- Email: [email protected]
A Study of Selected Characteristics of Hens’ Egg Yolk.
1327
INTERMINGLED CAGING OF HENS
King, S. C , and D. F. Bray, 1959. Competition between strains of chickens in separate versus intermingled flocks. Poultry Sci. 38: 86-94. Marks, H. L., L. D. Tindell and R. H. Lowe, 1970. Performance of egg production stocks under three cage densities. Poultry Sci. 49: 1094-1100. McBride, G., 1962. The interactions between genotypes and housing environments in the domestic hen. Proc. Australian Soc. Anim. Prod. 4: 95-102.
A Study of Selected Characteristics of Hens' Egg Yolk. 3. INFLUENCE OF BREED, STRAIN, AND AGE OF BIRD1-2'3 P. VARADARAJULU4 AND F. E. CUNNINGHAM Dairy and Poultry Science Department, Kansas State University, Manhattan,
Kansas 66502
(Received for publication November 23, 1971)
ABSTRACT Two experiments were designed to study the influence of genetic and age differences on emulsifying capacity, viscosity, pH, and solids content of egg yolk. In the first experiment, eggs from two inbred lines of Brown and White Leghorn birds 30, 40, SO, and 75 weeks of age were used. Emulsion stability differed significantly (P < .01) by breed. Differences in viscosity, pH, and percent solids between the two breeds were not significant. Age of bird significantly (P < .05) affected yolk viscosity and emulsion stability. Yolk pH was not affected by age of bird. Yolk solids tended to increase with increased age. Emulsion stability, yolk viscosity, and solids content were significantly correlated (P < .01). In the second experiment, eggs from hens selected for high and low aggressiveness from White Leghorn and Rhode Island Red breeds were used to study the effect of social behavior on selected yolk characteristics. Less aggressive birds of R.I.R. breed produced yolks with greater emulsifying capacity than yolks from the more aggressive birds (P = 0.06). Percentage of yolk solids differed significantly (P < .01) between breeds, and the breed X strain interaction for viscosity was significant (P < .05). POULTRY SCIENCE 51: 1327-1331,
INTRODUCTION
G
ENETIC variation in chickens related to functional performance of egg yolk has not been reported. However information on differences in yolk composition by 1 Contribution No. 831, Department of Dairy and Poultry Sciences, Kansas Agricultural Experiment Station, Manhattan, Kansas 66502. 2 From a dissertation by the senior author submitted to the Graduate School of K.S.U. in partial fulfillment of the requirements for the Ph.D. degree. 3 Presented in part at the 60th annual meeting of the Poultry Science Association, University of Arkansas, Fayetteville, August, 1971. 4 Present address: College of Veterinary Science, Tirupati, A. P., India.
1972
breeds and strains is available (Edwards, 1964; Chen et al., 1965; Donaldson et al., 1965; Snell et al., 1968). Ion-exchange chromatography of egg yolk has revealed certain genetic differences in the fractions. Seideman and Cotterill (1969) and Cotterill et al. (1962) found that yolk percentages differed significantly between strains. However, differences in yolk solids among genetically different lines were not significant and varied little (Cotterill et al., 1962, and Marion et al., 1964). Selection for aggressiveness was shown to produce correlated responses in certain traits such as egg production and egg weight (Craig, 1968). Effect of age of hen or yield, composi-
Downloaded from http://ps.oxfordjournals.org/ at National Institute of Education Library, Serials Unit on May 30, 2015
mance and interactions of seven egg production stocks in three cage housing regimes. Poultry Sci. 45: 17-21. Jaap, R. G., 1954. Tests of laying ability in intermingled versus separate pens. Poultry Sci. 33 : 1061. James, J. W., and F. Foenander, 1961. Social behaviour studies on domestic animals. 1. Hens in laying cages. Australian J. Agri. Res. 12: 1239-1252.
1328
P. VARADAEAJULU AND F. E. CUNNINGHAM
MATERIALS AND METHODS
Eggs from two inbred lines of White and Brown Leghorn chickens of four age groups (30, 40, SO, and 75 weeks) were used in the first experiment to study the influence of breed and age in emulsifying capacity, viscosity, pH, and percent solids of egg yolk. All birds were housed in individual cages but received the same diet. Yolks from three eggs from each hen were collected and pooled for evaluation. All eggs were evaluated within four days of collec1
TABLE 1.--Effect
tion. Emulsion stability tests (Varadarajulu and Cunningham, 1972) employing an oil-in-water system were used to determine emulsifying capacity of yolk samples. Eggs from hens selected for high and low aggressiveness (Craig, 1968) from White Leghorn and Rhode Island Red breeds maintained at the Kansas State University Avery Research Center were used in a second experiment to test the influence of social behavior (aggressiveness) on selected yolk characteristics. All birds were the same age. They were housed in floor pens and fed identical rations. Four batches of 12 eggs from each of the four strains (high and low aggressive strains from W.L. and R.I.R. breeds) were randomly selected. Yolks were collected and pooled for each batch within each strain for evaluation. The yolks were blended and emulsion stability, pH, viscosity, and percent solids were determined according to methods described previously. Data were statistically analyzed (Snedecor and Cochran, 1967) to find the effect of breed, strain (high and low aggressiveness) and age of bird on selected yolk characteristics. Relationships among the characteristics were also statistically determined. RESULTS AND DISCUSSION Mean values with standard errors (Table 1) and analysis of variance (Table 2)
of breed and age on selected yolk characteristics Emulsion separation (ml.)
Viscosity (cp.s.)
Solids
(%)
after 60 min.
after 120 min.
Breed: B X . W.L.
2350*+172 1964*+ 170
53.33* + 0.175 52.89*±0.173
0.404» + 0.090 0.868 b ±0.089
1.425" ±0.137 2.293i> ±0.136
Age (wks.) 30 40 50 75
1784* ±174 1814»±154 2330 b ±283 27O0b±283
52.78*±0.178 53.01*±0.157 53.20"+ 0.185 53.43" ±0.389
0.844*±0.117 0.634"+ 0.104 0.716* + 0.122 0.350b ±0.158
2.302»±0.178 1.837" ±0.159 2.038"±0.186 1.260 b ±0.240
1
Means with standard errors. Means with the same superscript do not differ significantly ( P < .05).
Downloaded from http://ps.oxfordjournals.org/ at National Institute of Education Library, Serials Unit on May 30, 2015
tion, and quality of egg yolk has been studied (Cunningham et al, 1960; Lineweaver et al, 1962; Cotterill et al, 1962; Palafox, 1968). Cunningham et al. (1960) found that the season has less influence than age of the layer on relative yield of yolk. Lineweaver et al (1962) suggested that the performance characteristic of yolks does not decrease with age of the layer. Jordan et al (1962) studied the effect of diets supplemented with different kinds of fats on the emulsifying capacity of egg yolk. Few reports are available regarding functional properties of egg yolk as influenced by genetic and age differences of layers. Because egg yolk is one of the best natural emulsifying agents (Kilgore, 1935), we studied effects of breed, strain, and age on the emulsifying capacity, viscosity, pH and, solids content of egg yolk.
1329
HENS' EGG YOLK TABLE 2.—Analysis of variance for breed and age effect on viscosity percent solids and emulsion stability of yolk Mean Squares Emulsion separation
Source Solids
after 60 min.
after 120 min.
0.185 0.235* 0.183 0.073
0.968 0.389 0.141 0.303
2.001" 0.328 0.128 0.150
6.982" 1.479 0.603 0.345
" Highly significant ( P < . 0 1 ) . * Significant ( P < . 0 5 ) .
show that only emulsifying capacity was significantly (P < .01) affected by breed. Brown Leghorns produced yolks with emulsifying capacity twice that of White Leghorns (Fig. 1). Viscosity, pH, and percent solids did not differ significantly between the two breeds. Cotterill et al. (1962) and 1-5-1 White Leghorn Brown Leghorn
10
TABLE 3.—Correlation coefficients among age of the bird and selected yolk characteristics Emulsion separation V iscosity
40 50 Age (wks) FIG.
1. Effect of breed and age of the bird on emulsion stability of yolk.
Age Viscosity pH % solids Emulsion separation (60 min.)
0.339»
P«
solids
after 60 nun.
-0.268 - 0 . 1 7 5 0.302 0.127 0.716*' -0.519** -0.162 0.184 -0.523"
** Highly significant ( P < . 0 1 ) . •Significant ( P < . 0 5 ) .
after 120 min. -0.329* -0.625** -0.112 -0.647** 0.930**
Downloaded from http://ps.oxfordjournals.org/ at National Institute of Education Library, Serials Unit on May 30, 2015
Breed 1 Age 3 Breed XAge 3 Residual 33
Viscosity
Marion et al. (1964) also reported no significant differences in percent solids among genetically different strains of chickens. Chromatographic study of the yolk has revealed genetic differences in certain fractions, thought to be mostly phospholipids (Seideman and Cotterill, 1969). Such variation might have contributed to breed differences we observed in emulsifying abilities. Age of bird significantly (P < .05) affected viscosity and emulsifying capacity (Tables 1 and 2). A similar age effect on viscosity of yolks was shown by Lineweaver et al. (1962), who observed yolk viscosity somewhat greater in older (18-20 months) than in younger hens (7-8 months) but found yolk performance in layer and sponge cakes not influenced by age. We found pH of yolk not affected by age. Even though no significant affect of age on solids content was found, there was a trend toward increased solids with increased age (Table 1). A similar (but significant) influence of age on solids content was observed by Cotterill et al. (1962) although the effect was indirect through increased egg size. Data in Table 3 show that emulsion stability, viscosity, and percent solids of the yolk were correlated highly (P < .01). Viscosity of yolk has been reported as a function of solids content with spring and summer eggs producing more stable mayon-
1330
P. VARADARAJULU AND F. E.
CUNNINGHAM
TABLE S.—Analysis of variance for breed and strain (aggressiveness) effect Mean Squares Source
1 1 1
u
Emulsion separation Viscosity
% Solids
after 60 min.
after 120 min.
0.7225 0.3025 0.9025* 0.1583
2.504** 0.104 0.823
0.0022 0.315 0.0085 0.0087
0.0473 0.3052" 0.0976 0.0728
0.177
** Highly significant (P<.01). * Significant (1><.05). ' (P=0.06).
RIR
WLH
FIG. 2. Effect of high (H) and low (L) social dominance on emulsion stability of yolk.
naise due to higher solids (Romanoff and Romanoff, 1949). We found pH of yolk (within normal range) not associated with any other yolk characteristic studied. Two observations of yolk emulsion stability (separation after 60 TABLE 4.—Effect1 of high and low aggressiveness on yolk characteristics Emulsion separation
Strain Viscosity (c.p.s.)
Solids
(%)
After 60 min.
After 120 min.
R.I.R.
High Low
2450" 3950"
53.04" 53.66"
0.39" 0.26"
1.39" 0.96"
W.L.
High Low
2550" 2150"
52.71b 52.41b
0.37" 0.33"
1.34" 1.22"
.047
.135
Breed
I X 398 1
.21
Average of four replicates means with same superscript do not differ (P<.01).
and 120 min.) were closely related (r = 0.93). Effects of high and low aggressiveness in the two breeds (W.L. and R.I.R., second experiment) on emulsifying capacity, viscosity, pH, and solids content are shown in Table 4. Low social dominant strains in R.I.R. breed produced eggs whose yolks had greater (P = 0.06) emulsifying capacity than the high social dominant strains (Fig. 2). The difference between high and low strains was greater in the R.I.R. breed than in the W.L. breed. However, the reverse trend was observed in egg production (Craig, 1968; Craig and Toth, 1969). Solids content differed significantly (P < .01) between the two breeds; 53.35% in R.I.R. and 52.56% in W.L. breeds. Marion et al. (1964) observed that yolk solids varied least of the factors they studied. The difference in viscosity was not significant, but a significant (P < .05) breed X strain interaction was found for yolk viscosity; that is, the viscosity of egg yolk from the non aggressive strain was greater in R.I.R. and lower in W.L. breed than from the aggressive strain (Table 5). REFERENCES Chen, P. H., R. H. Common, N. Nikolaiczuk and H. F. MacRae, 1965. Some effects of added dietary fats on the lipid composition of hen's egg yolk. J. Food Sci. 30: 838-845. Cotterill, O. J., A. B. Stephenson and E. M. Funk, 1962. Factors affecting the yield of egg
Downloaded from http://ps.oxfordjournals.org/ at National Institute of Education Library, Serials Unit on May 30, 2015
Breed Strain BXS Residual
d.f.
1331
HENS' EGG YOLK
Lineweaver, H., J. J. Meehan, J. A. Garibaldi and L. Kline, 1962. Shell egg factors and egg product quality. Proc. Twelfth World's Poultry Congress, Sydney: 439-442. Marion, W. W., A. W. Nordskog, H. S. Tolman and R. H. Forsythe, 1964. Egg composition as influenced by breeding, egg size, age and season. Poultry Sci. 43 : 255-264. Palafox, A. L., 1968. Effect of age, energy source and concentration on yolk lipids and cholesterol. Poultry Sci. 47 : 1705. Romanoff, A. L., and A. J. Romanoff, 1949. The Avian Egg. John Wiley & Son, Inc., N. Y. Seideman, W. E., and O. J. Cotterill, 1969. Ion-exchange chromatography of egg yolk. 3. Species differences. Poultry Sci. 48: 900-903. Snell, 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. Snedecor, G. W., and W. G. Cochran, 1967. Statistical Methods. 6th ed. The Iowa State Univ. Press. Ames, Iowa. pp. 593. Varadarajulu, P., and F. E. Cunningham, 1972. A study of selected characteristics of hen's egg yolk 1. Influence of albumen and selected additives. Poultry Sci. 5 1 : 542-546.
NEWS AND NOTES (Continued from page 1322) Medicine, Louisiana State University, to establish a discretionary fund for the dean of the new school. WISCONSIN NOTES The Rector of the Institut Pertanian Bogor has appointed Dr. H. R. Bird as Honorary Professor of the Science of Poultry Nutrition in the Faculty of Animal Husbandry. Dr. Bird plans to be in Indonesia for the next year and a half. C.A.H.I. NOTES The Canadian Animal Health Institute, representing 42 member companies marketing animal health products, has the following officers: President—H. D. Sansom, Pitman-Moore Limited; Past President—W. G. Macaskill, Cyanamid of Canada Limited; Secretary-Treasurer—J. M. Roe, Tuco Products Company; Directors—J. D. Harvey, Delmar Chemicals Limited; T. Henderson, B.T.I. Products Limited; G. I. MacDonald, O. M. Franklin Serum Company; and A. J. MacKinnon, Salsbury Laboratories Limited.
P.I.M.Co. NOTES The officers of the Poultry Industry Manufacturers Council for 1972 are: President—G. B . Johnson, American Coolair Corporation, Jacksonville, Florida; First Vice President—W. G. McCollum, Cumberland Corporation, Chattanooga, Tennessee; Second Vice President—R. C. Hafer, Bramco Products, Canton, Georgia; and Treasurer— L. E. Gage, H. D. Hudson Manufacturing Co., Chicago, Illinois. James H. Ebbinghaus is Executive Director. NEW JERSEY NOTES John Bezpa, Extension Poultryman, Rutgers University, New Brunswick, was presented with the 1972 Golden Egg Award of the New Jersey poultry industry, at a dinner held during the New Jersey Farmers Week. K E N T FEED NOTES
Dr. Dan Smith has been appointed Poultry Feeds Product Manager for Kent Feeds Inc., Musca(Continued on page 1338)
Downloaded from http://ps.oxfordjournals.org/ at National Institute of Education Library, Serials Unit on May 30, 2015
products from shell eggs. Proc. Twelfth World's Poultry Congress, Sydney, Australia: 443-447. Craig, J. V., 1968. Correlated responses in body weight and egg production traits in chickens selected for social dominance. Poultry Sci. 47: 1033-1035. Craig, J. V., and A. Toth, 1969. Productivity of pullets influenced by genetic selection for social dominance abillity and by stability of flock membership. Poultry Sci. 48: 1729-1736. Cunningham, F. E., 0. J. Cotterill and E. M. Funk, 1960. The effect of season and age of the bird on egg size, quality and yield. Poultry Sci. 39: 289-299. Donaldson, W. E., W. L. Blow and R. J. Monroe, 1965. Variations in egg fatty acid composition among several inbred lines and their crosses. Poultry Sci. 44: 136S. Edwards, H. M. Jr., 1964. The influence of breed and/or strain on the fatty acid composition of egg lipids. Poultry Sci. 43: 751-754. Jordan, R., G. E. Vail, J. C. Rogler and W. J. Stadelman, 1962. Further studies on eggs from hens on diets differing in fat content. Food Technol. 16: 118-120. Kilgore, L. B., 1935. Egg yolk makes mayonnasie. Food Inds. 7 : 229-230.
INTERMINGLED CAGING OF HENS
King, S. C , and D. F. Bray, 1959. Competition between strains of chickens in separate versus intermingled flocks. Poultry Sci. 38: 86-94. Marks, H. L., L. D. Tindell and R. H. Lowe, 1970. Performance of egg production stocks under three cage densities. Poultry Sci. 49: 1094-1100. McBride, G., 1962. The interactions between genotypes and housing environments in the domestic hen. Proc. Australian Soc. Anim. Prod. 4: 95-102.
A Study of Selected Characteristics of Hens' Egg Yolk. 3. INFLUENCE OF BREED, STRAIN, AND AGE OF BIRD1-2'3 P. VARADARAJULU4 AND F. E. CUNNINGHAM Dairy and Poultry Science Department, Kansas State University, Manhattan,
Kansas 66502
(Received for publication November 23, 1971)
ABSTRACT Two experiments were designed to study the influence of genetic and age differences on emulsifying capacity, viscosity, pH, and solids content of egg yolk. In the first experiment, eggs from two inbred lines of Brown and White Leghorn birds 30, 40, SO, and 75 weeks of age were used. Emulsion stability differed significantly (P < .01) by breed. Differences in viscosity, pH, and percent solids between the two breeds were not significant. Age of bird significantly (P < .05) affected yolk viscosity and emulsion stability. Yolk pH was not affected by age of bird. Yolk solids tended to increase with increased age. Emulsion stability, yolk viscosity, and solids content were significantly correlated (P < .01). In the second experiment, eggs from hens selected for high and low aggressiveness from White Leghorn and Rhode Island Red breeds were used to study the effect of social behavior on selected yolk characteristics. Less aggressive birds of R.I.R. breed produced yolks with greater emulsifying capacity than yolks from the more aggressive birds (P = 0.06). Percentage of yolk solids differed significantly (P < .01) between breeds, and the breed X strain interaction for viscosity was significant (P < .05). POULTRY SCIENCE 51: 1327-1331,
INTRODUCTION
G
ENETIC variation in chickens related to functional performance of egg yolk has not been reported. However information on differences in yolk composition by 1 Contribution No. 831, Department of Dairy and Poultry Sciences, Kansas Agricultural Experiment Station, Manhattan, Kansas 66502. 2 From a dissertation by the senior author submitted to the Graduate School of K.S.U. in partial fulfillment of the requirements for the Ph.D. degree. 3 Presented in part at the 60th annual meeting of the Poultry Science Association, University of Arkansas, Fayetteville, August, 1971. 4 Present address: College of Veterinary Science, Tirupati, A. P., India.
1972
breeds and strains is available (Edwards, 1964; Chen et al., 1965; Donaldson et al., 1965; Snell et al., 1968). Ion-exchange chromatography of egg yolk has revealed certain genetic differences in the fractions. Seideman and Cotterill (1969) and Cotterill et al. (1962) found that yolk percentages differed significantly between strains. However, differences in yolk solids among genetically different lines were not significant and varied little (Cotterill et al., 1962, and Marion et al., 1964). Selection for aggressiveness was shown to produce correlated responses in certain traits such as egg production and egg weight (Craig, 1968). Effect of age of hen or yield, composi-
Downloaded from http://ps.oxfordjournals.org/ at National Institute of Education Library, Serials Unit on May 30, 2015
mance and interactions of seven egg production stocks in three cage housing regimes. Poultry Sci. 45: 17-21. Jaap, R. G., 1954. Tests of laying ability in intermingled versus separate pens. Poultry Sci. 33 : 1061. James, J. W., and F. Foenander, 1961. Social behaviour studies on domestic animals. 1. Hens in laying cages. Australian J. Agri. Res. 12: 1239-1252.
1328
P. VARADAEAJULU AND F. E. CUNNINGHAM
MATERIALS AND METHODS
Eggs from two inbred lines of White and Brown Leghorn chickens of four age groups (30, 40, SO, and 75 weeks) were used in the first experiment to study the influence of breed and age in emulsifying capacity, viscosity, pH, and percent solids of egg yolk. All birds were housed in individual cages but received the same diet. Yolks from three eggs from each hen were collected and pooled for evaluation. All eggs were evaluated within four days of collec1
TABLE 1.--Effect
tion. Emulsion stability tests (Varadarajulu and Cunningham, 1972) employing an oil-in-water system were used to determine emulsifying capacity of yolk samples. Eggs from hens selected for high and low aggressiveness (Craig, 1968) from White Leghorn and Rhode Island Red breeds maintained at the Kansas State University Avery Research Center were used in a second experiment to test the influence of social behavior (aggressiveness) on selected yolk characteristics. All birds were the same age. They were housed in floor pens and fed identical rations. Four batches of 12 eggs from each of the four strains (high and low aggressive strains from W.L. and R.I.R. breeds) were randomly selected. Yolks were collected and pooled for each batch within each strain for evaluation. The yolks were blended and emulsion stability, pH, viscosity, and percent solids were determined according to methods described previously. Data were statistically analyzed (Snedecor and Cochran, 1967) to find the effect of breed, strain (high and low aggressiveness) and age of bird on selected yolk characteristics. Relationships among the characteristics were also statistically determined. RESULTS AND DISCUSSION Mean values with standard errors (Table 1) and analysis of variance (Table 2)
of breed and age on selected yolk characteristics Emulsion separation (ml.)
Viscosity (cp.s.)
Solids
(%)
after 60 min.
after 120 min.
Breed: B X . W.L.
2350*+172 1964*+ 170
53.33* + 0.175 52.89*±0.173
0.404» + 0.090 0.868 b ±0.089
1.425" ±0.137 2.293i> ±0.136
Age (wks.) 30 40 50 75
1784* ±174 1814»±154 2330 b ±283 27O0b±283
52.78*±0.178 53.01*±0.157 53.20"+ 0.185 53.43" ±0.389
0.844*±0.117 0.634"+ 0.104 0.716* + 0.122 0.350b ±0.158
2.302»±0.178 1.837" ±0.159 2.038"±0.186 1.260 b ±0.240
1
Means with standard errors. Means with the same superscript do not differ significantly ( P < .05).
Downloaded from http://ps.oxfordjournals.org/ at National Institute of Education Library, Serials Unit on May 30, 2015
tion, and quality of egg yolk has been studied (Cunningham et al, 1960; Lineweaver et al, 1962; Cotterill et al, 1962; Palafox, 1968). Cunningham et al. (1960) found that the season has less influence than age of the layer on relative yield of yolk. Lineweaver et al (1962) suggested that the performance characteristic of yolks does not decrease with age of the layer. Jordan et al (1962) studied the effect of diets supplemented with different kinds of fats on the emulsifying capacity of egg yolk. Few reports are available regarding functional properties of egg yolk as influenced by genetic and age differences of layers. Because egg yolk is one of the best natural emulsifying agents (Kilgore, 1935), we studied effects of breed, strain, and age on the emulsifying capacity, viscosity, pH and, solids content of egg yolk.
1329
HENS' EGG YOLK TABLE 2.—Analysis of variance for breed and age effect on viscosity percent solids and emulsion stability of yolk Mean Squares Emulsion separation
Source Solids
after 60 min.
after 120 min.
0.185 0.235* 0.183 0.073
0.968 0.389 0.141 0.303
2.001" 0.328 0.128 0.150
6.982" 1.479 0.603 0.345
" Highly significant ( P < . 0 1 ) . * Significant ( P < . 0 5 ) .
show that only emulsifying capacity was significantly (P < .01) affected by breed. Brown Leghorns produced yolks with emulsifying capacity twice that of White Leghorns (Fig. 1). Viscosity, pH, and percent solids did not differ significantly between the two breeds. Cotterill et al. (1962) and 1-5-1 White Leghorn Brown Leghorn
10
TABLE 3.—Correlation coefficients among age of the bird and selected yolk characteristics Emulsion separation V iscosity
40 50 Age (wks) FIG.
1. Effect of breed and age of the bird on emulsion stability of yolk.
Age Viscosity pH % solids Emulsion separation (60 min.)
0.339»
P«
solids
after 60 nun.
-0.268 - 0 . 1 7 5 0.302 0.127 0.716*' -0.519** -0.162 0.184 -0.523"
** Highly significant ( P < . 0 1 ) . •Significant ( P < . 0 5 ) .
after 120 min. -0.329* -0.625** -0.112 -0.647** 0.930**
Downloaded from http://ps.oxfordjournals.org/ at National Institute of Education Library, Serials Unit on May 30, 2015
Breed 1 Age 3 Breed XAge 3 Residual 33
Viscosity
Marion et al. (1964) also reported no significant differences in percent solids among genetically different strains of chickens. Chromatographic study of the yolk has revealed genetic differences in certain fractions, thought to be mostly phospholipids (Seideman and Cotterill, 1969). Such variation might have contributed to breed differences we observed in emulsifying abilities. Age of bird significantly (P < .05) affected viscosity and emulsifying capacity (Tables 1 and 2). A similar age effect on viscosity of yolks was shown by Lineweaver et al. (1962), who observed yolk viscosity somewhat greater in older (18-20 months) than in younger hens (7-8 months) but found yolk performance in layer and sponge cakes not influenced by age. We found pH of yolk not affected by age. Even though no significant affect of age on solids content was found, there was a trend toward increased solids with increased age (Table 1). A similar (but significant) influence of age on solids content was observed by Cotterill et al. (1962) although the effect was indirect through increased egg size. Data in Table 3 show that emulsion stability, viscosity, and percent solids of the yolk were correlated highly (P < .01). Viscosity of yolk has been reported as a function of solids content with spring and summer eggs producing more stable mayon-
1330
P. VARADARAJULU AND F. E.
CUNNINGHAM
TABLE S.—Analysis of variance for breed and strain (aggressiveness) effect Mean Squares Source
1 1 1
u
Emulsion separation Viscosity
% Solids
after 60 min.
after 120 min.
0.7225 0.3025 0.9025* 0.1583
2.504** 0.104 0.823
0.0022 0.315 0.0085 0.0087
0.0473 0.3052" 0.0976 0.0728
0.177
** Highly significant (P<.01). * Significant (1><.05). ' (P=0.06).
RIR
WLH
FIG. 2. Effect of high (H) and low (L) social dominance on emulsion stability of yolk.
naise due to higher solids (Romanoff and Romanoff, 1949). We found pH of yolk (within normal range) not associated with any other yolk characteristic studied. Two observations of yolk emulsion stability (separation after 60 TABLE 4.—Effect1 of high and low aggressiveness on yolk characteristics Emulsion separation
Strain Viscosity (c.p.s.)
Solids
(%)
After 60 min.
After 120 min.
R.I.R.
High Low
2450" 3950"
53.04" 53.66"
0.39" 0.26"
1.39" 0.96"
W.L.
High Low
2550" 2150"
52.71b 52.41b
0.37" 0.33"
1.34" 1.22"
.047
.135
Breed
I X 398 1
.21
Average of four replicates means with same superscript do not differ (P<.01).
and 120 min.) were closely related (r = 0.93). Effects of high and low aggressiveness in the two breeds (W.L. and R.I.R., second experiment) on emulsifying capacity, viscosity, pH, and solids content are shown in Table 4. Low social dominant strains in R.I.R. breed produced eggs whose yolks had greater (P = 0.06) emulsifying capacity than the high social dominant strains (Fig. 2). The difference between high and low strains was greater in the R.I.R. breed than in the W.L. breed. However, the reverse trend was observed in egg production (Craig, 1968; Craig and Toth, 1969). Solids content differed significantly (P < .01) between the two breeds; 53.35% in R.I.R. and 52.56% in W.L. breeds. Marion et al. (1964) observed that yolk solids varied least of the factors they studied. The difference in viscosity was not significant, but a significant (P < .05) breed X strain interaction was found for yolk viscosity; that is, the viscosity of egg yolk from the non aggressive strain was greater in R.I.R. and lower in W.L. breed than from the aggressive strain (Table 5). REFERENCES Chen, P. H., R. H. Common, N. Nikolaiczuk and H. F. MacRae, 1965. Some effects of added dietary fats on the lipid composition of hen's egg yolk. J. Food Sci. 30: 838-845. Cotterill, O. J., A. B. Stephenson and E. M. Funk, 1962. Factors affecting the yield of egg
Downloaded from http://ps.oxfordjournals.org/ at National Institute of Education Library, Serials Unit on May 30, 2015
Breed Strain BXS Residual
d.f.
1331
HENS' EGG YOLK
Lineweaver, H., J. J. Meehan, J. A. Garibaldi and L. Kline, 1962. Shell egg factors and egg product quality. Proc. Twelfth World's Poultry Congress, Sydney: 439-442. Marion, W. W., A. W. Nordskog, H. S. Tolman and R. H. Forsythe, 1964. Egg composition as influenced by breeding, egg size, age and season. Poultry Sci. 43 : 255-264. Palafox, A. L., 1968. Effect of age, energy source and concentration on yolk lipids and cholesterol. Poultry Sci. 47 : 1705. Romanoff, A. L., and A. J. Romanoff, 1949. The Avian Egg. John Wiley & Son, Inc., N. Y. Seideman, W. E., and O. J. Cotterill, 1969. Ion-exchange chromatography of egg yolk. 3. Species differences. Poultry Sci. 48: 900-903. Snell, 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. Snedecor, G. W., and W. G. Cochran, 1967. Statistical Methods. 6th ed. The Iowa State Univ. Press. Ames, Iowa. pp. 593. Varadarajulu, P., and F. E. Cunningham, 1972. A study of selected characteristics of hen's egg yolk 1. Influence of albumen and selected additives. Poultry Sci. 5 1 : 542-546.
NEWS AND NOTES (Continued from page 1322) Medicine, Louisiana State University, to establish a discretionary fund for the dean of the new school. WISCONSIN NOTES The Rector of the Institut Pertanian Bogor has appointed Dr. H. R. Bird as Honorary Professor of the Science of Poultry Nutrition in the Faculty of Animal Husbandry. Dr. Bird plans to be in Indonesia for the next year and a half. C.A.H.I. NOTES The Canadian Animal Health Institute, representing 42 member companies marketing animal health products, has the following officers: President—H. D. Sansom, Pitman-Moore Limited; Past President—W. G. Macaskill, Cyanamid of Canada Limited; Secretary-Treasurer—J. M. Roe, Tuco Products Company; Directors—J. D. Harvey, Delmar Chemicals Limited; T. Henderson, B.T.I. Products Limited; G. I. MacDonald, O. M. Franklin Serum Company; and A. J. MacKinnon, Salsbury Laboratories Limited.
P.I.M.Co. NOTES The officers of the Poultry Industry Manufacturers Council for 1972 are: President—G. B . Johnson, American Coolair Corporation, Jacksonville, Florida; First Vice President—W. G. McCollum, Cumberland Corporation, Chattanooga, Tennessee; Second Vice President—R. C. Hafer, Bramco Products, Canton, Georgia; and Treasurer— L. E. Gage, H. D. Hudson Manufacturing Co., Chicago, Illinois. James H. Ebbinghaus is Executive Director. NEW JERSEY NOTES John Bezpa, Extension Poultryman, Rutgers University, New Brunswick, was presented with the 1972 Golden Egg Award of the New Jersey poultry industry, at a dinner held during the New Jersey Farmers Week. K E N T FEED NOTES
Dr. Dan Smith has been appointed Poultry Feeds Product Manager for Kent Feeds Inc., Musca(Continued on page 1338)
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products from shell eggs. Proc. Twelfth World's Poultry Congress, Sydney, Australia: 443-447. Craig, J. V., 1968. Correlated responses in body weight and egg production traits in chickens selected for social dominance. Poultry Sci. 47: 1033-1035. Craig, J. V., and A. Toth, 1969. Productivity of pullets influenced by genetic selection for social dominance abillity and by stability of flock membership. Poultry Sci. 48: 1729-1736. Cunningham, F. E., 0. J. Cotterill and E. M. Funk, 1960. The effect of season and age of the bird on egg size, quality and yield. Poultry Sci. 39: 289-299. Donaldson, W. E., W. L. Blow and R. J. Monroe, 1965. Variations in egg fatty acid composition among several inbred lines and their crosses. Poultry Sci. 44: 136S. Edwards, H. M. Jr., 1964. The influence of breed and/or strain on the fatty acid composition of egg lipids. Poultry Sci. 43: 751-754. Jordan, R., G. E. Vail, J. C. Rogler and W. J. Stadelman, 1962. Further studies on eggs from hens on diets differing in fat content. Food Technol. 16: 118-120. Kilgore, L. B., 1935. Egg yolk makes mayonnasie. Food Inds. 7 : 229-230.