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The Effect of Film Permeability and Concentration of Nitrogen, Oxygen and Helium Gases on Hatching Eggs Stored in Polyethylene and Cryovac Bags1
636
N. P. ZEEVAS AND W. M. COLLINS
components analysis in heritability studies. Poultry Sci. 3 3 : 147-154. Krzanowska, H., 1959. Early embryonal growth in inbred lines of Brown Leghorns and their crosses. Poultry Sci. 38: 1446-1455. Lush, J. L., 1948. The genetics of populations. Mimeographed lecture notes. Copyright by J. L. Lush, June, 1948. Dept. of Animal Husbandry, Iowa State University, Ames, Iowa. McNally, E. H., and T. C. Byerly, 1936. Variation in the development of embryos of hen's eggs. Poultry Sci. IS : 280-283.
McNary, H. W., A. E. Bell and C. H. Moore, 1960. The growth of inbred and hybrid chicken embryos. Poultry Sci. 39: 378-384. Rahnfeld, G. W., W. J. Boylan, R. E. Comstock and M. Singh, 1964. Mass selection for postweaning growth in mice. Genetics, 48: 15671583. Snedecor, G. W., 1956. Statistical Methods. Sth Ed. Iowa State University Press, Ames, Iowa. Toleman, H. S., J. L. Adams and T. S. Yao, 1962. Embryonic growth of two- and three-way crosses of chickens. Poultry Sci. 4 1 : 1689.
F.
G.
PROUDFOOT
Canada Department of Agriculture, Kentville, Nova Scotia (Received for publication August 20, 1964)
AN EXTENSION of the pre-incubation •L*~ holding period for hatching eggs facilitates the reproduction of stock for both poultry breeders and commercial hatcheries. The poultry breeder can obtain larger families and thus reduce the environmental variance associated with numerous broods. Prolonging the practical pre-incubation holding time can also provide increased flexibility in handling the hatching egg inventories of commercial hatcheries. Reports by Becker et al. (1963) and Proudfoot (1964a, b), provide evidence that plastic packaging extends the preservation of hatching eggs. The adverse effect of flushing plastic packaged hatching eggs with carbon dioxide was reported by Proudfoot (1964a). Proudfoot (1964b) also reported on the beneficial effects of flushing plastic packaged hatching eggs with nitrogen gas which resulted in a fur1
Contribution No. 1188 from the Research Station, Canada Department of Agriculture, Kentville, Nova Scotia.
ther improvement in hatchability after 25 days in storage. The experiments reported here were undertaken to study the effect of film permeability and to provide further evidence on the effect of flushing plastic packaged eggs with nitrogen and other gases on hatchability, egg and check weights. These traits were also studied for effects of storage temperature and time and their interrelationship with different packaging methods. MATERIALS AND METHODS This series of experiments was initiated in the autumn of 1963. Eggs used in these experiments were collected from a flock of the Kentville Leghorn Control strain consisting of 240 females flock mated with 24 males. The age of this stock ranged from 199 to 380 days during egg collections for the six tests reported here. Test 1 was designed to study the effect of film permeability on the hatchability of
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The Effect of Film Permeability and Concentration of Nitrogen, Oxygen and Helium Gases on Hatching Eggs Stored in Polyethylene and Cryovac Bags1
STORAGE OF HATCHING EGGS
637
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plastic packaged hatching eggs stored not be the same as one might expect under at two temperatures (50-54°F. and optimum conditions. 60-64° F.). Eggs were held overnight in an Tests 2, 3, 4, 5 and 6 were designed to egg cooler at 50-54°F. and then were as- study the effects of packaging hatching signed randomly to the respective treat- eggs in Cryovac and polyethylene encloments. All eggs were packed on fiber trays. sures supplemented with nitrogen, helium One-third of the samples were left un- and oxygen gases and the interrelationwrapped, the other two-thirds were en- ships between these packaging treatments closed in 8" X 14.5" polyethylene bags, with storage time and temperature. With sealed with plastic adhesive tape. Two the exception of the eggs in Test 6 all types of bags were used and were classed hatching eggs were incubated and hatched. by the manufacturer as (1) high permeaFor these tests, duplicate samples of 60 bility, and (2) low permeability. The film eggs each were stored at a 50° angle and thickness of both types was 1.5 mil. The turned daily. Relative humidity was appermeability ratings of the two films ap- proximately 80% and with the exception of proximated 2550 and 1475 cc. of C0 2 and Test 3, all eggs were stored at a temperature 520 and 365 cc. of O2/100 sq. in./mil/24 of 50-54°F. Test 3 eggs were stored at 60hr./atmos. at 25°C. and at 0% relative 64°F. Three days were required to accuhumidity. Densities were 0.919 and 0.927 mulate the eggs for each sample of Tests 2 for the high and low permeability films, and 3; two days were required for Tests 4 respectively. Duplicate samples were as- and 5 and eggs were collected over a 5-day signed to each of two egg coolers operating period for Test 6. Egg samples were accuat 50-54°F. and at 60-64°F. respectively. mulated in an egg holding room at Each day 15 eggs were added to each sam- 50-54°F. and assigned to their respective ple. Three days were required to accumu- package and storage treatments the day late 45 eggs per sample. Storage time was following the last egg collection day. Plas14, 21 and 28 days calculated from the tic bags used were all 16" X 19" in dimensecond day. Samples of each storage period sions and were sealed with plastic adhesive were randomly assigned to 15-dozen size tape. Samples were placed in corrugated cases with two samples per case; extra cardboard cases sealed with paper adhesive space in the case was restricted to the tape. The Cryovac film used was 1.5 mil in centre of the pack and filled with fiber thickness and was a polyvinylidene chlotrays. ride co-polymer resin. Storage periods studied were 7, 14, 21 At hatching time each sample was reduced to a maximum of 25 chicks. Chicks and 28 days in Tests 2 and 3; 12, 19, 26 from all samples, except eggs stored 28 and 33 days in Test 4; 13, 20 and 27 days days (excluded because some samples ei- in Test 5; and 4, 8, 11, 16, 20 and 25 days ther failed to hatch or exhibited very low for Test 6. The eggs used in Tests 2 and 3 were hatchability), were placed under brooders and week-old body weights were measured randomly assigned to 4 packaging treatby mass weighing to the nearest gram. Un- ments within each storage period, (1) fortunately, brooding conditions were not Cryovac flushed with nitrogen gas, (2) entirely satisfactory as extremely cold Cryovac flushed with oxygen gas, (3) weather reduced brooder temperatures Cryovac with air, and (4) unwrapped conbelow recommended levels; results pre- trol without plastic film. sented here on week-old body weight may The packaging treatments studied in
638
F. G. PROUDFOOT
dom—10 eggs were used to measure yolk pH, 10 eggs were used to measure albumen pH, and the remaining 40 eggs were broken and albumen height was measured and converted to Haugh units. All Test 4, 5 and 6 samples were checked for gas leaks by submerging in water for several seconds. For the analysis of variance of all tests, percentage data were transformed to angles (except week-old body weight in Test 1) and treatment effects were considered random. The assumption was made that time lapse during the collection of samples for each test had no effect on hatchability or relative egg and chick weights. Hatchability was measured as a percent of total eggs set and egg and chick weights are reported as a percent of egg weight at time of packaging as described by Proudfoot (1964a). RESULTS AND DISCUSSION Hatchability. The results of Test 1 provide evidence that the eggs held in the plastic film of low permeability exhibited higher hatchability than those packaged in the high permeability film (Tables 1 and 2). As all plastic films used in Test 1 were of constant thickness (1.5 mil), the difference in hatchability levels can be attributed to the permeability of the film. A slight vacuum was noticeable after eggs had been stored in plastic bags; particularly after 21 and 28 days in storage. The cause of this partial vacuum is not known although it may have been brought about by some relationship between the permeability of the egg shell and the permeability of the plastic film to water, and/or to specific gases, e.g. N 2 and 0 2 . Tests 2 and 3 were designed primarily to test the effect of nitrogen and other gases on hatching eggs stored in Cryovac enclosures. These data (Tables 1 and 3) demonstrate that eggs stored in Cryovac bags
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Test 4 were: (1) Cryovac flushed with nitrogen, (2) polyethylene flushed with helium, (3) polyethylene flushed with nitrogen, (4) polyethylene with air, and (5) unwrapped control on fiber egg trays without a plastic enclosure. The polyethylene film used was 1.5 mil in thickness and of high permeability. Treatment effects on egg and chick weight were estimated for Tests 1, 2, 3 and 4. In Test 5a, packaging treatments studied consisted of: (1) Cryovac with air, (2) polyethylene flushed with nitrogen, (3) polyethylene flushed with nitrogen and recharged weekly, (4) Cryovac flushed with nitrogen, (5) Cryovac flushed with nitrogen and recharged weekly, and (6) Cryovac flushed with nitrogen, recharged weekly with nitrogen and flushed with oxygen 4 days prior to setting. Duplicate samples were stored for 27 days. In Test 5b, samples were packaged in: (1) Cryovac with air, (2) Cryovac flushed with nitrogen, (3) Cryovac flushed with helium, and (4) unwrapped control on fiber trays. Test 5b samples were stored for 13 and 20 days. Test 6 was designed to study the effect of various packaging treatments on the oxygen content of the package, the interior quality of the eggs and pH of the albumen and yolk at different storage intervals. Eggs used in Test 6 were packaged as follows: (1) unwrapped control, (2) Cryovac flushed with nitrogen, (3) polyethylene flushed with nitrogen, (4) Cryovac with air, and (5) a "dummy" package containing 3 sealed glass jars on fiber trays, displacing a volume equivalent to 60 eggs, enclosed in a Cryovac bag flushed with nitrogen gas. After 4, 8, 11, 16, 20 and 25 days, samples were withdrawn from storage and the oxygen content of all plastic packages was determined by using a gas chromatograph. Each egg sample was then divided at ran-
639
STORAGE OF HATCHING EGGS
TABLE 1.—Percent hatchability of plastic packaged hatching eggs as ajfected by film permeability, storage time, temperature and flushing with nitrogen, helium and oxygen gases (Tests 1, 2, 3, 4 and 5).
Packaging Method
Mean Storag;e Temperatun
°F.
Storage Time (Days) 7
12-14
19-21
26-28
85.6 84.4 77.8 83.3 76.6 83.4
78.9 60.0 56.7 57.8 57.8 53.4
31.1 1.1 31.2 0.0 25.6 1.1
33
Test No. 1 52 62 52 62 52 62
Cryovac with N Cryovac with 0 Cryovac with Air Control (unwrapped)
52 52 52 52
Test No. 2 90.7 90.8 89.1 83.3
87.4 77.5 77.5 77.5
78.3 65.0 77.5 80.0
67.5 24.2 61.4 63.3
Cryovac with N Cryovac with 0 Cryovac with Air Control (unwrapped)
62 62 62 62
Test No. 3 87.5 85.8 92.5 85.0
86.7 67.5 76.7 85.0
74.2 33.3 59.2 61.3
15.0 0.8 27.5 21.1
Cryovac with N Poly. (1.5 mil) with He Poly. (1.5 mil) with N Poly. (1.5 mil) with Air Control (unwrapped)
52 52 52 52 52
75.0 76.5 84.7 79.9 75.8
72.5 68.0 75.6 72.5 58.0
70.8 50.8 50.8 57.1 45.8
Cryovac with N Cryovac with Air Cryovac with He Control (unwrapped) Poly. (1.5 mil) with N Poly. (1.5 mil) with N 1 Cryovac with N 1 Cryovac with N 2
52 52 52 52 52 52 52 52
82.5 84.2 82.4 80.7
80.4 79.2 76.3 77.5
67.0 73.2
Test No. 4 32.5 40.8 31.7 25.8 14.2
Test No. 5a &• 5b
1 2
70.7 67.2 56.2 49.2
Recharged with nitrogen weekly. Recharged with nitrogen weekly and flushed with oxygen four days prior to setting,
flushed with nitrogen exhibited the highest hatchability after 14 days or more in storage. For the 7-day storage period the oxygen flushed pack was superior but after 21 days of storage there was a severe reduction in hatchability which was probably responsible for the pack X storage time interaction. The hatchability of the control pack was surprisingly high (compared with Test 1) which may have been due to the packaging method. A corrugated cardboard case designed for 60 eggs was used and sealed with paper adhesive tape. The adhesive paper was 3 " wide and probably
served as an effective seal on the package as quite a large portion of the case surface was covered with the paper tape. Nevertheless, the pack flushed with nitrogen exhibited higher hatchability (67.5% after a pre-incubation holding period of 28 days), which is similar to results reported by Proudfoot (1964b). The hatchability level of 74.2% in Test 3 (Table 1) for the Cryovac-nitrogen pack after storage for 21 days at 60-64°F. is particularly interesting. A pack X temperature interaction is suggested by a comparison of this with the other packs and
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Plastic Packed (low permeability film) Plastic Packed (high permeability film) Control (unwrapped)
640
F. G. PROUDFOOT
TABLE 2.—Analyses of variance showing mean squares for the traits hatchability, egg and chick weights as affected by film permeability, storage time and temperature (Test 1).
Source of variance
Hatchability
Setting egg weight
18th day egg weight
Initial chick weight1
Week-old chick weight1
2 1 2 2 4 2 4 18
78.238f 1,005.361** 7,102.706** 29.019 14.546 868.063** 18.835 23.977
21.536** 0.074 3.909** 0.061 0.536** 0.143 0.065 0.032
3.581 10.208* 6.203* 5.665f 4.599f 7.254* 3.964f 1.600
0.483 0.099 2.148* 0.179 0.254 0.089 0.900 0.411
4.942 23.542* 113.231** 12.934* 9.126f 27.800** 1.554 2.729
0.348 0.122 0.060 0.476 0.416 0.001 0.416 0.284
0.413 0.000 0.636t 0.178 0.030 1.035* 0.002 0.150
9.440f 7.036f 43.924** 20.725* 5.511 26.807** 0.824 1.865
Excluding data from control pack and 28-day storage period Packing method 118.538* 0.022 Temperature 16.954 0.046 Storage time 634.158** 0.112** Pack X temperature 74.952f 0.002 Pack X storage time 17.619 0.073* Temp.Xstorage time 52.526 0.031 PackX temp.Xstorage time 14.726 0.029 Replicates 8 17.003 0.014
**P<.01. *P<.05. tP<.10. 1 Data from 28-day storage were omitted because of either complete or almost complete failure of eggs stored at 60°F. to hatch. Appropriate changes were made in degrees of freedom.
the 50-54°F. temperature test results. Eggs in the Cryovac-nitrogen pack (Test 4) exhibited higher hatchability than the other packs tested after 26 days' storage (Tables 1 and 4). The poly-nitrogen (polyethylene flushed with nitrogen) and the poly-helium (polyethylene flushed with helium) packs had slightly higher hatchability after 12 and 33 days' storage respectively. The 4 1 % hatchability of the
eggs stored in the poly-helium package for 33 days may be of some biological importance. Again in this test the Cryovac-nitrogen pack maintained a high hatchability level up to 26 days in storage with only a slight decline from 12 to 26 days. In Test 5, the decline was more noticeable and the Cryovac-air pack maintained a high hatchability level (Table 5). The lack of a response to the nitrogen atmosphere in this
TABLE 3.—Analyses of variance showing mean squares for the traits hatchability, egg and chick weights as affected by Cryovac packaging supplemented with nitrogen and oxygen gases at two storage temperatures (Tests 2 and 3) Hatchability Source of variance
Setting ;gg weight
d.£.
18th day egg weight
Initial chick weight
Test 2
Test 3
Test 2
Test 3
Test 2
11.543** 7.619** 0.973" 0.112
9.399" 9.207** 0.195* 0.054
1.436** 0.801* 0.359 0.242
167.428 200.168 176.472 140.864
0.301 3.125** 0.157 0.361
Excluding data from plastic packages with oxyger and air 1 Packing method 55 168t 21 856 21.973** Storage time 3 169 690** 1,760.688** 7.213** Pack Xstorage time 3 15 236 20 601 1.706** Replicates 8 11 465 66 006 0.173
17.872** 6.104** 0.499" 0.019
0.141 0.790* 0.253 0.128
Test 2 Packing method 3 Storage time 3 Pack X storage time 9 Replicates 16
«P<.01 *P<.05 tP<.10
161 154** 787 101** 82 193* 26.484
Test 3 373 115** 3814.263** 69 852 57 980
0.648 0.937t 0.172 0.236
0.255 1.725 0.149 0.599
Test 3 151.191 101.086 125.595 83.675 0.624 0.207 0.518 0.276
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Packing method Temperature Storage time Pack X temperature Pack X storage time Temp. X storage time PackX temp. Xstorage time Replicates
d.f.
641
STORAGE OF HATCHING EGGS
TABLE 4.—Analyses ofvarinace showing mean squares for hatchability, egg and chick weights as affected by plastic packages flushed with nitrogen and helium gases (Test 4). Source of variance
d.f.
Hatchability
Setting egg weight
18th day egg weight
Initial chick weight
Packing method Storage time Pack X storage time Replicates
4 3 12 20
104.424** 1,734.719** 35.609f 16.989
3.328** 1.905* 0.76S 0.522
0.108 0.471 0.180 0.533
0.461 5.960** 0.319 0.364
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test may have been due to excessive The chicks hatched from the nitrogeninflation of the package. Other data in this storage packs were observed to be more test provide evidence that excessive expo- active at hatching time than chicks from sure to nitrogen resulting in an extremely other packs. low oxygen content over prolonged periods The results of Test 6 provide evidence can have a detrimental effect on hatchabili- that the oxygen content of the nitrogenty. This occurred when Cryovac and poly flushed Cryovac package tends to rise samples were recharged weekly with nitro- within 4 days to about 4% and be maingen gas (Table 1). It has also been ob- tained at that level to the end of the storserved that samples which maintained a age period (Fig. 1). This experiment failed high degree of inflation throughout the to reveal any large difference in oxygen storage period exhibited reduced hatchabil- content between the packages containing ity levels so that the permeation of the sealed jars and those containing eggs. This gases, e.g., nitrogen and oxygen, through suggests that the eggs had little effect on the film appears to be of prime importance. the gas content of the package although a Probably the most important interac- more refined test may reveal a difference. tion, affecting hatchability, demonstrated The higher oxygen gas permeability rate in these tests was the temperature X stor- of the polyethylene film (1.5 mil) is demage time interaction in Test 1. This inter- onstrated by the rapid diffusion of oxygen action was also found to be significant at into the package in this test. This packagthe 1% level when data of Tests 2 and 3 ing method failed to reveal superior were combined; however, this latter com- hatchability which suggests a lower oxygen parison may not be valid since temperature TABLE 5.—Analyses of variance showing mean squares effects may be confounded with hatch time for the trait hatchability as affected by plastic packaging and incubator unit effects. These data sug- and storage atmospheric alterations by the use of helium, nitrogen and oxygen gases (Tests 5a and b) . gest, however, that a storage temperature of 60-64°F. may be superior to 50-54°F. Source of Variance d.f. M.S. for short storage periods (up to 14 days), Test 5a which provide evidence to support that rePacking method 5 60.404* 11.503 6 Replicates ported by Proudfoot (1964a). Test 5b Packing method 3 4.089 The pack X storage time interaction 35.701f Storage time 1 demonstrated in Tests 2 and 4 provide fur. PackXstorage time 3 1.555 ther evidence that the Cryovac-nitrogen 8.029 Replicates 8 pack maintains hatchability better after * P<.05. prolonged storage, than other packs tested. fP<.10.
642
F. G. PROUDFOOT
4
• n i» STORAGE TIME (DAYS)
jo
i«
FIG. 1. Packaging effects on oxygen gas content, Haugh units, and yolk and albumen p H levels in Test 6.
content would be desirable. The oxygen content of the Cryovac-air sample remained quite constant with a slight decline toward the end of the holding period. The Haugh unit values of eggs from the different packs were significantly different (Table 6). The unwrapped standard pack was the lowest and there was little difference among the other packs (Fig. 1). Cryovac films had a significant effect in stabilizing yolk pH although differences among packs were of low magnitude. The
Egg and Chick Weight. Egg and chick weights were measured in Tests 1, 2, 3 and 4 and eggs enclosed in plastic film were significantly heavier at setting time than TABLE 6.—Analyses of variance for Haugh unit
values and albumen pH and yolk pH of hatching eggs stored in plastic packages flushed with nitrogen {Test 6). Source of variance Packing method Storage time Pack Xstorage time Replicates **P<.01. *P<,05,
a
.. -'-
Haugh unit M.S.
™D™?en jg g
Yolk pH M.S.
3 5
63.376" 106.483**
0.558" 0.006
0.008* 0.019**
15 24
7.598** 1.779
0.012" 0.004
0.001 0.002
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0
most significant chemical change apparently occurred in the albumen of the egg. The albumen pH of the unwrapped standard package markedly increased during the storage period. That of the eggs in the Cryovac-air package remained the lowest, being actually below the fresh egg level while the Cryovac-nitrogen package tended to maintain albumen pH at fresh egg levels. The results indicate that the Cryovacnitrogen packing method tends to maintain the oxygen level at about 4% and to improve the biological stability of the egg as estimated by the stabilizing effect on the albumen and yolk pH. It seems that an alteration in the atmospheric nitrogen: oxygen ratio is desirable for the preservation of hatchability. The temporary displacement of oxygen by nitrogen may result in more chemical stability during the pre-incubation period. An increase in nitrogen atmosphere reduces the oxygen content and thereby may be functioning as an antioxidant thus minimizing the production of carbon dioxide which appears to have a severe toxic effect on the embryo as demonstrated by reduced hatchability (Proudfoot 1964a, b).
643
STORAGE OF HATCHING EGGS
TABLE 7.—Initial chick weights as affected by packaging method, storage time and temperature reported as a percent of egg weight at time of packaging (Tests 1, 2, 3 and 4).
Packaging Method
Storagie Time (Days)
Mean Storage Temperatui °F.
7
12-14
19-21
70.1 69.7 70.2 68.9 69.6 70.0
70.2 71.2 69.8 70.3 72.1 70.5
26-28
33
Test No. 1 52 62 52 62 52 62
Cryovac with N Cryovac with 0 Cryovac with Air Control (unwrapped)
52 52 52 52
Test No. 2 67.0 67.3 67.0 67.0
67.5 68.2 66.9 66.4
67.7 68.2 68.9 67.9
69.7 69.6 69.1 68.8
Cryovac with N Cryovac with 0 Cryovac with Air Control (unwrapped)
62 62 62 62
Test No. 3 68.4 69.7 67.8 68.9
69.7 70.3 69.4 69.1
69.5 69.0 70.2 69.4
70.3 61.5 72.9 68.0
Cryovac with N Poly. (1.5 mil) with He Poly. (1.5 mil) with N Poly. (1.5 mil) with Air Control (unwrapped)
52 52 52 52 52
67.6 67.6 67.4 67.0 68.1
69.1 68.3 68.6 68.5 69.4
69.1 69.0 70.5 70.4 71.3
Test No. 4
eggs packed on conventional trays in all tests (Tables 2, 3 and 4). However, this weight difference did not persist in these experiments and packaging had no apparent effect on day-old chick weight (Table 7). As demonstrated by Proudfoot (1964a), storage time had an effect on day-old chick weight which was probably due to the "longer-storage-time" eggs hatching later and thus resulting in less shrinkage or dehydration prior to weighing at the time of hatch removal. In Test 1, after one week of age, this weight difference was reversed and the birds hatched from eggs stored for shorter periods were heavier (Table 2). As storage time was increased, week-old body weight decreased significantly. This supports the findings of Merritt (1964). The data presented in Tables 2, 3 and 7
69.7 70.2 69.6 71.3 70.1
suggest that the temperature at which hatching eggs are stored may have important effects on subsequent chick weight. In Test 1 a temperature and storage time effect and a temperature X storage time interaction were demonstrated for week-old chick weight. Chicks which hatched from eggs stored for 14 days at 50-54°F. were lighter in body weight at one week of age than chicks which hatched from eggs stored 14 days at 60-64°F.; however, after 21 days in storage this weight difference had disappeared so that with longer storage periods, storage temperature had no apparent effect on week-old chick weight. Although brooding conditions were somewhat inadequate, interactions for week-old body weights are particularly interesting and suggest that egg storage conditions may have important effects on early chick growth.
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Plastic packed (low permeability film) Plastic packed (high permeability film) Control (unwrapped)
644
F. G. PROUDFOOT SUMMARY
stored at 50-54°F. up to 14 days, but for storage periods exceeding 14 days, the eggs stored in plastic packs at 50-54 days°F. exhibited higher hatchability and body weights were about the same at one week of age. ACKNOWLEDGEMENTS
The polyethylene bags were provided by Canadian Industries Limited, Brampton, Ontario. The Cryovac bags were supplied by W. R. Grace and Co., of Canada Ltd., Cooksville, Ontario. The author also wishes to thank Dr. W. J. Plank, Canadian Industries Limited, for providing permeability ratings of different plastic films, and Dr. Keith Stewart, Research Station, Kentville, who conducted the chromatograph oxygen gas evaluations. REFERENCES Becker, W. A., J. V. Spencer and J. L. Smartwood, 1963. Storing hatching eggs in plastic bags. Poultry Sci. 42: 1256. Merritt, E. S., 1964. Pre-incubation storage effects on subsequent performance of chickens. British Poultry Sci. 5: 67-73. Proudfoot, F. G., 1964a. The effect of plastic packaging and other treatment on hatching eggs. Can. J. Animal Sci. 44: 87-9S. Proudfoot, F. G., 1964b. Note on the effect of nitrogen and other gases on hatching eggs stored in plastic bags. Can. J. Animal Sci. 44: 120-121.
The Influence of Comb and Feathering Phenotypes on Body Weight and Dressing Percentage in Broilers B.
L.
G O O D M A N A N D F O R E S T V.
MUIR1
Southern Illinois University, Carbondale, Illinois (Received for publication September 4, 1964)
T
HE INFLUENCE of the phenotype for a simply inherited or qualitative trait on a more complex trait such as body weight has been studied to some extent in chickens.
Kan et al. (1959) reported that comb type (single or pea) had no significant 1
Present address: Poultry Science Department, Ohio State University, Columbus 10, Ohio.
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These studies provide further evidence that the maintenance of high hatchability during the pre-incubation period is enhanced by the use of plastic packaging. Permeability of the plastic film had significant effects on the preservation of hatchability levels. This was demonstrated by testing two films of the same thickness but of different densities. Hatchability was higher for the film of lower permeability. An additional improvement in hatchability was attained by altering the storage atmosphere through flushing the package with nitrogen gas. Although optimum levels of nitrogen were not determined, it was demonstrated that excessively high levels maintained over extended periods were detrimental to hatching qualities possibly because oxygen content was reduced below a critical point. Packaging methods had a significant effect on setting egg weight but did not appear to have any effect on chick weight, although a low magnitude effect was found on week-old chick weight. A temperature X storage time interaction was demonstrated for hatchability and egg and chick weight. The hatchability of eggs stored at 60-64°F. was superior and week-old weight was heavier than from eggs
N. P. ZEEVAS AND W. M. COLLINS
components analysis in heritability studies. Poultry Sci. 3 3 : 147-154. Krzanowska, H., 1959. Early embryonal growth in inbred lines of Brown Leghorns and their crosses. Poultry Sci. 38: 1446-1455. Lush, J. L., 1948. The genetics of populations. Mimeographed lecture notes. Copyright by J. L. Lush, June, 1948. Dept. of Animal Husbandry, Iowa State University, Ames, Iowa. McNally, E. H., and T. C. Byerly, 1936. Variation in the development of embryos of hen's eggs. Poultry Sci. IS : 280-283.
McNary, H. W., A. E. Bell and C. H. Moore, 1960. The growth of inbred and hybrid chicken embryos. Poultry Sci. 39: 378-384. Rahnfeld, G. W., W. J. Boylan, R. E. Comstock and M. Singh, 1964. Mass selection for postweaning growth in mice. Genetics, 48: 15671583. Snedecor, G. W., 1956. Statistical Methods. Sth Ed. Iowa State University Press, Ames, Iowa. Toleman, H. S., J. L. Adams and T. S. Yao, 1962. Embryonic growth of two- and three-way crosses of chickens. Poultry Sci. 4 1 : 1689.
F.
G.
PROUDFOOT
Canada Department of Agriculture, Kentville, Nova Scotia (Received for publication August 20, 1964)
AN EXTENSION of the pre-incubation •L*~ holding period for hatching eggs facilitates the reproduction of stock for both poultry breeders and commercial hatcheries. The poultry breeder can obtain larger families and thus reduce the environmental variance associated with numerous broods. Prolonging the practical pre-incubation holding time can also provide increased flexibility in handling the hatching egg inventories of commercial hatcheries. Reports by Becker et al. (1963) and Proudfoot (1964a, b), provide evidence that plastic packaging extends the preservation of hatching eggs. The adverse effect of flushing plastic packaged hatching eggs with carbon dioxide was reported by Proudfoot (1964a). Proudfoot (1964b) also reported on the beneficial effects of flushing plastic packaged hatching eggs with nitrogen gas which resulted in a fur1
Contribution No. 1188 from the Research Station, Canada Department of Agriculture, Kentville, Nova Scotia.
ther improvement in hatchability after 25 days in storage. The experiments reported here were undertaken to study the effect of film permeability and to provide further evidence on the effect of flushing plastic packaged eggs with nitrogen and other gases on hatchability, egg and check weights. These traits were also studied for effects of storage temperature and time and their interrelationship with different packaging methods. MATERIALS AND METHODS This series of experiments was initiated in the autumn of 1963. Eggs used in these experiments were collected from a flock of the Kentville Leghorn Control strain consisting of 240 females flock mated with 24 males. The age of this stock ranged from 199 to 380 days during egg collections for the six tests reported here. Test 1 was designed to study the effect of film permeability on the hatchability of
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The Effect of Film Permeability and Concentration of Nitrogen, Oxygen and Helium Gases on Hatching Eggs Stored in Polyethylene and Cryovac Bags1
STORAGE OF HATCHING EGGS
637
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plastic packaged hatching eggs stored not be the same as one might expect under at two temperatures (50-54°F. and optimum conditions. 60-64° F.). Eggs were held overnight in an Tests 2, 3, 4, 5 and 6 were designed to egg cooler at 50-54°F. and then were as- study the effects of packaging hatching signed randomly to the respective treat- eggs in Cryovac and polyethylene encloments. All eggs were packed on fiber trays. sures supplemented with nitrogen, helium One-third of the samples were left un- and oxygen gases and the interrelationwrapped, the other two-thirds were en- ships between these packaging treatments closed in 8" X 14.5" polyethylene bags, with storage time and temperature. With sealed with plastic adhesive tape. Two the exception of the eggs in Test 6 all types of bags were used and were classed hatching eggs were incubated and hatched. by the manufacturer as (1) high permeaFor these tests, duplicate samples of 60 bility, and (2) low permeability. The film eggs each were stored at a 50° angle and thickness of both types was 1.5 mil. The turned daily. Relative humidity was appermeability ratings of the two films ap- proximately 80% and with the exception of proximated 2550 and 1475 cc. of C0 2 and Test 3, all eggs were stored at a temperature 520 and 365 cc. of O2/100 sq. in./mil/24 of 50-54°F. Test 3 eggs were stored at 60hr./atmos. at 25°C. and at 0% relative 64°F. Three days were required to accuhumidity. Densities were 0.919 and 0.927 mulate the eggs for each sample of Tests 2 for the high and low permeability films, and 3; two days were required for Tests 4 respectively. Duplicate samples were as- and 5 and eggs were collected over a 5-day signed to each of two egg coolers operating period for Test 6. Egg samples were accuat 50-54°F. and at 60-64°F. respectively. mulated in an egg holding room at Each day 15 eggs were added to each sam- 50-54°F. and assigned to their respective ple. Three days were required to accumu- package and storage treatments the day late 45 eggs per sample. Storage time was following the last egg collection day. Plas14, 21 and 28 days calculated from the tic bags used were all 16" X 19" in dimensecond day. Samples of each storage period sions and were sealed with plastic adhesive were randomly assigned to 15-dozen size tape. Samples were placed in corrugated cases with two samples per case; extra cardboard cases sealed with paper adhesive space in the case was restricted to the tape. The Cryovac film used was 1.5 mil in centre of the pack and filled with fiber thickness and was a polyvinylidene chlotrays. ride co-polymer resin. Storage periods studied were 7, 14, 21 At hatching time each sample was reduced to a maximum of 25 chicks. Chicks and 28 days in Tests 2 and 3; 12, 19, 26 from all samples, except eggs stored 28 and 33 days in Test 4; 13, 20 and 27 days days (excluded because some samples ei- in Test 5; and 4, 8, 11, 16, 20 and 25 days ther failed to hatch or exhibited very low for Test 6. The eggs used in Tests 2 and 3 were hatchability), were placed under brooders and week-old body weights were measured randomly assigned to 4 packaging treatby mass weighing to the nearest gram. Un- ments within each storage period, (1) fortunately, brooding conditions were not Cryovac flushed with nitrogen gas, (2) entirely satisfactory as extremely cold Cryovac flushed with oxygen gas, (3) weather reduced brooder temperatures Cryovac with air, and (4) unwrapped conbelow recommended levels; results pre- trol without plastic film. sented here on week-old body weight may The packaging treatments studied in
638
F. G. PROUDFOOT
dom—10 eggs were used to measure yolk pH, 10 eggs were used to measure albumen pH, and the remaining 40 eggs were broken and albumen height was measured and converted to Haugh units. All Test 4, 5 and 6 samples were checked for gas leaks by submerging in water for several seconds. For the analysis of variance of all tests, percentage data were transformed to angles (except week-old body weight in Test 1) and treatment effects were considered random. The assumption was made that time lapse during the collection of samples for each test had no effect on hatchability or relative egg and chick weights. Hatchability was measured as a percent of total eggs set and egg and chick weights are reported as a percent of egg weight at time of packaging as described by Proudfoot (1964a). RESULTS AND DISCUSSION Hatchability. The results of Test 1 provide evidence that the eggs held in the plastic film of low permeability exhibited higher hatchability than those packaged in the high permeability film (Tables 1 and 2). As all plastic films used in Test 1 were of constant thickness (1.5 mil), the difference in hatchability levels can be attributed to the permeability of the film. A slight vacuum was noticeable after eggs had been stored in plastic bags; particularly after 21 and 28 days in storage. The cause of this partial vacuum is not known although it may have been brought about by some relationship between the permeability of the egg shell and the permeability of the plastic film to water, and/or to specific gases, e.g. N 2 and 0 2 . Tests 2 and 3 were designed primarily to test the effect of nitrogen and other gases on hatching eggs stored in Cryovac enclosures. These data (Tables 1 and 3) demonstrate that eggs stored in Cryovac bags
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Test 4 were: (1) Cryovac flushed with nitrogen, (2) polyethylene flushed with helium, (3) polyethylene flushed with nitrogen, (4) polyethylene with air, and (5) unwrapped control on fiber egg trays without a plastic enclosure. The polyethylene film used was 1.5 mil in thickness and of high permeability. Treatment effects on egg and chick weight were estimated for Tests 1, 2, 3 and 4. In Test 5a, packaging treatments studied consisted of: (1) Cryovac with air, (2) polyethylene flushed with nitrogen, (3) polyethylene flushed with nitrogen and recharged weekly, (4) Cryovac flushed with nitrogen, (5) Cryovac flushed with nitrogen and recharged weekly, and (6) Cryovac flushed with nitrogen, recharged weekly with nitrogen and flushed with oxygen 4 days prior to setting. Duplicate samples were stored for 27 days. In Test 5b, samples were packaged in: (1) Cryovac with air, (2) Cryovac flushed with nitrogen, (3) Cryovac flushed with helium, and (4) unwrapped control on fiber trays. Test 5b samples were stored for 13 and 20 days. Test 6 was designed to study the effect of various packaging treatments on the oxygen content of the package, the interior quality of the eggs and pH of the albumen and yolk at different storage intervals. Eggs used in Test 6 were packaged as follows: (1) unwrapped control, (2) Cryovac flushed with nitrogen, (3) polyethylene flushed with nitrogen, (4) Cryovac with air, and (5) a "dummy" package containing 3 sealed glass jars on fiber trays, displacing a volume equivalent to 60 eggs, enclosed in a Cryovac bag flushed with nitrogen gas. After 4, 8, 11, 16, 20 and 25 days, samples were withdrawn from storage and the oxygen content of all plastic packages was determined by using a gas chromatograph. Each egg sample was then divided at ran-
639
STORAGE OF HATCHING EGGS
TABLE 1.—Percent hatchability of plastic packaged hatching eggs as ajfected by film permeability, storage time, temperature and flushing with nitrogen, helium and oxygen gases (Tests 1, 2, 3, 4 and 5).
Packaging Method
Mean Storag;e Temperatun
°F.
Storage Time (Days) 7
12-14
19-21
26-28
85.6 84.4 77.8 83.3 76.6 83.4
78.9 60.0 56.7 57.8 57.8 53.4
31.1 1.1 31.2 0.0 25.6 1.1
33
Test No. 1 52 62 52 62 52 62
Cryovac with N Cryovac with 0 Cryovac with Air Control (unwrapped)
52 52 52 52
Test No. 2 90.7 90.8 89.1 83.3
87.4 77.5 77.5 77.5
78.3 65.0 77.5 80.0
67.5 24.2 61.4 63.3
Cryovac with N Cryovac with 0 Cryovac with Air Control (unwrapped)
62 62 62 62
Test No. 3 87.5 85.8 92.5 85.0
86.7 67.5 76.7 85.0
74.2 33.3 59.2 61.3
15.0 0.8 27.5 21.1
Cryovac with N Poly. (1.5 mil) with He Poly. (1.5 mil) with N Poly. (1.5 mil) with Air Control (unwrapped)
52 52 52 52 52
75.0 76.5 84.7 79.9 75.8
72.5 68.0 75.6 72.5 58.0
70.8 50.8 50.8 57.1 45.8
Cryovac with N Cryovac with Air Cryovac with He Control (unwrapped) Poly. (1.5 mil) with N Poly. (1.5 mil) with N 1 Cryovac with N 1 Cryovac with N 2
52 52 52 52 52 52 52 52
82.5 84.2 82.4 80.7
80.4 79.2 76.3 77.5
67.0 73.2
Test No. 4 32.5 40.8 31.7 25.8 14.2
Test No. 5a &• 5b
1 2
70.7 67.2 56.2 49.2
Recharged with nitrogen weekly. Recharged with nitrogen weekly and flushed with oxygen four days prior to setting,
flushed with nitrogen exhibited the highest hatchability after 14 days or more in storage. For the 7-day storage period the oxygen flushed pack was superior but after 21 days of storage there was a severe reduction in hatchability which was probably responsible for the pack X storage time interaction. The hatchability of the control pack was surprisingly high (compared with Test 1) which may have been due to the packaging method. A corrugated cardboard case designed for 60 eggs was used and sealed with paper adhesive tape. The adhesive paper was 3 " wide and probably
served as an effective seal on the package as quite a large portion of the case surface was covered with the paper tape. Nevertheless, the pack flushed with nitrogen exhibited higher hatchability (67.5% after a pre-incubation holding period of 28 days), which is similar to results reported by Proudfoot (1964b). The hatchability level of 74.2% in Test 3 (Table 1) for the Cryovac-nitrogen pack after storage for 21 days at 60-64°F. is particularly interesting. A pack X temperature interaction is suggested by a comparison of this with the other packs and
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Plastic Packed (low permeability film) Plastic Packed (high permeability film) Control (unwrapped)
640
F. G. PROUDFOOT
TABLE 2.—Analyses of variance showing mean squares for the traits hatchability, egg and chick weights as affected by film permeability, storage time and temperature (Test 1).
Source of variance
Hatchability
Setting egg weight
18th day egg weight
Initial chick weight1
Week-old chick weight1
2 1 2 2 4 2 4 18
78.238f 1,005.361** 7,102.706** 29.019 14.546 868.063** 18.835 23.977
21.536** 0.074 3.909** 0.061 0.536** 0.143 0.065 0.032
3.581 10.208* 6.203* 5.665f 4.599f 7.254* 3.964f 1.600
0.483 0.099 2.148* 0.179 0.254 0.089 0.900 0.411
4.942 23.542* 113.231** 12.934* 9.126f 27.800** 1.554 2.729
0.348 0.122 0.060 0.476 0.416 0.001 0.416 0.284
0.413 0.000 0.636t 0.178 0.030 1.035* 0.002 0.150
9.440f 7.036f 43.924** 20.725* 5.511 26.807** 0.824 1.865
Excluding data from control pack and 28-day storage period Packing method 118.538* 0.022 Temperature 16.954 0.046 Storage time 634.158** 0.112** Pack X temperature 74.952f 0.002 Pack X storage time 17.619 0.073* Temp.Xstorage time 52.526 0.031 PackX temp.Xstorage time 14.726 0.029 Replicates 8 17.003 0.014
**P<.01. *P<.05. tP<.10. 1 Data from 28-day storage were omitted because of either complete or almost complete failure of eggs stored at 60°F. to hatch. Appropriate changes were made in degrees of freedom.
the 50-54°F. temperature test results. Eggs in the Cryovac-nitrogen pack (Test 4) exhibited higher hatchability than the other packs tested after 26 days' storage (Tables 1 and 4). The poly-nitrogen (polyethylene flushed with nitrogen) and the poly-helium (polyethylene flushed with helium) packs had slightly higher hatchability after 12 and 33 days' storage respectively. The 4 1 % hatchability of the
eggs stored in the poly-helium package for 33 days may be of some biological importance. Again in this test the Cryovac-nitrogen pack maintained a high hatchability level up to 26 days in storage with only a slight decline from 12 to 26 days. In Test 5, the decline was more noticeable and the Cryovac-air pack maintained a high hatchability level (Table 5). The lack of a response to the nitrogen atmosphere in this
TABLE 3.—Analyses of variance showing mean squares for the traits hatchability, egg and chick weights as affected by Cryovac packaging supplemented with nitrogen and oxygen gases at two storage temperatures (Tests 2 and 3) Hatchability Source of variance
Setting ;gg weight
d.£.
18th day egg weight
Initial chick weight
Test 2
Test 3
Test 2
Test 3
Test 2
11.543** 7.619** 0.973" 0.112
9.399" 9.207** 0.195* 0.054
1.436** 0.801* 0.359 0.242
167.428 200.168 176.472 140.864
0.301 3.125** 0.157 0.361
Excluding data from plastic packages with oxyger and air 1 Packing method 55 168t 21 856 21.973** Storage time 3 169 690** 1,760.688** 7.213** Pack Xstorage time 3 15 236 20 601 1.706** Replicates 8 11 465 66 006 0.173
17.872** 6.104** 0.499" 0.019
0.141 0.790* 0.253 0.128
Test 2 Packing method 3 Storage time 3 Pack X storage time 9 Replicates 16
«P<.01 *P<.05 tP<.10
161 154** 787 101** 82 193* 26.484
Test 3 373 115** 3814.263** 69 852 57 980
0.648 0.937t 0.172 0.236
0.255 1.725 0.149 0.599
Test 3 151.191 101.086 125.595 83.675 0.624 0.207 0.518 0.276
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Packing method Temperature Storage time Pack X temperature Pack X storage time Temp. X storage time PackX temp. Xstorage time Replicates
d.f.
641
STORAGE OF HATCHING EGGS
TABLE 4.—Analyses ofvarinace showing mean squares for hatchability, egg and chick weights as affected by plastic packages flushed with nitrogen and helium gases (Test 4). Source of variance
d.f.
Hatchability
Setting egg weight
18th day egg weight
Initial chick weight
Packing method Storage time Pack X storage time Replicates
4 3 12 20
104.424** 1,734.719** 35.609f 16.989
3.328** 1.905* 0.76S 0.522
0.108 0.471 0.180 0.533
0.461 5.960** 0.319 0.364
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test may have been due to excessive The chicks hatched from the nitrogeninflation of the package. Other data in this storage packs were observed to be more test provide evidence that excessive expo- active at hatching time than chicks from sure to nitrogen resulting in an extremely other packs. low oxygen content over prolonged periods The results of Test 6 provide evidence can have a detrimental effect on hatchabili- that the oxygen content of the nitrogenty. This occurred when Cryovac and poly flushed Cryovac package tends to rise samples were recharged weekly with nitro- within 4 days to about 4% and be maingen gas (Table 1). It has also been ob- tained at that level to the end of the storserved that samples which maintained a age period (Fig. 1). This experiment failed high degree of inflation throughout the to reveal any large difference in oxygen storage period exhibited reduced hatchabil- content between the packages containing ity levels so that the permeation of the sealed jars and those containing eggs. This gases, e.g., nitrogen and oxygen, through suggests that the eggs had little effect on the film appears to be of prime importance. the gas content of the package although a Probably the most important interac- more refined test may reveal a difference. tion, affecting hatchability, demonstrated The higher oxygen gas permeability rate in these tests was the temperature X stor- of the polyethylene film (1.5 mil) is demage time interaction in Test 1. This inter- onstrated by the rapid diffusion of oxygen action was also found to be significant at into the package in this test. This packagthe 1% level when data of Tests 2 and 3 ing method failed to reveal superior were combined; however, this latter com- hatchability which suggests a lower oxygen parison may not be valid since temperature TABLE 5.—Analyses of variance showing mean squares effects may be confounded with hatch time for the trait hatchability as affected by plastic packaging and incubator unit effects. These data sug- and storage atmospheric alterations by the use of helium, nitrogen and oxygen gases (Tests 5a and b) . gest, however, that a storage temperature of 60-64°F. may be superior to 50-54°F. Source of Variance d.f. M.S. for short storage periods (up to 14 days), Test 5a which provide evidence to support that rePacking method 5 60.404* 11.503 6 Replicates ported by Proudfoot (1964a). Test 5b Packing method 3 4.089 The pack X storage time interaction 35.701f Storage time 1 demonstrated in Tests 2 and 4 provide fur. PackXstorage time 3 1.555 ther evidence that the Cryovac-nitrogen 8.029 Replicates 8 pack maintains hatchability better after * P<.05. prolonged storage, than other packs tested. fP<.10.
642
F. G. PROUDFOOT
4
• n i» STORAGE TIME (DAYS)
jo
i«
FIG. 1. Packaging effects on oxygen gas content, Haugh units, and yolk and albumen p H levels in Test 6.
content would be desirable. The oxygen content of the Cryovac-air sample remained quite constant with a slight decline toward the end of the holding period. The Haugh unit values of eggs from the different packs were significantly different (Table 6). The unwrapped standard pack was the lowest and there was little difference among the other packs (Fig. 1). Cryovac films had a significant effect in stabilizing yolk pH although differences among packs were of low magnitude. The
Egg and Chick Weight. Egg and chick weights were measured in Tests 1, 2, 3 and 4 and eggs enclosed in plastic film were significantly heavier at setting time than TABLE 6.—Analyses of variance for Haugh unit
values and albumen pH and yolk pH of hatching eggs stored in plastic packages flushed with nitrogen {Test 6). Source of variance Packing method Storage time Pack Xstorage time Replicates **P<.01. *P<,05,
a
.. -'-
Haugh unit M.S.
™D™?en jg g
Yolk pH M.S.
3 5
63.376" 106.483**
0.558" 0.006
0.008* 0.019**
15 24
7.598** 1.779
0.012" 0.004
0.001 0.002
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0
most significant chemical change apparently occurred in the albumen of the egg. The albumen pH of the unwrapped standard package markedly increased during the storage period. That of the eggs in the Cryovac-air package remained the lowest, being actually below the fresh egg level while the Cryovac-nitrogen package tended to maintain albumen pH at fresh egg levels. The results indicate that the Cryovacnitrogen packing method tends to maintain the oxygen level at about 4% and to improve the biological stability of the egg as estimated by the stabilizing effect on the albumen and yolk pH. It seems that an alteration in the atmospheric nitrogen: oxygen ratio is desirable for the preservation of hatchability. The temporary displacement of oxygen by nitrogen may result in more chemical stability during the pre-incubation period. An increase in nitrogen atmosphere reduces the oxygen content and thereby may be functioning as an antioxidant thus minimizing the production of carbon dioxide which appears to have a severe toxic effect on the embryo as demonstrated by reduced hatchability (Proudfoot 1964a, b).
643
STORAGE OF HATCHING EGGS
TABLE 7.—Initial chick weights as affected by packaging method, storage time and temperature reported as a percent of egg weight at time of packaging (Tests 1, 2, 3 and 4).
Packaging Method
Storagie Time (Days)
Mean Storage Temperatui °F.
7
12-14
19-21
70.1 69.7 70.2 68.9 69.6 70.0
70.2 71.2 69.8 70.3 72.1 70.5
26-28
33
Test No. 1 52 62 52 62 52 62
Cryovac with N Cryovac with 0 Cryovac with Air Control (unwrapped)
52 52 52 52
Test No. 2 67.0 67.3 67.0 67.0
67.5 68.2 66.9 66.4
67.7 68.2 68.9 67.9
69.7 69.6 69.1 68.8
Cryovac with N Cryovac with 0 Cryovac with Air Control (unwrapped)
62 62 62 62
Test No. 3 68.4 69.7 67.8 68.9
69.7 70.3 69.4 69.1
69.5 69.0 70.2 69.4
70.3 61.5 72.9 68.0
Cryovac with N Poly. (1.5 mil) with He Poly. (1.5 mil) with N Poly. (1.5 mil) with Air Control (unwrapped)
52 52 52 52 52
67.6 67.6 67.4 67.0 68.1
69.1 68.3 68.6 68.5 69.4
69.1 69.0 70.5 70.4 71.3
Test No. 4
eggs packed on conventional trays in all tests (Tables 2, 3 and 4). However, this weight difference did not persist in these experiments and packaging had no apparent effect on day-old chick weight (Table 7). As demonstrated by Proudfoot (1964a), storage time had an effect on day-old chick weight which was probably due to the "longer-storage-time" eggs hatching later and thus resulting in less shrinkage or dehydration prior to weighing at the time of hatch removal. In Test 1, after one week of age, this weight difference was reversed and the birds hatched from eggs stored for shorter periods were heavier (Table 2). As storage time was increased, week-old body weight decreased significantly. This supports the findings of Merritt (1964). The data presented in Tables 2, 3 and 7
69.7 70.2 69.6 71.3 70.1
suggest that the temperature at which hatching eggs are stored may have important effects on subsequent chick weight. In Test 1 a temperature and storage time effect and a temperature X storage time interaction were demonstrated for week-old chick weight. Chicks which hatched from eggs stored for 14 days at 50-54°F. were lighter in body weight at one week of age than chicks which hatched from eggs stored 14 days at 60-64°F.; however, after 21 days in storage this weight difference had disappeared so that with longer storage periods, storage temperature had no apparent effect on week-old chick weight. Although brooding conditions were somewhat inadequate, interactions for week-old body weights are particularly interesting and suggest that egg storage conditions may have important effects on early chick growth.
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Plastic packed (low permeability film) Plastic packed (high permeability film) Control (unwrapped)
644
F. G. PROUDFOOT SUMMARY
stored at 50-54°F. up to 14 days, but for storage periods exceeding 14 days, the eggs stored in plastic packs at 50-54 days°F. exhibited higher hatchability and body weights were about the same at one week of age. ACKNOWLEDGEMENTS
The polyethylene bags were provided by Canadian Industries Limited, Brampton, Ontario. The Cryovac bags were supplied by W. R. Grace and Co., of Canada Ltd., Cooksville, Ontario. The author also wishes to thank Dr. W. J. Plank, Canadian Industries Limited, for providing permeability ratings of different plastic films, and Dr. Keith Stewart, Research Station, Kentville, who conducted the chromatograph oxygen gas evaluations. REFERENCES Becker, W. A., J. V. Spencer and J. L. Smartwood, 1963. Storing hatching eggs in plastic bags. Poultry Sci. 42: 1256. Merritt, E. S., 1964. Pre-incubation storage effects on subsequent performance of chickens. British Poultry Sci. 5: 67-73. Proudfoot, F. G., 1964a. The effect of plastic packaging and other treatment on hatching eggs. Can. J. Animal Sci. 44: 87-9S. Proudfoot, F. G., 1964b. Note on the effect of nitrogen and other gases on hatching eggs stored in plastic bags. Can. J. Animal Sci. 44: 120-121.
The Influence of Comb and Feathering Phenotypes on Body Weight and Dressing Percentage in Broilers B.
L.
G O O D M A N A N D F O R E S T V.
MUIR1
Southern Illinois University, Carbondale, Illinois (Received for publication September 4, 1964)
T
HE INFLUENCE of the phenotype for a simply inherited or qualitative trait on a more complex trait such as body weight has been studied to some extent in chickens.
Kan et al. (1959) reported that comb type (single or pea) had no significant 1
Present address: Poultry Science Department, Ohio State University, Columbus 10, Ohio.
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These studies provide further evidence that the maintenance of high hatchability during the pre-incubation period is enhanced by the use of plastic packaging. Permeability of the plastic film had significant effects on the preservation of hatchability levels. This was demonstrated by testing two films of the same thickness but of different densities. Hatchability was higher for the film of lower permeability. An additional improvement in hatchability was attained by altering the storage atmosphere through flushing the package with nitrogen gas. Although optimum levels of nitrogen were not determined, it was demonstrated that excessively high levels maintained over extended periods were detrimental to hatching qualities possibly because oxygen content was reduced below a critical point. Packaging methods had a significant effect on setting egg weight but did not appear to have any effect on chick weight, although a low magnitude effect was found on week-old chick weight. A temperature X storage time interaction was demonstrated for hatchability and egg and chick weight. The hatchability of eggs stored at 60-64°F. was superior and week-old weight was heavier than from eggs