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Quality Characteristics of Eggs From Different Strains of Hens as Related to Time of Oviposition1
EDUCATION AND PRODUCTION Quality Characteristics of Eggs From Different Strains of Hens as Related to Time of Oviposition1 A. S. ARAFA, R. H. HARMS, R. D. MILES, R. B. CHRISTMAS, and J. H. CHOI Department of Poultry Science, Florida Agricultural Experiment Station, Gainesville, Florida 32611 (Received for publication November 5, 1980)
1982 Poultry Science 61:842-847
INTRODUCTION Studies concerning t h e p r o p o r t i o n s of c o m p o n e n t s of t h e egg are of particular interest t o processors wanting t o alter t h e relative yield of yolk and a l b u m e n . In an early s t u d y , Olsson ( 1 9 3 6 ) r e p o r t e d t h a t pullets coming i n t o prod u c t i o n laid eggs with a lower p r o p o r t i o n of y o l k and a higher p r o p o r t i o n of a l b u m e n as c o m p a r e d t o eggs laid b y older birds. This finding was confirmed b y C u n n i n g h a m et al. ( 1 9 6 0 ) w h o r e p o r t e d t h a t t h e relative a m o u n t of albumen t o y o l k per egg was n o t influenced by t h e seasons of t h e year, b u t t h a t as t h e birds aged t h e p e r c e n t of y o l k per egg increased. Hafez et al. ( 1 9 5 5 ) t a b u l a t e d t h e p r o p o r tions of egg c o m p o n e n t s from different breeds of chicken and indicated t h a t breed differences were m o r e m a r k e d in t h e egg weight t h a n in p r o p o r t i o n s of c o m p o n e n t s . These a u t h o r s also reported t h a t yolk percentage increased while a l b u m e n percentage decreased in eggs laid by F a y o m i pullets during the first year of laying. Shell percentage, however, remained c o n s t a n t
1 Florida Agricultural Experiment Station Journal No. 2695.
as p r o d u c t i o n p r o c e e d e d . It has also been rep o r t e d t h a t individual hens p r o d u c e eggs of different c o m p o s i t i o n (Jull, 1 9 2 4 ; Cotterill and Winter, 1 9 5 4 ; Smith et al, 1 9 5 4 ) . Marion et al. ( 1 9 6 4 ) found significant difference in egg weights of albumen, y o l k and shell from three lines of White Leghorns. Since egg size was correlated with m o s t factors, t h e y concluded t h a t m o s t of t h e genetic variation in c o m p o n e n t s was covariation with egg size. Scott and Warren ( 1 9 4 1 ) also presented evidence t h a t egg c o m p o s i t i o n was influenced by egg weight. Shell thickness also appears t o vary with season and t h e age of t h e h e n s (Romanoff and Romanoff, 1949). Marion et al. ( 1 9 6 4 ) r e p o r t e d t h a t hens in their second year of p r o d u c t i o n laid eggs with .7% less shell and . 5 % m o r e yolk as c o m p a r e d with eggs laid during their first year. In contrast, Mueller et al. ( 1 9 6 0 ) observed a significant increase in shell thickness during t h e second year of p r o d u c t i o n w h e n compared with shell thickness during t h e pullet year, b u t these a u t h o r s indicated t h a t this increase was p r o b ably caused by e n v i r o n m e n t a l factors and n o t by aging. Although it is evident t h a t egg characteristics are influenced b y season and age of bird,
842
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ABSTRACT Two experiments were conducted to determine if time of oviposition would affect characteristics of eggs from five different strains of commercial type laying hens. A corn-soybean meal type diet containing 17% protein, 3.5% calcium, and .75% total phosphorus was fed. Eggs were collected at 2-hr intervals beginning at 0600 hr with each egg individually identified. Egg weight, yolk weight, albumen weight, shell weight, and shell thickness of each egg were measured, and die percentage of the components was calculated. Hens laid the heaviest eggs between 0600 and 0800 hr. Egg weights decreased gradually during the day while yolk weights decreased after 1000 hr. Shell weights, thickness, and percent were somewhat higher in eggs laid in the early morning, decreased slightly for eggs laid between 1000 and 1200 hr, and increased for eggs laid in the afternoon. Albumen weight and albumen percentage decreased during the day in Experiment 2 but increased slighdy later in the afternoon in Experiment 1. Significant differences were found among different strains of hens for all parameters, except in shell thickness of eggs from the older hens. (Key words: quality, eggs, strains, oviposition)
QUALITY CHARACTERISTICS OF EGGS
MATERIALS AND METHODS A corn-soybean meal type laying diet containing 17% protein, 3.5% calcium, and .75% total phosphorus was fed ad libitum to a total of 3600 hens in two experiments. Birds at the Poultry Evaluation Center located in Chipley, FL were housed in a cage-type house contain-
ing two rows of stair step cages located on either side of a concrete aisle. Birds were housed 2 per 25.0 X 45.7 cm cage. Fifteen hours of continuous natural and artificial lighting was furnished each day. Experiment 1 was conducted in late December and Experiment 2 in March of the following year using the same strains and housing conditions. One day's eggs were collected at 2-hr intervals beginning at 0600 and ending at 1800 hr. Efforts were made to insure that all eggs laid the previous day were removed. Each egg was individually identified according to the time of oviposition and the strain involved. Five different laying hen strains were used. Those strains were: Hisex (Hisex), Carries Nick310 (C-Nick), Ideal-236, H & N Nick Chick (H & N), and Shaver 288 (Shaver). Eighteen replicates of 20 birds in each strain were used. The layers were 52 weeks of age in the first experiment and 64 weeks of age in the second. Measurements of Egg Characteristics. Eggs were transported from the University of Florida Poultry Evaluation Center at Chipley to the Poultry Science Department at Gainesville where egg analysis was conducted. The individual weight of eggs was recorded, then subsequently each egg was broken out. Egg yolk and albumen were carefully separated. Further separation of the chalazae from the yolk was made by carefully rolling the yolk several times on a moistened paper towel. Yolk weight and shell weight of each egg were then recorded. Egg shell weights included the shell membrane. Albumen weight was calculated by subtracting yolk and shell weight from egg weight. A top loading Mettler balance was used for all weights, which were measured to the nearest
TABLE 1. Egg, yolk, and albumen weight(grams) of eggs collected from five strains of commercial laying hensat 52 and 64 weeks of age Egg weight Time of oviposition 0600 0800 10001200 1400 1600 -
0800 1000 1200 1400 1600 1800
hr hr hr hr hr hr
Yolk weight
Albumen weight
52 wk hens
64 wk hens
52 wk hens
64 wk hens
52 wk hens
64 wk hens
65.3 a 63.8 b 62.9cd 61.6 d 63.1bc
67.8 a 66.6 a 64.1bc 65.2 a c 63.0 b 61.0 b
17.8 a 18.6 b 18.1 c 17. l d 16.9 d
21.5 a 21. l a 20.5 b 20.6 a b 20.3 b 20.0 b
41.6 a 39.3bc 38.8 b 38.5 b 40.0 a c
40.7 a 40.0 a 38.4 b c 39.3ac 37.3bd 35.7 d
Means within a column with different superscripts are significantly different (P<.05).
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information is limited on the influence of time of oviposition on egg characteristics. Funk (1934) reported that hatchability of eggs laid in the afternoon was significantly higher than that of eggs laid in the morning. Washburn and Potts (1975) observed a pattern of relatively lower shell strength in eggs collected at 1000 hr with an increase in quality of eggs collected at 1200, 1400, and 1600 hr for all measures of shell strength as well as egg weight. They also observed no consistent significant differences between strains and time of oviposition. In a study conducted to determine the influence of time of oviposition and egg weight on egg specific gravity, Roland and Harms (1974) indicated that time of oviposition was related to specific gravity and egg weight. Eggs laid in the afternoon weighed less and had a higher specific gravity than did eggs laid in the morning. They concluded that egg weight was not responsible for the change in the specific gravity observed. Cipera (1976) confirmed that eggs laid in the afternoon had higher specific gravities than those laid in the morning and concluded that the evident cause was the increase in thickness of the egg shell and of its mass relative to egg size. This study was conducted to determine if oviposition time would influence egg characteristics from five different strains of hens.
843
844
ARAFA ET AL. TABLE 2. Egg, yolk, and albumen weight (grams) of eggs collected from five strains of commercial laying bens at 52 and 64 weeks of age Yolk weight
Egg weight
Albumen weight
Strain
52 wk hens
64 wk hens
52 wk hens
64 wk hens
52 wk hens
64 wk hens
Hisex C-Nick Ideal H&N Shaver
62.3 a 61.9 a 65.6 b 60.2 C 66.7 b
63.6 a b 62.6 a 66.0bc 64.3ab 66.6 C
17.7 a b 17.8 a b 18.1 b 17.3 a 17.6 a b
20.5ab 20.4 b 21.3 a 20.6 a b 20.5ab
38.8a 38.3 a 41.4 b 37.0 d 42.6 C
37.9 a b 36.8b 39.2 a 38.3 a b 40.6 C
a,b,c;Means within a column with different superscripts are significantly different (P<.05).
RESULTS AND DISCUSSION Hens laid the heaviest eggs during the period of 0600 to 0800 hr (Table 1). Egg weights gradually decreased during the later periods of the day. Data collected from Experiment 1 (younger hens) indicated a statistically significant difference of 2.2 g between eggs laid early in the morning hours (0600 to 0800 hr) and those laid late in the afternoon hours (1400 to 1800 hr). This difference was greater with the older hens in Experiment 2 (6.8 g for eggs laid 0600 to 0800 hr as compared to those laid 1600 to 1800 hr). However, regardless of the time of oviposition, Shaver and Ideal hens laid the heaviest eggs, averaging 66.7 and 65.6 g in Experiment 1 and 66.6 and 66.0 g in Experiment 2 (Table 2). It was also observed, regardless of the strain involved or time of oviposition, that older hens laid an average 1.28 g heavier egg when compared with younger hens. Egg yolks were significantly heavier for eggs
TABLE 3. Percent albumen, percent yolk, and percent egg shell of eggs collected from five different strains of commercial laying bens at 52 and 64 weeks of age Albumen
Yolk
Strain
52 wk hens
64 wk hens
52 wk hens
Hisex C-Nick Ideal H&N Shaver
62.ia 61.9ab 63.0 C 61.3 b 64.0 d
59.5a 58.7 a 59.3a 59.5a 60.9 b
28.4a 28.8 a 27.7b 28.9 a 26.5 C
Egg shell 64 wk hens
52 wk hens
64 wk hens
32.4a 32.8 a 32.3a 32.la 30.9 b
9.5a 9.4a 9.4a 9.8 b 9.5a
8.ia 8.5b 8.5b 8.4b 8.2a
(%)
'' Means within a column with different superscripts are significantly different (P<.05).
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.01 g. Egg shells were washed and allowed to dry at room temperature for 24 hr before egg shell thickness was measured in millimeters. Egg shell thickness did not include the shell membrane. Each egg shell thickness value reported in this study represents the average of five different measurements. Using the individual weight of each egg and the weights of its components, percent yolk, percent albumen, and percent shell were determined. Statistically weighed means were used in the strain comparison reported in this study. Data from both experiments were subjected to the analysis of variance and regression analysis according to methods described by Steel and Torrie (1961). Separation of the means was made using Duncan's new multiple range test (1955). Since no consistent significant strain X time interaction was found, only the main effect of time of oviposition and hen strains will be discussed in this report.
QUALITY CHARACTERISTICS OF EGGS
The albumen weight from eggs laid between 0600 to 0800 hr was 41.6 and 40.7 g for younger and older hens, respectively (Table 1). A gradual decline in albumen weight was
detected later in the day. Statistically significant differences were observed in albumen weights between the strains tested in Experiment 2, with Shaver hens having the heaviest albumen and C-Nick having the lightest, 40.6 and 36.8 g, respectively (Table 2). A similar trend was observed in Experiment 1; however, H & N hens laid eggs with the lowest albumen contents. These data do not agree with an earlier report by Hafez et al. (1955) who reported that breed differences were more marked in the egg weight than in the proportion of components. Again, as was observed with yolk, no significant difference in percent albumen was observed in eggs collected from Hisex, C-Nick, Ideal, and H & N (Table 3). Both young and old Shaver hens laid eggs with significantly higher percent albumen when compared with other strains tested. No consistent trend was observed for percent albumen from eggs laid during different times of day (Table 4). In fact, albumen percent decreased during the day in the first experiment while a slight increase was observed later in the afternoon in the second experiment. Contrary to the observation made earlier in this report concerning the differences in yolk contents between younger and older hens, albumen contents were 1.09 g heavier or 2.89 percentage points higher in eggs collected from the younger hens than in those collected from the older hens. Heavier shells were found on eggs laid by the older hens during the morning hours when compared with eggs laid in the afternoon and evening hours (Table 5). This difference was
TABLE 4. Percent albumen, percent yolk, and percent egg shell of eggs collected from five different strains of commercial laying hens at 52 and 64 weeks of age Albumen Time of oviposition
Egg shell
Yolk
52 wk hens
64 wk hens
63.5* 61.5 b 61.7 b 62.4 b 63.2 a
5 9 . 9 ab 599ab 59.8 a b 60.2 a 59.1bc 58.4 C
52 wk hens
64 wk hens
52 wk hens
64 wk hens
31.8 a b 31.8 a b 32.0 a b 31.6 a 32.4 b c 32.9 C
9.25 a 9.23 a 9.37 a 9.78 b 9.87 b
8.25abc 8.20 a b 8.13 a 8.17 a b c 8.52 b c 8.72 c
(%) 0600 0800 100012001400 1600-
0800 1000 1200 1400 1600 1800
hr hr hr hr hr hr
a
27.2 29.3 b 29.0 b 27.8 a 26.9 a
' ' Means within a column with different superscripts are significantly different (P<.05).
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laid early in the day (Table 1). Data also indicated that significant differences in yolk weight exist between different strains of hens regardless of their age (Table 2). Statistically significant differences (P<.05) were observed in percent yolk between the strains in Experiment 1 (Table 3). In the second experiment, however, a statistically significant difference in percent egg yolk was found for eggs from Hisex, CNick, Ideal, and H & N as compared to Shaver. Regardless of age, Shaver hens laid eggs with less percent yolk when compared with other strains in both experiments (Table 3). Regardless of the strain involved in this study, a difference of 1.5% in yolk proportion was detected between early morning and late afternoon eggs. This is interesting since data on the absolute weight of the yolk, as presented earlier in Table 1, showed morning eggs to have heavier egg yolk when compared with afternoon eggs. An explanation could be offered based on the fact that morning eggs were heavier than afternoon eggs. It is apparent, however, that the changes in egg weight as the time of day proceeds is not proportionally correlated to the changes in egg components. When the overall mean of yolk weight was compared for both experiments without regard to the strain effect or time of lay, eggs collected from older hens had a mean yolk weight 2.97 g greater (4.06%) when compared to mean yolk weight of eggs laid by younger hens.
845
846
ARAFA ET AL. TABLE 5. Eggshell weight (grams) and egg shell thickness (millimeters) of eggs collected from five strains of commercial laying hens at 52 and 64 weeks of age Egg shell weight
Time of oviposition 0600 0800 100012001400 1600-
0800 1000 1200 1400 1600 1800
hr hr hr hr hr hr
Egg shell thickness
52 wk hens
64 wk hens
52 wk hens
64 wk hens
6.04 a 5.88 a 5.87 a 6.03 a 6.23 c
5.58 a 5.46 a 5.21 b 5.33 a b 5.36 a b 5.32 a b
.364 a .361 a .361 a .377b .382 b
.325 a bc .3343b .322a .325 a b c .333 b c .341 c
a,b,cMeans within a column with different superscripts are significantly different (P-C.05).
Egg shell weight
Strain
52 wk hens
64 wk hens
52 wk hens
Hisex C-Nick Ideal H&N Shaver
5.92 a 5.78 a 6.12b 5.90 a 6.33b
5.14a 5.31 a 5.56 b 5.40 a b 5.48 a b
.368 a .362b .367ab .374 a c .375 c
Egg shell thickness 64 wk hens .325 a .330 a .333 a .328 a .325 a
' ' Means within a column with different superscripts are significantly different (P<.05).
not found for eggs laid by the 52-week-old hens. A gradual decline in shell weight was then observed at 1000 and 1200 hr, 5.88 and 5.87 g, respectively. This gradual decline was followed by a gradual increase in egg shell weight in the afternoon eggs. Percent shell, in both experiments, was higher for eggs collected in the afternoon (Table 4). The Ideal and Shaver hens maintained a heavier shell during the day (Table 6). Statistically significant differences in percent shell were observed between the Shaver and Hisex hens as compared to the rest of the strains tested in Experiment 2 (Table 3). Regardless of the strain involved or time of oviposition, younger hens laid eggs which were .63 g/egg heavier or had 1.17 percentage points higher shell weight when compared with eggs laid by older hens. Egg shell thickness significantly increased for eggs collected after 1200 hr in Experiment 1
and after 1600 hr in Experiment 2 (Table 5). This finding is in agreement with Roland and Harms (1974), Washburn and Potts (1975), and Cipera (1976), who reported that eggs laid in the afternoon have an average specific gravity greater than eggs laid in the morning. An average thicker shell was observed in the first experiment. This was expected since hens in the first experiment were younger than those in the second experiment. In the second experiment, numerically but not statistically significant differences were observed in egg shell thickness between strains (Table 6). It appears that the differences in shell thickness between different strains of laying hens will diminish as the hen ages. Significant interactions between time of oviposition and strains were found for yolk weight, percent yolk, and percent albumen of eggs collected from Experiment 1 (52-week-old hens). However, no interaction was found for
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TABLE 6. Egg shell weight (grams) and egg shell thickness (millimeters) of eggs collected from five different strains of commercial laying hens at 52 and 64 weeks of age
QUALITY CHARACTERISTICS OF EGGS
any of t h e egg characteristics tested in Experim e n t 2 (64-week-old hens). Based on t h e data o b t a i n e d in this s t u d y it was concluded t h a t significant differences in egg characteristics existed a m o n g t h e five strains tested.
REFERENCES
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. Mueller, W. J., A.J.G. Maw, and E. G. Buss, 1960. The influence of season and the age of layers on egg weight, shape index, albumen quality and shell thickness. Poultry Sci. 39:854-860. Olsson, N., 1936. Studies on some physical and physiological characters in hens' egg. Proc. World's Poultry Congr. 6:310-320. Roland, D. A., Sr., and R. H. Harms, 1974. Specific gravity of eggs in relation to egg weight and time of oviposition. Poultry Sci. 53:1494—1498. Romanoff, A. L., and A. J. Romanoff, 1949. The Avian Egg. John Wiley and Sons, Inc., New York, NY. Scott, H. M., and D. C. Warren, 1941. The relation of total weight and the weight of the component parts of the egg to hatching power. Poultry Sci. 20:75-78. Smith, A. H., W. O. Wilson, and J. G. Brown, 1954. Composition of eggs from individual hens maintained under controlled environments. Poultry Sci. 3 3:898-908. Steel, R.G.D., and J. H. Torrie, 1961. Principles and Procedures of Statistics. McGraw-Hill Book Co., Inc., New York, NY. Washburn, K. W., and P. L. Potts, 1975. Effect of strain and production age on the relationship of oviposition time to various shell strength characteristics. Poultry Sci. 54:1348.
Downloaded from http://ps.oxfordjournals.org/ at UCSF Library on April 29, 2015
Cipera, J. D., 1976. Effect of oviposition time and storage conditions on the specific gravities of eggs. Poultry Sci. 56:1132-1134. Cotterill, 0 . J., and A. R. Winter, 1954. Egg white lysozyme. I. Relative lysozyme activity in fresh eggs having low and high interior quality. Poultry Sci. 3 3 : 6 0 7 - 6 1 1 . Cunningham, F. E., O. J. Cotterill, and E. M. Funk, 1960. The effect of season and age of bird. 1. On egg size, quality, and yield. Poultry Sci. 39: 289-299. Duncan, D. B., 1955. New multiple range and multiple F tests. Biometrics 11:1—42. Funk, E. M., 1934. Relation of time of laying to hatchability. Poultry Sci. 13:184-187. Hafez, E.S.E., A. L. Badreldin, and G.A.R. Kamar, 1955. Egg components in the Fayomi fowl during the first laying year. Poultry Sci. 34:400— 410. Jull, M. A., 1924. Egg weight in relation to production. Part I. The relationship of the weights of the parts of the egg to the total egg weight. Poultry Sci. 3:77-88.
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1982 Poultry Science 61:842-847
INTRODUCTION Studies concerning t h e p r o p o r t i o n s of c o m p o n e n t s of t h e egg are of particular interest t o processors wanting t o alter t h e relative yield of yolk and a l b u m e n . In an early s t u d y , Olsson ( 1 9 3 6 ) r e p o r t e d t h a t pullets coming i n t o prod u c t i o n laid eggs with a lower p r o p o r t i o n of y o l k and a higher p r o p o r t i o n of a l b u m e n as c o m p a r e d t o eggs laid b y older birds. This finding was confirmed b y C u n n i n g h a m et al. ( 1 9 6 0 ) w h o r e p o r t e d t h a t t h e relative a m o u n t of albumen t o y o l k per egg was n o t influenced by t h e seasons of t h e year, b u t t h a t as t h e birds aged t h e p e r c e n t of y o l k per egg increased. Hafez et al. ( 1 9 5 5 ) t a b u l a t e d t h e p r o p o r tions of egg c o m p o n e n t s from different breeds of chicken and indicated t h a t breed differences were m o r e m a r k e d in t h e egg weight t h a n in p r o p o r t i o n s of c o m p o n e n t s . These a u t h o r s also reported t h a t yolk percentage increased while a l b u m e n percentage decreased in eggs laid by F a y o m i pullets during the first year of laying. Shell percentage, however, remained c o n s t a n t
1 Florida Agricultural Experiment Station Journal No. 2695.
as p r o d u c t i o n p r o c e e d e d . It has also been rep o r t e d t h a t individual hens p r o d u c e eggs of different c o m p o s i t i o n (Jull, 1 9 2 4 ; Cotterill and Winter, 1 9 5 4 ; Smith et al, 1 9 5 4 ) . Marion et al. ( 1 9 6 4 ) found significant difference in egg weights of albumen, y o l k and shell from three lines of White Leghorns. Since egg size was correlated with m o s t factors, t h e y concluded t h a t m o s t of t h e genetic variation in c o m p o n e n t s was covariation with egg size. Scott and Warren ( 1 9 4 1 ) also presented evidence t h a t egg c o m p o s i t i o n was influenced by egg weight. Shell thickness also appears t o vary with season and t h e age of t h e h e n s (Romanoff and Romanoff, 1949). Marion et al. ( 1 9 6 4 ) r e p o r t e d t h a t hens in their second year of p r o d u c t i o n laid eggs with .7% less shell and . 5 % m o r e yolk as c o m p a r e d with eggs laid during their first year. In contrast, Mueller et al. ( 1 9 6 0 ) observed a significant increase in shell thickness during t h e second year of p r o d u c t i o n w h e n compared with shell thickness during t h e pullet year, b u t these a u t h o r s indicated t h a t this increase was p r o b ably caused by e n v i r o n m e n t a l factors and n o t by aging. Although it is evident t h a t egg characteristics are influenced b y season and age of bird,
842
Downloaded from http://ps.oxfordjournals.org/ at UCSF Library on April 29, 2015
ABSTRACT Two experiments were conducted to determine if time of oviposition would affect characteristics of eggs from five different strains of commercial type laying hens. A corn-soybean meal type diet containing 17% protein, 3.5% calcium, and .75% total phosphorus was fed. Eggs were collected at 2-hr intervals beginning at 0600 hr with each egg individually identified. Egg weight, yolk weight, albumen weight, shell weight, and shell thickness of each egg were measured, and die percentage of the components was calculated. Hens laid the heaviest eggs between 0600 and 0800 hr. Egg weights decreased gradually during the day while yolk weights decreased after 1000 hr. Shell weights, thickness, and percent were somewhat higher in eggs laid in the early morning, decreased slightly for eggs laid between 1000 and 1200 hr, and increased for eggs laid in the afternoon. Albumen weight and albumen percentage decreased during the day in Experiment 2 but increased slighdy later in the afternoon in Experiment 1. Significant differences were found among different strains of hens for all parameters, except in shell thickness of eggs from the older hens. (Key words: quality, eggs, strains, oviposition)
QUALITY CHARACTERISTICS OF EGGS
MATERIALS AND METHODS A corn-soybean meal type laying diet containing 17% protein, 3.5% calcium, and .75% total phosphorus was fed ad libitum to a total of 3600 hens in two experiments. Birds at the Poultry Evaluation Center located in Chipley, FL were housed in a cage-type house contain-
ing two rows of stair step cages located on either side of a concrete aisle. Birds were housed 2 per 25.0 X 45.7 cm cage. Fifteen hours of continuous natural and artificial lighting was furnished each day. Experiment 1 was conducted in late December and Experiment 2 in March of the following year using the same strains and housing conditions. One day's eggs were collected at 2-hr intervals beginning at 0600 and ending at 1800 hr. Efforts were made to insure that all eggs laid the previous day were removed. Each egg was individually identified according to the time of oviposition and the strain involved. Five different laying hen strains were used. Those strains were: Hisex (Hisex), Carries Nick310 (C-Nick), Ideal-236, H & N Nick Chick (H & N), and Shaver 288 (Shaver). Eighteen replicates of 20 birds in each strain were used. The layers were 52 weeks of age in the first experiment and 64 weeks of age in the second. Measurements of Egg Characteristics. Eggs were transported from the University of Florida Poultry Evaluation Center at Chipley to the Poultry Science Department at Gainesville where egg analysis was conducted. The individual weight of eggs was recorded, then subsequently each egg was broken out. Egg yolk and albumen were carefully separated. Further separation of the chalazae from the yolk was made by carefully rolling the yolk several times on a moistened paper towel. Yolk weight and shell weight of each egg were then recorded. Egg shell weights included the shell membrane. Albumen weight was calculated by subtracting yolk and shell weight from egg weight. A top loading Mettler balance was used for all weights, which were measured to the nearest
TABLE 1. Egg, yolk, and albumen weight(grams) of eggs collected from five strains of commercial laying hensat 52 and 64 weeks of age Egg weight Time of oviposition 0600 0800 10001200 1400 1600 -
0800 1000 1200 1400 1600 1800
hr hr hr hr hr hr
Yolk weight
Albumen weight
52 wk hens
64 wk hens
52 wk hens
64 wk hens
52 wk hens
64 wk hens
65.3 a 63.8 b 62.9cd 61.6 d 63.1bc
67.8 a 66.6 a 64.1bc 65.2 a c 63.0 b 61.0 b
17.8 a 18.6 b 18.1 c 17. l d 16.9 d
21.5 a 21. l a 20.5 b 20.6 a b 20.3 b 20.0 b
41.6 a 39.3bc 38.8 b 38.5 b 40.0 a c
40.7 a 40.0 a 38.4 b c 39.3ac 37.3bd 35.7 d
Means within a column with different superscripts are significantly different (P<.05).
Downloaded from http://ps.oxfordjournals.org/ at UCSF Library on April 29, 2015
information is limited on the influence of time of oviposition on egg characteristics. Funk (1934) reported that hatchability of eggs laid in the afternoon was significantly higher than that of eggs laid in the morning. Washburn and Potts (1975) observed a pattern of relatively lower shell strength in eggs collected at 1000 hr with an increase in quality of eggs collected at 1200, 1400, and 1600 hr for all measures of shell strength as well as egg weight. They also observed no consistent significant differences between strains and time of oviposition. In a study conducted to determine the influence of time of oviposition and egg weight on egg specific gravity, Roland and Harms (1974) indicated that time of oviposition was related to specific gravity and egg weight. Eggs laid in the afternoon weighed less and had a higher specific gravity than did eggs laid in the morning. They concluded that egg weight was not responsible for the change in the specific gravity observed. Cipera (1976) confirmed that eggs laid in the afternoon had higher specific gravities than those laid in the morning and concluded that the evident cause was the increase in thickness of the egg shell and of its mass relative to egg size. This study was conducted to determine if oviposition time would influence egg characteristics from five different strains of hens.
843
844
ARAFA ET AL. TABLE 2. Egg, yolk, and albumen weight (grams) of eggs collected from five strains of commercial laying bens at 52 and 64 weeks of age Yolk weight
Egg weight
Albumen weight
Strain
52 wk hens
64 wk hens
52 wk hens
64 wk hens
52 wk hens
64 wk hens
Hisex C-Nick Ideal H&N Shaver
62.3 a 61.9 a 65.6 b 60.2 C 66.7 b
63.6 a b 62.6 a 66.0bc 64.3ab 66.6 C
17.7 a b 17.8 a b 18.1 b 17.3 a 17.6 a b
20.5ab 20.4 b 21.3 a 20.6 a b 20.5ab
38.8a 38.3 a 41.4 b 37.0 d 42.6 C
37.9 a b 36.8b 39.2 a 38.3 a b 40.6 C
a,b,c;Means within a column with different superscripts are significantly different (P<.05).
RESULTS AND DISCUSSION Hens laid the heaviest eggs during the period of 0600 to 0800 hr (Table 1). Egg weights gradually decreased during the later periods of the day. Data collected from Experiment 1 (younger hens) indicated a statistically significant difference of 2.2 g between eggs laid early in the morning hours (0600 to 0800 hr) and those laid late in the afternoon hours (1400 to 1800 hr). This difference was greater with the older hens in Experiment 2 (6.8 g for eggs laid 0600 to 0800 hr as compared to those laid 1600 to 1800 hr). However, regardless of the time of oviposition, Shaver and Ideal hens laid the heaviest eggs, averaging 66.7 and 65.6 g in Experiment 1 and 66.6 and 66.0 g in Experiment 2 (Table 2). It was also observed, regardless of the strain involved or time of oviposition, that older hens laid an average 1.28 g heavier egg when compared with younger hens. Egg yolks were significantly heavier for eggs
TABLE 3. Percent albumen, percent yolk, and percent egg shell of eggs collected from five different strains of commercial laying bens at 52 and 64 weeks of age Albumen
Yolk
Strain
52 wk hens
64 wk hens
52 wk hens
Hisex C-Nick Ideal H&N Shaver
62.ia 61.9ab 63.0 C 61.3 b 64.0 d
59.5a 58.7 a 59.3a 59.5a 60.9 b
28.4a 28.8 a 27.7b 28.9 a 26.5 C
Egg shell 64 wk hens
52 wk hens
64 wk hens
32.4a 32.8 a 32.3a 32.la 30.9 b
9.5a 9.4a 9.4a 9.8 b 9.5a
8.ia 8.5b 8.5b 8.4b 8.2a
(%)
'' Means within a column with different superscripts are significantly different (P<.05).
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.01 g. Egg shells were washed and allowed to dry at room temperature for 24 hr before egg shell thickness was measured in millimeters. Egg shell thickness did not include the shell membrane. Each egg shell thickness value reported in this study represents the average of five different measurements. Using the individual weight of each egg and the weights of its components, percent yolk, percent albumen, and percent shell were determined. Statistically weighed means were used in the strain comparison reported in this study. Data from both experiments were subjected to the analysis of variance and regression analysis according to methods described by Steel and Torrie (1961). Separation of the means was made using Duncan's new multiple range test (1955). Since no consistent significant strain X time interaction was found, only the main effect of time of oviposition and hen strains will be discussed in this report.
QUALITY CHARACTERISTICS OF EGGS
The albumen weight from eggs laid between 0600 to 0800 hr was 41.6 and 40.7 g for younger and older hens, respectively (Table 1). A gradual decline in albumen weight was
detected later in the day. Statistically significant differences were observed in albumen weights between the strains tested in Experiment 2, with Shaver hens having the heaviest albumen and C-Nick having the lightest, 40.6 and 36.8 g, respectively (Table 2). A similar trend was observed in Experiment 1; however, H & N hens laid eggs with the lowest albumen contents. These data do not agree with an earlier report by Hafez et al. (1955) who reported that breed differences were more marked in the egg weight than in the proportion of components. Again, as was observed with yolk, no significant difference in percent albumen was observed in eggs collected from Hisex, C-Nick, Ideal, and H & N (Table 3). Both young and old Shaver hens laid eggs with significantly higher percent albumen when compared with other strains tested. No consistent trend was observed for percent albumen from eggs laid during different times of day (Table 4). In fact, albumen percent decreased during the day in the first experiment while a slight increase was observed later in the afternoon in the second experiment. Contrary to the observation made earlier in this report concerning the differences in yolk contents between younger and older hens, albumen contents were 1.09 g heavier or 2.89 percentage points higher in eggs collected from the younger hens than in those collected from the older hens. Heavier shells were found on eggs laid by the older hens during the morning hours when compared with eggs laid in the afternoon and evening hours (Table 5). This difference was
TABLE 4. Percent albumen, percent yolk, and percent egg shell of eggs collected from five different strains of commercial laying hens at 52 and 64 weeks of age Albumen Time of oviposition
Egg shell
Yolk
52 wk hens
64 wk hens
63.5* 61.5 b 61.7 b 62.4 b 63.2 a
5 9 . 9 ab 599ab 59.8 a b 60.2 a 59.1bc 58.4 C
52 wk hens
64 wk hens
52 wk hens
64 wk hens
31.8 a b 31.8 a b 32.0 a b 31.6 a 32.4 b c 32.9 C
9.25 a 9.23 a 9.37 a 9.78 b 9.87 b
8.25abc 8.20 a b 8.13 a 8.17 a b c 8.52 b c 8.72 c
(%) 0600 0800 100012001400 1600-
0800 1000 1200 1400 1600 1800
hr hr hr hr hr hr
a
27.2 29.3 b 29.0 b 27.8 a 26.9 a
' ' Means within a column with different superscripts are significantly different (P<.05).
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laid early in the day (Table 1). Data also indicated that significant differences in yolk weight exist between different strains of hens regardless of their age (Table 2). Statistically significant differences (P<.05) were observed in percent yolk between the strains in Experiment 1 (Table 3). In the second experiment, however, a statistically significant difference in percent egg yolk was found for eggs from Hisex, CNick, Ideal, and H & N as compared to Shaver. Regardless of age, Shaver hens laid eggs with less percent yolk when compared with other strains in both experiments (Table 3). Regardless of the strain involved in this study, a difference of 1.5% in yolk proportion was detected between early morning and late afternoon eggs. This is interesting since data on the absolute weight of the yolk, as presented earlier in Table 1, showed morning eggs to have heavier egg yolk when compared with afternoon eggs. An explanation could be offered based on the fact that morning eggs were heavier than afternoon eggs. It is apparent, however, that the changes in egg weight as the time of day proceeds is not proportionally correlated to the changes in egg components. When the overall mean of yolk weight was compared for both experiments without regard to the strain effect or time of lay, eggs collected from older hens had a mean yolk weight 2.97 g greater (4.06%) when compared to mean yolk weight of eggs laid by younger hens.
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ARAFA ET AL. TABLE 5. Eggshell weight (grams) and egg shell thickness (millimeters) of eggs collected from five strains of commercial laying hens at 52 and 64 weeks of age Egg shell weight
Time of oviposition 0600 0800 100012001400 1600-
0800 1000 1200 1400 1600 1800
hr hr hr hr hr hr
Egg shell thickness
52 wk hens
64 wk hens
52 wk hens
64 wk hens
6.04 a 5.88 a 5.87 a 6.03 a 6.23 c
5.58 a 5.46 a 5.21 b 5.33 a b 5.36 a b 5.32 a b
.364 a .361 a .361 a .377b .382 b
.325 a bc .3343b .322a .325 a b c .333 b c .341 c
a,b,cMeans within a column with different superscripts are significantly different (P-C.05).
Egg shell weight
Strain
52 wk hens
64 wk hens
52 wk hens
Hisex C-Nick Ideal H&N Shaver
5.92 a 5.78 a 6.12b 5.90 a 6.33b
5.14a 5.31 a 5.56 b 5.40 a b 5.48 a b
.368 a .362b .367ab .374 a c .375 c
Egg shell thickness 64 wk hens .325 a .330 a .333 a .328 a .325 a
' ' Means within a column with different superscripts are significantly different (P<.05).
not found for eggs laid by the 52-week-old hens. A gradual decline in shell weight was then observed at 1000 and 1200 hr, 5.88 and 5.87 g, respectively. This gradual decline was followed by a gradual increase in egg shell weight in the afternoon eggs. Percent shell, in both experiments, was higher for eggs collected in the afternoon (Table 4). The Ideal and Shaver hens maintained a heavier shell during the day (Table 6). Statistically significant differences in percent shell were observed between the Shaver and Hisex hens as compared to the rest of the strains tested in Experiment 2 (Table 3). Regardless of the strain involved or time of oviposition, younger hens laid eggs which were .63 g/egg heavier or had 1.17 percentage points higher shell weight when compared with eggs laid by older hens. Egg shell thickness significantly increased for eggs collected after 1200 hr in Experiment 1
and after 1600 hr in Experiment 2 (Table 5). This finding is in agreement with Roland and Harms (1974), Washburn and Potts (1975), and Cipera (1976), who reported that eggs laid in the afternoon have an average specific gravity greater than eggs laid in the morning. An average thicker shell was observed in the first experiment. This was expected since hens in the first experiment were younger than those in the second experiment. In the second experiment, numerically but not statistically significant differences were observed in egg shell thickness between strains (Table 6). It appears that the differences in shell thickness between different strains of laying hens will diminish as the hen ages. Significant interactions between time of oviposition and strains were found for yolk weight, percent yolk, and percent albumen of eggs collected from Experiment 1 (52-week-old hens). However, no interaction was found for
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TABLE 6. Egg shell weight (grams) and egg shell thickness (millimeters) of eggs collected from five different strains of commercial laying hens at 52 and 64 weeks of age
QUALITY CHARACTERISTICS OF EGGS
any of t h e egg characteristics tested in Experim e n t 2 (64-week-old hens). Based on t h e data o b t a i n e d in this s t u d y it was concluded t h a t significant differences in egg characteristics existed a m o n g t h e five strains tested.
REFERENCES
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Cipera, J. D., 1976. Effect of oviposition time and storage conditions on the specific gravities of eggs. Poultry Sci. 56:1132-1134. Cotterill, 0 . J., and A. R. Winter, 1954. Egg white lysozyme. I. Relative lysozyme activity in fresh eggs having low and high interior quality. Poultry Sci. 3 3 : 6 0 7 - 6 1 1 . Cunningham, F. E., O. J. Cotterill, and E. M. Funk, 1960. The effect of season and age of bird. 1. On egg size, quality, and yield. Poultry Sci. 39: 289-299. Duncan, D. B., 1955. New multiple range and multiple F tests. Biometrics 11:1—42. Funk, E. M., 1934. Relation of time of laying to hatchability. Poultry Sci. 13:184-187. Hafez, E.S.E., A. L. Badreldin, and G.A.R. Kamar, 1955. Egg components in the Fayomi fowl during the first laying year. Poultry Sci. 34:400— 410. Jull, M. A., 1924. Egg weight in relation to production. Part I. The relationship of the weights of the parts of the egg to the total egg weight. Poultry Sci. 3:77-88.
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