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The Effects of Various Factors on Air Cell Tremulosity
The Effects of Various Factors on Air Cell Tremulosity N. S. COWEN, J. W. DODGE AND J. C. WHITMAN
Agway Research Laboratory, Ithaca, New York 14850 (Received for publication February 27, 1969)
INTRODUCTION
T
EXPERIMENTAL PROCEDURES
Eggs were utilized from two flocks of caged Kimber Leghorns at a nearby cooperating poultry farm. In the first experiment, 1,152 eggs were divided among six storage conditions, one-half of which were oiled with "Sta-Good" egg spray (liquid paraffin with silicone manufactured by Mattox and Moore, Inc.). The experiment was repeated with one week's time intervening in June, 1967. Four flats of freshly layed eggs (192 eggs) were assigned at ran-
dom to each of the following storage conditions: (A) Eggs stored in the laboratory cooler within one hour of gathering; (B) Eggs stored in the laboratory cooler within two hours of gathering; (C) Eggs stored in the laboratory cooler within three hours of gathering; (D) Eggs stored in the laboratory cooler within four hours of gathering; (E) Eggs stored in the farm cooler overnight and the following day until transported to the egg receiving station; and (F) Eggs stored in the laying house 20 hours, then in the laboratory cooler until transported to the egg receiving station. One-half of each randomly assigned group of eggs was oiled immediately after gathering. Following storage time approximating 30 hours, all eggs were transported by automobile to the Weedsport, New York (64 kilometers) egg receiving station and held overnight in a cooler. The following morning (third day) all eggs were washed, candled and packed in filler flats, approximately 90 per storagetreatment subgroup. The eggs were then returned to the laboratory, individually candled, and broken out (first repetition only). Records were kept on shell mottling, candled quality, Haugh units (first repetition only), and air cell movement. Supplemental to the second repetition of the experiment, eggs were stored over a weekend, one-half of each storage-treatment group at room temperature, the other half in the laboratory cooler, and then recandled for air cell movement. The second experiment, designed to provide a test of seasonal differences as well, was repeated with a six week interval in February and April, 1968, using
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HE downgrading of eggs with tremulous air cells, which occurs during farm-to-store processing, has for some time been an economic problem to the poultry industry. Depending on the ultimate marketing location, tolerance in tremulosity varies; that is, the economic consequence of downgrading varies by states according to the magnitude in tremulosity which their shell egg marketing laws permit. Up to twenty-five percent downgrading of eggs with tremulous air cells occurs in some Northeastern States which permit no movement of the air cell in some grades. It is a generally accepted fact that transportation is the cause of tremulosity in air cells. A review of the literature provided no evidence of any reported work on the effects of various factors on air cell tremulosity. In this study, differing storage or holding conditions in temperature and percent relative humidity, and oiling, were examined to determine what effect, if any, these may have in reducing the incidence of tremulosity.
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N. S. COWEN, J. W. DODGE AND J. C. WHITMAN
identified as cracked prior to and during candling were eliminated from the experiment. Having identified those eggs with tremulous air cells, it was a simple matter to select an equal number of eggs having no air cell movement, but proportional to the first group according to storage condition for a test of interior quality difference. These eggs were broken out and the Haugh unit determined for each. It was possible to test for differences in tremulosity among storage conditions after completing the first repetition of the experiment, since each storage condition was duplicated. When no statistically significant differences were determined, greater replication was planned for the second repetition by further subdividing the same number of eggs per storage condition as utilized in repetition one. RESULTS AND DISCUSSION
Experiment 1. In experiment one, storage conditions were not replicated within repetitions so that the experimental error utilized in testing differences among storage conditions was also confounded with differences in days. A high percent relative humidity (80%) was noted on the first day the experiment was performed unlike the second day. The average percentage of eggs with tremulous air cells was 17 on the first day and 61 percent on the second day the experiment was performed. Although the range in tremulosity among storage conditions was 14 percent, no statistically significant differences were determined. Likewise, the 27 percent difference between eggs oiled (25 percent with tremulous air cells) and those not oiled (52 percent with tremulous air cells) was not significant. The interaction of these two main effects, calculated in an analysis of variance based on arcsine transformed percentages, was
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1,536 and 1,152 eggs, respectively, from a second flock of caged Kimber Leghorns. In this experiment, six storage conditions considered more variable in temperature and percent relative humidity were planned. Provision for retesting the difference in air cell movement between eggs oiled and those not oiled was included in the first repetition only. The two storage conditions considered most different in temperature and percent relative humidity were utilized. The following numbers of eggs were randomly assigned the six storage conditions: (A) Four flats of eggs (192 eggs) stored in the laboratory cooler within one hour of gathering for 29 hours; (B;Bo) Eight flats of eggs (one-half oiled) stored in the farm cooler within one hour of gathering for 29 hours; (C) Four flats of eggs stored in the laboratory cooler within 8 hours of gathering for 22 hours; (D) Four flats of eggs stored in the farm cooler within 8 hours of gathering for 22 hours; (E ;Eo) Eight flats of eggs (one-half oiled) stored in the laboratory within one hour of gathering and removed after 22 hours to laboratory room temperature for 7 hours; (F) Four flats of eggs stored in the farm cooler within one hour of gathering and removed after 22 hours to the laying house for 7 hours. In all situations, eggs held at room temperature, either in the laying house or laboratory room before and after storage in a cooler, were stored in filler flats not cased. When eggs were stored in a cooler, they were stored in 24dozen cases. Following the 30 hour storage period, all eggs were transported by automobile to the Weedsport egg receiving station and processed as before. At this time, eggs having obvious tremulous air cells were identified (later determined to have free and/or divided air cells). The eggs were then returned to the laboratory, individually candled, and those having air cell movement identified. Eggs
AIR CELL TREMULOSITY TABLE 1.—Average percentage of eggs with tremulous air cells according to storage condition and oiling vs. no oiling {192 eggs per storage-oiling group) Storage condition
Eggs not oiled
Eggs oiled
Both
A B C D E F
58.2 59.5 51.9 44.2 41.4 53.7
21.4 22.3 31.7 29.3 16.1 28.5
39.0 40.1 41.6 36.6 27.8 40.8
All
51.5
24.7
37.6
provided no statements of probability can be made regarding these differences. Furthermore, initial identity of those eggs with tremulous air cells was not maintained so that the percentages by supplemental storage may not be accurate. However, in general, it was seen that considerable reduction in tremulosity did occur following supplemental storage, and, at least, a portion of this may be attributed to fixation of previously identified tremulous cells. While the difference in tremulosity between eggs oiled and those not oiled was shown to be non-significant, one would suspect a difference of this magnitude could be significant. The supplemental tremulosity data suggested another test of the difference between these. This was possible with the effect due to supplemental storage utilized as the experimental error, where the two observations per initial storage condition were then treated like duplications. Therefore, the analysis, as before, considered the initial six storage conditions, the effect due to oiling, and their interaction. Utilized in this fashion, these data demonstrated a highly significant difference between the oiled and nonoiled eggs, in spite of the confounded experimental error. The average percentage of eggs with tremulous air cells among those not oiled was 50, while among those oiled the average was 13 percent. Table 2 shows the average percentage of eggs with tremulous air cells for each storage condition and for eggs oiled and those not oiled. Again, the difference among storage conditions was not significant, nor was the interaction effect of storage conditions and oiling. Twelve randomly chosen eggs per storage-treatment sub-group from the first repetition of the experiment were broken out at four days post-lay and the Haugh units determined. An analysis of variance
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also non-significant. Table 1 shows the average percentage of eggs with tremulous air cells for each storage condition and for eggs oiled and those not oiled. The results of this initial analysis demonstrated the desirability of replicating within days any further experiments dealing with this egg quality characteristic. Supplemental to the second repetition of the experiment was the weekend storage of these eggs at room and cooler temperatures, one-half of each storage-treatment group in each environment, after which they were recandled for air cell movement. The purpose of this adjunct to the experiment was to ascertain if cells once determined tremulous became fixed after further storage, and if so, the differential effect by the two storage environments. The percentage of all eggs having tremulous air cells on the first candling was 60, while only 32 percent of the total eggs were determined to have air cell movement following supplemental storage. Twenty-five percent of all eggs supplementally stored at room temperature had tremulous air cells, while 39 percent stored in the laboratory cooler had tremulous air cells. Only among oiled eggs from two of the initial storage conditions was the percentage with tremulous air cells less among those stored in the laboratory cooler. Again, since replication was not
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N. S. COWEN, J. W. DODGE AND J. C. WHITMAN
TABLE 2.—Average percentage of eggs with tremulous air cells according to storage condition and oiling vs. no oiling {96 eggs per storage-oiling group) Eggs not oiled
Eggs oiled
Both
A B C D E F
44.0 48.8 43.2 39.9 46.5 74.0
10.0 5.5 25.1 17.7 17.7 8.3
25.0 23.4 33.8 28.1 31.2 37.9
All
49.5*
13.3*
29.8
* Significantly different probability.
at the 5% level of
of these data considered the same main effects and interaction as before. The differences among storage conditions were shown to be significant at the five percent level. According to the Duncan "new multiple range test" (for mean separation) the average Haugh unit measure among eggs stored in the laboratory cooler within three hours of gathering (C) was significantly greater than those stored in the farm cooler (E), or the laying house initially (F). Likewise, the average Haugh unit measures among eggs stored in the laboratory cooler within one (A) and four (D) hours of gathering were significantly greater than those stored in the laying house 20 hours, then in the laboratory cooler (F). Thus, the value of cooling eggs shortly after lay is evident. The difference between eggs oiled and those not oiled was significant at the one percent level. The average Haugh unit measure for non-oiled eggs was 86, while that for oiled eggs was 90. This difference points out the value of oiling eggs with respect to retention of interior quality. The non-significant interaction effect indicates that oiling had an equal effect of superior interior quality retention for all treatments. Table 3 shows the average Haugh unit for each storage condition and for eggs oiled and those not oiled. The
TABLE 3.—Average Haugh unit according to storage condition and oiling vs. no oiling (12 eggs per storage-oiling group) Storage condition
Eggs not oiled
Eggs oiled
Both*
C D A B E F
89.2 89.2 88.1 87.1 83.5 81.3
91.4 90.7 90.4 89.2 89.9 89.8
90.3" 89.9 a b 89.2" b 88.2*b0 86.7 b ° 85.6"
All
86.4**
90.2**
88.3
* Significantly different at the 5% level of probability (storage conditions denoted by same letter not significantly different). ** Significantly different at the 1% level of probability.
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Storage condition
data recorded on shell mottling and candled quality indicated little or no difference among storage conditions for these characteristics. Experiment 2. The second experiment was designed so that data from the two repetitions of the experiment could be analyzed independently, and, collectively, as well. Short and Mason hygro-thermographs were utilized in each of the storage facilities. The temperature and percent relative humidity was quite similar during both repetitions of the experiment in each of the respective facilities, excepting that greater variation was recorded in the laying house during April (second repetition). The temperatures and percents relative humidity were as follows: 33°F. and 93%; 73°F. and 20% to 33%; 46°F. and 87%; 47°F. to 70°F. and 70% to 90% in the laboratory cooler, the laboratory room, the farm cooler and the laying house, respectively. Analyses of tremulous air cell and Haugh unit data were calculated for the first repetition initially. According to the analysis of the arcsine transformed percentage data there were no differences among storage conditions in air cell movement. The calculated F-statistic ap-
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AIR CELL TREMULOSITY
TABLE 4.—Average percentage of eggs with tremulous air cells according to storage condition and duplication {96 eggs per storage-duplication group) Storage condition
Replication Replication 2 1
Both
A B C D E F
15.9 20.7 24.4 3.3 13.3 9.0
6.7 21.1 28.1 12.2 18.4 11.1
10.9 20.9 26.2 7.1 15.8 10.0
All
14.4
16.2
15.3
TABLE 5.—Average percentage of eggs with tremulous air cells according to storage condition and oiling vs. no oiling (192 eggs per storage-oiling group) Storage condition
Eggs not oiled
Eggs oiled
B E
20.9 15.8
5.0 2.1
11.8 7.5
18.3**
3.4**
11.0
All
B
th
** Significantly different at the 1% level of probability.
of oiling by the two storage conditions. Table 5 shows the average percentage of eggs with tremulous air cells for each storage condition and for eggs oiled and those not oiled. The Haugh unit data were derived from 177 eggs having tremulous air cells and an equal number of randomly chosen eggs having no air cell movement, but proportional to the first group according to storage condition. In the analysis of these data, the difference between eggs with air cell movement and those without was not significant. The average Haugh unit among eggs having tremulous air cells was 77.3, while that for eggs having no air cell movement was 78.2. Table 6 shows the average Haugh unit for each storage condition and for eggs having air cell movement and those not. It was possible also from these data to test the difference between the oiled and non-oiled eggs. Since the number of observations with respect to treatment (oiled vs. non-oiled) by storage condition and replication were disproportionate, they were proportionalized by choosing at random an equal number of non-oiled eggs according to storageduplication subclass. The choice of eggs purposely included equal numbers having tremulous and non-tremulous air cells per subclass, also. In so doing, greater numbers of observations were utilized and yet the effect of tremulosity was held constant. The analysis demonstrated no dif-
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proached the 5 percent significance level, however. Nevertheless, it was apparent that considerable variation among duplications was present. Table 4 shows the average percentage of eggs with tremulous air cells for each storage condition and duplication. This repetition of the experiment was also designed so that again the effect of oiling on this egg quality characteristic could be tested. The two storage conditions considered to be most extreme in their effects were utilized; that is, (B) eggs stored in the farm cooler within one hour of gathering for 29 hours, and (E) eggs stored in the laboratory cooler within one hour of gathering and removed after 22 hours to laboratory room temperature for 7 hours. Double the number of eggs randomly assigned the other storage conditions were assigned these, in order that replication and equal numbers of non-oiled could be maintained throughout. The analysis of these data demonstrated no difference in the two storage conditions, as before. The difference between oiled eggs and those not oiled was highly significant, however. Eggs with tremulous air cells averaged 3 percent among those oiled, 18 percent among the eggs not oiled, or a difference of 15 percent. The interaction effect of oiling and storage conditions was not significant, indicating no difference in the effect
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N. S. COWEN, J. W. DODGE AND J. C. WHITMAN
TABLE 6.—Average Haugh unit according to storage condition and tremulosity (number of eggs per storagetremulosity group indicated in parentheses) Tremulous
Nontremulous
Both
A B C D E F
77.1(20) 76.7(46) 76.9(47) 74.8(14) 79.3 (32) 79.0(18)
75.6(20) 79.1(46) 78.1(47) 75.1(14) 78.4(32) 80.7(18)
76.3 77.9 77.5 75.0 78.8 79.9
All
77.3
78.2
77.8
ference in Haugh units between the 26 oiled eggs and an equal number of eggs not oiled. This was not the case in Experiment 1, where a highly significant difference was observed. Likely, environmental conditions associated with seasonal differences accounts for this. However, a difference of one day post-lay at break out (5 days in this experiment) existed between the two. The average Haugh unit among the oiled eggs was 80; for the nonoiled eggs the average was 77 Haugh units. Table 7 shows the average Haugh unit for each storage condition and for eggs oiled and those not oiled. The second repetition of the experiment was identical to the first with respect to randomization procedures, storage time and facilities used, and the number of eggs per storage condition, excepting the additional numbers used for the oiling trial in the first repetition. However, in view of the variation that existed among duplications in the first repetition, it seemed logical on theoretical grounds that greater replication by further sub-division of the numbers per storage condition could detect differences among them, if they were present. Thus, the number of eggs randomly assigned each storage condition were subdivided as randomized into duplications, triplications and quadruplications, and processed with identity throughout the experiment. In other
To determine if a significant difference between repetitions of the experiment existed, an analysis of variance of the duplicated data from both repetitions was TABLE 7.—Average Haugh unit according to storage condition and oiling vs. no oiling {number of eggs per storage-oiling group indicated in parentheses) Storage condition
Eggs not oiled
Eggs oiled
B
th
B E
77.6(18) 75.9 (8)
79.3(18) 82.5 (8)
78.5 79.2
All
77.1
80.3
78.7
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Storage condition
words, the initial number of eggs randomly assigned each storage condition consisted of 96 eggs per duplication, 64 eggs per triplication and 48 eggs per quadruplication. As before, the percentage of eggs having tremulous air cells was calculated for each duplication by storage condition, and additionally for each triplication and quadruplication by storage condition. These percentages were then arcsine transformed for analysis, one each according to the degree of replication. No difference in the percentage of eggs with tremulous air cells among storage conditions was determined in any one of the three analyses. Table 8 shows the average percentages of eggs with tremulous air cells according to storage condition and according to replication. It was apparent, as before, that sufficient variation among replications rendered the tests of differences among storage conditions non-significant. However, had eggs with air cell movement been more equally distributed among all eggs, the theoretical advantage of greater replication, as executed here, would likely have demonstrated significant differences were they present. The fact that eggs having air cell movement were not equally distributed became apparent also when they were candled and so identified.
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AIR CELL TREMULOSITY
TABLE 8.—Average percentage of eggs with tremulous air cells according to storage condition and replication (48, 64, and 96 eggs per storage-replication group) Storage condition
4 Reps 3 Reps 2 Reps
Total
A
16.7 17.4 44.7 34.0
12.5 32.8 39.7
17.0 39.4
28.2
B
35.4 8.7 15.9 23.4
26.6 12.1 23.8
22.3 19.8
21.1
C
25.0 50.0 19.6 23.4
30.2 37.7 20.6
37.2 21.5
29.4
D
31.8 15.2 36.2 42.6
26.7 29.5 38.1
23.3 39.4
31.5
E
29.2 21.3 24.4 36.4
28.6 22.6 32.2
25.3 30.3
27.7
F
29.5 8.7 27.9 25.0
25.0 18.6 24.1
18.9 26.4
22.6
TABLE 9.—Average percentage of eggs with tremulous air cells according to storage condition and repetition (192 eggs per storage-repetition group) Storage condition
Repetition 1
Repetition 2
Both
A B C D E F
10.9 20.9 26.2 7.1 15.8 10.0
27.5 21.0 29.0 31.1 27.8 22.5
18.4 21.0 27.6 17.4 21.5 15.8
All
14.6**
26.4**
20.2
** Significantly different at the 1% level of probability.
losity. Table 9 shows the average percentage of tremulous air cells for each storage condition as determined for repetition One, repetition Two, and for both collectively. SUMMARY AND CONCLUSIONS According to results of these experiments no significant differences in tremulosity were determined among the storage conditions imposed. Therefore, it appears doubtful that storage conditions have any reducing effect in the magnitude of tremulosity which would otherwise be present. Sufficient variation among replications of storage conditions utilized in the second experiment rendered all tests of differences among them non-significant. However, it was apparent by observation as the eggs were candled, in addition to no change in proportion of error to total variance with increased replication, that eggs with air cell movement were not equally distributed throughout. The highly significant difference in percentage of eggs with tremulous air cells between repetitions of the second experiment is more likely due to a difference in age of the birds, than the small difference in environmental temperature and relative humidity between them. Oiling eggs relatively soon after lay and
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calculated. Main effects due to storage conditions, repetitions and their interaction were considered. Again, differences among storage conditions were non-significant, as was the interaction effect. However, the difference between repetitions was highly significant. The average percentage of eggs with tremulous air cells in repetition One was 15; for repetition Two, it was 26 percent. This difference may be due to environmental differences associated with the times the two repetitions were performed, although, as pointed out earlier, little difference in temperature and relative humidity existed among the storage facilities in this regard. Then, too, the age of the birds was advanced by six weeks at the time of the second repetition, and this may better explain the repetition difference in tremu-
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N . S. C O W E N , J. W. D O D G E AND J. C.
gathering had a highly significant effect in reducing the percentage of eggs with tremulous air cells in these experiments. Also, oiling was shown to be beneficial in the retention of interior quality as measured b y the H a u g h unit. I t is apparent t h a t oiling is a good practice for superior
WHITMAN
egg quality with respect to both characteristics. T h a t eggs having tremulous air cells were not significantly different in interior quality as measured b y the H a u g h unit dispels the time honored inference t h a t these eggs are of inferior interior quality.
W. F . HOLLANDER AND J. A. BRUMBAUGH Genetics Department, Iowa State University, Ames, Iowa 50010, and Department of Zoology, University of Nebraska, Lincoln, Nebraska (Received for publication March 1, 1969)
INTRODUCTION
N
O R M A L chickens have small webs between toes 2 and 3, and 3 and 4, sufficient to permit the use of a punch for identification purposes with b a b y chicks. By contrast, pigeons and m a n y other kinds of birds normally are devoid of web, and waterfowl typically have complete webbing. Partial webbing or syndactylism is normal in some of the Coraciiformes, such as kingfishers, in which toes 3 and 4 are joined closely. T h e purpose of this paper is to record our observations on spontaneous occurrences of increased web development and syndactylism in the fowl and to relate these to previous studies on the condition, b o t h genetic and teratological. N o t m a n y poultrymen have ever seen the condition, and it is not specified as a characteristic of a n y breed, though varieties with heavily-feathered feet are reported to have a tendency to increased web or syndactyly between toes 3 and 4 (review 1 Journal Paper No. J-6167 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa. Project 1380. Some of the work has received support from the University of Nebraska.
b y H u t t , 1949). T h e relation is by no means necessary; m a n y feather-footed fowls have normal webbing, and cleanlegged fowls m a y have increased webbing and syndactylism. Warren (1950) made an extensive study of a genetic type found in White Rocks, which are not featherfooted. I n a personal letter, in 1968, H u t t states t h a t he has occasionally observed the condition in Leghorns. Our examples originated in clean-legged mongrels and in Jungle Fowls (Gallus gallus). I t seems likely t h a t the latter m a y prove useful in future experimental studies on the development of the embryonic foot. MATERIALS AND METHODS Our general management practices and sources of stocks have been set forth in previous papers (Brumbaugh and Hollander, 1965, 1966). T h e Jungle Fowl stock is a blend of a pair of birds from each of two sources: Dr. Walter Landauer at Storrs, Conn., and the Lincoln Park Zoo of Chicago, 111. Since the original mixing, in 1958, the stock has been carried on by moderately close inbreeding, with some
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Web-Foot or Syndactylism in the Fowl1
Agway Research Laboratory, Ithaca, New York 14850 (Received for publication February 27, 1969)
INTRODUCTION
T
EXPERIMENTAL PROCEDURES
Eggs were utilized from two flocks of caged Kimber Leghorns at a nearby cooperating poultry farm. In the first experiment, 1,152 eggs were divided among six storage conditions, one-half of which were oiled with "Sta-Good" egg spray (liquid paraffin with silicone manufactured by Mattox and Moore, Inc.). The experiment was repeated with one week's time intervening in June, 1967. Four flats of freshly layed eggs (192 eggs) were assigned at ran-
dom to each of the following storage conditions: (A) Eggs stored in the laboratory cooler within one hour of gathering; (B) Eggs stored in the laboratory cooler within two hours of gathering; (C) Eggs stored in the laboratory cooler within three hours of gathering; (D) Eggs stored in the laboratory cooler within four hours of gathering; (E) Eggs stored in the farm cooler overnight and the following day until transported to the egg receiving station; and (F) Eggs stored in the laying house 20 hours, then in the laboratory cooler until transported to the egg receiving station. One-half of each randomly assigned group of eggs was oiled immediately after gathering. Following storage time approximating 30 hours, all eggs were transported by automobile to the Weedsport, New York (64 kilometers) egg receiving station and held overnight in a cooler. The following morning (third day) all eggs were washed, candled and packed in filler flats, approximately 90 per storagetreatment subgroup. The eggs were then returned to the laboratory, individually candled, and broken out (first repetition only). Records were kept on shell mottling, candled quality, Haugh units (first repetition only), and air cell movement. Supplemental to the second repetition of the experiment, eggs were stored over a weekend, one-half of each storage-treatment group at room temperature, the other half in the laboratory cooler, and then recandled for air cell movement. The second experiment, designed to provide a test of seasonal differences as well, was repeated with a six week interval in February and April, 1968, using
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HE downgrading of eggs with tremulous air cells, which occurs during farm-to-store processing, has for some time been an economic problem to the poultry industry. Depending on the ultimate marketing location, tolerance in tremulosity varies; that is, the economic consequence of downgrading varies by states according to the magnitude in tremulosity which their shell egg marketing laws permit. Up to twenty-five percent downgrading of eggs with tremulous air cells occurs in some Northeastern States which permit no movement of the air cell in some grades. It is a generally accepted fact that transportation is the cause of tremulosity in air cells. A review of the literature provided no evidence of any reported work on the effects of various factors on air cell tremulosity. In this study, differing storage or holding conditions in temperature and percent relative humidity, and oiling, were examined to determine what effect, if any, these may have in reducing the incidence of tremulosity.
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N. S. COWEN, J. W. DODGE AND J. C. WHITMAN
identified as cracked prior to and during candling were eliminated from the experiment. Having identified those eggs with tremulous air cells, it was a simple matter to select an equal number of eggs having no air cell movement, but proportional to the first group according to storage condition for a test of interior quality difference. These eggs were broken out and the Haugh unit determined for each. It was possible to test for differences in tremulosity among storage conditions after completing the first repetition of the experiment, since each storage condition was duplicated. When no statistically significant differences were determined, greater replication was planned for the second repetition by further subdividing the same number of eggs per storage condition as utilized in repetition one. RESULTS AND DISCUSSION
Experiment 1. In experiment one, storage conditions were not replicated within repetitions so that the experimental error utilized in testing differences among storage conditions was also confounded with differences in days. A high percent relative humidity (80%) was noted on the first day the experiment was performed unlike the second day. The average percentage of eggs with tremulous air cells was 17 on the first day and 61 percent on the second day the experiment was performed. Although the range in tremulosity among storage conditions was 14 percent, no statistically significant differences were determined. Likewise, the 27 percent difference between eggs oiled (25 percent with tremulous air cells) and those not oiled (52 percent with tremulous air cells) was not significant. The interaction of these two main effects, calculated in an analysis of variance based on arcsine transformed percentages, was
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1,536 and 1,152 eggs, respectively, from a second flock of caged Kimber Leghorns. In this experiment, six storage conditions considered more variable in temperature and percent relative humidity were planned. Provision for retesting the difference in air cell movement between eggs oiled and those not oiled was included in the first repetition only. The two storage conditions considered most different in temperature and percent relative humidity were utilized. The following numbers of eggs were randomly assigned the six storage conditions: (A) Four flats of eggs (192 eggs) stored in the laboratory cooler within one hour of gathering for 29 hours; (B;Bo) Eight flats of eggs (one-half oiled) stored in the farm cooler within one hour of gathering for 29 hours; (C) Four flats of eggs stored in the laboratory cooler within 8 hours of gathering for 22 hours; (D) Four flats of eggs stored in the farm cooler within 8 hours of gathering for 22 hours; (E ;Eo) Eight flats of eggs (one-half oiled) stored in the laboratory within one hour of gathering and removed after 22 hours to laboratory room temperature for 7 hours; (F) Four flats of eggs stored in the farm cooler within one hour of gathering and removed after 22 hours to the laying house for 7 hours. In all situations, eggs held at room temperature, either in the laying house or laboratory room before and after storage in a cooler, were stored in filler flats not cased. When eggs were stored in a cooler, they were stored in 24dozen cases. Following the 30 hour storage period, all eggs were transported by automobile to the Weedsport egg receiving station and processed as before. At this time, eggs having obvious tremulous air cells were identified (later determined to have free and/or divided air cells). The eggs were then returned to the laboratory, individually candled, and those having air cell movement identified. Eggs
AIR CELL TREMULOSITY TABLE 1.—Average percentage of eggs with tremulous air cells according to storage condition and oiling vs. no oiling {192 eggs per storage-oiling group) Storage condition
Eggs not oiled
Eggs oiled
Both
A B C D E F
58.2 59.5 51.9 44.2 41.4 53.7
21.4 22.3 31.7 29.3 16.1 28.5
39.0 40.1 41.6 36.6 27.8 40.8
All
51.5
24.7
37.6
provided no statements of probability can be made regarding these differences. Furthermore, initial identity of those eggs with tremulous air cells was not maintained so that the percentages by supplemental storage may not be accurate. However, in general, it was seen that considerable reduction in tremulosity did occur following supplemental storage, and, at least, a portion of this may be attributed to fixation of previously identified tremulous cells. While the difference in tremulosity between eggs oiled and those not oiled was shown to be non-significant, one would suspect a difference of this magnitude could be significant. The supplemental tremulosity data suggested another test of the difference between these. This was possible with the effect due to supplemental storage utilized as the experimental error, where the two observations per initial storage condition were then treated like duplications. Therefore, the analysis, as before, considered the initial six storage conditions, the effect due to oiling, and their interaction. Utilized in this fashion, these data demonstrated a highly significant difference between the oiled and nonoiled eggs, in spite of the confounded experimental error. The average percentage of eggs with tremulous air cells among those not oiled was 50, while among those oiled the average was 13 percent. Table 2 shows the average percentage of eggs with tremulous air cells for each storage condition and for eggs oiled and those not oiled. Again, the difference among storage conditions was not significant, nor was the interaction effect of storage conditions and oiling. Twelve randomly chosen eggs per storage-treatment sub-group from the first repetition of the experiment were broken out at four days post-lay and the Haugh units determined. An analysis of variance
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also non-significant. Table 1 shows the average percentage of eggs with tremulous air cells for each storage condition and for eggs oiled and those not oiled. The results of this initial analysis demonstrated the desirability of replicating within days any further experiments dealing with this egg quality characteristic. Supplemental to the second repetition of the experiment was the weekend storage of these eggs at room and cooler temperatures, one-half of each storage-treatment group in each environment, after which they were recandled for air cell movement. The purpose of this adjunct to the experiment was to ascertain if cells once determined tremulous became fixed after further storage, and if so, the differential effect by the two storage environments. The percentage of all eggs having tremulous air cells on the first candling was 60, while only 32 percent of the total eggs were determined to have air cell movement following supplemental storage. Twenty-five percent of all eggs supplementally stored at room temperature had tremulous air cells, while 39 percent stored in the laboratory cooler had tremulous air cells. Only among oiled eggs from two of the initial storage conditions was the percentage with tremulous air cells less among those stored in the laboratory cooler. Again, since replication was not
1403
1404
N. S. COWEN, J. W. DODGE AND J. C. WHITMAN
TABLE 2.—Average percentage of eggs with tremulous air cells according to storage condition and oiling vs. no oiling {96 eggs per storage-oiling group) Eggs not oiled
Eggs oiled
Both
A B C D E F
44.0 48.8 43.2 39.9 46.5 74.0
10.0 5.5 25.1 17.7 17.7 8.3
25.0 23.4 33.8 28.1 31.2 37.9
All
49.5*
13.3*
29.8
* Significantly different probability.
at the 5% level of
of these data considered the same main effects and interaction as before. The differences among storage conditions were shown to be significant at the five percent level. According to the Duncan "new multiple range test" (for mean separation) the average Haugh unit measure among eggs stored in the laboratory cooler within three hours of gathering (C) was significantly greater than those stored in the farm cooler (E), or the laying house initially (F). Likewise, the average Haugh unit measures among eggs stored in the laboratory cooler within one (A) and four (D) hours of gathering were significantly greater than those stored in the laying house 20 hours, then in the laboratory cooler (F). Thus, the value of cooling eggs shortly after lay is evident. The difference between eggs oiled and those not oiled was significant at the one percent level. The average Haugh unit measure for non-oiled eggs was 86, while that for oiled eggs was 90. This difference points out the value of oiling eggs with respect to retention of interior quality. The non-significant interaction effect indicates that oiling had an equal effect of superior interior quality retention for all treatments. Table 3 shows the average Haugh unit for each storage condition and for eggs oiled and those not oiled. The
TABLE 3.—Average Haugh unit according to storage condition and oiling vs. no oiling (12 eggs per storage-oiling group) Storage condition
Eggs not oiled
Eggs oiled
Both*
C D A B E F
89.2 89.2 88.1 87.1 83.5 81.3
91.4 90.7 90.4 89.2 89.9 89.8
90.3" 89.9 a b 89.2" b 88.2*b0 86.7 b ° 85.6"
All
86.4**
90.2**
88.3
* Significantly different at the 5% level of probability (storage conditions denoted by same letter not significantly different). ** Significantly different at the 1% level of probability.
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Storage condition
data recorded on shell mottling and candled quality indicated little or no difference among storage conditions for these characteristics. Experiment 2. The second experiment was designed so that data from the two repetitions of the experiment could be analyzed independently, and, collectively, as well. Short and Mason hygro-thermographs were utilized in each of the storage facilities. The temperature and percent relative humidity was quite similar during both repetitions of the experiment in each of the respective facilities, excepting that greater variation was recorded in the laying house during April (second repetition). The temperatures and percents relative humidity were as follows: 33°F. and 93%; 73°F. and 20% to 33%; 46°F. and 87%; 47°F. to 70°F. and 70% to 90% in the laboratory cooler, the laboratory room, the farm cooler and the laying house, respectively. Analyses of tremulous air cell and Haugh unit data were calculated for the first repetition initially. According to the analysis of the arcsine transformed percentage data there were no differences among storage conditions in air cell movement. The calculated F-statistic ap-
1405
AIR CELL TREMULOSITY
TABLE 4.—Average percentage of eggs with tremulous air cells according to storage condition and duplication {96 eggs per storage-duplication group) Storage condition
Replication Replication 2 1
Both
A B C D E F
15.9 20.7 24.4 3.3 13.3 9.0
6.7 21.1 28.1 12.2 18.4 11.1
10.9 20.9 26.2 7.1 15.8 10.0
All
14.4
16.2
15.3
TABLE 5.—Average percentage of eggs with tremulous air cells according to storage condition and oiling vs. no oiling (192 eggs per storage-oiling group) Storage condition
Eggs not oiled
Eggs oiled
B E
20.9 15.8
5.0 2.1
11.8 7.5
18.3**
3.4**
11.0
All
B
th
** Significantly different at the 1% level of probability.
of oiling by the two storage conditions. Table 5 shows the average percentage of eggs with tremulous air cells for each storage condition and for eggs oiled and those not oiled. The Haugh unit data were derived from 177 eggs having tremulous air cells and an equal number of randomly chosen eggs having no air cell movement, but proportional to the first group according to storage condition. In the analysis of these data, the difference between eggs with air cell movement and those without was not significant. The average Haugh unit among eggs having tremulous air cells was 77.3, while that for eggs having no air cell movement was 78.2. Table 6 shows the average Haugh unit for each storage condition and for eggs having air cell movement and those not. It was possible also from these data to test the difference between the oiled and non-oiled eggs. Since the number of observations with respect to treatment (oiled vs. non-oiled) by storage condition and replication were disproportionate, they were proportionalized by choosing at random an equal number of non-oiled eggs according to storageduplication subclass. The choice of eggs purposely included equal numbers having tremulous and non-tremulous air cells per subclass, also. In so doing, greater numbers of observations were utilized and yet the effect of tremulosity was held constant. The analysis demonstrated no dif-
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proached the 5 percent significance level, however. Nevertheless, it was apparent that considerable variation among duplications was present. Table 4 shows the average percentage of eggs with tremulous air cells for each storage condition and duplication. This repetition of the experiment was also designed so that again the effect of oiling on this egg quality characteristic could be tested. The two storage conditions considered to be most extreme in their effects were utilized; that is, (B) eggs stored in the farm cooler within one hour of gathering for 29 hours, and (E) eggs stored in the laboratory cooler within one hour of gathering and removed after 22 hours to laboratory room temperature for 7 hours. Double the number of eggs randomly assigned the other storage conditions were assigned these, in order that replication and equal numbers of non-oiled could be maintained throughout. The analysis of these data demonstrated no difference in the two storage conditions, as before. The difference between oiled eggs and those not oiled was highly significant, however. Eggs with tremulous air cells averaged 3 percent among those oiled, 18 percent among the eggs not oiled, or a difference of 15 percent. The interaction effect of oiling and storage conditions was not significant, indicating no difference in the effect
1406
N. S. COWEN, J. W. DODGE AND J. C. WHITMAN
TABLE 6.—Average Haugh unit according to storage condition and tremulosity (number of eggs per storagetremulosity group indicated in parentheses) Tremulous
Nontremulous
Both
A B C D E F
77.1(20) 76.7(46) 76.9(47) 74.8(14) 79.3 (32) 79.0(18)
75.6(20) 79.1(46) 78.1(47) 75.1(14) 78.4(32) 80.7(18)
76.3 77.9 77.5 75.0 78.8 79.9
All
77.3
78.2
77.8
ference in Haugh units between the 26 oiled eggs and an equal number of eggs not oiled. This was not the case in Experiment 1, where a highly significant difference was observed. Likely, environmental conditions associated with seasonal differences accounts for this. However, a difference of one day post-lay at break out (5 days in this experiment) existed between the two. The average Haugh unit among the oiled eggs was 80; for the nonoiled eggs the average was 77 Haugh units. Table 7 shows the average Haugh unit for each storage condition and for eggs oiled and those not oiled. The second repetition of the experiment was identical to the first with respect to randomization procedures, storage time and facilities used, and the number of eggs per storage condition, excepting the additional numbers used for the oiling trial in the first repetition. However, in view of the variation that existed among duplications in the first repetition, it seemed logical on theoretical grounds that greater replication by further sub-division of the numbers per storage condition could detect differences among them, if they were present. Thus, the number of eggs randomly assigned each storage condition were subdivided as randomized into duplications, triplications and quadruplications, and processed with identity throughout the experiment. In other
To determine if a significant difference between repetitions of the experiment existed, an analysis of variance of the duplicated data from both repetitions was TABLE 7.—Average Haugh unit according to storage condition and oiling vs. no oiling {number of eggs per storage-oiling group indicated in parentheses) Storage condition
Eggs not oiled
Eggs oiled
B
th
B E
77.6(18) 75.9 (8)
79.3(18) 82.5 (8)
78.5 79.2
All
77.1
80.3
78.7
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Storage condition
words, the initial number of eggs randomly assigned each storage condition consisted of 96 eggs per duplication, 64 eggs per triplication and 48 eggs per quadruplication. As before, the percentage of eggs having tremulous air cells was calculated for each duplication by storage condition, and additionally for each triplication and quadruplication by storage condition. These percentages were then arcsine transformed for analysis, one each according to the degree of replication. No difference in the percentage of eggs with tremulous air cells among storage conditions was determined in any one of the three analyses. Table 8 shows the average percentages of eggs with tremulous air cells according to storage condition and according to replication. It was apparent, as before, that sufficient variation among replications rendered the tests of differences among storage conditions non-significant. However, had eggs with air cell movement been more equally distributed among all eggs, the theoretical advantage of greater replication, as executed here, would likely have demonstrated significant differences were they present. The fact that eggs having air cell movement were not equally distributed became apparent also when they were candled and so identified.
1407
AIR CELL TREMULOSITY
TABLE 8.—Average percentage of eggs with tremulous air cells according to storage condition and replication (48, 64, and 96 eggs per storage-replication group) Storage condition
4 Reps 3 Reps 2 Reps
Total
A
16.7 17.4 44.7 34.0
12.5 32.8 39.7
17.0 39.4
28.2
B
35.4 8.7 15.9 23.4
26.6 12.1 23.8
22.3 19.8
21.1
C
25.0 50.0 19.6 23.4
30.2 37.7 20.6
37.2 21.5
29.4
D
31.8 15.2 36.2 42.6
26.7 29.5 38.1
23.3 39.4
31.5
E
29.2 21.3 24.4 36.4
28.6 22.6 32.2
25.3 30.3
27.7
F
29.5 8.7 27.9 25.0
25.0 18.6 24.1
18.9 26.4
22.6
TABLE 9.—Average percentage of eggs with tremulous air cells according to storage condition and repetition (192 eggs per storage-repetition group) Storage condition
Repetition 1
Repetition 2
Both
A B C D E F
10.9 20.9 26.2 7.1 15.8 10.0
27.5 21.0 29.0 31.1 27.8 22.5
18.4 21.0 27.6 17.4 21.5 15.8
All
14.6**
26.4**
20.2
** Significantly different at the 1% level of probability.
losity. Table 9 shows the average percentage of tremulous air cells for each storage condition as determined for repetition One, repetition Two, and for both collectively. SUMMARY AND CONCLUSIONS According to results of these experiments no significant differences in tremulosity were determined among the storage conditions imposed. Therefore, it appears doubtful that storage conditions have any reducing effect in the magnitude of tremulosity which would otherwise be present. Sufficient variation among replications of storage conditions utilized in the second experiment rendered all tests of differences among them non-significant. However, it was apparent by observation as the eggs were candled, in addition to no change in proportion of error to total variance with increased replication, that eggs with air cell movement were not equally distributed throughout. The highly significant difference in percentage of eggs with tremulous air cells between repetitions of the second experiment is more likely due to a difference in age of the birds, than the small difference in environmental temperature and relative humidity between them. Oiling eggs relatively soon after lay and
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calculated. Main effects due to storage conditions, repetitions and their interaction were considered. Again, differences among storage conditions were non-significant, as was the interaction effect. However, the difference between repetitions was highly significant. The average percentage of eggs with tremulous air cells in repetition One was 15; for repetition Two, it was 26 percent. This difference may be due to environmental differences associated with the times the two repetitions were performed, although, as pointed out earlier, little difference in temperature and relative humidity existed among the storage facilities in this regard. Then, too, the age of the birds was advanced by six weeks at the time of the second repetition, and this may better explain the repetition difference in tremu-
1408
N . S. C O W E N , J. W. D O D G E AND J. C.
gathering had a highly significant effect in reducing the percentage of eggs with tremulous air cells in these experiments. Also, oiling was shown to be beneficial in the retention of interior quality as measured b y the H a u g h unit. I t is apparent t h a t oiling is a good practice for superior
WHITMAN
egg quality with respect to both characteristics. T h a t eggs having tremulous air cells were not significantly different in interior quality as measured b y the H a u g h unit dispels the time honored inference t h a t these eggs are of inferior interior quality.
W. F . HOLLANDER AND J. A. BRUMBAUGH Genetics Department, Iowa State University, Ames, Iowa 50010, and Department of Zoology, University of Nebraska, Lincoln, Nebraska (Received for publication March 1, 1969)
INTRODUCTION
N
O R M A L chickens have small webs between toes 2 and 3, and 3 and 4, sufficient to permit the use of a punch for identification purposes with b a b y chicks. By contrast, pigeons and m a n y other kinds of birds normally are devoid of web, and waterfowl typically have complete webbing. Partial webbing or syndactylism is normal in some of the Coraciiformes, such as kingfishers, in which toes 3 and 4 are joined closely. T h e purpose of this paper is to record our observations on spontaneous occurrences of increased web development and syndactylism in the fowl and to relate these to previous studies on the condition, b o t h genetic and teratological. N o t m a n y poultrymen have ever seen the condition, and it is not specified as a characteristic of a n y breed, though varieties with heavily-feathered feet are reported to have a tendency to increased web or syndactyly between toes 3 and 4 (review 1 Journal Paper No. J-6167 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa. Project 1380. Some of the work has received support from the University of Nebraska.
b y H u t t , 1949). T h e relation is by no means necessary; m a n y feather-footed fowls have normal webbing, and cleanlegged fowls m a y have increased webbing and syndactylism. Warren (1950) made an extensive study of a genetic type found in White Rocks, which are not featherfooted. I n a personal letter, in 1968, H u t t states t h a t he has occasionally observed the condition in Leghorns. Our examples originated in clean-legged mongrels and in Jungle Fowls (Gallus gallus). I t seems likely t h a t the latter m a y prove useful in future experimental studies on the development of the embryonic foot. MATERIALS AND METHODS Our general management practices and sources of stocks have been set forth in previous papers (Brumbaugh and Hollander, 1965, 1966). T h e Jungle Fowl stock is a blend of a pair of birds from each of two sources: Dr. Walter Landauer at Storrs, Conn., and the Lincoln Park Zoo of Chicago, 111. Since the original mixing, in 1958, the stock has been carried on by moderately close inbreeding, with some
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Web-Foot or Syndactylism in the Fowl1