax + oats improved linolenic acid deposition in D, compared to a negative effect in B and no change in H. There were no significant effects of diet or strain on linoleic acid, arachidonic acid, or docosahexaeonic acid in the egg. Age did significantly
TABLE 4. Effects on egg composition
Strain
Diet
Babcock B300
Flax Flax Flax Flax Flax Flax
Egg albumen
Egg yolk
Eggshell
Egg yolk lipids
Total yolk lipids
59.2 59.7 61.7 60.6 59.6 59.4 0.84
28.0 28.0 26.0 27.1 28.3 27.7 0.78
11.3 11.3 10.5 11.2 10.8 11.5 0.25
32.0 31.2 30.2 31.6 32.9 31.6 0.24
(g) 5.89 5.46 4.79 5.27 5.52 5.10 0.10
0.06 NS NS
NS NS NS
NS 0.05 NS
0.01 NS 0.01
0.01 NS 0.01
(%)
DeKalb Delta Hy-Line W-36 SEM Probabilities Strain Diet Strain × diet
+ – + – + –
oats oats oats oats oats oats
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hens when fed flax + oats compared to flax – oats (Table 3). Specific gravity significantly (P < 0.05) improved in eggs from hens fed flax – oats compared to flax + oats. There was no strain effect on egg specific gravity. Diet had no effect on percentage albumen or yolk (Table 4). Strain had a marked effect on percentage albumen, which was greater (P < 0.06) in strain D (61.2%) than in strain B (59.4%) or H (59.5%). Percentage eggshell was decreased in the D and H strains when oats were included in the flax diet compared to flax diets without oats. Deposition of total and percentage lipids in the yolk showed significant strain and strain by diet effects (Table 4). Percentage of yolk fat and total grams of yolk lipid were lower in eggs from the D strain than in those from the H or B strains (P < 0.05). Egg yolk lipids and percentage showed significant strain by diet interaction effects (P < 0.01). Egg yolk lipids increased in B and H when fed flax + oats compared to flax – oats, whereas in the D strain, the opposite effect of feeding flax + oats occurred, resulting in a reduction of yolk lipid. The strain effect on egg yolk fatty acid composition was significant for C16:0 (palmitic), C18:0 (stearic), and C18:1 (oleic) (P < 0.05) acids at both age intervals (Table
STRAIN, AGE, AND DIETARY n-3 FATTY ACIDS AFFECTS EGG COMPOSITION
195
increase the level of docosahexaeonic acid in the egg at 58 wk compared to 36 wk with no strain or diet effects. Eicosapentaenoic acid (C20:5) levels averaged less than 0.10% of the yolk fatty acids for all strains and diets and are therefore not reported in Table 4.
DISCUSSION
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The strain effect on feed consumption and egg weight is not unprecedented. Anderson (1994) reported, in the results of the 30th North Carolina Layer Performance and Management Test, increased feed consumption and egg mass production in the D strain compared to the H strain from 133 to 441 d of age. The findings in that study also showed that the B hens consumed more feed and produced more egg mass than the H or D hens, which was not consistent with the findings of this report. Anderson (1994) also reported an improved rate of lay in the B strain compared to D or H strain. In this research, an advantage for the B strain did occur to 50 wk of age only. After 50 wk of age, the eight hens were split into two groups and given more floor and feeder space per hen, which may have reduced stress and improved overall flock performance. Strain had a significant effect on percentage egg albumen, percentage egg yolk lipids, and total yolk lipid in this study with the D strain eggs having a larger proportion of white and less percentage yolk lipid and total lipids than eggs from the H or B strains. It appears that genetic selection for increased feed consumption and larger egg size in the D strain has resulted in more egg albumen and less yolk lipid compared to B and H at the same age. This difference provides an opportunity for the commercial egg producer to minimize egg yolk and associated lipids if desired in a designer egg. Diet significantly affected percentage eggshell, and egg specific gravity. Flax + oats caused a decline in shell quality, as measured by percentage eggshell and specific gravity. The negative effect of flax + oats compared to flax – oats on shell quality may be a result of the higher dietary fiber in these rations and potential interactions with calcium availability for shell formation. The effect of strain on yolk fatty acid profile has been previously demonstrated (Sell et al., 1968; Ahn et al., 1995) but not in today’s prolific strains of White Leghorns. As found almost 30 yr ago (Sell et al., 1968), strain of White Leghorn significantly affected proportion of palmitic, oleic, and stearic acids in the egg yolk. Significant strain effects were found in the present study for yolk palmitic, oleic, and stearic acids with B having more palmitic acid than the other two strains and H having more oleic and stearic acids than B and D strains at 36 wk. These strain results indicate genetic differences in dietary feed consumption and utilization and storage of dietary fats, with the H strain having perhaps more efficient utilization of dietary fat (oleic and stearic acids) than the B and D strains. The high level of palmitic acid in the B strain indicates more dependence on body lipid stores for egg yolk fatty acid deposition. Sell et al. (1968) also noted diet by strain interactions for fatty acid deposition, which was confirmed by the interactions in
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ACKNOWLEDGMENTS The authors would like to thank Lyle Robeson and Lynn Niemann for their technical support, and Minnie Stephens for preparing this manuscript.
REFERENCES Ahn, D. U., H. H. Sunwoo, F. H. Wolfe, and J. S. Sim, 1995. Effects of dietary a-linolenic acid and strain of hen on the fatty acid composition, storage stability and flavor characteristics of chicken eggs. Poultry Sci. 74:1540–1547. Anderson, K. E., 1994. Final Report of the 30th North Carolina Layer Performance and Management Test. North Carolina. Cooperative Extension Service, Department of Poultry Science, University of North Carolina, Raleigh, NC. Aymond, W. M., and M. E. Van Elswyk, 1995. Yolk thiobarbituric acid reactive substances and n-3 fatty acids
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this study. When strains were given a more insoluble fiber source (oats), D strain hens responded to flax + oats diet with decreased yolk stearic acid and increased linolenic and oleic acids. The B strain showed an increase in yolk oleic acid and a decrease in linolenic acid on the flax + oats, whereas H strain hens showed no change in yolk fatty acid composition with either dietary treatment. The different strain responses to flax + oats on egg fatty acid profile indicates genetic difference in utilizing dietary fat sources and a potential fiber interaction with fat utilization. In the D strain, a combination of soluble fiber from flax mucilage and insoluble fiber from whole oats improved utilization of dietary fat and deposition of C18:3 in the egg. This result could have been due to improved gizzard and digestive function with added insoluble fiber. This interaction effect was not observed in the H strain and was the reverse in the B strain. Strain by diet interactions for egg yolk lipids and composition could be important in the construction of a modified fat egg. Certain strain and diet effects could be utilized to create a low lipid egg for the health-conscious consumer (Hargis and Van Elswyk, 1993). By feeding the D strain a high fiber diet (flax + oats), percentage yolk and total yolk lipids can be substantially reduced to produce a lower fat n-3 fatty acid enriched egg. Strain effects on yolk composition also indicate varying efficiencies of fatty acid metabolism and lipid store turnovers in the hens fed different types of diets.