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Role of the Magnum and Uterus in the Determination of Albumen Quality of Laid Eggs
POULTRY S C I E N C E January, 1954, Vol. 3 3 , N o . 1 •
Role of the Magnum and Uterus in the Determination of Albumen Quality of Laid Eggs Laboratory of Avian Physiology, Rutgers University, New Brunswick, N. J. (Received for publication April 8, 1953)
T
egg, or one taken from the magnum, has usually only one layer of albumen, which is viscous and jelly-like in consistency. Thus, the arrangement of the albumen in strata and the relative decrease in protein of the laid egg indicate that the addition of water to the egg in the uterus plus physical changes resulting from rotation of the egg in the uterus are mainly responsible for the stratification of the albumen. The viscosity of the middle thick layer decreases with age of the egg, temperature, and other factors, so that in time the albumen of this layer becomes thin like the other layers, and the albumen appears as one thin, watery layer. Heredity also influences the type of albumen in the egg. Strains of chickens have been developed by selective breeding differing markedly in this respect (Lorenz et al., 1934; Lorenz and Taylor, 1940; Knox and Godfrey, 1940). The viscosity of the thick albumen of the egg is also decreased in hens afflicted with, or recovering from, certain respiratory diseases, such as Newcastle and bronchitis. Histological studies by a number of workers have revealed that the magnum contains two types of glands, tubular and unicellular (Surface, 1912; Bradley, 1928; Richardson, 1935; Cole, 1938).
HERE are four distinct layers or divisions of albumen in the laid egg. These are: the chalazae which are attached at the poles of the yolk, the inner liquid layer surrounding the yolk, the dense or middle thick layer, and the outer thin or fluid layer. Approximately one fourth of the total albumen of a normal egg is found in the outer layer, 50-60 percent in the thick layer, and the remainder in the inner thin and chalaziferous areas. The principal difference in the thick and thin layers is the presence of large amounts of mucin in the thick layer, which accounts for its higher viscosity. Virtually all of the protein of the albumen of the egg is formed in the magnum or upper part of the oviduct. The egg then moves on to the isthmus where the shell membranes and some water are added, and then on to the uterus where most of the water is added to albumen. The laid egg contains approximately twice the volume of albumen and half the protein per given volume of the early isthmian egg. Moreover, the early isthmian 1
Paper of the Journal Series, New Jersey Agricultural Experiment Station, Rutgers University— The State University of New Jersey, Department of Poultry Husbandry.
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PAUL D. STURKIE AND DONALD POLIN 1
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P. D. STURKIE AND D. POLIN
PROCEDURE The birds used in the experiments were laying White Leghorns, ranging in age from 8 to 30 months. They were maintained in batteries on a commercial all mash ration, supplemented ad libitum with calcium. The birds received 14 hours of light daily.
A number of measurements or determinations were made on albumen of normally laid eggs and eggs intercepted from the oviduct. To prevent deterioration, the laid eggs were gathered every morning and determinations were made on the same day, or the eggs were stored for one day at 38°F. before determinations were made. These eggs were then broken open, scored and classified according to quality and condition of the albumen. First they were scored by the visual method of Van Wagenen and Wilgus (1935). An egg with the highest score, 1, represents one in which the albumen is thick and upstanding, and the boundary between thick albumen and the outer thin layer is sharp and distinct. In eggs scoring 4 or 5, the albumen is low and appears to have collapsed, so that the middle thick albumen appears thin and is intermingled with the outer thin. The eggs were also scored by the height of the albumen. The heights of the albumen of the laid and intercepted eggs were determined by taking the average of two measurements at the highest point adjacent to the yolk. A number of investigators have shown that the height thus taken is a fair measure of the quality of albumen, and there is fairly close correlation between height of albumen and visual score. The size of the yolk also influences height of albumen. Eggs with larger and wider yolks tend to lower the albumen height somewhat. The albumen index (height/ width) is considered a better index of quality of albumen than is height alone (according to Heiman and Carver, 1936). Haugh (1937) devised a system of scoring albumen quality based upon the albumen index in relation to total weight of egg, which takes into account variations in size of yolk. The quality of the egg is evaluated in terms of Haugh units. Thus an egg scoring 1 by the visual method ranges
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The goblet cells of the unicellular glands are tiighly developed, and according to most observers, produce the mucin fibers, which are mainly responsible for the high viscosity of the albumen. Cole (1938) reported that the goblet cells are significantly taller and more highly developed in hens laying eggs containing more viscous albumen. These results might suggest that the qualitative differences in albumen of laid eggs is due principally to the relative amounts of thick and thin albumen secreted in the magnum. Results from experiments involving surgical removal of different parts of the magnum tend to support this view (Asmundson and Burmester, 1938; Scott and Burmester, 1939). Resection of the anterior portion of magnum reduced the amount of thin albumen formed; whereas removal of the posterior part decreased the amount of thick albumen formed in the laid egg. Conrad and Scott (1942), however, found only slight and insignificant differences in the development and height of the goblet cells of the magnum of hens laying eggs containing different amounts of thick albumen. The decrease in viscosity of the albumen of normally laid eggs with age, length of storage, temperature, and certain other factors suggests that freshly laid eggs containing albumen of low viscosity (thin, watery albumen) may result also from deteriorative changes in the uterus, which produce a breakdown of mucin. The results reported herein support this view.
ROLE OF THE MAGNUM AND UTERUS IN EGG QUALITY
In an attempt to minimize this, the readings were taken immediately after the cylinder began revolving and before visible winding occurred, but the readings still varied considerably. Several readings were averaged. The viscosities of the thin and thick albumen are not reported in absolute units, but are relative to the viscosities of glycerol solutions of known concentration or of water under definite conditions. Since these conditions for the thick and thin albumen were different, because of modification of the spindles of the instrument, the values reported for the thick and the thin albumen are not comparable. The values reported in the tables represent actual readings of the viscosimeter. For example, a reading of 30 for thin albumen represents a viscosity 3.3 times that of water or 0.24 that of a glycerol solution, the specific gravity of which was 1.1984 under the same conditions. A reading of 155 for thick albumen means that it is 10 times as viscous as a 95.5 percent glycerol solution (specific gravity 1.2503) or 130.4 times as viscous as glycerol with a specific gravity of 1.1984 under the same conditions. The type and speed of the spindle used for thick albumen gave no reading for water. The refractive indices were determined on homogenized albumen by means of an Abbe refractometer after the method of Almquist, Lorenz and Burmester (1932). The refractive index is a measure of the percentage solids, and the protein of albumen represents approximately 95 percent of the solids. The albumen of the laid egg was separated into three fractions—inner thin, middle thick, and outer thin—by the screening method of Almquist and Lorenz (1933). Usually the intercepted eggs contained some thin albumen but little or no outer
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in Haugh units from about 92 to slightly above 100. This system was also used in scoring the laid eggs. It is generally believed that the deterioration or breakdown of the middle thick albumen is due mainly to physical and not chemical change's in the mucin fibers; these fibers normally give thick albumen its viscous, gel-like characteristics. The ovomucin content of eggs with watery albumen (determined chemically) is approximately the same as, or slightly lower than, that of viscous albumen (Romanoff and Romanoff, 1949; Forsythe and Berquist, 1951; Feeney el al., 1952; Conrad and Scott, 1939). Viscosity of the different fractions of albumen of the laid egg and intercepted egg was determined with a Brookfield, spinning-type viscosimeter. Two types of spindles were used. The one used for the inner and outer thin albumen had a shank 2 mm. in diameter and 5.0 cm. long, which was attached to a cylinder 15 mm. long and 19 mm. in diameter. The overall weight of shank and cylinder was 18.9 grams. The cylinder was immersed in the albumen and revolved at 60 RPM. The friction exerted by the liquid against the moving spindle and the slowing of the latter are proportional to the viscosity of the liquid. All records of viscosity were taken at a temperautre of 25°C. The shank of the spindle used for thick albumen was 8.9 cm. long, and 2mm. in diameter. It was attached to a smooth cylinder, 1.5 mm. long and 8 mm. in diameter. The weight of the shank and cylinder was 8.72 grams. The cylinder was barely immersed in the albumen and made to revolve at 12 RPM. The readings of the thick albumen were markedly variable, mainly because of the presence of many mucin fibers which tend to wind around the revolving cylinder. This tendency is increased at higher revolutions of the cylinder. When winding occurs, the readings are unduly high.
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P. D. STTJRKIE AND D. POLIN
TABLE 1.—Measures of albumen quality of laid and intercepted eggs. The eggs are grouped according to quality of albumen of laid eggs (A, B, and C). The best quality group (A) had higher means for Haugh units, albumen height and viscosity, and a lower Van Wagenen index
Haugh units laid
Van Wagenen index
Height of albumen, mm.
Laid
Laid
Inter.
Inter.
Viscosity of Albumen Middle thick Laid
Inter.
Inner thin Laid
Inter.
Outer thin laid
11 91.4 8.74 2.64
11 1.5 0.2236 0.0671
11 1.0 0 0
11 8.18 1.5043 0.4535
A 11 12.42 1.7822 0.5373
9 148.4 109.63 36.54
8 303.1 126.23 44.63
10 25.2 4.24 1.34
6 48.3 27.18 11.10
10 47 23.76 7.51
No. Mean S.D. S.E.
15 75.4 2.32 0.5983
15 2.6 0.3873 0.1000
15 1.0 0.2315 0.0600
15 5.86 0.3895 0.1005
B 15 9.97 1.1483 0.2965
14 99.8 51.46 13.75
14 275.8 138.73 37.08
15 25.6 8.28 2.14
8 40.5 19.46 6.88
12 49.4 18.93 5.47
No. Mean S.D. S.E.
19 59.6 11.91 2.73
19 3.7 0.6625 0.1520
19 1.4 0.6101 0.1400
19 4.26 0.9849 0.2261
C 18 8.35 1.6228 0.3825
19 90.4 65.71 15.08
19 246.3 91.38 20.96
17 29.1 8.88 2.15
10 33.1 13.37 4.23
17 40.6 11.81 2.86
M.D. S.E.M.D. t
16.0 2.7033 5.91
1.1 0.1204 8.39
0 0 0
2.32 0.4645 4.99
A&B 2.45 0.6137 3.99
48.6 39.04 1.24
27.3 54.01 0.50
0.4 2.52 0.15
7.8 13.05 0.59
2.4 9.29 0.25
M.D. S.E.M.D. t
15.8 2.7961 5.65
1.1 0.1819 6.05
0.4 0.1523 2.63
1.60 0.2474 6.47
B&C 1.62 0.4839 3.35
9.4 20.41 0.46
29.5 42.05 0.61
3.5 4.15 0.84
7.4 8.07 0.91
8.8 6.17 1.43
M.D. S.E.M.D. t
31.8 3.80 8.37
0 0 0
3.92 0.5068 7.73
A&C 4.07 0.6595 6.17
58.0 39.53 1.47
56.8 49.31 1.15
3.9 2.54 1.54
2.2 0.1661 12.16
15.2 11.8 1.2
6.4 8.04 0.79
according to the albumen quality of laid eggs. The means of laid eggs for Haugh units and albumen height were highest for Group A, intermediate for Group B, and lowest for Group C. The Van Wagenen index was lowest (highest score) for Group A, intermediate for B, and lowest for Group C. The differences between the means of the groups were highly significant statistically. There appeared to be close correlation between these three indices for albumen quality. Mean viscosity of the thick albumen of the laid egg was also highest for Group A, intermediate for B and lowest for Group C. The differences, however, are not staRESULTS tistically significant. The heterogeneous Albumen Quality of Laid and Oviducal nature of thick albumen, due to the presEggs ence of mucin fibers, caused considerable Laid eggs. Different indices of ablumen variation in the readings. The viscosity readings of the inner thin quality of laid and oviducal eggs are compared in Table 1. The birds were grouped albumen were less variable than those of
thin depending on time of interception. Oviducal eggs can first be detected when they are about to enter the isthmus, or approximately three hours after the previous egg has been laid. Two hours later, the egg enters the uterus. By manual expulsion most of the oviducal eggs were removed within two hours after they entered the uterus. Pressure was applied to the sides of the uterus and the egg in such a manner as to force the egg out without rupturing the shell membrane. Laid and intercepted eggs were obtained from each hen within a period of 3-7 days.
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No. Mean S.D. S.E.
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ROLE or THE MAGNUM AND UTERUS IN EGG QUALITY
TABLE 2.—Relative proportions of total albumen and fractions of albumen of laid and intercepted eggs {Groups A, B, and C) Albumen of inter. egg/laid egg in percent
Percent outer thin laid
No. Mean S.D. S.E.
11 83 7.89 2.38
11 14.71 4.03 1.21
No. Mean S.D. S.E.
15 81.7 21.46 5.54
15 15.28 6.22 1.60
No. Mean S.D. S.E.
19 72.3 13.39 3.07
19 20.27 13.70 3.14
M.D. S.E.M.D. t
1.3 6.03 0.21
0.57 2.01 0.28
M.D. S.E.M.D. t
9.4 6.33 1.48
4.99 3.53 1.41
M.D. S.E.M.D. t
10.7 3.88 2.76
5.56 3.37 1.65
Percent inner thin
Percent middle thick
Laid
Inter.
Laid
Inter.
11 24.11 8.40 2.53
11 12.04 5.99 1.80
11 59.14 10.97 3.30
11 85.14 6.65 2.00
15 24.35 4.45 1.14
15 10.76 5.29 1.36
15 57.77 5.81 1.50
15 84.60 8.39 2.16
19 19.61 8.21 1.88
17 11.82 6.72 1.62
19 55.65 9.97 2.28
19 84.02 11.56 2.65
0.24 2.78 0.86
1.28 2.26 0.56
1.37 3.63 0.37
0.54 2.95 0.18
4.74 2.20 2.15
1.06 2.12 0.49
2.12 2.73 0.77
0.58 3.42 0.16
4.50 3.15 1.43
0.22 2.43 0.09
3.49 4.02 0.86
1.12 3.32 0.33
A
B
C
A&B
B&C
A&C
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thick albumen was not significantly different for the three groups of laid eggs, although it was somewhat lower for the poorest quality eggs than for the other two groups. This indicates, as others have shown, that there is little correlation between the relative amount of thick albumen, and the height of albumen, Van Wagenen index and viscosity of albumen. Oviducal eggs. There was litle difference in the appearance of albumen of most of the oviducal eggs, even between the poorest and the best quality eggs. The intercepted eggs of Groups A and B had the same rating, based on appearance (Van Wagenen index, 1). The poorest quality eggs (Group C) rated 1.4 by the same index. The difference between the ratings of
the middle thick, but the differences between the groups of eggs were not significant. The inner thin albumen was approximately three times as viscous as water at 25°C. Viscosity of the outer thin albumen was higher than that of inner thin, and was 4.5 to 5.5 times as viscous as water at 25°C, despite the fact that outer thin contains more water (see later section). Outer thin viscosity for the poor quality eggs was lower than for the other groups of eggs, but the differences were not statistically significant. Smith (1935) reported that mixed thin albumen of fresh eggs at 0°C. had a viscosity 4 times that of water. Table 2 shows that the percentage of
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P. D. STURKIE AND D. POLIN
had been added to the albumen, and that probably other changes involving the breakdown of mucin had occurred. It is known that normal eggs leaving the magnum contain from 50 to 60 percent of the albumen of the laid egg. The percentage of thick albumen of the oviducal eggs was approximately 25 to 30 percent greater than that of the laid eggs, but there was no difference between the different groups of intercepted eggs. Thus the percentage of thick albumen of intercepted eggs, as well as that of the laid egg, bears little relationship to albumen quality, as indicated by height, appearance, or viscosity of albumen. The intercepted eggs of all groups averaged about one half as much inner thin albumen as the laid eggs. There was no appreciable difference in the amounts of thin albumen between the different groups of oviducal eggs. Water and Solids Content of Albumen A number of investigators have shown that the albumen of oviducal eggs contains less water and more solids than does that of laid eggs (Pearl and Curtis, 1912; McNally, 1934; Scott el al., 1937; Burmester, 1940; Asmundson, 1939). This was confirmed by the results of this study, which showed that the refractive indices of albumen of oviducal eggs weie higher than those of laid eggs (Table 3). It is known that the index of refraction varies with the fraction or layer of albumen. The index for inner thin of the laid egg is slightly higher than that for middle thick, and it is lowest for the outer thin (Almquist and Lorenz, 1933; Burmester, 1940). These results were confirmed in this study. There was no difference in the refractive index, however, of a given layer of albumen for laid eggs of different albumen quality. In other words, the water content
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Group C and that of A or B was, however, statistically significant. Many of the group C eggs rated 1.0, but some few had indices as low as 3 and 4. The albumen height of the oviducal eggs of each group was significantly higher than for the corresponding groups of laid eggs. Moreover, the difference between the groups of oviducal eggs was highly significant. The viscosity of the thick albumen of the intercepted eggs was considerably higher than that of laid eggs. Although the poor quality oviducal eggs had lower viscosities than the best quality eggs, the differences were not significant. The high consistency and gel-like nature of the thick albumen of intercepted eggs made it impossible to obtain accurate viscosity readings. The viscosities of the inner thin albumen of oviducal eggs of Groups A and B were significantly higher than those of the corresponding laid eggs, but the difference between laid and oviducal eggs of Group C was slight and insignificant. Among the oviducal eggs, those of Group C had the lowest inner thin viscosity, but the differences between the groups were not statistically significant. Inner thin viscosity readings of oviducal eggs are subject to a great deal of variation due, in part, to the time at which the eggs are intercepted and the relative amount of inner thin albumen formed. Relative amounts of albumen of oviducal eggs. The amount of total albumen of the oviducal egg in percent of the albumen of laid eggs is shown in Table 2. This figure for the Group C eggs was significantly lower than that for the Group A eggs. The reason for this is unknown. The oviducal eggs contained from 72 to 83 percent as much albumen as the laid eggs. This means that by the time the eggs were intercepted in the uterus considerable water
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R O L E OF T H E M A G N U M AND U T E R U S I N E G G QUALITY
TABLE 3.—Refractive indices of albumen of laid and intercepted eggs (Groups A, B, and C) Refractive index outer thin Laid
Inter.
Refractive index middle thick
Refractive index inner thin
Laid
Inter.
Laid
Inter.
11 1.3532 0.009866 0.002974
9 1.3520 0.014916 0.004971
A 11 1.3551 0.010639 0.003207
11 1.3584 0.004130 0.001244
11 1.3571 0.005539 0.001670
10 1.3593 0.011953 0.003780
No. Mean S.D. S.E.
15 1.3532 0.006685 0.001726
11 1.3513 0.009223 0.002780
B 15 1.3542 0.008539 0.002204
15 1.3603 0.011301 0.002917
15 1.3551 0.010906 0.002816
15 1.3634 0.009834 0.002539
No. Mean S.D. S.E.
18 1.3530 0.003162 0.000748
12 1.3489 0.010521 0.003038
19 1.3537 0.006104 0.001438
19 1.3581 0.010882 0.002496
19 1.3545 0.007998 0.001835
19 1.3621 0.010922 0.002505
M.D. S.E.M.D. t
0.0010 0.003439 0.02
0.0007 0.005696 0.12
A&B 0.0009 0.003892 0.23
0.0019 0.003172 0.59
0.0020 0.003274 0.61
0.0041 0.004554 0.90
M.D. S.E.M.D. t
0.0008 0.001882 0.42
0.0024 0.004118 0.58
B&C 0.0005 0.002632 0.19
0.0022 0.003839 0.57
0.0006 0.003362 0.17
0.0013 0.003568 0.36
M.D. S.E.M.D. t
0.0002 0.003068 0.06
0.0031 0.005827 0.53
A&C 0.0014 0.003516 0.39
0.0003 0.002789 0.10
0.0026 0.002482 1.05
0.0028 0.004535 0.61
of the different layers of albumen of poor quality laid eggs was no different from that of eggs of good quality, and this held true also for oviducal eggs.
num and hence some changes in albumen quality may have already occurred. Determinations of albumen quality of eggs intercepted in the magnum would show to what extent decreased secretion of DISCUSSION mucin in the magnum accounts for differThe results of this study indicate that ences in albumen quality of laid eggs. albumen quality of freshly laid eggs is inBased upon differences in the height, fluenced by the breakdown of mucin oc- viscosity, and visual scores of albumen of curring after the egg leaves the magnum. uterine and laid eggs, albumen quality These data, however, do not rule out the deteriorates after the egg leaves the magprobability that variation in the amount num and before being laid. For example, of mucin secreted in the magnum may ac- the albumen height of the poor quality count for some of the changes in albumen laid eggs (Group C) averaged 4.26 mm. quality of laid eggs. compared to 8.35 mm. for the correspondThe extent to which each of these fac- ing oviducal eggs. This difference repretors was operative cannot be ascertained, sents a decrease of 51 percent. The debecause the oviducal eggs were inter- crease in albumen height of the laid eggs cepted 2 to 3 hours after they left the mag- of best quality (Group A) as compared to
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No. Mean S.D. S.E.
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P. D. STURKIE AND D. POLIN SUMMARY
Oviducal eggs were removed from the uterus 2 to 3 hours after such eggs had left the magnum, and the quality of their albumen was compared with that of freshly laid eggs which varied greatly in albumen quality. Based upon differences in height, viscosity and visual scores of albumen of laid and uterine eggs, albumen quality deteriorates after the egg leaves the magnum and enters the uterus. The deterioration is, however, not accompained by changes in the contents of water or solids. These data also suggest that variation in the amount of mucin secreted in the magnum may account for some of the changes in albumen quality of laid eggs. The results demonstrate that there is little correlation between the amount of thick albumen collected by the screening technique and albumen quality as indicated by height, visual score and viscosity of the albumen. REFERENCES Almquist, H. J., and F. W. Lorenz, 1933. The solids content of egg white. Poultry Sci. 12: 83-89. Almquist, H. J., F. W. Lorenz and B. R. Burmester, 1932. Determination of the total solids matter and density of egg white by refractometer. Ind. Eng. Chem. 4: 305-306. Asmundson, V. S., and B. R. Burmester, 1938. The effect of resecting a part of the uterus on the formation of the hen's egg. Poultry Sci. 17: 126130. Asmundson, V. S., 1939. Formation of the egg in the oviduct of birds. Observations on turkeys. Proc. Seventh World's Poultry Congress, 96-99. Bradley, O. C , 1928. Notes on the histology of the oviduct of the domestic hen. J. Anat. 62: 339345. Burmester, B. R., 1940. A study of the physical and chemical changes of the egg during its passage through the isthmus and uterus of the hen's oviduct. J. Exp. Zool. 84: 445-500. Cole, R. K., 1938. Histology of the oviduct of the fowl in relation to variations in the condition of the firm egg albumen. Anat. Rec. 71: 349-358. Conrad, R. M., and H. M. Scott, 1939. Changes in
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the oviducal eggs was only 34.6 percent and for eggs of intermediate quality (Group B), 41.2 percent. Thus the rate of decrease in albumen height is greater in the poorer quality eggs. The fact that albumen height of the Group A intercepted eggs was considerably higher than that of the poorest quality eggs, means either that the breakdown in mucin, during the intervening 2-3 hours from the time the eggs left the magnum until they were intercepted, was considerably greater in the poor quality eggs, or that less mucin was secreted in them. It is probable that the latter factor accounted for some of the differences. It is known that water is added to the egg in the isthmus and uterus. This is shown by the higher refractive indices of the oviducal eggs as compared to laid eggs, but the water content of laid or oviducal eggs of poor albumen quality is no greater than that of eggs of good quality albumen. The nature of the changes resulting in the thinning of the albumen in the uterus is not understood. That the thinning is not due to changes in the amount of ovomucin was discussed previously. A number of theories have been proposed for the thinning of albumen in laid eggs. (See Feeney et al., 1950, for a review.) Proponents of two of the more popular ones attribute the thinning of albumen to enzyme action and to chemical hydrolysis. The enzyme theory has been virtually discarded and there is no evidence supporting chemical hydrolysis, according to these reviewers. Hoover (1940) and MacDonnell et al. (1951) have shown that a number of reducing agents cause thinning of albumen of laid eggs. They believed that the thinning was associated with the reduction of the S-S bonds of ovomucin, and their evidence supported this view.
ASSOCIATION NOTICE
Feeney, 1951. Chemistry of shell egg deterioration. Poultry Sci. 30: 856-863. McNally, E., 1934. Passage of ovoglobulins through the shell membrane. Proc. Soc. Exp. Biol. Med. 31: 946-947. Pearl, R., and M. R. Curtis, 1912. Studies on the physiology of reproduction in the domestic fowl. V. Data regarding the physiology of the oviduct. J. Exp. Zool. 12: 99-132. Richardson, K. C , 1935. The secretory phenomena in the oviduct of the fowl, including the process of shell formation examined by the microincineration technique. Phil. Trans. Roy. Soc. Lond. Series B, 225: 149-195. Romanoff, A. L., and A. J. Romanoff, 1949. The Avian Egg. John Wiley and Sons, Inc., New York, New York. Scott, H. M., and B. R. Burmester, 1939. Effect of resection of the albumen tube on secretion of egg white. Proc. Seventh World's Poultry Congress, 102-106. Scott, H. M., J. S. Hughes and D. C. Warren, 1937, Augmentation of nitrogen to the egg white after formation of the shell membranes in the fowl. Poultry Sci. 16: 53-61. Smith, A. J. M., 1935. Viscosity of the white and of yolk. Dept. Sci. Ind. Research (Brit.) Food Invest. Reports 1934: 53-56. Surface, F. M., 1912. The histology of the oviduct of the hen. Maine Agric. Exp. Sta. Bui. 206. Van Wagenen, A., and H. S. Wilgus, 1935. The determination and importance of the condition of the firm albumen in studies of egg white quality. J. Agric. Res. 51: 1129-1137.
ASSOCIATION NOTICE (Continued from page 8) meeting. Reference to the Constitution and ByLaws of the Association will give the information with regard to these honors, awards and prizes. Research Award Committee (American Feed Manufacturers' Association, Borden, and Poultry Science Association)—W. W. Cravens, McMillen Feed Mills, Decatur, Indiana. Extension Award Committee (Poultry Science As-
sociation)—O. E. Goff, Poultry Department, University of Tennessee, Knoxville, Tennessee. Teaching Award Committee (Poultry Science Association)—M. A. Jull, Poultry Department, University of Maryland, College Park, Maryland. Committee on Fellows—J. H. Martin, Department of Poultry Husbandry, Purdue University, Lafayette, Indiana.
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ovomucin during egg storage. Proc. Seventh World's Poultry Congress, 528-530. Conrad, R. M., and H. M. Scott, 1942. Differences between high and low quality fresh eggs. Poultry Sci. 21: 77-80. Feeney, R. E., F. D. Ducay, R. B. Silva and L. R. MacDonnell, 1952. Chemistry of shell egg deterioration: the egg white proteins. Poultry Sci. 31: 639-647. Feeney, R. E., R. B. Silva and L. R. MacDonnell, 1950. Chemistry of shell egg deterioration. The deterioration of separated components. Poultry Sci. 30: 645-650. Forsythe, R. S., and D. H. Berquist, 1951. The effects of physical treatments on some properties of egg white. Poultry Sci. 30: 302-311. Haugh, R. R., 1937. Egg quality. U. S. Egg and Poultry Magazine, 43: 552-555. Heiman, V., and J. S. Carver, 1936. The albumen index as a physical measurement of observed egg quality. Poultry Sci. 15: 141-148. Hoover, S. R., 1940. A physical and chemical study of ovomucin. Doctoral thesis, Georgetown Univ., Washington, D. C. Knox, C. W., and A. B. Godfrey, 1940. Five years of breeding for high and low percentage of thick albumen in the eggs of Rhode Island Reds. Poultry Sci. 19: 291-294. Lorenz, F. W., and L. W. Taylor, 1940. The inheritance of albumen quality characteristic of chicken eggs. J. Agric. Res. 61: 293-301. Lorenz, F. W., L. W. Taylor and H. J. Almquist, 1934. Firmness of albumen as an inherited character. Poultry Sci. 13:14-17. MacDonnell, L. R., H. Lineweaver and R. E.
17
Role of the Magnum and Uterus in the Determination of Albumen Quality of Laid Eggs Laboratory of Avian Physiology, Rutgers University, New Brunswick, N. J. (Received for publication April 8, 1953)
T
egg, or one taken from the magnum, has usually only one layer of albumen, which is viscous and jelly-like in consistency. Thus, the arrangement of the albumen in strata and the relative decrease in protein of the laid egg indicate that the addition of water to the egg in the uterus plus physical changes resulting from rotation of the egg in the uterus are mainly responsible for the stratification of the albumen. The viscosity of the middle thick layer decreases with age of the egg, temperature, and other factors, so that in time the albumen of this layer becomes thin like the other layers, and the albumen appears as one thin, watery layer. Heredity also influences the type of albumen in the egg. Strains of chickens have been developed by selective breeding differing markedly in this respect (Lorenz et al., 1934; Lorenz and Taylor, 1940; Knox and Godfrey, 1940). The viscosity of the thick albumen of the egg is also decreased in hens afflicted with, or recovering from, certain respiratory diseases, such as Newcastle and bronchitis. Histological studies by a number of workers have revealed that the magnum contains two types of glands, tubular and unicellular (Surface, 1912; Bradley, 1928; Richardson, 1935; Cole, 1938).
HERE are four distinct layers or divisions of albumen in the laid egg. These are: the chalazae which are attached at the poles of the yolk, the inner liquid layer surrounding the yolk, the dense or middle thick layer, and the outer thin or fluid layer. Approximately one fourth of the total albumen of a normal egg is found in the outer layer, 50-60 percent in the thick layer, and the remainder in the inner thin and chalaziferous areas. The principal difference in the thick and thin layers is the presence of large amounts of mucin in the thick layer, which accounts for its higher viscosity. Virtually all of the protein of the albumen of the egg is formed in the magnum or upper part of the oviduct. The egg then moves on to the isthmus where the shell membranes and some water are added, and then on to the uterus where most of the water is added to albumen. The laid egg contains approximately twice the volume of albumen and half the protein per given volume of the early isthmian egg. Moreover, the early isthmian 1
Paper of the Journal Series, New Jersey Agricultural Experiment Station, Rutgers University— The State University of New Jersey, Department of Poultry Husbandry.
9
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PAUL D. STURKIE AND DONALD POLIN 1
10
P. D. STURKIE AND D. POLIN
PROCEDURE The birds used in the experiments were laying White Leghorns, ranging in age from 8 to 30 months. They were maintained in batteries on a commercial all mash ration, supplemented ad libitum with calcium. The birds received 14 hours of light daily.
A number of measurements or determinations were made on albumen of normally laid eggs and eggs intercepted from the oviduct. To prevent deterioration, the laid eggs were gathered every morning and determinations were made on the same day, or the eggs were stored for one day at 38°F. before determinations were made. These eggs were then broken open, scored and classified according to quality and condition of the albumen. First they were scored by the visual method of Van Wagenen and Wilgus (1935). An egg with the highest score, 1, represents one in which the albumen is thick and upstanding, and the boundary between thick albumen and the outer thin layer is sharp and distinct. In eggs scoring 4 or 5, the albumen is low and appears to have collapsed, so that the middle thick albumen appears thin and is intermingled with the outer thin. The eggs were also scored by the height of the albumen. The heights of the albumen of the laid and intercepted eggs were determined by taking the average of two measurements at the highest point adjacent to the yolk. A number of investigators have shown that the height thus taken is a fair measure of the quality of albumen, and there is fairly close correlation between height of albumen and visual score. The size of the yolk also influences height of albumen. Eggs with larger and wider yolks tend to lower the albumen height somewhat. The albumen index (height/ width) is considered a better index of quality of albumen than is height alone (according to Heiman and Carver, 1936). Haugh (1937) devised a system of scoring albumen quality based upon the albumen index in relation to total weight of egg, which takes into account variations in size of yolk. The quality of the egg is evaluated in terms of Haugh units. Thus an egg scoring 1 by the visual method ranges
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The goblet cells of the unicellular glands are tiighly developed, and according to most observers, produce the mucin fibers, which are mainly responsible for the high viscosity of the albumen. Cole (1938) reported that the goblet cells are significantly taller and more highly developed in hens laying eggs containing more viscous albumen. These results might suggest that the qualitative differences in albumen of laid eggs is due principally to the relative amounts of thick and thin albumen secreted in the magnum. Results from experiments involving surgical removal of different parts of the magnum tend to support this view (Asmundson and Burmester, 1938; Scott and Burmester, 1939). Resection of the anterior portion of magnum reduced the amount of thin albumen formed; whereas removal of the posterior part decreased the amount of thick albumen formed in the laid egg. Conrad and Scott (1942), however, found only slight and insignificant differences in the development and height of the goblet cells of the magnum of hens laying eggs containing different amounts of thick albumen. The decrease in viscosity of the albumen of normally laid eggs with age, length of storage, temperature, and certain other factors suggests that freshly laid eggs containing albumen of low viscosity (thin, watery albumen) may result also from deteriorative changes in the uterus, which produce a breakdown of mucin. The results reported herein support this view.
ROLE OF THE MAGNUM AND UTERUS IN EGG QUALITY
In an attempt to minimize this, the readings were taken immediately after the cylinder began revolving and before visible winding occurred, but the readings still varied considerably. Several readings were averaged. The viscosities of the thin and thick albumen are not reported in absolute units, but are relative to the viscosities of glycerol solutions of known concentration or of water under definite conditions. Since these conditions for the thick and thin albumen were different, because of modification of the spindles of the instrument, the values reported for the thick and the thin albumen are not comparable. The values reported in the tables represent actual readings of the viscosimeter. For example, a reading of 30 for thin albumen represents a viscosity 3.3 times that of water or 0.24 that of a glycerol solution, the specific gravity of which was 1.1984 under the same conditions. A reading of 155 for thick albumen means that it is 10 times as viscous as a 95.5 percent glycerol solution (specific gravity 1.2503) or 130.4 times as viscous as glycerol with a specific gravity of 1.1984 under the same conditions. The type and speed of the spindle used for thick albumen gave no reading for water. The refractive indices were determined on homogenized albumen by means of an Abbe refractometer after the method of Almquist, Lorenz and Burmester (1932). The refractive index is a measure of the percentage solids, and the protein of albumen represents approximately 95 percent of the solids. The albumen of the laid egg was separated into three fractions—inner thin, middle thick, and outer thin—by the screening method of Almquist and Lorenz (1933). Usually the intercepted eggs contained some thin albumen but little or no outer
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in Haugh units from about 92 to slightly above 100. This system was also used in scoring the laid eggs. It is generally believed that the deterioration or breakdown of the middle thick albumen is due mainly to physical and not chemical change's in the mucin fibers; these fibers normally give thick albumen its viscous, gel-like characteristics. The ovomucin content of eggs with watery albumen (determined chemically) is approximately the same as, or slightly lower than, that of viscous albumen (Romanoff and Romanoff, 1949; Forsythe and Berquist, 1951; Feeney el al., 1952; Conrad and Scott, 1939). Viscosity of the different fractions of albumen of the laid egg and intercepted egg was determined with a Brookfield, spinning-type viscosimeter. Two types of spindles were used. The one used for the inner and outer thin albumen had a shank 2 mm. in diameter and 5.0 cm. long, which was attached to a cylinder 15 mm. long and 19 mm. in diameter. The overall weight of shank and cylinder was 18.9 grams. The cylinder was immersed in the albumen and revolved at 60 RPM. The friction exerted by the liquid against the moving spindle and the slowing of the latter are proportional to the viscosity of the liquid. All records of viscosity were taken at a temperautre of 25°C. The shank of the spindle used for thick albumen was 8.9 cm. long, and 2mm. in diameter. It was attached to a smooth cylinder, 1.5 mm. long and 8 mm. in diameter. The weight of the shank and cylinder was 8.72 grams. The cylinder was barely immersed in the albumen and made to revolve at 12 RPM. The readings of the thick albumen were markedly variable, mainly because of the presence of many mucin fibers which tend to wind around the revolving cylinder. This tendency is increased at higher revolutions of the cylinder. When winding occurs, the readings are unduly high.
11
12
P. D. STTJRKIE AND D. POLIN
TABLE 1.—Measures of albumen quality of laid and intercepted eggs. The eggs are grouped according to quality of albumen of laid eggs (A, B, and C). The best quality group (A) had higher means for Haugh units, albumen height and viscosity, and a lower Van Wagenen index
Haugh units laid
Van Wagenen index
Height of albumen, mm.
Laid
Laid
Inter.
Inter.
Viscosity of Albumen Middle thick Laid
Inter.
Inner thin Laid
Inter.
Outer thin laid
11 91.4 8.74 2.64
11 1.5 0.2236 0.0671
11 1.0 0 0
11 8.18 1.5043 0.4535
A 11 12.42 1.7822 0.5373
9 148.4 109.63 36.54
8 303.1 126.23 44.63
10 25.2 4.24 1.34
6 48.3 27.18 11.10
10 47 23.76 7.51
No. Mean S.D. S.E.
15 75.4 2.32 0.5983
15 2.6 0.3873 0.1000
15 1.0 0.2315 0.0600
15 5.86 0.3895 0.1005
B 15 9.97 1.1483 0.2965
14 99.8 51.46 13.75
14 275.8 138.73 37.08
15 25.6 8.28 2.14
8 40.5 19.46 6.88
12 49.4 18.93 5.47
No. Mean S.D. S.E.
19 59.6 11.91 2.73
19 3.7 0.6625 0.1520
19 1.4 0.6101 0.1400
19 4.26 0.9849 0.2261
C 18 8.35 1.6228 0.3825
19 90.4 65.71 15.08
19 246.3 91.38 20.96
17 29.1 8.88 2.15
10 33.1 13.37 4.23
17 40.6 11.81 2.86
M.D. S.E.M.D. t
16.0 2.7033 5.91
1.1 0.1204 8.39
0 0 0
2.32 0.4645 4.99
A&B 2.45 0.6137 3.99
48.6 39.04 1.24
27.3 54.01 0.50
0.4 2.52 0.15
7.8 13.05 0.59
2.4 9.29 0.25
M.D. S.E.M.D. t
15.8 2.7961 5.65
1.1 0.1819 6.05
0.4 0.1523 2.63
1.60 0.2474 6.47
B&C 1.62 0.4839 3.35
9.4 20.41 0.46
29.5 42.05 0.61
3.5 4.15 0.84
7.4 8.07 0.91
8.8 6.17 1.43
M.D. S.E.M.D. t
31.8 3.80 8.37
0 0 0
3.92 0.5068 7.73
A&C 4.07 0.6595 6.17
58.0 39.53 1.47
56.8 49.31 1.15
3.9 2.54 1.54
2.2 0.1661 12.16
15.2 11.8 1.2
6.4 8.04 0.79
according to the albumen quality of laid eggs. The means of laid eggs for Haugh units and albumen height were highest for Group A, intermediate for Group B, and lowest for Group C. The Van Wagenen index was lowest (highest score) for Group A, intermediate for B, and lowest for Group C. The differences between the means of the groups were highly significant statistically. There appeared to be close correlation between these three indices for albumen quality. Mean viscosity of the thick albumen of the laid egg was also highest for Group A, intermediate for B and lowest for Group C. The differences, however, are not staRESULTS tistically significant. The heterogeneous Albumen Quality of Laid and Oviducal nature of thick albumen, due to the presEggs ence of mucin fibers, caused considerable Laid eggs. Different indices of ablumen variation in the readings. The viscosity readings of the inner thin quality of laid and oviducal eggs are compared in Table 1. The birds were grouped albumen were less variable than those of
thin depending on time of interception. Oviducal eggs can first be detected when they are about to enter the isthmus, or approximately three hours after the previous egg has been laid. Two hours later, the egg enters the uterus. By manual expulsion most of the oviducal eggs were removed within two hours after they entered the uterus. Pressure was applied to the sides of the uterus and the egg in such a manner as to force the egg out without rupturing the shell membrane. Laid and intercepted eggs were obtained from each hen within a period of 3-7 days.
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No. Mean S.D. S.E.
13
ROLE or THE MAGNUM AND UTERUS IN EGG QUALITY
TABLE 2.—Relative proportions of total albumen and fractions of albumen of laid and intercepted eggs {Groups A, B, and C) Albumen of inter. egg/laid egg in percent
Percent outer thin laid
No. Mean S.D. S.E.
11 83 7.89 2.38
11 14.71 4.03 1.21
No. Mean S.D. S.E.
15 81.7 21.46 5.54
15 15.28 6.22 1.60
No. Mean S.D. S.E.
19 72.3 13.39 3.07
19 20.27 13.70 3.14
M.D. S.E.M.D. t
1.3 6.03 0.21
0.57 2.01 0.28
M.D. S.E.M.D. t
9.4 6.33 1.48
4.99 3.53 1.41
M.D. S.E.M.D. t
10.7 3.88 2.76
5.56 3.37 1.65
Percent inner thin
Percent middle thick
Laid
Inter.
Laid
Inter.
11 24.11 8.40 2.53
11 12.04 5.99 1.80
11 59.14 10.97 3.30
11 85.14 6.65 2.00
15 24.35 4.45 1.14
15 10.76 5.29 1.36
15 57.77 5.81 1.50
15 84.60 8.39 2.16
19 19.61 8.21 1.88
17 11.82 6.72 1.62
19 55.65 9.97 2.28
19 84.02 11.56 2.65
0.24 2.78 0.86
1.28 2.26 0.56
1.37 3.63 0.37
0.54 2.95 0.18
4.74 2.20 2.15
1.06 2.12 0.49
2.12 2.73 0.77
0.58 3.42 0.16
4.50 3.15 1.43
0.22 2.43 0.09
3.49 4.02 0.86
1.12 3.32 0.33
A
B
C
A&B
B&C
A&C
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thick albumen was not significantly different for the three groups of laid eggs, although it was somewhat lower for the poorest quality eggs than for the other two groups. This indicates, as others have shown, that there is little correlation between the relative amount of thick albumen, and the height of albumen, Van Wagenen index and viscosity of albumen. Oviducal eggs. There was litle difference in the appearance of albumen of most of the oviducal eggs, even between the poorest and the best quality eggs. The intercepted eggs of Groups A and B had the same rating, based on appearance (Van Wagenen index, 1). The poorest quality eggs (Group C) rated 1.4 by the same index. The difference between the ratings of
the middle thick, but the differences between the groups of eggs were not significant. The inner thin albumen was approximately three times as viscous as water at 25°C. Viscosity of the outer thin albumen was higher than that of inner thin, and was 4.5 to 5.5 times as viscous as water at 25°C, despite the fact that outer thin contains more water (see later section). Outer thin viscosity for the poor quality eggs was lower than for the other groups of eggs, but the differences were not statistically significant. Smith (1935) reported that mixed thin albumen of fresh eggs at 0°C. had a viscosity 4 times that of water. Table 2 shows that the percentage of
14
P. D. STURKIE AND D. POLIN
had been added to the albumen, and that probably other changes involving the breakdown of mucin had occurred. It is known that normal eggs leaving the magnum contain from 50 to 60 percent of the albumen of the laid egg. The percentage of thick albumen of the oviducal eggs was approximately 25 to 30 percent greater than that of the laid eggs, but there was no difference between the different groups of intercepted eggs. Thus the percentage of thick albumen of intercepted eggs, as well as that of the laid egg, bears little relationship to albumen quality, as indicated by height, appearance, or viscosity of albumen. The intercepted eggs of all groups averaged about one half as much inner thin albumen as the laid eggs. There was no appreciable difference in the amounts of thin albumen between the different groups of oviducal eggs. Water and Solids Content of Albumen A number of investigators have shown that the albumen of oviducal eggs contains less water and more solids than does that of laid eggs (Pearl and Curtis, 1912; McNally, 1934; Scott el al., 1937; Burmester, 1940; Asmundson, 1939). This was confirmed by the results of this study, which showed that the refractive indices of albumen of oviducal eggs weie higher than those of laid eggs (Table 3). It is known that the index of refraction varies with the fraction or layer of albumen. The index for inner thin of the laid egg is slightly higher than that for middle thick, and it is lowest for the outer thin (Almquist and Lorenz, 1933; Burmester, 1940). These results were confirmed in this study. There was no difference in the refractive index, however, of a given layer of albumen for laid eggs of different albumen quality. In other words, the water content
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Group C and that of A or B was, however, statistically significant. Many of the group C eggs rated 1.0, but some few had indices as low as 3 and 4. The albumen height of the oviducal eggs of each group was significantly higher than for the corresponding groups of laid eggs. Moreover, the difference between the groups of oviducal eggs was highly significant. The viscosity of the thick albumen of the intercepted eggs was considerably higher than that of laid eggs. Although the poor quality oviducal eggs had lower viscosities than the best quality eggs, the differences were not significant. The high consistency and gel-like nature of the thick albumen of intercepted eggs made it impossible to obtain accurate viscosity readings. The viscosities of the inner thin albumen of oviducal eggs of Groups A and B were significantly higher than those of the corresponding laid eggs, but the difference between laid and oviducal eggs of Group C was slight and insignificant. Among the oviducal eggs, those of Group C had the lowest inner thin viscosity, but the differences between the groups were not statistically significant. Inner thin viscosity readings of oviducal eggs are subject to a great deal of variation due, in part, to the time at which the eggs are intercepted and the relative amount of inner thin albumen formed. Relative amounts of albumen of oviducal eggs. The amount of total albumen of the oviducal egg in percent of the albumen of laid eggs is shown in Table 2. This figure for the Group C eggs was significantly lower than that for the Group A eggs. The reason for this is unknown. The oviducal eggs contained from 72 to 83 percent as much albumen as the laid eggs. This means that by the time the eggs were intercepted in the uterus considerable water
15
R O L E OF T H E M A G N U M AND U T E R U S I N E G G QUALITY
TABLE 3.—Refractive indices of albumen of laid and intercepted eggs (Groups A, B, and C) Refractive index outer thin Laid
Inter.
Refractive index middle thick
Refractive index inner thin
Laid
Inter.
Laid
Inter.
11 1.3532 0.009866 0.002974
9 1.3520 0.014916 0.004971
A 11 1.3551 0.010639 0.003207
11 1.3584 0.004130 0.001244
11 1.3571 0.005539 0.001670
10 1.3593 0.011953 0.003780
No. Mean S.D. S.E.
15 1.3532 0.006685 0.001726
11 1.3513 0.009223 0.002780
B 15 1.3542 0.008539 0.002204
15 1.3603 0.011301 0.002917
15 1.3551 0.010906 0.002816
15 1.3634 0.009834 0.002539
No. Mean S.D. S.E.
18 1.3530 0.003162 0.000748
12 1.3489 0.010521 0.003038
19 1.3537 0.006104 0.001438
19 1.3581 0.010882 0.002496
19 1.3545 0.007998 0.001835
19 1.3621 0.010922 0.002505
M.D. S.E.M.D. t
0.0010 0.003439 0.02
0.0007 0.005696 0.12
A&B 0.0009 0.003892 0.23
0.0019 0.003172 0.59
0.0020 0.003274 0.61
0.0041 0.004554 0.90
M.D. S.E.M.D. t
0.0008 0.001882 0.42
0.0024 0.004118 0.58
B&C 0.0005 0.002632 0.19
0.0022 0.003839 0.57
0.0006 0.003362 0.17
0.0013 0.003568 0.36
M.D. S.E.M.D. t
0.0002 0.003068 0.06
0.0031 0.005827 0.53
A&C 0.0014 0.003516 0.39
0.0003 0.002789 0.10
0.0026 0.002482 1.05
0.0028 0.004535 0.61
of the different layers of albumen of poor quality laid eggs was no different from that of eggs of good quality, and this held true also for oviducal eggs.
num and hence some changes in albumen quality may have already occurred. Determinations of albumen quality of eggs intercepted in the magnum would show to what extent decreased secretion of DISCUSSION mucin in the magnum accounts for differThe results of this study indicate that ences in albumen quality of laid eggs. albumen quality of freshly laid eggs is inBased upon differences in the height, fluenced by the breakdown of mucin oc- viscosity, and visual scores of albumen of curring after the egg leaves the magnum. uterine and laid eggs, albumen quality These data, however, do not rule out the deteriorates after the egg leaves the magprobability that variation in the amount num and before being laid. For example, of mucin secreted in the magnum may ac- the albumen height of the poor quality count for some of the changes in albumen laid eggs (Group C) averaged 4.26 mm. quality of laid eggs. compared to 8.35 mm. for the correspondThe extent to which each of these fac- ing oviducal eggs. This difference repretors was operative cannot be ascertained, sents a decrease of 51 percent. The debecause the oviducal eggs were inter- crease in albumen height of the laid eggs cepted 2 to 3 hours after they left the mag- of best quality (Group A) as compared to
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No. Mean S.D. S.E.
16
P. D. STURKIE AND D. POLIN SUMMARY
Oviducal eggs were removed from the uterus 2 to 3 hours after such eggs had left the magnum, and the quality of their albumen was compared with that of freshly laid eggs which varied greatly in albumen quality. Based upon differences in height, viscosity and visual scores of albumen of laid and uterine eggs, albumen quality deteriorates after the egg leaves the magnum and enters the uterus. The deterioration is, however, not accompained by changes in the contents of water or solids. These data also suggest that variation in the amount of mucin secreted in the magnum may account for some of the changes in albumen quality of laid eggs. The results demonstrate that there is little correlation between the amount of thick albumen collected by the screening technique and albumen quality as indicated by height, visual score and viscosity of the albumen. REFERENCES Almquist, H. J., and F. W. Lorenz, 1933. The solids content of egg white. Poultry Sci. 12: 83-89. Almquist, H. J., F. W. Lorenz and B. R. Burmester, 1932. Determination of the total solids matter and density of egg white by refractometer. Ind. Eng. Chem. 4: 305-306. Asmundson, V. S., and B. R. Burmester, 1938. The effect of resecting a part of the uterus on the formation of the hen's egg. Poultry Sci. 17: 126130. Asmundson, V. S., 1939. Formation of the egg in the oviduct of birds. Observations on turkeys. Proc. Seventh World's Poultry Congress, 96-99. Bradley, O. C , 1928. Notes on the histology of the oviduct of the domestic hen. J. Anat. 62: 339345. Burmester, B. R., 1940. A study of the physical and chemical changes of the egg during its passage through the isthmus and uterus of the hen's oviduct. J. Exp. Zool. 84: 445-500. Cole, R. K., 1938. Histology of the oviduct of the fowl in relation to variations in the condition of the firm egg albumen. Anat. Rec. 71: 349-358. Conrad, R. M., and H. M. Scott, 1939. Changes in
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the oviducal eggs was only 34.6 percent and for eggs of intermediate quality (Group B), 41.2 percent. Thus the rate of decrease in albumen height is greater in the poorer quality eggs. The fact that albumen height of the Group A intercepted eggs was considerably higher than that of the poorest quality eggs, means either that the breakdown in mucin, during the intervening 2-3 hours from the time the eggs left the magnum until they were intercepted, was considerably greater in the poor quality eggs, or that less mucin was secreted in them. It is probable that the latter factor accounted for some of the differences. It is known that water is added to the egg in the isthmus and uterus. This is shown by the higher refractive indices of the oviducal eggs as compared to laid eggs, but the water content of laid or oviducal eggs of poor albumen quality is no greater than that of eggs of good quality albumen. The nature of the changes resulting in the thinning of the albumen in the uterus is not understood. That the thinning is not due to changes in the amount of ovomucin was discussed previously. A number of theories have been proposed for the thinning of albumen in laid eggs. (See Feeney et al., 1950, for a review.) Proponents of two of the more popular ones attribute the thinning of albumen to enzyme action and to chemical hydrolysis. The enzyme theory has been virtually discarded and there is no evidence supporting chemical hydrolysis, according to these reviewers. Hoover (1940) and MacDonnell et al. (1951) have shown that a number of reducing agents cause thinning of albumen of laid eggs. They believed that the thinning was associated with the reduction of the S-S bonds of ovomucin, and their evidence supported this view.
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Feeney, 1951. Chemistry of shell egg deterioration. Poultry Sci. 30: 856-863. McNally, E., 1934. Passage of ovoglobulins through the shell membrane. Proc. Soc. Exp. Biol. Med. 31: 946-947. Pearl, R., and M. R. Curtis, 1912. Studies on the physiology of reproduction in the domestic fowl. V. Data regarding the physiology of the oviduct. J. Exp. Zool. 12: 99-132. Richardson, K. C , 1935. The secretory phenomena in the oviduct of the fowl, including the process of shell formation examined by the microincineration technique. Phil. Trans. Roy. Soc. Lond. Series B, 225: 149-195. Romanoff, A. L., and A. J. Romanoff, 1949. The Avian Egg. John Wiley and Sons, Inc., New York, New York. Scott, H. M., and B. R. Burmester, 1939. Effect of resection of the albumen tube on secretion of egg white. Proc. Seventh World's Poultry Congress, 102-106. Scott, H. M., J. S. Hughes and D. C. Warren, 1937, Augmentation of nitrogen to the egg white after formation of the shell membranes in the fowl. Poultry Sci. 16: 53-61. Smith, A. J. M., 1935. Viscosity of the white and of yolk. Dept. Sci. Ind. Research (Brit.) Food Invest. Reports 1934: 53-56. Surface, F. M., 1912. The histology of the oviduct of the hen. Maine Agric. Exp. Sta. Bui. 206. Van Wagenen, A., and H. S. Wilgus, 1935. The determination and importance of the condition of the firm albumen in studies of egg white quality. J. Agric. Res. 51: 1129-1137.
ASSOCIATION NOTICE (Continued from page 8) meeting. Reference to the Constitution and ByLaws of the Association will give the information with regard to these honors, awards and prizes. Research Award Committee (American Feed Manufacturers' Association, Borden, and Poultry Science Association)—W. W. Cravens, McMillen Feed Mills, Decatur, Indiana. Extension Award Committee (Poultry Science As-
sociation)—O. E. Goff, Poultry Department, University of Tennessee, Knoxville, Tennessee. Teaching Award Committee (Poultry Science Association)—M. A. Jull, Poultry Department, University of Maryland, College Park, Maryland. Committee on Fellows—J. H. Martin, Department of Poultry Husbandry, Purdue University, Lafayette, Indiana.
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ovomucin during egg storage. Proc. Seventh World's Poultry Congress, 528-530. Conrad, R. M., and H. M. Scott, 1942. Differences between high and low quality fresh eggs. Poultry Sci. 21: 77-80. Feeney, R. E., F. D. Ducay, R. B. Silva and L. R. MacDonnell, 1952. Chemistry of shell egg deterioration: the egg white proteins. Poultry Sci. 31: 639-647. Feeney, R. E., R. B. Silva and L. R. MacDonnell, 1950. Chemistry of shell egg deterioration. The deterioration of separated components. Poultry Sci. 30: 645-650. Forsythe, R. S., and D. H. Berquist, 1951. The effects of physical treatments on some properties of egg white. Poultry Sci. 30: 302-311. Haugh, R. R., 1937. Egg quality. U. S. Egg and Poultry Magazine, 43: 552-555. Heiman, V., and J. S. Carver, 1936. The albumen index as a physical measurement of observed egg quality. Poultry Sci. 15: 141-148. Hoover, S. R., 1940. A physical and chemical study of ovomucin. Doctoral thesis, Georgetown Univ., Washington, D. C. Knox, C. W., and A. B. Godfrey, 1940. Five years of breeding for high and low percentage of thick albumen in the eggs of Rhode Island Reds. Poultry Sci. 19: 291-294. Lorenz, F. W., and L. W. Taylor, 1940. The inheritance of albumen quality characteristic of chicken eggs. J. Agric. Res. 61: 293-301. Lorenz, F. W., L. W. Taylor and H. J. Almquist, 1934. Firmness of albumen as an inherited character. Poultry Sci. 13:14-17. MacDonnell, L. R., H. Lineweaver and R. E.
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