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Effect of Albumen pH on Yolk Mottling
1330
N . FUJIHARA AND H . NlSHlYAMA
cation by exogenous FSH, LH, and testosterone—a stereologic evaluation. Poultry Sci. 54: 1115-1122. Taber, E., D. E. Davis andL. V. Domra, 1943. Effect of sex hormones on the erythrocyte number in the blood of the domestic fowl. Amer. J. Physiol. 138: 479-487. Tapper, D. N., and M. R. Kare, 1956. Distribution of glucose in blood of the chicken. Proc. Soc. Exp. Biol. Med. 92: 120-122. Tingari, M. D., 1971. On the structure of the epididymal region and ductus deferens of the domestic fowl (Gallus domesticus). J. Anat. 109: 423-435. Tingari, M. D., 1972. The fine structure of the epithelial lining of the excurrent duct system of the testis of the domestic fowl (Gallus domesticus). Q. J. Exp. Physiol. 57: 271-295. Wolfson,A., 1954. Notes on the cloacal protuberance, seminal vesicles, and a possible copulatory organ in male passerine birds. Bull. Chicago Acad. Sci. 10: 1-23.
Effect of Albumen pH on Yolk Mottling W . M . BRITTON
Department of Poultry Science, University of Georgia, Athens, Georgia 30602 (Received for publication October 10, 1975)
ABSTRACT Experiments were conducted to evaluate the effect of albumen pH on the incidence and degree of yolk mottling. Eggs stored for 5 days at 24° C. in a high C 0 2 or HCI environment, oiled on the top half or completely oiled had lower albumen pH and less yolk mottling than untreated control eggs. Eggs with higher albumen pH had the greatest degree of yolk mottling and lowest vitelline membrane weight. Washed eggs had higher albumen pH and more yolk mottling after 5 days of storage at 24° C. than unwashed eggs. Albumen pH and yolk mottling increased during storage. Oiling the eggs reduced the increase in albumen pH and yolk mottling during storage. Vitelline membrane weight decreased during storage, but was retarded in oiled eggs. Membranes retained in buffers of pH 7.6, 8.0, 8.4, 8.8, or 9.2 for 15 or 24 hours decreased in weight as the pH increased and a significant decrease was obtained at the two higher pH's. These experiments support the idea that increasing albumen pH causes increased yolk mottling, probably by altering the vitelline membrane. POULTRY SCIENCE 55: 1330-1335, 1976
INTRODUCTION
T
HE incidence of yolk mottling in eggs is quite high (Blackshear et al., 1968; Britton, 1973) and mottling increases both in incidence and degree when eggs are stored (Britton, 1973). Yolk mottling is associated with increased moisture content of the yolk which suggests an altered vitelline membrane permeability (Polin, 1957; van Tienhoven et a/.,1958;Britton,1973).Fromm(1966)showed
that water moved from the albumen to the yolk as the pH of the albumen increased. It is well established that the pH of albumen increases upon storage. These studies were conducted to evaluate the effect of albumen pH on yolk mottling. MATERIALS AND METHODS A series of six experiments were conducted to study the influence of pH on egg yolk
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on the accessory organs of the phallus. 10th World's Poultry Cong. Edinburgh, 88-91. Nishiyama, H., 1955. Studies on the accessory reproductive organs in the cock. J. Fac. Agr., Kyushu Univ. 10: 277-305. Nishiyama, H., N. Nakashima and N. Fujihara, 1976. Studies on the accessory reproductive organs in the drake. 1. Addition to semen of the fluid from the ejaculatory groove region. Poultry Sci. 55: 234-242. Parkes, A. S., 1966. The internal secretions of the testis. In: Marshall's Physiology of Reproduction, Vol. Ill, 3rd ed., Ed. A. S. Parkes, Longmans Green & Co. Ltd., London, pp. 412-569. Price, D., and H. G. Williams-Ashman, 1961. The accessory reproductive glands of mammals. In: Sex and Internal Secretions, Vol. 1, 3rd ed., Ed. W. C. Young, The Williams & Wilkins Co., Maryland, pp. 366-448. Purcell, S. M., and W. O. Wilson, 1975. Growth and maturation of testes in young coturnix and modifi-
ALBUMEN P H AND YOLK MOTTLING
mottling. Eggs used in these studies were obtained within 24 hours of oviposition from S.C. White Leghorn hens. Yolk mottling was evaluated using a 0 to 5 scale with 0 being no mottling and 5 very severe mottling (Britton, 1973). Yolk with a mottling score of 3 is not considered acceptable for commercial use. The pH in all studies was determined using a digital pH meter.'
Experiment 2. A total of 120 eggs was divided equally and one group was washed and one group left unwashed. The washing was done with a commercial spray-type egg washer. Fifteen eggs in each group of 60 were: (1) oiled on the top only, (2) the entire egg oiled, (3) placed in a high C 0 2 environment and (4) untreated controls. Other experimental conditions were similar to those used in Experiment 1. Albumen pH and yolk
1. Model 701, Orion Research Inc., Cambridge, Massachusetts. 2. Sta-Good Egg Spray, Mattox & Moore, Inc., Indianapolis, Indiana.
mottling were determined after 5 days of storage at room temperature (24° C ) . Experiment 3. This experiment was similar to Experiment 2 except the high C 0 2 environment treatment was omitted. Experiment 4. A total of 120 unwashed eggs was divided into equal groups and one group was stored for 5 days and the other group for 7 days at room temperature. In each group of eggs 20 were oiled on the top only, 20 were entirely oiled and 20 were kept as untreated controls. After the appropriate storage time, albumen pH, yolk mottling scores, and vitelline membrane weights were determined as previously described. The eggs used in this study were small eggs (—50.0 g.), but all other studies were done with large eggs (-60.0 g.). Experiment 5. A total of 360 unwashed eggs was equally divided into 6 groups and stored for 1,2, 3,4,5, or 7 days at room temperature. In each group 20 eggs were oiled on the top only, 20 were entirely oiled and 20 kept as untreated controls. After the appropriate storage time, albumen pH and yolk mottling scores were determined. Experiment 6. This experiment was an in vitro evaluation of pH effect on vitelline membrane weight. A total of 75 eggs was obtained that weighed 58 grams. The eggs were broken and the vitelline membranes obtained as previously described. Fifteen groups of 5 membranes each were prepared with 5 groups serving as control, 5 groups placed in Tris buffer solutions for 15 hours and 5 groups for 24 hours. The buffer solutions were prepared at pH 7.6, 8.0, 8.4, 8.8 and 9.2. Each group of 5 membranes was immersed in 100 ml. of the appropriate buffer solution at room temperature (24° C ) . The membranes were individually freeze-dried and weighed.
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Experiment 1. Four methods of influencing albumen pH were evaluated for their effect on yolk mottling and vitelline membrane weight. A total of 100 unwashed eggs was divided in 5 equal groups and stored for 5 days at room temperature (24° C ) . Group 1 was the untreated control, group 2 was oiled by spraying 2 the large end of the shell (top oiled), group 3 was sprayed on both ends (all oiled), group 4 was placed in a high C 0 2 environment (2.5%) and group 5 was placed in an environment saturated with fumes from concentrated HC1. After 5 days the eggs were broken and within 2 minutes scored for yolk mottling and albumen pH determined. The yolks were separated and the vitelline membranes removed under water (Britton, 1973). The membranes were freeze-dried and weighed individually.
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W. M. BRITTON
Statistical Analysis. All data were analyzed using a general linear model through the SAS REGR computer program (Barr and Goodnight, 1972). Significance (P < 0.05) of treatment means was tested using the multiple range test of Duncan's as outlined in Steel and Torrie (1960). RESULTS
TABLE 1.—Influence of oiling method and storage environment on albumen pH, yolk mottling score, and vitelline membrane weight after 5 days of storage at 24° C. (Experiment I) Yolk V.M. mottling wt.3 Albumen treat2 1 score (mg.) pH ment Control 9.24d4 1.15d 7.96c Top oiled 8.39c 0.80bcd 9.92b All oiled 7.90b 0.50bc 10.84b HighC0 2 6.74a 0.35ab 12.98a 1 20 eggs per treatment group. 2 Scored on the basis of 0 for no mottling to 5 very severe mottling. 3 V.M. Wt.—Vitelline membrane dry weight. 4 Means within the same factor followed by different letters differ significantly (P < .05).
Egg treatment'
Unwashed
Control Albumen pH 9.55e2 Mottling score 3 1.47cd2 Top oiled 9.08d Albumen pH Mottling score 1.13c All oiled 8.69c Albumen pH Mottling score .07ab High C 0 2 8.11a Albumen pH .00a Mottling score Marginal means 4 Albumen pH 8.86A Mottling score .67A
Washed
Marginal means 4
9.52e 1.60d
9.53D 1.53C
9.39e 1.40cd
9.24C 1.26B
8.75c .33ab
8.72B .20A
8.28b .40b
8.19A .20A
9.00B .93B
1 15 2
eggs per treatment group. Means within the same factor followed by different small letters differ significantly (P < .05). 3 Scored on the basis of 0 for no mottling to 5 very severe mottling. 4 Marginal means followed by different large letters differ significantly (P < .05).
TABLE 3.—Albumen pH and yolk mottling score of unwashed and washed eggs stored for 5 days at 24° C. as affected by oiling (Experiment 3) Egg treatment'
Unwashed
Control 9.29d2 Albumen pH Mottling score 3 1.05abc2 Top oiled Albumen pH 8.41a Mottling score .60a All oiled Albumen pH 8.40a Mottling score ,75ab Marginal means. 4 Albumen pH 8.69A Mottling score .80A 1 20 2
Washed
Marginal means 4
9.36d 2.25d
9.32C 1.65B
8.95c 1.50c
8.68B 1.05A
8.63b 1.25bc
8.52A 1.00A
8.98B 1.67B
eggs per treatment group. Means within the same factor followed by different small letters differ significantly (P < .05). 3 Scored on the basis of 0 for no mottling to 5 very severe mottling. 4 Marginal means followed by different large letters differ significantly (P < .05).
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Oiling or storage in a high C 0 2 or HC1 environment retarded the increase in albumen pH when compared with the untreated control eggs (Table 1). Less yolk mottling was observed in the treated eggs. Vitelline membrane weight decreased in the eggs subjected to conditions allowing the largest increase in albumen pH. The controls had significantly lower membrane weight, oiled eggs were intermediate and eggs stored in a high C 0 2 or HC1 environment had the heaviest membranes. Experiment 2 again tested the effect of oiling and high C 0 2 environment on albumen pH and yolk mottling score in washed and unwashed eggs (Table 2). Oiling and a high C 0 2 environment retarded the increase in albumen pH seen in the controls. Yolk mottling score increased in the eggs showing higher pH of the albumen. Washing eggs caused a significantly higher albumen pH and
TABLE 2.—Albumen pH and yolk mottling score of unwashed and washed eggs stored for 5 days at 24° C. as affected by oiling or a high C02 environment (Experiment 2)
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ALBUMEN P H AND YOLK MOTTLING
TABLE 4.—Effect of egg storage time at 24° C. and oiling on albumen pH, yolk mottling score and vitelline membrane weight (Experiment 4) Egg treatment'
Storage time (days) 5
Marginal means 3
9.40d 2.00d 5.49a
9.31C 1.75B 6.03A
9.19c 1.85cd 6.46b
8.94B 1.50B 6.88B
9.08c 1.35b 6.90bc
8.65A 1.07A 7.32C
9.22B 1.73B 6.28A
1 20 2
eggs per treatment group. Means within the same factor followed by different small letters differ significantly (P < .05). 3 Marginal means followed by different large letters differ significantly (P s .05). 4 Scored on the basis of 0 for no mottling to 5 very severe mottling. 5 V.M. wt.—vitelline membrane dry weight. more yolk mottling, but the differences were relatively small. Experiment 3 (Table 3) confirmed the influence of washing on albumen pH and yolk TABLE 5.—Effect
DISCUSSION Storage of eggs at room temperature (24° C.) caused an increase in albumen pH which was retarded in a high C 0 2 environment or
of egg storage time at 24° C. and oiling on albumen pH and yolk mottling score (Experiment 5)
Storage time (days) Egg Marginal 1 2 3 4 7 Treatment' means 3 5 Control Albumen pH 4 8.50e2 9.00h 9.06h 9.31i 9.33i 9.40i 9.10C Mottling score .80defg2 1.90jk 1.85jk 1.20h 2.05k 2.551 1.72C Top oiled Albumen pH 8.39d 8.64f 9.09h 8.28c 8.80g 8.61B 8.46de Mottling score .50abc 1.05gh l.OOfgh 1.70ij 1.24B 1.50i 1.70ij All oiled Albumen pH 8.07b 7.98ab 7.91a 7.90a 7.97'A 7.91a 8.03b Mottling score .35a .60abcd .45ab .70bcde ,75cdef .63A .95efgh : Marginal means Albumen pH 8.32A 8.79E 8.42B 8.67D 8.53C 8.60CD Mottling score .55 A 1.67D 1.13B .93B 1.50CD 1.42C 1 20 eggs per treatment group. 2 Means within the same factor followed by different small letters differ significantly (P : .05). 3 MarginaI means followed by different large letters differ significantly (P < .05). "Scored on the basis of 0 for no mottling to 5 very severe mottling.
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Control 9.22cd2 Albumen pH Mottling score 4 1.50bc2 5 6.57bc 2 V.M. wt. (mg.) Top oiled Albumen pH 8.70b 1.15ab Mottling score 7.29cd V.M. wt. (mg.) All oiled Albumen pH 8.22a Mottling score .80a 7.75d V.M. wt. (mg.) Marginal means 3 8.71A Albumen pH 1.15A Mottling score 7.20B V.M. wt.
7
mottling seen in Experiment 2 (Table 2). Unwashed eggs had lower albumen pH and showed less yolk mottling. Again, oiling was shown to prevent the increase in yolk mottling and albumen pH. In experiment 4 (Table 4) increasing storage time from five to seven days caused an increase in albumen pH and yolk mottling and a decrease in the weight of vitelline membranes. Oiling retarded these changes at both storage times. The effect of storage time on albumen pH and yolk mottling was further studied in experiments (Table 5). Albumen pH and yolk mottling increased with increasing storage time. The increase in albumen pH and yolk mottling was much smaller in oiled eggs than in the control eggs. Experiment 6 showed that maintaining vitelline membranes in buffer of pH 8.8 or higher caused a decrease in membrane weight (Table 6). This change had occurred after 15 hours and showed no further change at 24 hours.
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W.
M.
TABLE 6.—The invitro effect of buffer pH and time in buffer on vitelline membrane weight (Experiment 6)
Buffer PH 7.6 8.0 8.4 8.8 9.2
Vitelline membrane weight (mg.)12 Time• in buffer (hi••) 24 15 0 12.75c 12.28bc 12.74c 12.52c 11.68abc 11.84abc 12.54c 11.66abc 12.10bc 12.58c 10.62ab 10.16a 12.60c 10.54ab 10.40a
1
Each value is a mean of 5 membranes. Means followed by different letters differ significantly (P < .05).
BRITTON
the cuticle would produce eggs that have the greatest need to be oiled properly. These studies further demonstrate the need for oiling of eggs to maintain interior egg quality. It is generally accepted that oiling the shell prevents moisture and CO 2 loss from the egg and helps to maintain interior quality. The results presented in this study indicate that oiling can reduce the incidence and degree of yolk mottling.
2
A higher yolk moisture content of mottled yolk has been shown (Polin, 1957; van Tienhoven et al., 1958; Britton, 1973) and indicates that an increase in albumen pH causes changes in the vitelline membrane that increase yolk mottling. Washing eggs caused a more rapid increase in albumen pH and increased the degree of yolk mottling. Washing removes at least part of the cuticle, increases moisture loss and decreases Haugh units (Homier and Stadelman, 1963). Oiling helps to prevent the decline in quality caused by washing. A decline in Haugh units is usually associated with the loss of CO 2 through the shell causing an increase in the albumen pH. The washing process that does the best job of removing
The technical assistance of Jan Carter Brunn is gratefully acknowledged. This work was supported in part by a grant from the Georgia Egg Commission. REFERENCES Barr, A. J., and J. H. Goodnight, 1972. SAS, a user guide to the statistical analysis system. North Carolina State Univ., Raleigh, N.C. Blackshear, C. D., K. N. May and R. K. Noles, 1968. A survey of egg yolk mottling and other quality attributes in North Georgia flocks. Poultry Sci. 47: 625-630. Britton, W. M., 1973. Vitelline membrane chemical composition in natural and induced yolk mottling. Poultry Sci. 52: 459-464. Fromm, D., 1964. Strength distribution, weight and some histological aspects of the vitelline membrane of hen's egg yolk. Poultry Sci. 43: 1240-1247. Fromm, D., 1966. The influence of ambient pH on moisture content and yolk index of the hen's yolk. Poultry Sci. 45: 374-379. Goodwin, T. L., M. L. Wilson and W. J. Stadelman, 1962. Effects of oiling time, storage position and storage time on the condition of shell eggs. Poultry Sci. 41: 840-844. Homier, B. E., and W. J. Stadelman, 1963. The effect of oiling before and after cleaning in maintaining the albumen condition of shell eggs. Poultry Sci. 42: 190-194. McKerley, R. G., G. W. Newell, J. G. Berry, G. V. O'Dell and R. D. Morrison, 1967. The effects of some acidic and alkaline atmospheres on the change in pH and Haugh units in chicken eggs. Poultry Sci. 46: 118-132. Polin, D., 1957. Biochemical and weight changes of mottled yolk in eggs from hens fed nicarbazin. Poultry Sci. 36: 831-835.
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HC1 environment supporting the work of McKerley et al. (1967). Oiling of eggs retarded the increase in albumen pH seen upon storage supporting the early work of Goodwin et al. (1962). Not only did these egg treatments retard the rise in albumen pH usually seen upon storage, but they also retarded the incidence and degree of yolk mottling that usually occurs when eggs are aged (Britton, 1973). The decrease in vitelline membrane weight noted in this study with storage is supported by the work of Fromm (1964). Fromm (1966) also showed that the moisture content of the yolk increased as the pH of the albumen increased and that oiling the shell would retard this change.
ACKNOWLEDGEMENTS
ALBUMEN P H AND Y O L K MOTTLING
Steel, R. G. D., and J. H. Torrie, 1960. Principles and Procedures of Statistics. McGraw-Hill Book Co., Inc., New York.
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van Tienhoven, A. F., W. Hill, A. Prock and R. C. Baker, 1958. The effect of nicarbazin on yolk quality. Poultry Sci. 37: 129-132.
Metabolizable Energy Values of Some Poultry Feeds Determined by Various Methods and Their Estimation Using Metabolizability of the Dry Matter I. K. H A N , ' H . W . HOCHSTETLER AND M . L . SCOTT
(Received for publication October 15, 1975)
ABSTRACT Metabolizable energy (M.E.) values of 12 U.S. feedstuffs and 10 Korean feed ingredients for poultry were determined both by the total collection method and by the chromic oxide indicator method. It was found that M.E. values of most poultry feedstuffs can be measured accurately by either method. Limitation of feed intake to almost maintenance level (approximately 60% of ad libitum) did not increase or decrease the M.E. value of the feeds. An attempt was made to establish a prediction equation to estimate the M.E. values based on the apparent metabolizability of dry matter (D.M.) in the feedstuffs. The results indicated that linear relationships do exist between D.M. metabolizability and M.E. values of carbohydraterich feedstuffs (grains and their by-products) or protein-rich feed ingredients (oil seed meals and animal protein feeds) or lipid-rich feeds (fats and oils) as follows: The prediction equation for carbohydrate-rich feedstuffs was Y = 0.0947x - 3.498 (r2 = 0.99, Sy.x = 0.015); for proteinrich feed ingredients, it was Y = 0.1294x - 4.898 (r2 = 0.99, Sy.x = 0.027); and for lipid-rich feedstuffs it was Y = 0.0844x + 0.774 (r2 = 0.99, Sy.x = 0.032), where x = metabolizability of dry matter of feeds in %, and Y = metabolizable energy values in kcal./g. The errors attached to these estimations were relatively small. Thus these prediction equations may be very useful for estimation of the M.E. values from D.M. apparent metabolizability of feeds, especially in areas of the world where calorimetry is not possible. POULTRY SCIENCE 55: 1335-1342, 1976
INTRODUCTION ETABOLIZABLE energy values of poultry feeds are computed as the difference between gross energy content of the feed and the energy lost through the excreta. Metabolizable energy (M.E.) is the most widely used energy term for expressing calorific concentration of poultry feeds, and is a more precise measure than productive energy (Hill and Anderson, 1958). The methods usually used for the determination of M.E. of poultry diets are based on the studies developed by Hill and his associates, and on the use of chromic oxide as an index
M
1. Present address: Department of Animal Sciences, College of Agriculture, Seoul National University, Suwon, Korea 170-00.
substance (Hill and Anderson, 1958; Hill et al., 1960). The latter method avoids the necessity for total collection and weighing of feed intake and excreta. Methods employing index substances are more commonly used in measuring M.E. values for poultry, while the total collection method is the predominant technique employed with swine and ruminants (Carew, 1973). The reliability of M.E. values and the reproducibility of analytical data for chromic oxide have been questioned by many scientists (Lee and Han, 1974; Carew, 1973; Kohler and Kuzmicky, 1970; Halloran, 1972). The amount of intestinal absorption of chromic oxide in poultry may be open to question (Vohraand Kratzer, 1967). However, Sibbald et al. (1960) suggested that the use of chromic oxide may lead to greater precision than the
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Department of Poultry Science, Cornell University, Ithaca, N. Y. 14853
N . FUJIHARA AND H . NlSHlYAMA
cation by exogenous FSH, LH, and testosterone—a stereologic evaluation. Poultry Sci. 54: 1115-1122. Taber, E., D. E. Davis andL. V. Domra, 1943. Effect of sex hormones on the erythrocyte number in the blood of the domestic fowl. Amer. J. Physiol. 138: 479-487. Tapper, D. N., and M. R. Kare, 1956. Distribution of glucose in blood of the chicken. Proc. Soc. Exp. Biol. Med. 92: 120-122. Tingari, M. D., 1971. On the structure of the epididymal region and ductus deferens of the domestic fowl (Gallus domesticus). J. Anat. 109: 423-435. Tingari, M. D., 1972. The fine structure of the epithelial lining of the excurrent duct system of the testis of the domestic fowl (Gallus domesticus). Q. J. Exp. Physiol. 57: 271-295. Wolfson,A., 1954. Notes on the cloacal protuberance, seminal vesicles, and a possible copulatory organ in male passerine birds. Bull. Chicago Acad. Sci. 10: 1-23.
Effect of Albumen pH on Yolk Mottling W . M . BRITTON
Department of Poultry Science, University of Georgia, Athens, Georgia 30602 (Received for publication October 10, 1975)
ABSTRACT Experiments were conducted to evaluate the effect of albumen pH on the incidence and degree of yolk mottling. Eggs stored for 5 days at 24° C. in a high C 0 2 or HCI environment, oiled on the top half or completely oiled had lower albumen pH and less yolk mottling than untreated control eggs. Eggs with higher albumen pH had the greatest degree of yolk mottling and lowest vitelline membrane weight. Washed eggs had higher albumen pH and more yolk mottling after 5 days of storage at 24° C. than unwashed eggs. Albumen pH and yolk mottling increased during storage. Oiling the eggs reduced the increase in albumen pH and yolk mottling during storage. Vitelline membrane weight decreased during storage, but was retarded in oiled eggs. Membranes retained in buffers of pH 7.6, 8.0, 8.4, 8.8, or 9.2 for 15 or 24 hours decreased in weight as the pH increased and a significant decrease was obtained at the two higher pH's. These experiments support the idea that increasing albumen pH causes increased yolk mottling, probably by altering the vitelline membrane. POULTRY SCIENCE 55: 1330-1335, 1976
INTRODUCTION
T
HE incidence of yolk mottling in eggs is quite high (Blackshear et al., 1968; Britton, 1973) and mottling increases both in incidence and degree when eggs are stored (Britton, 1973). Yolk mottling is associated with increased moisture content of the yolk which suggests an altered vitelline membrane permeability (Polin, 1957; van Tienhoven et a/.,1958;Britton,1973).Fromm(1966)showed
that water moved from the albumen to the yolk as the pH of the albumen increased. It is well established that the pH of albumen increases upon storage. These studies were conducted to evaluate the effect of albumen pH on yolk mottling. MATERIALS AND METHODS A series of six experiments were conducted to study the influence of pH on egg yolk
Downloaded from http://ps.oxfordjournals.org/ at North Dakota State University on June 2, 2015
on the accessory organs of the phallus. 10th World's Poultry Cong. Edinburgh, 88-91. Nishiyama, H., 1955. Studies on the accessory reproductive organs in the cock. J. Fac. Agr., Kyushu Univ. 10: 277-305. Nishiyama, H., N. Nakashima and N. Fujihara, 1976. Studies on the accessory reproductive organs in the drake. 1. Addition to semen of the fluid from the ejaculatory groove region. Poultry Sci. 55: 234-242. Parkes, A. S., 1966. The internal secretions of the testis. In: Marshall's Physiology of Reproduction, Vol. Ill, 3rd ed., Ed. A. S. Parkes, Longmans Green & Co. Ltd., London, pp. 412-569. Price, D., and H. G. Williams-Ashman, 1961. The accessory reproductive glands of mammals. In: Sex and Internal Secretions, Vol. 1, 3rd ed., Ed. W. C. Young, The Williams & Wilkins Co., Maryland, pp. 366-448. Purcell, S. M., and W. O. Wilson, 1975. Growth and maturation of testes in young coturnix and modifi-
ALBUMEN P H AND YOLK MOTTLING
mottling. Eggs used in these studies were obtained within 24 hours of oviposition from S.C. White Leghorn hens. Yolk mottling was evaluated using a 0 to 5 scale with 0 being no mottling and 5 very severe mottling (Britton, 1973). Yolk with a mottling score of 3 is not considered acceptable for commercial use. The pH in all studies was determined using a digital pH meter.'
Experiment 2. A total of 120 eggs was divided equally and one group was washed and one group left unwashed. The washing was done with a commercial spray-type egg washer. Fifteen eggs in each group of 60 were: (1) oiled on the top only, (2) the entire egg oiled, (3) placed in a high C 0 2 environment and (4) untreated controls. Other experimental conditions were similar to those used in Experiment 1. Albumen pH and yolk
1. Model 701, Orion Research Inc., Cambridge, Massachusetts. 2. Sta-Good Egg Spray, Mattox & Moore, Inc., Indianapolis, Indiana.
mottling were determined after 5 days of storage at room temperature (24° C ) . Experiment 3. This experiment was similar to Experiment 2 except the high C 0 2 environment treatment was omitted. Experiment 4. A total of 120 unwashed eggs was divided into equal groups and one group was stored for 5 days and the other group for 7 days at room temperature. In each group of eggs 20 were oiled on the top only, 20 were entirely oiled and 20 were kept as untreated controls. After the appropriate storage time, albumen pH, yolk mottling scores, and vitelline membrane weights were determined as previously described. The eggs used in this study were small eggs (—50.0 g.), but all other studies were done with large eggs (-60.0 g.). Experiment 5. A total of 360 unwashed eggs was equally divided into 6 groups and stored for 1,2, 3,4,5, or 7 days at room temperature. In each group 20 eggs were oiled on the top only, 20 were entirely oiled and 20 kept as untreated controls. After the appropriate storage time, albumen pH and yolk mottling scores were determined. Experiment 6. This experiment was an in vitro evaluation of pH effect on vitelline membrane weight. A total of 75 eggs was obtained that weighed 58 grams. The eggs were broken and the vitelline membranes obtained as previously described. Fifteen groups of 5 membranes each were prepared with 5 groups serving as control, 5 groups placed in Tris buffer solutions for 15 hours and 5 groups for 24 hours. The buffer solutions were prepared at pH 7.6, 8.0, 8.4, 8.8 and 9.2. Each group of 5 membranes was immersed in 100 ml. of the appropriate buffer solution at room temperature (24° C ) . The membranes were individually freeze-dried and weighed.
Downloaded from http://ps.oxfordjournals.org/ at North Dakota State University on June 2, 2015
Experiment 1. Four methods of influencing albumen pH were evaluated for their effect on yolk mottling and vitelline membrane weight. A total of 100 unwashed eggs was divided in 5 equal groups and stored for 5 days at room temperature (24° C ) . Group 1 was the untreated control, group 2 was oiled by spraying 2 the large end of the shell (top oiled), group 3 was sprayed on both ends (all oiled), group 4 was placed in a high C 0 2 environment (2.5%) and group 5 was placed in an environment saturated with fumes from concentrated HC1. After 5 days the eggs were broken and within 2 minutes scored for yolk mottling and albumen pH determined. The yolks were separated and the vitelline membranes removed under water (Britton, 1973). The membranes were freeze-dried and weighed individually.
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W. M. BRITTON
Statistical Analysis. All data were analyzed using a general linear model through the SAS REGR computer program (Barr and Goodnight, 1972). Significance (P < 0.05) of treatment means was tested using the multiple range test of Duncan's as outlined in Steel and Torrie (1960). RESULTS
TABLE 1.—Influence of oiling method and storage environment on albumen pH, yolk mottling score, and vitelline membrane weight after 5 days of storage at 24° C. (Experiment I) Yolk V.M. mottling wt.3 Albumen treat2 1 score (mg.) pH ment Control 9.24d4 1.15d 7.96c Top oiled 8.39c 0.80bcd 9.92b All oiled 7.90b 0.50bc 10.84b HighC0 2 6.74a 0.35ab 12.98a 1 20 eggs per treatment group. 2 Scored on the basis of 0 for no mottling to 5 very severe mottling. 3 V.M. Wt.—Vitelline membrane dry weight. 4 Means within the same factor followed by different letters differ significantly (P < .05).
Egg treatment'
Unwashed
Control Albumen pH 9.55e2 Mottling score 3 1.47cd2 Top oiled 9.08d Albumen pH Mottling score 1.13c All oiled 8.69c Albumen pH Mottling score .07ab High C 0 2 8.11a Albumen pH .00a Mottling score Marginal means 4 Albumen pH 8.86A Mottling score .67A
Washed
Marginal means 4
9.52e 1.60d
9.53D 1.53C
9.39e 1.40cd
9.24C 1.26B
8.75c .33ab
8.72B .20A
8.28b .40b
8.19A .20A
9.00B .93B
1 15 2
eggs per treatment group. Means within the same factor followed by different small letters differ significantly (P < .05). 3 Scored on the basis of 0 for no mottling to 5 very severe mottling. 4 Marginal means followed by different large letters differ significantly (P < .05).
TABLE 3.—Albumen pH and yolk mottling score of unwashed and washed eggs stored for 5 days at 24° C. as affected by oiling (Experiment 3) Egg treatment'
Unwashed
Control 9.29d2 Albumen pH Mottling score 3 1.05abc2 Top oiled Albumen pH 8.41a Mottling score .60a All oiled Albumen pH 8.40a Mottling score ,75ab Marginal means. 4 Albumen pH 8.69A Mottling score .80A 1 20 2
Washed
Marginal means 4
9.36d 2.25d
9.32C 1.65B
8.95c 1.50c
8.68B 1.05A
8.63b 1.25bc
8.52A 1.00A
8.98B 1.67B
eggs per treatment group. Means within the same factor followed by different small letters differ significantly (P < .05). 3 Scored on the basis of 0 for no mottling to 5 very severe mottling. 4 Marginal means followed by different large letters differ significantly (P < .05).
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Oiling or storage in a high C 0 2 or HC1 environment retarded the increase in albumen pH when compared with the untreated control eggs (Table 1). Less yolk mottling was observed in the treated eggs. Vitelline membrane weight decreased in the eggs subjected to conditions allowing the largest increase in albumen pH. The controls had significantly lower membrane weight, oiled eggs were intermediate and eggs stored in a high C 0 2 or HC1 environment had the heaviest membranes. Experiment 2 again tested the effect of oiling and high C 0 2 environment on albumen pH and yolk mottling score in washed and unwashed eggs (Table 2). Oiling and a high C 0 2 environment retarded the increase in albumen pH seen in the controls. Yolk mottling score increased in the eggs showing higher pH of the albumen. Washing eggs caused a significantly higher albumen pH and
TABLE 2.—Albumen pH and yolk mottling score of unwashed and washed eggs stored for 5 days at 24° C. as affected by oiling or a high C02 environment (Experiment 2)
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ALBUMEN P H AND YOLK MOTTLING
TABLE 4.—Effect of egg storage time at 24° C. and oiling on albumen pH, yolk mottling score and vitelline membrane weight (Experiment 4) Egg treatment'
Storage time (days) 5
Marginal means 3
9.40d 2.00d 5.49a
9.31C 1.75B 6.03A
9.19c 1.85cd 6.46b
8.94B 1.50B 6.88B
9.08c 1.35b 6.90bc
8.65A 1.07A 7.32C
9.22B 1.73B 6.28A
1 20 2
eggs per treatment group. Means within the same factor followed by different small letters differ significantly (P < .05). 3 Marginal means followed by different large letters differ significantly (P s .05). 4 Scored on the basis of 0 for no mottling to 5 very severe mottling. 5 V.M. wt.—vitelline membrane dry weight. more yolk mottling, but the differences were relatively small. Experiment 3 (Table 3) confirmed the influence of washing on albumen pH and yolk TABLE 5.—Effect
DISCUSSION Storage of eggs at room temperature (24° C.) caused an increase in albumen pH which was retarded in a high C 0 2 environment or
of egg storage time at 24° C. and oiling on albumen pH and yolk mottling score (Experiment 5)
Storage time (days) Egg Marginal 1 2 3 4 7 Treatment' means 3 5 Control Albumen pH 4 8.50e2 9.00h 9.06h 9.31i 9.33i 9.40i 9.10C Mottling score .80defg2 1.90jk 1.85jk 1.20h 2.05k 2.551 1.72C Top oiled Albumen pH 8.39d 8.64f 9.09h 8.28c 8.80g 8.61B 8.46de Mottling score .50abc 1.05gh l.OOfgh 1.70ij 1.24B 1.50i 1.70ij All oiled Albumen pH 8.07b 7.98ab 7.91a 7.90a 7.97'A 7.91a 8.03b Mottling score .35a .60abcd .45ab .70bcde ,75cdef .63A .95efgh : Marginal means Albumen pH 8.32A 8.79E 8.42B 8.67D 8.53C 8.60CD Mottling score .55 A 1.67D 1.13B .93B 1.50CD 1.42C 1 20 eggs per treatment group. 2 Means within the same factor followed by different small letters differ significantly (P : .05). 3 MarginaI means followed by different large letters differ significantly (P < .05). "Scored on the basis of 0 for no mottling to 5 very severe mottling.
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Control 9.22cd2 Albumen pH Mottling score 4 1.50bc2 5 6.57bc 2 V.M. wt. (mg.) Top oiled Albumen pH 8.70b 1.15ab Mottling score 7.29cd V.M. wt. (mg.) All oiled Albumen pH 8.22a Mottling score .80a 7.75d V.M. wt. (mg.) Marginal means 3 8.71A Albumen pH 1.15A Mottling score 7.20B V.M. wt.
7
mottling seen in Experiment 2 (Table 2). Unwashed eggs had lower albumen pH and showed less yolk mottling. Again, oiling was shown to prevent the increase in yolk mottling and albumen pH. In experiment 4 (Table 4) increasing storage time from five to seven days caused an increase in albumen pH and yolk mottling and a decrease in the weight of vitelline membranes. Oiling retarded these changes at both storage times. The effect of storage time on albumen pH and yolk mottling was further studied in experiments (Table 5). Albumen pH and yolk mottling increased with increasing storage time. The increase in albumen pH and yolk mottling was much smaller in oiled eggs than in the control eggs. Experiment 6 showed that maintaining vitelline membranes in buffer of pH 8.8 or higher caused a decrease in membrane weight (Table 6). This change had occurred after 15 hours and showed no further change at 24 hours.
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W.
M.
TABLE 6.—The invitro effect of buffer pH and time in buffer on vitelline membrane weight (Experiment 6)
Buffer PH 7.6 8.0 8.4 8.8 9.2
Vitelline membrane weight (mg.)12 Time• in buffer (hi••) 24 15 0 12.75c 12.28bc 12.74c 12.52c 11.68abc 11.84abc 12.54c 11.66abc 12.10bc 12.58c 10.62ab 10.16a 12.60c 10.54ab 10.40a
1
Each value is a mean of 5 membranes. Means followed by different letters differ significantly (P < .05).
BRITTON
the cuticle would produce eggs that have the greatest need to be oiled properly. These studies further demonstrate the need for oiling of eggs to maintain interior egg quality. It is generally accepted that oiling the shell prevents moisture and CO 2 loss from the egg and helps to maintain interior quality. The results presented in this study indicate that oiling can reduce the incidence and degree of yolk mottling.
2
A higher yolk moisture content of mottled yolk has been shown (Polin, 1957; van Tienhoven et al., 1958; Britton, 1973) and indicates that an increase in albumen pH causes changes in the vitelline membrane that increase yolk mottling. Washing eggs caused a more rapid increase in albumen pH and increased the degree of yolk mottling. Washing removes at least part of the cuticle, increases moisture loss and decreases Haugh units (Homier and Stadelman, 1963). Oiling helps to prevent the decline in quality caused by washing. A decline in Haugh units is usually associated with the loss of CO 2 through the shell causing an increase in the albumen pH. The washing process that does the best job of removing
The technical assistance of Jan Carter Brunn is gratefully acknowledged. This work was supported in part by a grant from the Georgia Egg Commission. REFERENCES Barr, A. J., and J. H. Goodnight, 1972. SAS, a user guide to the statistical analysis system. North Carolina State Univ., Raleigh, N.C. Blackshear, C. D., K. N. May and R. K. Noles, 1968. A survey of egg yolk mottling and other quality attributes in North Georgia flocks. Poultry Sci. 47: 625-630. Britton, W. M., 1973. Vitelline membrane chemical composition in natural and induced yolk mottling. Poultry Sci. 52: 459-464. Fromm, D., 1964. Strength distribution, weight and some histological aspects of the vitelline membrane of hen's egg yolk. Poultry Sci. 43: 1240-1247. Fromm, D., 1966. The influence of ambient pH on moisture content and yolk index of the hen's yolk. Poultry Sci. 45: 374-379. Goodwin, T. L., M. L. Wilson and W. J. Stadelman, 1962. Effects of oiling time, storage position and storage time on the condition of shell eggs. Poultry Sci. 41: 840-844. Homier, B. E., and W. J. Stadelman, 1963. The effect of oiling before and after cleaning in maintaining the albumen condition of shell eggs. Poultry Sci. 42: 190-194. McKerley, R. G., G. W. Newell, J. G. Berry, G. V. O'Dell and R. D. Morrison, 1967. The effects of some acidic and alkaline atmospheres on the change in pH and Haugh units in chicken eggs. Poultry Sci. 46: 118-132. Polin, D., 1957. Biochemical and weight changes of mottled yolk in eggs from hens fed nicarbazin. Poultry Sci. 36: 831-835.
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HC1 environment supporting the work of McKerley et al. (1967). Oiling of eggs retarded the increase in albumen pH seen upon storage supporting the early work of Goodwin et al. (1962). Not only did these egg treatments retard the rise in albumen pH usually seen upon storage, but they also retarded the incidence and degree of yolk mottling that usually occurs when eggs are aged (Britton, 1973). The decrease in vitelline membrane weight noted in this study with storage is supported by the work of Fromm (1964). Fromm (1966) also showed that the moisture content of the yolk increased as the pH of the albumen increased and that oiling the shell would retard this change.
ACKNOWLEDGEMENTS
ALBUMEN P H AND Y O L K MOTTLING
Steel, R. G. D., and J. H. Torrie, 1960. Principles and Procedures of Statistics. McGraw-Hill Book Co., Inc., New York.
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van Tienhoven, A. F., W. Hill, A. Prock and R. C. Baker, 1958. The effect of nicarbazin on yolk quality. Poultry Sci. 37: 129-132.
Metabolizable Energy Values of Some Poultry Feeds Determined by Various Methods and Their Estimation Using Metabolizability of the Dry Matter I. K. H A N , ' H . W . HOCHSTETLER AND M . L . SCOTT
(Received for publication October 15, 1975)
ABSTRACT Metabolizable energy (M.E.) values of 12 U.S. feedstuffs and 10 Korean feed ingredients for poultry were determined both by the total collection method and by the chromic oxide indicator method. It was found that M.E. values of most poultry feedstuffs can be measured accurately by either method. Limitation of feed intake to almost maintenance level (approximately 60% of ad libitum) did not increase or decrease the M.E. value of the feeds. An attempt was made to establish a prediction equation to estimate the M.E. values based on the apparent metabolizability of dry matter (D.M.) in the feedstuffs. The results indicated that linear relationships do exist between D.M. metabolizability and M.E. values of carbohydraterich feedstuffs (grains and their by-products) or protein-rich feed ingredients (oil seed meals and animal protein feeds) or lipid-rich feeds (fats and oils) as follows: The prediction equation for carbohydrate-rich feedstuffs was Y = 0.0947x - 3.498 (r2 = 0.99, Sy.x = 0.015); for proteinrich feed ingredients, it was Y = 0.1294x - 4.898 (r2 = 0.99, Sy.x = 0.027); and for lipid-rich feedstuffs it was Y = 0.0844x + 0.774 (r2 = 0.99, Sy.x = 0.032), where x = metabolizability of dry matter of feeds in %, and Y = metabolizable energy values in kcal./g. The errors attached to these estimations were relatively small. Thus these prediction equations may be very useful for estimation of the M.E. values from D.M. apparent metabolizability of feeds, especially in areas of the world where calorimetry is not possible. POULTRY SCIENCE 55: 1335-1342, 1976
INTRODUCTION ETABOLIZABLE energy values of poultry feeds are computed as the difference between gross energy content of the feed and the energy lost through the excreta. Metabolizable energy (M.E.) is the most widely used energy term for expressing calorific concentration of poultry feeds, and is a more precise measure than productive energy (Hill and Anderson, 1958). The methods usually used for the determination of M.E. of poultry diets are based on the studies developed by Hill and his associates, and on the use of chromic oxide as an index
M
1. Present address: Department of Animal Sciences, College of Agriculture, Seoul National University, Suwon, Korea 170-00.
substance (Hill and Anderson, 1958; Hill et al., 1960). The latter method avoids the necessity for total collection and weighing of feed intake and excreta. Methods employing index substances are more commonly used in measuring M.E. values for poultry, while the total collection method is the predominant technique employed with swine and ruminants (Carew, 1973). The reliability of M.E. values and the reproducibility of analytical data for chromic oxide have been questioned by many scientists (Lee and Han, 1974; Carew, 1973; Kohler and Kuzmicky, 1970; Halloran, 1972). The amount of intestinal absorption of chromic oxide in poultry may be open to question (Vohraand Kratzer, 1967). However, Sibbald et al. (1960) suggested that the use of chromic oxide may lead to greater precision than the
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Department of Poultry Science, Cornell University, Ithaca, N. Y. 14853