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Solids Content of Eggs
Solids Content of Eggs DYSON ROSE, 1 N. T. GRIDG MAN1 AND D. A. FLETCHER2 (Received for publi ition June 10, 1965)
INTRODUCTION
T
MATERIALS AND METHODS
1962-1963 season. Twenty flocks consisting of duplicate pens initially containing 60 birds each, were randomly selected for study from amongst those being tested in the random-sample egg laying contest by the Poultry Division, Canada Department of Agriculture, Ottawa. Flock-pen distribution was random within the hen house, and all pens received uniform treatment in all known factors. An intestinal disease Issued as N.R.C. No. 8946. 1 Division of Biosciences, National Research Council, Ottawa, Canada. ' Marketing Branch, Canada Department of Agriculture, Ottawa, Canada.
developed during early October, and was treated with an accidental overdose of a recommended drug. On the first Monday of each month, eggs from hens in the selected duplicate pens were graded and duplicate, 6-egg lots of each available size (medium, large and extra-large) were transferred to the laboratory. These were stored at about 4°C. for one week to simulate commercial conditions, then broken out in 6-egg lots, thoroughly mixed, and sampled for total solids estimation. 1963-1964 season. Twenty flocks (40 pens) were again selected; 12 of these were repeat flocks of the strains studies in 1962-3. All other conditions were the same as in 1962-3, but no illness affected the flock during the months under study. Eggs from hens in the selected pens were again collected on the first Monday of each month and graded for size. Duplicate 6-egg lots representative of the days' collection were supplied to the laboratory. After storage for 1 week at 4°C, the eggs were broken out and whites and yolks separated manually. To avoid losses, the yolks were not wiped before weighing. Lots of 6 yolks and of 6 whites were weighed, thoroughly mixed, and sampled for the determination of total solids. Total solids were determined on 5 gm. samples dried at 90°C. and atmospheric pressure for approximately 3 hr. and then at 90°C. and 1 to 2 mm. pressure for a further 4 hr. Duplicate determinations were made on each 6-egg sample (i.e. 8 determinations per flock for each size of egg) during the 1962-3 season; single deter1
Downloaded from http://ps.oxfordjournals.org/ at North Dakota State University on May 25, 2015
HE regulations of the Canada Department of Agriculture require that Canada grade A egg melange entering interprovincial market channels shall contain not less than 25.8% total solids (Anonymous, 1949). During 1961 and 1962 several manufacturers of egg melange encountered difficulty in obtaining eggs that provided this quantity of solids in the melange, and a study of factors influencing the solids content of fresh eggs was therefore requested. The fact that this minimum solids regulation has been enforced since 1949 and that processors are only now encountering difficulty in meeting the standard suggests that there has been a decline in the solids content of eggs used for the preparation of melange. Consideration of the technical changes involved in egg production led us to focus the present study on (a) age of hen and (b) genetic factors.
222
D. ROSE, N. T. GEIDGEMAN AND D. A. FLETCHER TABLE 1.—Percent of total solids in eggs, from 1962-3 season {figures in parentheses indicate the number of 6-egg samples) Total solids, % Month Medium eggs 24.16(78) 24.88(80) 25.42(79) 25.61(61) 25.95(38) 26.19(25) 26.38(9) 26.24(7) 26.17(3) 25.92(2) 25.89(1) 25.83(383)
24.53(2) 24.68 (43) 25.22(76) 25.59(80) 25.79(79) 26.13(80) 26.22(75) 26.17(67) 26.15(72) 26.23(64) 26.15(54) 25.70(692)
minations were made on separated yolks and whites from each of four 6-egg samples for each flock in 1963-4. During the period of study, several attributes relating to the care and management, and production efficiency of these flocks were recorded. These data were reviewed for possible relations with egg total solids, but are not reported in detail. RESULTS During the 1962-3 period the average total solids content of all eggs received was 25.70% ± 0.41, and during the 1963-4 period it was 26.19% ± 0 . 4 8 . During each experimental period, both the weight and total solids content of the eggs (Table 1 and 2) increased progressively from October to May or June (Fig. 1), then decreased slightly. Since the effect of season on egg size is small (Romanoff and Romanoff, 1949) these changes are probably related to the age of the hens. Detailed analysis of the 1963-4 data showed that the increase in percent total solids with time of laying (age of hen) resulted primarily from an increase in the percentage of yolk in the egg (Table 2, last column); a highly significant correlation (+0.39) was observed between percent solids and percent yolk. Comparison be-
Overall
— — — — —
24.17(80) 24.81 (123) 25.32(155) 25.60(141) 25.86(117) 26.08(139) 26.12(130) 26.06(138) 26.05(143) 26.07(131) 25.94(116) 25.70(1,413)
25.88(34) 25.91(46) 25.92(64) 25.94(68) 25.91 (65) 25.76(61) 25.42(338)
tween flocks (Table 3) indicated that an increase of 1% in yolk content increased solids by 0.32%. There was also a slight increase with time of laying in the percentage solids in the yolk, and a decrease in the percentage solids in the white (Table 2). These results are in agreement with those of Lineweaver et al. (1962). The increase in egg size and total solids content resulted in an increased yield of dry solids from about 11 to IS g. per egg. However, nearly all of this increase was directly attributable to an increase in yolk solids from 7 to 11 g. per egg; white solids remained relatively constant between 3.7 and 4.1 g. per egg (Fig. 2). The flocks included in these tests differed markedly both in the size of egg produced TABLE 2.—Percent total solids in eggs from 1963-4 season (Each figure is the average value from eighty 6-egg samples)
Month Oct. Nov. Dec. Jan. Feb. Mar. Apr. May June July Aug. Ave.
.%
Total solids,
Weight of egg contents
In yolk
In I n whole white egg
44.5 47.1 48.5 51.2 52.4 54.0 54.9 55.0 56.4 56.0 55.7 52.3
48.85 50.08 50.05 49.40 49.46 50.48 50.41 50.41 50.56 50.96 50.36 50.09
12.80 12.73 12.54 12.39 12.11 11.96 11.83 11.87 11.65 11.61 11.75 12.11
24.55 25.51 26.06 26.10 26.22 26.37 26.61 26.93 26.86 26.66 26.20 26.19
Yolk %of egg contents 32.6 34.2 36.1 37.1 38.1 37.6 38.6 39.0 39.1 38.2 37.4 37.1
Downloaded from http://ps.oxfordjournals.org/ at North Dakota State University on May 25, 2015
Oct. Nov. Dec. Jan. Feb. Mar. Apr. May June July Aug. Weighted ave.
Extra-large eggs
Large eggs
EGG SOLIDS
a < K
223
102
Ul
> < d <
IOO
K U
> o u. o
98
94
o
1962-3
•
1963-4
-
OCT.
_L DEC
_L
X
FEB.
_L
APR
_L
_L
JUNE
AUG.
Fio. 1. Changes in the solids content of eggs during the laying period.
(Table 4) and in the solids content of the eggs (Fig. 3). No significant difference between the duplicate pens of a single strain were observed in any attribute studied. During the 1962-3 period, the average solids content of "medium" size eggs was slightly more than that of "large" eggs, which in turn was slightly more than the "extra large" eggs (Table 1). However, this difference was very small relative to
OCT.
OEC
FEB.
APR
JUNE
AUG.
TABLE 3 . - Relation between percent yolk and percent solids among flocks (Averages for subgroups of 4 flocks from a ranking in order of percent yolk, 1963-4 season) Subgroup
Average volk
% 36.2 36.7 37.0 37.4 38.2
1
2 3 1
s
OCT.
Average solids
DEC.
FEB.
APR.
25.88 26.00 26.14 26.46 26.48
JUNE
AUG.
Kir,. 2. Changes in the composition of eggs during the laying period, 1963-4 data.
Downloaded from http://ps.oxfordjournals.org/ at North Dakota State University on May 25, 2015
96 -
224
D. ROSE, N. T. GRIDGEMAN AND D. A. FLETCHER
Flock No. 1 2 3 4 5 6
/
8 9 10 11 12 13 14 15 16 17 18 19 20
Ave.
4 . --Weights
Yolk %o£ total contents
Weight of egg tents (g.) 49.7 50.2 50.7 50.9 51.1 52.0 52.0 52.0 52.2 52.6 52.6 52.6 52.8 53.0 53.0 53.5 53.5 53.9 54.0 54.1 52.3
37.9 36.5 36.6 37.7 36.7 36.6 37.5 38.6 38.4 36.8 37.4 37.4 37.3 36.9 37.1 36.9 35.8 36.4 37.1 36.1
Total solids, % Yolk
White Whole egg
50.33 49.75 50.08 50.65 50.38 49.98 50.43 49.54 49.77 49.51 50.83 50.31 50.54 49.91 49.99 49.70 50.07 49.56 50.34 49.61 50.09
12.09 12.31 12.16 11.90 12.13 12.06 12.11 11.88 11.91 12.03 11.95 12.20 12.09 12.49 12.05 11.85 12.07 12.36 12.18 12.46 12.11
26.53 26.01 26.06 26.50 26.18 25.93 26.51 26.45 26.45 25.82 26.51 26.40 26.42 26.36 26.15 25.82 25.67 25.98 26.22 25.88 26.19
Egg production per hen housed 171 232 239 232 231 223 208 204 207 213 209 202 222 257 212 236 220 225 206 198
the differences between monthly averages or between flocks. A statistical study (1963-4, Table S) of the relation between solids content and egg size (weight of egg contents) as the laying
-
I962-: FLOCK NO.
1963-4 FLOCK NO. 16 17 6 5 20 10 14 15 7 19 II 1
a
ME
~i6 1 ,7 ' l 6
1
5
20 10
— \
1
J
14 IS 7 19 II 1
-H
25
.1
1 1
"~l
1
1
26
1
1
1
2 3 4 8 9 12 13 18
1
27 SOLIDS,
25
ME AN
r1 |
I I 1
1
\
|, I 1
26
%
FIG. 3. Variations in solids content of eggs from different flocks, i.e. different breeding strains.
27
Downloaded from http://ps.oxfordjournals.org/ at North Dakota State University on May 25, 2015
season progressed indicated that there was an increase of ca. 0.15% in percentage solids for each gram increase in the weight of egg contents (with a probability of about 0.12 that this relation is fortuitous). However, there was no significant relation between these quantities from flock to flock or residually. A study of Table 4 clearly shows that some flocks produced large eggs with relatively high solids content (e.g. flock No. 19) and other flocks (e.g. Nos. 2 and 3) produced small eggs with relatively low solids content. In the 1962-3 period, the percent henday production (number of eggs produced per hen as a percentage of the number of days in the laying period) was weakly related to percent egg solids (correlation coeff 0.3S, significant to 10% point), but this relation was not repeated in 1963-4. During the 1963-4 season, pounds of feed used required to produce a dozen eggs was weakly correlated with the weight of dry solids per egg.
and total solids content of eggs from individual flocks (11 months averages 1963-64 season, each figure represents forty-four 6-egg samples) TABLE
225
EGG SOLIDS TABLE 5.—Analysis of cmiariance of egg-solids (x) and total egg-content (z) (Egg solids as percentage, egg-content in g. wet wt) Sz2
Source of variation Among 11 months (M) Among 20 flocks (F) Residual regression Deviates from regression M X F interaction
:
12,969.09 1,349.14
2,003.248 -108.256
532.81
-10.633
2x 2
df
MS(x)
F
374.3666 64.1711 0.2122 89.9417 90.1539
10 19 1 189 190
3.3774 0.2121 0.4759
7.10 <1 1
0.154+0.024 -0.080+0.048 - 0 . 0 2 0 + 0.030
In terms of increase in percent solids per gram increase in weight of egg contents. DISCUSSION
These results indicate that with selected groups of hens the most important factor influencing solids content of the eggs was the length of time a hen had been laying. Present egg production techniques often involve direct shipment of all the eggs produced by some farms directly to breaking and freezing plants. If several of the farms serving a breaking plant bring new pullets into production at about the same time, a drastic decrease in the solids content of the melange produced could occur. Furthermore, the domestic shell-egg market tends to discriminate against small eggs, and farms serving the shell-egg market as well as a breaking plant will therefore supply a disproportionate number of small eggs to the breaking plants. This will in effect involve a selection of eggs from young hens, and hence of eggs that are low in total solids content. It is highly probable that these factors were the principal cause of the reported inability of breaking plants to meet the specification of 25.8% solids in melange. When eggs from hens of equal age are compared, there is a tendency for the large eggs to be lower in percent solids content than the small eggs. A similar variation of solids content with egg size has been reported by Marion et al. (1964). However,
this difference is very small relative to the differences between flocks observed during both the 1962-3 and 1963-4 periods. It is unlikely, therefore, that this factor has an effect of any practical importance on the solids content of commercial melange. It is difficult to assess the effect of genetic studies on the solids content of eggs on the basis of this two year test. However, it can be noted that the differences between flocks were large, and that farms using certain strains (e.g. flock 17, Fig. 3) would not supply an "average" egg capable of producing Grade A melange. These differences between flocks which were maintained from 1962-3 to 1963-4,* may have been the result of breeding programs that have focussed their attention on egg production and size of egg but have neglected the solids content. Because large eggs are often low in percent solids, Marion et al. (1964), and Cotterill et al. (1962), have suggested that genetic differences influence the size of the eggs produced by different strains but have only an indirect effect on solids content. However, our data, in agreement with the recent observations of Hill (1964), indicate that selection of strains giving large eggs of high solids content is possible. This could probably be * The lower solids content of eggs during 19623 was probably caused by the illness.
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Regression coefficients* Among 11 months Among 20 flocks Residual
2xz
226
D. ROSE, N. T. GRIDGEMAN AND D. A. FLETCHER
done by selecting for a high yield of yolk (as a percent of egg contents) as yolk size seems to be the major factor controlling solids content of eggs from hens of a given age. ACKNOWLEDGMENTS
REFERENCES Anonymous, 1949. Live stock and live stock products Act—The frozen egg regulations. Canada Gazette, (Part II) Apr. 27.
Egg Promotion: A Controlled Experiment Evaluation1 R. J. PEELER, JR. AND R. A. SCHRIMPER Department of Economics, North Carolina State University, Raleigh (Received for publication August 4, 1965)
E
XPANSION of consumer demand through various forms of advertising has attracted increased attention of many agricultural commodity groups during the current decade. Five years ago, eleven hundred farm groups in this country spent some $75 million in various commodity promotional efforts (Frye et al., 1962). It is estimated that today similar groups number over twelve hundred and have an annual budget over $90 million.2 Numerous methods are being used to evaluate the effectiveness of promotional efforts. Evaluations are generally based on the extent to which sales volume is ex1 Published with the approval of the Director of the North Carolina Agricultural Experiment Station as Paper No. 2023 of the Journal Series. 2 Estimates obtained through personal correspondence with Marketing Economics Division, U.S. Department of Agriculture.
panded after promoting the product. Basically, the idea of measuring increased sales is sound, if handled properly. However, accurate measurement of increased sales due solely to a particular promotional effort is not an easy task because of the many variables that may be relevant, i.e., price, season, location, previous promotional efforts, etc. In addition, considerable caution should be exercised before making general application from experiences of an isolated event. A description of recent studies of commodity promotion programs may be found in a published 1964 address to the National Peach Council (Hoofnagle, 1964). Promotional efforts for agricultural commodities include a wide array of activities from providing school children with book covers promoting the nutritional value of a given commodity to purchasing
Downloaded from http://ps.oxfordjournals.org/ at North Dakota State University on May 25, 2015
The authors wish to thank Mrs. E. Javorsky and Messrs. H. Tessier, J. Marier and T. Buckley, Division of Biosciences, N.R.C., for technical assistance, and the Biometrics Section, N.R.C. for statistical evaluation of the data.
Cotterill, O. J., A. B. Stephenson and E. M. Funk, 1962. Factors affecting the yield of egg products from shell eggs. Proc. X I I World's Poultry Congress, p. 443-447. Hill, A. T., 1964. A biometrical evaluation of the component parts of an egg and their relationship to other economically important traits in a strain of White Leghorns. Dissertation. Texas A and M College. Lineweaver, H., J. J. Meehan, J. A. Garibaldi and L. Kline, 1962. Shell egg factors and egg product quality. Proc. X I I World's Poulty Congress, p. 439-442. Marion, W. W., A. W. Nordskog, H. S. Tolman and R. H. Forsythe, 1964. Egg composition as influenced by breeding, egg size, age and season. Poultry Sci. 43 : 2SS-264. Romanoff, A. L., and A. J. Romanoff, 1949. The Avian Egg, p. 69. J. Wiley and Sons, Inc., N.Y.
INTRODUCTION
T
MATERIALS AND METHODS
1962-1963 season. Twenty flocks consisting of duplicate pens initially containing 60 birds each, were randomly selected for study from amongst those being tested in the random-sample egg laying contest by the Poultry Division, Canada Department of Agriculture, Ottawa. Flock-pen distribution was random within the hen house, and all pens received uniform treatment in all known factors. An intestinal disease Issued as N.R.C. No. 8946. 1 Division of Biosciences, National Research Council, Ottawa, Canada. ' Marketing Branch, Canada Department of Agriculture, Ottawa, Canada.
developed during early October, and was treated with an accidental overdose of a recommended drug. On the first Monday of each month, eggs from hens in the selected duplicate pens were graded and duplicate, 6-egg lots of each available size (medium, large and extra-large) were transferred to the laboratory. These were stored at about 4°C. for one week to simulate commercial conditions, then broken out in 6-egg lots, thoroughly mixed, and sampled for total solids estimation. 1963-1964 season. Twenty flocks (40 pens) were again selected; 12 of these were repeat flocks of the strains studies in 1962-3. All other conditions were the same as in 1962-3, but no illness affected the flock during the months under study. Eggs from hens in the selected pens were again collected on the first Monday of each month and graded for size. Duplicate 6-egg lots representative of the days' collection were supplied to the laboratory. After storage for 1 week at 4°C, the eggs were broken out and whites and yolks separated manually. To avoid losses, the yolks were not wiped before weighing. Lots of 6 yolks and of 6 whites were weighed, thoroughly mixed, and sampled for the determination of total solids. Total solids were determined on 5 gm. samples dried at 90°C. and atmospheric pressure for approximately 3 hr. and then at 90°C. and 1 to 2 mm. pressure for a further 4 hr. Duplicate determinations were made on each 6-egg sample (i.e. 8 determinations per flock for each size of egg) during the 1962-3 season; single deter1
Downloaded from http://ps.oxfordjournals.org/ at North Dakota State University on May 25, 2015
HE regulations of the Canada Department of Agriculture require that Canada grade A egg melange entering interprovincial market channels shall contain not less than 25.8% total solids (Anonymous, 1949). During 1961 and 1962 several manufacturers of egg melange encountered difficulty in obtaining eggs that provided this quantity of solids in the melange, and a study of factors influencing the solids content of fresh eggs was therefore requested. The fact that this minimum solids regulation has been enforced since 1949 and that processors are only now encountering difficulty in meeting the standard suggests that there has been a decline in the solids content of eggs used for the preparation of melange. Consideration of the technical changes involved in egg production led us to focus the present study on (a) age of hen and (b) genetic factors.
222
D. ROSE, N. T. GEIDGEMAN AND D. A. FLETCHER TABLE 1.—Percent of total solids in eggs, from 1962-3 season {figures in parentheses indicate the number of 6-egg samples) Total solids, % Month Medium eggs 24.16(78) 24.88(80) 25.42(79) 25.61(61) 25.95(38) 26.19(25) 26.38(9) 26.24(7) 26.17(3) 25.92(2) 25.89(1) 25.83(383)
24.53(2) 24.68 (43) 25.22(76) 25.59(80) 25.79(79) 26.13(80) 26.22(75) 26.17(67) 26.15(72) 26.23(64) 26.15(54) 25.70(692)
minations were made on separated yolks and whites from each of four 6-egg samples for each flock in 1963-4. During the period of study, several attributes relating to the care and management, and production efficiency of these flocks were recorded. These data were reviewed for possible relations with egg total solids, but are not reported in detail. RESULTS During the 1962-3 period the average total solids content of all eggs received was 25.70% ± 0.41, and during the 1963-4 period it was 26.19% ± 0 . 4 8 . During each experimental period, both the weight and total solids content of the eggs (Table 1 and 2) increased progressively from October to May or June (Fig. 1), then decreased slightly. Since the effect of season on egg size is small (Romanoff and Romanoff, 1949) these changes are probably related to the age of the hens. Detailed analysis of the 1963-4 data showed that the increase in percent total solids with time of laying (age of hen) resulted primarily from an increase in the percentage of yolk in the egg (Table 2, last column); a highly significant correlation (+0.39) was observed between percent solids and percent yolk. Comparison be-
Overall
— — — — —
24.17(80) 24.81 (123) 25.32(155) 25.60(141) 25.86(117) 26.08(139) 26.12(130) 26.06(138) 26.05(143) 26.07(131) 25.94(116) 25.70(1,413)
25.88(34) 25.91(46) 25.92(64) 25.94(68) 25.91 (65) 25.76(61) 25.42(338)
tween flocks (Table 3) indicated that an increase of 1% in yolk content increased solids by 0.32%. There was also a slight increase with time of laying in the percentage solids in the yolk, and a decrease in the percentage solids in the white (Table 2). These results are in agreement with those of Lineweaver et al. (1962). The increase in egg size and total solids content resulted in an increased yield of dry solids from about 11 to IS g. per egg. However, nearly all of this increase was directly attributable to an increase in yolk solids from 7 to 11 g. per egg; white solids remained relatively constant between 3.7 and 4.1 g. per egg (Fig. 2). The flocks included in these tests differed markedly both in the size of egg produced TABLE 2.—Percent total solids in eggs from 1963-4 season (Each figure is the average value from eighty 6-egg samples)
Month Oct. Nov. Dec. Jan. Feb. Mar. Apr. May June July Aug. Ave.
.%
Total solids,
Weight of egg contents
In yolk
In I n whole white egg
44.5 47.1 48.5 51.2 52.4 54.0 54.9 55.0 56.4 56.0 55.7 52.3
48.85 50.08 50.05 49.40 49.46 50.48 50.41 50.41 50.56 50.96 50.36 50.09
12.80 12.73 12.54 12.39 12.11 11.96 11.83 11.87 11.65 11.61 11.75 12.11
24.55 25.51 26.06 26.10 26.22 26.37 26.61 26.93 26.86 26.66 26.20 26.19
Yolk %of egg contents 32.6 34.2 36.1 37.1 38.1 37.6 38.6 39.0 39.1 38.2 37.4 37.1
Downloaded from http://ps.oxfordjournals.org/ at North Dakota State University on May 25, 2015
Oct. Nov. Dec. Jan. Feb. Mar. Apr. May June July Aug. Weighted ave.
Extra-large eggs
Large eggs
EGG SOLIDS
a < K
223
102
Ul
> < d <
IOO
K U
> o u. o
98
94
o
1962-3
•
1963-4
-
OCT.
_L DEC
_L
X
FEB.
_L
APR
_L
_L
JUNE
AUG.
Fio. 1. Changes in the solids content of eggs during the laying period.
(Table 4) and in the solids content of the eggs (Fig. 3). No significant difference between the duplicate pens of a single strain were observed in any attribute studied. During the 1962-3 period, the average solids content of "medium" size eggs was slightly more than that of "large" eggs, which in turn was slightly more than the "extra large" eggs (Table 1). However, this difference was very small relative to
OCT.
OEC
FEB.
APR
JUNE
AUG.
TABLE 3 . - Relation between percent yolk and percent solids among flocks (Averages for subgroups of 4 flocks from a ranking in order of percent yolk, 1963-4 season) Subgroup
Average volk
% 36.2 36.7 37.0 37.4 38.2
1
2 3 1
s
OCT.
Average solids
DEC.
FEB.
APR.
25.88 26.00 26.14 26.46 26.48
JUNE
AUG.
Kir,. 2. Changes in the composition of eggs during the laying period, 1963-4 data.
Downloaded from http://ps.oxfordjournals.org/ at North Dakota State University on May 25, 2015
96 -
224
D. ROSE, N. T. GRIDGEMAN AND D. A. FLETCHER
Flock No. 1 2 3 4 5 6
/
8 9 10 11 12 13 14 15 16 17 18 19 20
Ave.
4 . --Weights
Yolk %o£ total contents
Weight of egg tents (g.) 49.7 50.2 50.7 50.9 51.1 52.0 52.0 52.0 52.2 52.6 52.6 52.6 52.8 53.0 53.0 53.5 53.5 53.9 54.0 54.1 52.3
37.9 36.5 36.6 37.7 36.7 36.6 37.5 38.6 38.4 36.8 37.4 37.4 37.3 36.9 37.1 36.9 35.8 36.4 37.1 36.1
Total solids, % Yolk
White Whole egg
50.33 49.75 50.08 50.65 50.38 49.98 50.43 49.54 49.77 49.51 50.83 50.31 50.54 49.91 49.99 49.70 50.07 49.56 50.34 49.61 50.09
12.09 12.31 12.16 11.90 12.13 12.06 12.11 11.88 11.91 12.03 11.95 12.20 12.09 12.49 12.05 11.85 12.07 12.36 12.18 12.46 12.11
26.53 26.01 26.06 26.50 26.18 25.93 26.51 26.45 26.45 25.82 26.51 26.40 26.42 26.36 26.15 25.82 25.67 25.98 26.22 25.88 26.19
Egg production per hen housed 171 232 239 232 231 223 208 204 207 213 209 202 222 257 212 236 220 225 206 198
the differences between monthly averages or between flocks. A statistical study (1963-4, Table S) of the relation between solids content and egg size (weight of egg contents) as the laying
-
I962-: FLOCK NO.
1963-4 FLOCK NO. 16 17 6 5 20 10 14 15 7 19 II 1
a
ME
~i6 1 ,7 ' l 6
1
5
20 10
— \
1
J
14 IS 7 19 II 1
-H
25
.1
1 1
"~l
1
1
26
1
1
1
2 3 4 8 9 12 13 18
1
27 SOLIDS,
25
ME AN
r1 |
I I 1
1
\
|, I 1
26
%
FIG. 3. Variations in solids content of eggs from different flocks, i.e. different breeding strains.
27
Downloaded from http://ps.oxfordjournals.org/ at North Dakota State University on May 25, 2015
season progressed indicated that there was an increase of ca. 0.15% in percentage solids for each gram increase in the weight of egg contents (with a probability of about 0.12 that this relation is fortuitous). However, there was no significant relation between these quantities from flock to flock or residually. A study of Table 4 clearly shows that some flocks produced large eggs with relatively high solids content (e.g. flock No. 19) and other flocks (e.g. Nos. 2 and 3) produced small eggs with relatively low solids content. In the 1962-3 period, the percent henday production (number of eggs produced per hen as a percentage of the number of days in the laying period) was weakly related to percent egg solids (correlation coeff 0.3S, significant to 10% point), but this relation was not repeated in 1963-4. During the 1963-4 season, pounds of feed used required to produce a dozen eggs was weakly correlated with the weight of dry solids per egg.
and total solids content of eggs from individual flocks (11 months averages 1963-64 season, each figure represents forty-four 6-egg samples) TABLE
225
EGG SOLIDS TABLE 5.—Analysis of cmiariance of egg-solids (x) and total egg-content (z) (Egg solids as percentage, egg-content in g. wet wt) Sz2
Source of variation Among 11 months (M) Among 20 flocks (F) Residual regression Deviates from regression M X F interaction
:
12,969.09 1,349.14
2,003.248 -108.256
532.81
-10.633
2x 2
df
MS(x)
F
374.3666 64.1711 0.2122 89.9417 90.1539
10 19 1 189 190
3.3774 0.2121 0.4759
7.10 <1 1
0.154+0.024 -0.080+0.048 - 0 . 0 2 0 + 0.030
In terms of increase in percent solids per gram increase in weight of egg contents. DISCUSSION
These results indicate that with selected groups of hens the most important factor influencing solids content of the eggs was the length of time a hen had been laying. Present egg production techniques often involve direct shipment of all the eggs produced by some farms directly to breaking and freezing plants. If several of the farms serving a breaking plant bring new pullets into production at about the same time, a drastic decrease in the solids content of the melange produced could occur. Furthermore, the domestic shell-egg market tends to discriminate against small eggs, and farms serving the shell-egg market as well as a breaking plant will therefore supply a disproportionate number of small eggs to the breaking plants. This will in effect involve a selection of eggs from young hens, and hence of eggs that are low in total solids content. It is highly probable that these factors were the principal cause of the reported inability of breaking plants to meet the specification of 25.8% solids in melange. When eggs from hens of equal age are compared, there is a tendency for the large eggs to be lower in percent solids content than the small eggs. A similar variation of solids content with egg size has been reported by Marion et al. (1964). However,
this difference is very small relative to the differences between flocks observed during both the 1962-3 and 1963-4 periods. It is unlikely, therefore, that this factor has an effect of any practical importance on the solids content of commercial melange. It is difficult to assess the effect of genetic studies on the solids content of eggs on the basis of this two year test. However, it can be noted that the differences between flocks were large, and that farms using certain strains (e.g. flock 17, Fig. 3) would not supply an "average" egg capable of producing Grade A melange. These differences between flocks which were maintained from 1962-3 to 1963-4,* may have been the result of breeding programs that have focussed their attention on egg production and size of egg but have neglected the solids content. Because large eggs are often low in percent solids, Marion et al. (1964), and Cotterill et al. (1962), have suggested that genetic differences influence the size of the eggs produced by different strains but have only an indirect effect on solids content. However, our data, in agreement with the recent observations of Hill (1964), indicate that selection of strains giving large eggs of high solids content is possible. This could probably be * The lower solids content of eggs during 19623 was probably caused by the illness.
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Regression coefficients* Among 11 months Among 20 flocks Residual
2xz
226
D. ROSE, N. T. GRIDGEMAN AND D. A. FLETCHER
done by selecting for a high yield of yolk (as a percent of egg contents) as yolk size seems to be the major factor controlling solids content of eggs from hens of a given age. ACKNOWLEDGMENTS
REFERENCES Anonymous, 1949. Live stock and live stock products Act—The frozen egg regulations. Canada Gazette, (Part II) Apr. 27.
Egg Promotion: A Controlled Experiment Evaluation1 R. J. PEELER, JR. AND R. A. SCHRIMPER Department of Economics, North Carolina State University, Raleigh (Received for publication August 4, 1965)
E
XPANSION of consumer demand through various forms of advertising has attracted increased attention of many agricultural commodity groups during the current decade. Five years ago, eleven hundred farm groups in this country spent some $75 million in various commodity promotional efforts (Frye et al., 1962). It is estimated that today similar groups number over twelve hundred and have an annual budget over $90 million.2 Numerous methods are being used to evaluate the effectiveness of promotional efforts. Evaluations are generally based on the extent to which sales volume is ex1 Published with the approval of the Director of the North Carolina Agricultural Experiment Station as Paper No. 2023 of the Journal Series. 2 Estimates obtained through personal correspondence with Marketing Economics Division, U.S. Department of Agriculture.
panded after promoting the product. Basically, the idea of measuring increased sales is sound, if handled properly. However, accurate measurement of increased sales due solely to a particular promotional effort is not an easy task because of the many variables that may be relevant, i.e., price, season, location, previous promotional efforts, etc. In addition, considerable caution should be exercised before making general application from experiences of an isolated event. A description of recent studies of commodity promotion programs may be found in a published 1964 address to the National Peach Council (Hoofnagle, 1964). Promotional efforts for agricultural commodities include a wide array of activities from providing school children with book covers promoting the nutritional value of a given commodity to purchasing
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The authors wish to thank Mrs. E. Javorsky and Messrs. H. Tessier, J. Marier and T. Buckley, Division of Biosciences, N.R.C., for technical assistance, and the Biometrics Section, N.R.C. for statistical evaluation of the data.
Cotterill, O. J., A. B. Stephenson and E. M. Funk, 1962. Factors affecting the yield of egg products from shell eggs. Proc. X I I World's Poultry Congress, p. 443-447. Hill, A. T., 1964. A biometrical evaluation of the component parts of an egg and their relationship to other economically important traits in a strain of White Leghorns. Dissertation. Texas A and M College. Lineweaver, H., J. J. Meehan, J. A. Garibaldi and L. Kline, 1962. Shell egg factors and egg product quality. Proc. X I I World's Poulty Congress, p. 439-442. Marion, W. W., A. W. Nordskog, H. S. Tolman and R. H. Forsythe, 1964. Egg composition as influenced by breeding, egg size, age and season. Poultry Sci. 43 : 2SS-264. Romanoff, A. L., and A. J. Romanoff, 1949. The Avian Egg, p. 69. J. Wiley and Sons, Inc., N.Y.