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The Influence of Dietary Factors on Egg Shell Quality.*
T h e Influence of Dietary Factors on Egg Shell Quality.* II. Calcium ROBERT JOHN EVANS, J. S. CARVER, AND A. WADE BRANT
Division of Poultry Husbandry, Washington State Agricultural Experiment Station, Pullman
ONSIDERABLE data have been reported on the necessity of supplying supplemental calcium to laying hens. Collier (1892), by the use of balance experiments, showed the necessity of supplying extra calcium to laying hens and the value of oyster shell as such a supplement. Most of the material reported has dealt with the relative efficiency of different calcium supplements fed ad libitum. Very few data are available in the literature on the calcium requirements of laying hens, and those available are controversial. Norris, Heuser, Ringrose, and Wilgus (1934) reported that l.S percent calcium was not sufficient for heavy egg production, 1.65 percent appeared just adequate, and 1.80 percent was optimum. Mitchell and McClure (1937), assuming SO percent production and SO percent utilization of dietary calcium, calculated that 2.74 percent of calcium would be necessary in the diet. Titus, Byerly, Ellis, and Nestler (1937) recommended a level of 2.2 percent in the diet from data they obtained. Titus (1939) later recommended 2.4 percent calcium in the complete diet. Berg (1941), from balance studies, blood calcium levels, and shell thickness studies with laying pullets just entering production, concluded that the
calcium requirements are between 2.0 and 3.0 percent. Practically all of the above work depended on production as a measure of the calcium requirements of laying hens. The work reported in this paper was conducted to further study the calcium requirements of laying pullets and to determine the influence of different levels of calcium in the diet on egg shell quality.
* Published as Scientific Paper No. 559, College of Agriculture and Agricultural Experiment Station, State College of Washington.
"The diets were analyzed for calcium and phosphorus by Mr. Morris Rhian of the Division of Chemistry.
C
PROCEDURE The general procedure followed was the same as that previously used to determine the effect of the dietary phosphorus level on egg shell quality (Evans, Carver, and Brant, 1944). Two experiments were conducted. Eight Single Comb White Leghorn pullets comprised a group in the first (1941) experiment and IS in the,second (1942). The pullets were kept in laying cages. During a 28-day preliminary period all pullets received a commercial laying mash. After this period the pullets were distributed equally on the basis of body weight, health, and previous production. The calcium and phosphorus1 contents of the various experimental diets are presented in Table 1. Each diet was fed to duplicate groups of pullets. The diets used in 1941 were composed of:
[361
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(Received for publication June 22, 1943)
INFLUENCE OF DIETARY FACTORS ON EGG SHELL QUALITY. II. CALCIUM
37
TABLE 1.—Diets fed, changes in weight, feed consumption, and mortality of pullets fed different levels of calcium in the diet 1942 experiment
1941 experiment 1 2 3 4 5 1.0 1.5 2.5 1.0 1.5 0.6 0.6 0.6 0.8 0.8 1,957 1,969 1,972 1,990 1,889 1,924 1,841 1,936 1,713 1,793
—
—
.—
—
38
12
6
31
19
0
•7 8 9 10 2.5 3.0 2.5 3.0 0.8 0.8 1.0 1.0 1,745 1,806 1,771 1,750 1,693 1,867 1,741 1,761 1,794 1,924 1,808 1,773
85.85 7.0 5.S 0.5 1.0 0.1S
Percent 83.4 7.0 S.8 2.1 0.5 1.0 0.1S 0.05
Cereal basal, bone meal, and oyster shell were adjusted to give the desired levels of calcium and phosphorus.3 The diets for 2 Dicalcium phosphate was added to give the desired level of phosphorus, calcium carbonate to give the desired level of calcium, and the cereal basal to bring the total to 85.85 percent s Bone meal was added to give the desired level
11 3.5 1.0 1,763 1,772 1,770
3,213 3,367 3,175 3,205 3,337 3,202 3,174 3,069 3,087 3,216 10 0 3 7 3 30
The cereal basal on a percentage basis consisted of ground yellow corn, 10; ground wheat, 15; ground oats, 7; ground barley, 5; millrun, 38; and whole wheat, 25. The amounts of cereal basal, dicalcium phosphate, and calcium carbonate were varied to supply the desired levels of calcium and phosphorus.2 The diets used in 1942 were composed of: Cereal basal! Bone meal [ Oyster shellj Dehydrated alfalfa Herring fish meal Soybean oil meal Salt Silica grit Cod liver oil Manganese sulphate
—.
2,908 3,222 3,382 2,752 3,239 3,413
Percent Cereal basal 1 Dicalcium phosphate! Calcium carbonate J Dehydrated alfalfa Casein Iodized salt Silica grit Cod liver oil (400D)
—
6 2.5 0.8 1,923 1,795
14
24
40
17
both years contained 60 A.O.A.C. chick units of vitamin D per 100 grams of diet. This has been shown to be a borderline level for laying pullets (Murphy, Hunter, and Knandel, 1936; Carver, Robertson, Brazie, Johnson, and St. John, 1934). Unpublished work at this station, however, has demonstrated this level of vitamin D to be optimum for hens kept in laying cages. The 1941 experiment lasted for four 28day periods4 and the 1942 experiment for 10 periods. At the start of the preliminary period and of each other period, and at the end of the final period, the following measurements, as described previously (Evans, Carver, and Brant, 1944), were made on the first 2 eggs from each pullet: shell smoothness, egg weight, shell thickness, and shell weight. The pullets were weighed at the start of each period and feed consumption records kept for the period. During the first experiment egg shell porosity, albumen index, and shell texture measurements were also made. Calcium carbonate and dicalcium phosphate were used to supply the calcium and phosphorus, and casein to supply the proof phosphorus, oyster shell to give the desired level of calcium, and the cereal basal to bring the total to 83.4 percent. 4 The term "month" in this paper refers to a 28-day lunar month and is used in this way for convenience and clarity.
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Group No. Percent calcium Percent phosphorus Ave. initial weight Ave. weight at 4 months Ave. weight at 10 months Ave. monthly feed consumption to 4 months Ave. monthly feed consumption 5-10 months Mortality to 4 months (percent) Mortality to 10 months (percent)
38
ROBERT JOHN EVANS, J. S. CARVER, AND A. WADE BRANT TABLE 2.—The effect of the calcium level in the diet of laying pullets on production and eggshell quality {1941 experiment)
Percent p
Ca Prelim.! Ave.
%
%
Egg shell smoothness
Egg shell weight
Change Prelim.! Ave. Change* Prelim.' Ave. Change* Prelim. Ave. J Change*Prelim. Ave. Change*
%
mm. X100 29.3 -1.8 30.2 -2.4 33.1 -1.1
0.6 0.6 0.6
1.0 1.5 2.5
71 73 78
27 56 64
-43 -17 -15
31.5 32.3 34.0
0.8 0.8 0.8
1.0 1.5 2.5
67 69 67
32 54 70
-35 -15 + 3
31.8 32.8 32.9
Least sign, c iS.
Egg weight
Shell thickness
Production
15
30.2 20.6 33.0
-2.0 -2.2 +0.2
gms. 54.2 54.6 55.9
gms. 55.3 57.3 58.5
gms. +0.8 +3.4 +3.0
gms. 4.77 5.05 5.30
gms. 4.38 4.69 5.22
gms. -0.38 -0.41 -0.11
score 1.4 1.4 1.4
score 1.2 1.2 1.2
score -0.1 -0.2 -0.2
55.4 54.9 57.5
56.4 57.2 59.2
+ 1.4 +2.5 +2.0
5.09 5.12 5.26
4.62 4.75 5.26
-0.47 -0.38 +0.02
1.4 1.3 1.3
1.2 1.2 1.2
-0.2 -0.2 -0.1
1.0
1.4
0.33
0.2
tein in the 1941 experiment, since as few mineral impurities as possible were desired. It was necessary to use dicalcium phosphate rather than the more common tricalcium phosphate in order to give levels of O.S percent calcium and 0.8 percent phosphorus in diet 4. Oyster shell, bone meal, herring fish meal, and soybean oil meal were used as mineral and protein supplements in 1942, since it was desired to use more practical diets. RESULTS Diets 1 and 4 contained O.S percent calcium during the first period of the experiment. This was too low a level to maintain production or health. At the start of the second month the calcium level was raised to 1.0 percent. Production fell rapidly during the first month at the O.S percent level of calcium and was not appreciably improved when the level was increased to 1.0 percent. One percent calcium was not suffkent to meet the needs of the laying hens when kept in laying cages. Mortality was high (Table 1) and production was low (Table 2) both at 0.6 and 0.8 percent phosphorus levels. When the heavy producing hens were put on the low calcium diets, some of them immediately stopped laying, probably conserving the calcium to meet body requirements. Others dropped in production, pos-
sibly only laying an egg after sufficient calcium had been stored up to form a fairly normal egg shell. Others kept laying at a fairly normal rate, but laid eggs with very thin shells. The groups receiving O.S percent calcium and 0.8 percent phosphorus deposited more calcium in the eggs than was consumed in the diet. These must have drawn on the skeletal reserves to meet the needs for egg production as the bones of some hens became so soft they would not support the hens' weight. These starved to death because they could not get to the feed. On autopsy the bones were so soft that they bent easily (Fig. 1). The breastbone was red and in places appeared to be composed mainly of cartilage. Such soft bones were also observed occasionally with
FIG. 1. Breastbone and shank of a hen that died from decalcification of the bones. Both the breastbone and shank were soft and could be bent at will.
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* The change in shell thickness, egg weight, shell weight, and shell smoothness was calculated for each group on a pullet basis That is, the difference between the value for the period in question and the preliminary period was determined for each pullet. The average of these chages for each diet is presented in this column rather than the difference between the diet averages.
INFLUENCE OF DIETARY FACTORS ON EGG SHELL QUALITY. II. CALCIUM
ment. There were no significant differences in production during any period considered. Increases in egg shell thickness occurred on most diets during the first four months. The greatest increase occurred with levels of 3.5 percent calcium and 1.0 percent phosphorus. This was not significantly greater than produced by 3.0 percent calcium and 1.0 percent phosphorus or 3.0 percent calcium and 0.8 percent phosphorus, but was significantly better than 2.5 percent calcium at either phosphorus level. During the second four months no significant differences in shell thickness were observed, though 3.0 percent calcium gave the best results at either phosphorus level. Shell thickness decreased markedly on all diets during the last two months of the experiment. At both 0.8 and 1.0 percent phosphorus, 3.0 percent calcium best prevented the decrease in egg shell thickness.
Records of egg weight and egg shell weight for the 1942 experiment are presented in Table 4. No significant differences in egg weight were observed during the first eight months of the 1942 experiment. There was a general decrease in egg weight during the last two months over the preceding four months. No significant differences in shell weight were observed between any of the diets 'for the experiment. Table 5 contains the egg shell smoothness data for the 1942 experiment. At the Table 3 contains the production and egg 1.0 percent phosphorus level 3.0 and 3.5 shell thickness results for the 1942 experi- percent calcium produced rougher shells rABLE 3 .—The
production effect of the calcium level in the diet of laying .pullets on egg shell thickness (1942 experiment)
• Egg shell thickness (mm. X100)
Percent production
Percent 1-4 months
5-8 months.
and
9-10 months
Prelim.
1-4 months
5-8 months
9-10 months
P
Ca
Prelim.
0.8 0.8
"2.5 3.0
48 43
55 53
+7
+ 10
54 54
+ 116
+
51 52
+3 +9
33.3 33.7
33.5 34.7
+0.2 +1.0
31.7 33.2
-1.9 -0.2
27.9 30.4
-5.5 -3.0
1.0 1.0 1.0
2.5 3.0 3.5
44 47 50
59 55 59
+15 + 9 + 9
54 48 56
+10 + 1 + 6
57 55 56
+13 + 8 + 6
32.9 32.5 32.7
32.4 33.3 33.9
-0.7 +0.8 +1.3
31.2 32.1 32.2
-1.9 -0.4 -0.6
27.6 29.9 29.7
-5.2 -1.8 -3.2
Ave. Change Ave. Change Ave. Change
Least sign, di a. * See footnote Table 2.
15
21
22
Ave. Change* Ave. Change* Ave. Change*
1.0
1.8
2.4
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hens receiving l.S percent calcium in the diet but not as often as at the lower calcium levels. Records of change in body weight, feed consumption, and mortality for both experiments are presented in Table 1. Considerable mortality, directly attributable to a calcium deficiency, occurred during the first four months in the groups receiving 1.0 percent calcium in the diets. The high mortality during the last six months of the 1942 experiment was due to leucosis. The results of the first (1941) experiment are presented in Table 2. This table contains the average records of production, shell thickness, egg weight, shell weight, and shell smoothness for the four-month period. Production was significantly lower at the 1.0 percent level of calcium than at any other, and 2.5 percent calcium allowed significantly better production than 1.5 percent at an 0.8 percent level of phosphorus. A level of 2.5 percent calcium at either 0.6 or 0.8 percent phosphorus produced thicker egg shells than lower levels. Decreases in shell weight occurred at levels of calcium in the diet of 1.0 and 1.5 percent. These decreases were significantly greater than at a 2.5 percent level of'calcium. Eggs of hens receiving 1.0 percent calcium and 0.6 percent phosphorus failed to increase in weight normally. No significant differences in shell smoothness were observed.
39
ROBERT JOHN EVANS, J. S. CARVER, AND A. WADE BRANT
40
TABLE 4.—The eject of the calcium level in the diet of laying pullets on egg-weight and egg shell weight (1942 experiment) Egg Shell Weight
Egg Weight Percent
Prelim.
1-4 months
Ca
0.8 0.8
2.5 3.0
1.0 1.0 1.0
2.5 3.0 3.5
5-8 months
Prelim.
9-10 months
Ave.
Ave. Change* Ave. Change*, Ave. Change* gms. 52.4 55.2 52.5 53.3 52.2
gms. 58.9 +6.7 60.6 +5.6
gms. 60.6 +8.6 62.0
+7.2
gms. 58.0 +5.3 59.6 +5.4
gms. 4.96 5.24
58.9 58.6 58.5
60.2 59.6 60.7
+8.2 +6.9 +8.0
57.9 57.6 59.6
+7.2 +5.8 +6.8
4.90 4.88 4.90
+6.3 +5.8 +6.3
9-10 months
5-8 months
Change* Ave.
Change* Ave.
S.26 5.66
gms. +0.32 +0.42
5.06 5.46
gms. +0.07 +0.28
5.16 5.26 5.42
+0.22 +0.38 +0.50
4.98 5.16 5.24
+0.08 +0.26 +0.25
Change*
gms. 4.64 -0.33 5.15 -0.16 4.64 4.95 5.04
-0.16 -0.22 -0.11
0.31
0.33
1.4
1.6
1.4
Least sign. diff.
1-4 months
* See footnote Table 2.
TABLE 6.—Eject of level of calcium in the diet on the change in porosity, shell mottling, and albumen index (1941 experiment) Calcium
Phosphorus
percent percent 1.0 0.6 0.6 1.5 2.5 0.6 0.8 1.0 0.8 1.5 0.8 2.5 Least sign. diff.
Porosity-
Shell texture
Albumen index
score -0.3 +0.2 -0.3 -0.1 +0.9 -0.3 2.0
score +0.5 +0.7 +0.5 +0.4 +0.6 +0.8 0.2
units + 17 - 6 -11 + 15 -10 - 9 13
DISCUSSION
Considering production and egg shell quality (particularly shell thickness), pullets receiving a level of 3.0 percent calcium in the diet gave more satisfactory results than those receiving higher or lower levels. This is for the entire experiment. Thicker shells were observed at the 3.5 percent level for the first four months, although the
TABLE 5.—The eject of the calcium level in the diet of laying pullets on egg shell smoothness (1942 experiment) ' 5-8 months
[-4 months
9-10 months
cent Prelim.
Ave.
Change*
Ave.
Change*
Ave.
Change*
p 0.8 0.8
Ca 2.5 3.0
score 0.3 0.4
score 0.5 0.5
score 0.2 0.2
score 0.9 0.8
score 0.6 0.6
score 0.9 0.8
score 0.6 0.6
1.0 1.0 1.0 Least sign. dif f.
2.5 3.0 3.5
0.5 0.2 0.2
0.4 0.5 0.4
0.1 0.3 0.2 0.2
0.8 0.8 1.0
0.4 0.7 0.9 0.2
1.1 0.6 1.1
0.6 0.6 1.0 0.3
* See footnote Table 2.
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than 2.5 percent calcium during the first four months. During the remainder of the experiment the 3.5 percent level gave rougher shells than the 3.0 percent one. No significant differences were observed at a level of 0.8 percent phosphorus. No differences in shell porosity could be attributed to the calcium level in the diet (Table 6). Changes in shell texture were erratic, although at the 0.8 percent level of phosphorus the mottling increased as the calcium level increased. Losses in albumen index occurred at the 1.5 and 2.5 percent levels of calcium. A gain in albumen index occurred at the 1.0 percent level. This gain was due to decreased production, since it has been observed by Miller and Bearse (1937) that a hen produces eggs with a higher albumen index when she is laying only a few eggs than when she is in heavy production.
INFLUENCE OF DIETARY FACTORS ON EGG SHELL QUALITY. II. CALCIUM
SUMMARY Laying Single Comb White Leghorn hens kept in laying cages were fed 11 different diets containing levels of 1.0, 1.5, 2.5, 3.0, and 3.5 percent calcium. The phosphorus levels of these diets were 0.6, 0.8, or 1.0 percent, and the vitamin D content was 60 A.O.A.C. chick units per 100 grams of diet. Hens receiving 3.0 percent calcium in the diet gave more satisfactory results than those receiving higher or lower levels when egg shell thickness was used as the criterion. However, a level of 2.5 percent calcium allowed as satisfactory production as one of 3.0 percent. Production and egg shell quality were considerably decreased when the dietary calcium level was reduced to 1.0 percent. Many hens receiving this level of calcium withdrew calcium from the bones till the bones were so soft that they would not support the weight of the birds. REFERENCES
Berg, L. R., 1941. The effect of varying levels of calcium intake on the calcium balance, shell thickness, and blood calcium level of White Leghorn pullets. Thesis, Kansas State College of Agriculture and Applied Science. Carver, J. S., E. I. Robertson, D. Brazie, R. II. Johnson, and J. L. St. John, 1934. The vitamin D requirements of chickens. Wash. Agr. Expt. Sta., Bull. 299:5-40. Collier, P., 1892. Oyster shells as food for laying hens. New York Agr. Expt. Sta., Bull. 38:1-10. Common, R. H., 1938. Observations on the mineral metabolism of pullets. III. J. Agr. Sci. 28:347-66. Common, R. H., and R. W. Hale, 1941. Observations on the mineral metabolism of pullets. VI. The mobilization of body calcium for shell formation. J. Agr. Sci. 31:415-437. Deobald, H. J., E. J.'Lease, E. B. Hart, and J. G. Halpin, 1936. Studies on the calcium metabolism in laying hens. Poultry Sci. IS :179-18S. Evans, R. J., J. S. Carver, and A. W. Brant, 1944. The influence of dietary factors on egg shell quality. I. Phosphorus. Poultry Sci. 23 :9-15. Gutowska, M. S., and R. T. Parkhurst, 1942. Studies in mineral nutrition of laying hens. II.
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difference between 3.5 and 3.0 percent was not statistically significant. Three percent calcium is a higher level than other workers have found necessary to maintain high production. It will be observed that 3.0 percent calcium did not give any better production than lower levels; therefore, 2.5 percent may be considered as satisfactory for production, while 3.0 percent is necessary for the production of thicker egg shells. In this connection Berg (1941) observed that a 3.0 percent level of calcium caused an increase in shell thickness during the relatively short period of his experiment. Gutowska and Parkhurst (1942) fed Rhode Island Red pullets for six months on diets containing 2.35, 2.77, and 3.95 percent calcium. They observed no significant differences in egg shell breaking strength or egg weight between the different levels. The 3.95 percent level gave a decrease in production. Several investigators have pointed out that the hen has an unusually great capacity to metabolize calcium. Morgan, Mitchell, Ringrose, and Lease (1942) observed a 32 percent loss of body calcium from one hen during six weeks of production on a 2.4 percent level of dietary calcium. Morgan and Mitchell (1938) observed that the ability of the hen to utilize calcium was an individual characteristic. Deobald, Lease, Hart, and Halpin (1936) and Common (1938) also noted a withdrawal of body calcium for egg shell formation. Common and Hale (1941) and Tyler (1940) differentiated between two types of bone calcium, the "residual" calcium having the higher Ca:P ratio and being mobilized for egg shell formation. It is evident, however, that in our experiment not only the "residual" calcium but considerable of the structural calcium also was mobilized for egg shell formation by some of the hens receiving 0.5 and 1.0 percent dietary calcium.
41
42
BOOK REVIEWS chicks and laying hens. Pa. Agr. Expt. Sta., Bull. 334. Norris, L. C , G. F. Heuser, A. T. Ringrose, and H. S. Wilgus, Jr., 1934. Studies of the calcium requirements of laying hens. Poultry Sci. 13 :308309. Titus, H. W., T. C. Byerly, N. R. Ellis, and R. B. Nestler, 1937. Effect of calcium and phosphorus content of the diet of chickens on egg production and hatchability. Poultry Sci. 16:118. Titus, H. W., 1939. Practical nutritive requirements of poultry. Yearbook of Agriculture, 1939, 818. Tyler, C , 1940. Calcium and phosphorus metabolism in relation to the chemical structure of bone. I. Experiments with laying birds. Biochem. J. 34:202-212.
Book Reviews Ewing, W. Ray. Handbook of Poultry Nutrition (second edition). South Pasadena, California: W. R. Ewing, 1943. 1,245 pages, 118 figures. Price $10.00. The second edition of this outstanding; text contains 400 pages more than the first edition. It has been more completely illustrated also, the first edition containing 68'< figures whereas this edition has 118 figures. A large part of the increase in the size of' the text is due to the inclusion of the resultsi of new research. Many sections have beeni entirely rewritten because of new discoveries. Others have been expanded and some: entirely new topics have been included. Typical of new topics worthy of separate; chapters in this edition are those discussingI "Biotin" and "Wartime construction off poultry feed formulas." This edition contains six new chapters. Much of the material included in these new? chapters was incorporated in the "Miscellaneous" chapter in the first edition. Thee use of additional illustrations has aided materially in helping the reader to recognizee many of the nutritional disorders.—D.R.M.
Thompson, Willard C , and John Bird. The Home Poultry Flock. New York, New York: W. W. Norton & Company, Inc., 1943. 144 pages, 25 figures. Price $2.00. This small book, comprising 10 chapters, presents in an easily read form the essential details of caring for a home poultry flock. The general pattern of this text is somewhat similar to other texts reviewed in recent months but in many respects the approach is quite different. The reviewer observed a tendency to discuss some topics which have little application to a small home flock; for illustration, the presentation of several different rations, each adapted to a different purpose. Of the seven rations offered to the reader, none would conform to present day feeding restrictions and even though the rations did conform the reviewer would question the advisability of home mixing for a flock of 15 to 20 hens, especially such rations as a broiler finishing mash or special fattening mash. In many other places in the text there is evidence of large flock planning.—D. R. M.
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Excess of calcium in the diet. Poultry Sci. 21:321-328. Miller, M. W., and G. E. Bearse, 1937. Protein supplements for laying hens. Wash. Agr. Expt. Sta., Bull. 347 :S-16. Mitchell, H. H., and F. J. McClure, 1937. Mineral nutrition of farm animals. National Research Council, Bull. 99:127. Morgan, C. L., and J. H. Mitchell, 1938. The calcium and phosphorus balance of laying hens. Poultry Sci. 17:99-104. Morgan, C. L., J. H. Mitchell, R. C. Ringrose, and E. J. Lease, 1942. The study of calcium metabolism in the laying hen by the comparative slaughter method. Poultry Sci. 21:212-215. Murphy, R. R., J. E. Hunter, and H. C. Knandel, 1936. The vitamin D requirements of growing
Division of Poultry Husbandry, Washington State Agricultural Experiment Station, Pullman
ONSIDERABLE data have been reported on the necessity of supplying supplemental calcium to laying hens. Collier (1892), by the use of balance experiments, showed the necessity of supplying extra calcium to laying hens and the value of oyster shell as such a supplement. Most of the material reported has dealt with the relative efficiency of different calcium supplements fed ad libitum. Very few data are available in the literature on the calcium requirements of laying hens, and those available are controversial. Norris, Heuser, Ringrose, and Wilgus (1934) reported that l.S percent calcium was not sufficient for heavy egg production, 1.65 percent appeared just adequate, and 1.80 percent was optimum. Mitchell and McClure (1937), assuming SO percent production and SO percent utilization of dietary calcium, calculated that 2.74 percent of calcium would be necessary in the diet. Titus, Byerly, Ellis, and Nestler (1937) recommended a level of 2.2 percent in the diet from data they obtained. Titus (1939) later recommended 2.4 percent calcium in the complete diet. Berg (1941), from balance studies, blood calcium levels, and shell thickness studies with laying pullets just entering production, concluded that the
calcium requirements are between 2.0 and 3.0 percent. Practically all of the above work depended on production as a measure of the calcium requirements of laying hens. The work reported in this paper was conducted to further study the calcium requirements of laying pullets and to determine the influence of different levels of calcium in the diet on egg shell quality.
* Published as Scientific Paper No. 559, College of Agriculture and Agricultural Experiment Station, State College of Washington.
"The diets were analyzed for calcium and phosphorus by Mr. Morris Rhian of the Division of Chemistry.
C
PROCEDURE The general procedure followed was the same as that previously used to determine the effect of the dietary phosphorus level on egg shell quality (Evans, Carver, and Brant, 1944). Two experiments were conducted. Eight Single Comb White Leghorn pullets comprised a group in the first (1941) experiment and IS in the,second (1942). The pullets were kept in laying cages. During a 28-day preliminary period all pullets received a commercial laying mash. After this period the pullets were distributed equally on the basis of body weight, health, and previous production. The calcium and phosphorus1 contents of the various experimental diets are presented in Table 1. Each diet was fed to duplicate groups of pullets. The diets used in 1941 were composed of:
[361
Downloaded from http://ps.oxfordjournals.org/ at New York University on July 6, 2015
(Received for publication June 22, 1943)
INFLUENCE OF DIETARY FACTORS ON EGG SHELL QUALITY. II. CALCIUM
37
TABLE 1.—Diets fed, changes in weight, feed consumption, and mortality of pullets fed different levels of calcium in the diet 1942 experiment
1941 experiment 1 2 3 4 5 1.0 1.5 2.5 1.0 1.5 0.6 0.6 0.6 0.8 0.8 1,957 1,969 1,972 1,990 1,889 1,924 1,841 1,936 1,713 1,793
—
—
.—
—
38
12
6
31
19
0
•7 8 9 10 2.5 3.0 2.5 3.0 0.8 0.8 1.0 1.0 1,745 1,806 1,771 1,750 1,693 1,867 1,741 1,761 1,794 1,924 1,808 1,773
85.85 7.0 5.S 0.5 1.0 0.1S
Percent 83.4 7.0 S.8 2.1 0.5 1.0 0.1S 0.05
Cereal basal, bone meal, and oyster shell were adjusted to give the desired levels of calcium and phosphorus.3 The diets for 2 Dicalcium phosphate was added to give the desired level of phosphorus, calcium carbonate to give the desired level of calcium, and the cereal basal to bring the total to 85.85 percent s Bone meal was added to give the desired level
11 3.5 1.0 1,763 1,772 1,770
3,213 3,367 3,175 3,205 3,337 3,202 3,174 3,069 3,087 3,216 10 0 3 7 3 30
The cereal basal on a percentage basis consisted of ground yellow corn, 10; ground wheat, 15; ground oats, 7; ground barley, 5; millrun, 38; and whole wheat, 25. The amounts of cereal basal, dicalcium phosphate, and calcium carbonate were varied to supply the desired levels of calcium and phosphorus.2 The diets used in 1942 were composed of: Cereal basal! Bone meal [ Oyster shellj Dehydrated alfalfa Herring fish meal Soybean oil meal Salt Silica grit Cod liver oil Manganese sulphate
—.
2,908 3,222 3,382 2,752 3,239 3,413
Percent Cereal basal 1 Dicalcium phosphate! Calcium carbonate J Dehydrated alfalfa Casein Iodized salt Silica grit Cod liver oil (400D)
—
6 2.5 0.8 1,923 1,795
14
24
40
17
both years contained 60 A.O.A.C. chick units of vitamin D per 100 grams of diet. This has been shown to be a borderline level for laying pullets (Murphy, Hunter, and Knandel, 1936; Carver, Robertson, Brazie, Johnson, and St. John, 1934). Unpublished work at this station, however, has demonstrated this level of vitamin D to be optimum for hens kept in laying cages. The 1941 experiment lasted for four 28day periods4 and the 1942 experiment for 10 periods. At the start of the preliminary period and of each other period, and at the end of the final period, the following measurements, as described previously (Evans, Carver, and Brant, 1944), were made on the first 2 eggs from each pullet: shell smoothness, egg weight, shell thickness, and shell weight. The pullets were weighed at the start of each period and feed consumption records kept for the period. During the first experiment egg shell porosity, albumen index, and shell texture measurements were also made. Calcium carbonate and dicalcium phosphate were used to supply the calcium and phosphorus, and casein to supply the proof phosphorus, oyster shell to give the desired level of calcium, and the cereal basal to bring the total to 83.4 percent. 4 The term "month" in this paper refers to a 28-day lunar month and is used in this way for convenience and clarity.
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Group No. Percent calcium Percent phosphorus Ave. initial weight Ave. weight at 4 months Ave. weight at 10 months Ave. monthly feed consumption to 4 months Ave. monthly feed consumption 5-10 months Mortality to 4 months (percent) Mortality to 10 months (percent)
38
ROBERT JOHN EVANS, J. S. CARVER, AND A. WADE BRANT TABLE 2.—The effect of the calcium level in the diet of laying pullets on production and eggshell quality {1941 experiment)
Percent p
Ca Prelim.! Ave.
%
%
Egg shell smoothness
Egg shell weight
Change Prelim.! Ave. Change* Prelim.' Ave. Change* Prelim. Ave. J Change*Prelim. Ave. Change*
%
mm. X100 29.3 -1.8 30.2 -2.4 33.1 -1.1
0.6 0.6 0.6
1.0 1.5 2.5
71 73 78
27 56 64
-43 -17 -15
31.5 32.3 34.0
0.8 0.8 0.8
1.0 1.5 2.5
67 69 67
32 54 70
-35 -15 + 3
31.8 32.8 32.9
Least sign, c iS.
Egg weight
Shell thickness
Production
15
30.2 20.6 33.0
-2.0 -2.2 +0.2
gms. 54.2 54.6 55.9
gms. 55.3 57.3 58.5
gms. +0.8 +3.4 +3.0
gms. 4.77 5.05 5.30
gms. 4.38 4.69 5.22
gms. -0.38 -0.41 -0.11
score 1.4 1.4 1.4
score 1.2 1.2 1.2
score -0.1 -0.2 -0.2
55.4 54.9 57.5
56.4 57.2 59.2
+ 1.4 +2.5 +2.0
5.09 5.12 5.26
4.62 4.75 5.26
-0.47 -0.38 +0.02
1.4 1.3 1.3
1.2 1.2 1.2
-0.2 -0.2 -0.1
1.0
1.4
0.33
0.2
tein in the 1941 experiment, since as few mineral impurities as possible were desired. It was necessary to use dicalcium phosphate rather than the more common tricalcium phosphate in order to give levels of O.S percent calcium and 0.8 percent phosphorus in diet 4. Oyster shell, bone meal, herring fish meal, and soybean oil meal were used as mineral and protein supplements in 1942, since it was desired to use more practical diets. RESULTS Diets 1 and 4 contained O.S percent calcium during the first period of the experiment. This was too low a level to maintain production or health. At the start of the second month the calcium level was raised to 1.0 percent. Production fell rapidly during the first month at the O.S percent level of calcium and was not appreciably improved when the level was increased to 1.0 percent. One percent calcium was not suffkent to meet the needs of the laying hens when kept in laying cages. Mortality was high (Table 1) and production was low (Table 2) both at 0.6 and 0.8 percent phosphorus levels. When the heavy producing hens were put on the low calcium diets, some of them immediately stopped laying, probably conserving the calcium to meet body requirements. Others dropped in production, pos-
sibly only laying an egg after sufficient calcium had been stored up to form a fairly normal egg shell. Others kept laying at a fairly normal rate, but laid eggs with very thin shells. The groups receiving O.S percent calcium and 0.8 percent phosphorus deposited more calcium in the eggs than was consumed in the diet. These must have drawn on the skeletal reserves to meet the needs for egg production as the bones of some hens became so soft they would not support the hens' weight. These starved to death because they could not get to the feed. On autopsy the bones were so soft that they bent easily (Fig. 1). The breastbone was red and in places appeared to be composed mainly of cartilage. Such soft bones were also observed occasionally with
FIG. 1. Breastbone and shank of a hen that died from decalcification of the bones. Both the breastbone and shank were soft and could be bent at will.
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* The change in shell thickness, egg weight, shell weight, and shell smoothness was calculated for each group on a pullet basis That is, the difference between the value for the period in question and the preliminary period was determined for each pullet. The average of these chages for each diet is presented in this column rather than the difference between the diet averages.
INFLUENCE OF DIETARY FACTORS ON EGG SHELL QUALITY. II. CALCIUM
ment. There were no significant differences in production during any period considered. Increases in egg shell thickness occurred on most diets during the first four months. The greatest increase occurred with levels of 3.5 percent calcium and 1.0 percent phosphorus. This was not significantly greater than produced by 3.0 percent calcium and 1.0 percent phosphorus or 3.0 percent calcium and 0.8 percent phosphorus, but was significantly better than 2.5 percent calcium at either phosphorus level. During the second four months no significant differences in shell thickness were observed, though 3.0 percent calcium gave the best results at either phosphorus level. Shell thickness decreased markedly on all diets during the last two months of the experiment. At both 0.8 and 1.0 percent phosphorus, 3.0 percent calcium best prevented the decrease in egg shell thickness.
Records of egg weight and egg shell weight for the 1942 experiment are presented in Table 4. No significant differences in egg weight were observed during the first eight months of the 1942 experiment. There was a general decrease in egg weight during the last two months over the preceding four months. No significant differences in shell weight were observed between any of the diets 'for the experiment. Table 5 contains the egg shell smoothness data for the 1942 experiment. At the Table 3 contains the production and egg 1.0 percent phosphorus level 3.0 and 3.5 shell thickness results for the 1942 experi- percent calcium produced rougher shells rABLE 3 .—The
production effect of the calcium level in the diet of laying .pullets on egg shell thickness (1942 experiment)
• Egg shell thickness (mm. X100)
Percent production
Percent 1-4 months
5-8 months.
and
9-10 months
Prelim.
1-4 months
5-8 months
9-10 months
P
Ca
Prelim.
0.8 0.8
"2.5 3.0
48 43
55 53
+7
+ 10
54 54
+ 116
+
51 52
+3 +9
33.3 33.7
33.5 34.7
+0.2 +1.0
31.7 33.2
-1.9 -0.2
27.9 30.4
-5.5 -3.0
1.0 1.0 1.0
2.5 3.0 3.5
44 47 50
59 55 59
+15 + 9 + 9
54 48 56
+10 + 1 + 6
57 55 56
+13 + 8 + 6
32.9 32.5 32.7
32.4 33.3 33.9
-0.7 +0.8 +1.3
31.2 32.1 32.2
-1.9 -0.4 -0.6
27.6 29.9 29.7
-5.2 -1.8 -3.2
Ave. Change Ave. Change Ave. Change
Least sign, di a. * See footnote Table 2.
15
21
22
Ave. Change* Ave. Change* Ave. Change*
1.0
1.8
2.4
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hens receiving l.S percent calcium in the diet but not as often as at the lower calcium levels. Records of change in body weight, feed consumption, and mortality for both experiments are presented in Table 1. Considerable mortality, directly attributable to a calcium deficiency, occurred during the first four months in the groups receiving 1.0 percent calcium in the diets. The high mortality during the last six months of the 1942 experiment was due to leucosis. The results of the first (1941) experiment are presented in Table 2. This table contains the average records of production, shell thickness, egg weight, shell weight, and shell smoothness for the four-month period. Production was significantly lower at the 1.0 percent level of calcium than at any other, and 2.5 percent calcium allowed significantly better production than 1.5 percent at an 0.8 percent level of phosphorus. A level of 2.5 percent calcium at either 0.6 or 0.8 percent phosphorus produced thicker egg shells than lower levels. Decreases in shell weight occurred at levels of calcium in the diet of 1.0 and 1.5 percent. These decreases were significantly greater than at a 2.5 percent level of'calcium. Eggs of hens receiving 1.0 percent calcium and 0.6 percent phosphorus failed to increase in weight normally. No significant differences in shell smoothness were observed.
39
ROBERT JOHN EVANS, J. S. CARVER, AND A. WADE BRANT
40
TABLE 4.—The eject of the calcium level in the diet of laying pullets on egg-weight and egg shell weight (1942 experiment) Egg Shell Weight
Egg Weight Percent
Prelim.
1-4 months
Ca
0.8 0.8
2.5 3.0
1.0 1.0 1.0
2.5 3.0 3.5
5-8 months
Prelim.
9-10 months
Ave.
Ave. Change* Ave. Change*, Ave. Change* gms. 52.4 55.2 52.5 53.3 52.2
gms. 58.9 +6.7 60.6 +5.6
gms. 60.6 +8.6 62.0
+7.2
gms. 58.0 +5.3 59.6 +5.4
gms. 4.96 5.24
58.9 58.6 58.5
60.2 59.6 60.7
+8.2 +6.9 +8.0
57.9 57.6 59.6
+7.2 +5.8 +6.8
4.90 4.88 4.90
+6.3 +5.8 +6.3
9-10 months
5-8 months
Change* Ave.
Change* Ave.
S.26 5.66
gms. +0.32 +0.42
5.06 5.46
gms. +0.07 +0.28
5.16 5.26 5.42
+0.22 +0.38 +0.50
4.98 5.16 5.24
+0.08 +0.26 +0.25
Change*
gms. 4.64 -0.33 5.15 -0.16 4.64 4.95 5.04
-0.16 -0.22 -0.11
0.31
0.33
1.4
1.6
1.4
Least sign. diff.
1-4 months
* See footnote Table 2.
TABLE 6.—Eject of level of calcium in the diet on the change in porosity, shell mottling, and albumen index (1941 experiment) Calcium
Phosphorus
percent percent 1.0 0.6 0.6 1.5 2.5 0.6 0.8 1.0 0.8 1.5 0.8 2.5 Least sign. diff.
Porosity-
Shell texture
Albumen index
score -0.3 +0.2 -0.3 -0.1 +0.9 -0.3 2.0
score +0.5 +0.7 +0.5 +0.4 +0.6 +0.8 0.2
units + 17 - 6 -11 + 15 -10 - 9 13
DISCUSSION
Considering production and egg shell quality (particularly shell thickness), pullets receiving a level of 3.0 percent calcium in the diet gave more satisfactory results than those receiving higher or lower levels. This is for the entire experiment. Thicker shells were observed at the 3.5 percent level for the first four months, although the
TABLE 5.—The eject of the calcium level in the diet of laying pullets on egg shell smoothness (1942 experiment) ' 5-8 months
[-4 months
9-10 months
cent Prelim.
Ave.
Change*
Ave.
Change*
Ave.
Change*
p 0.8 0.8
Ca 2.5 3.0
score 0.3 0.4
score 0.5 0.5
score 0.2 0.2
score 0.9 0.8
score 0.6 0.6
score 0.9 0.8
score 0.6 0.6
1.0 1.0 1.0 Least sign. dif f.
2.5 3.0 3.5
0.5 0.2 0.2
0.4 0.5 0.4
0.1 0.3 0.2 0.2
0.8 0.8 1.0
0.4 0.7 0.9 0.2
1.1 0.6 1.1
0.6 0.6 1.0 0.3
* See footnote Table 2.
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than 2.5 percent calcium during the first four months. During the remainder of the experiment the 3.5 percent level gave rougher shells than the 3.0 percent one. No significant differences were observed at a level of 0.8 percent phosphorus. No differences in shell porosity could be attributed to the calcium level in the diet (Table 6). Changes in shell texture were erratic, although at the 0.8 percent level of phosphorus the mottling increased as the calcium level increased. Losses in albumen index occurred at the 1.5 and 2.5 percent levels of calcium. A gain in albumen index occurred at the 1.0 percent level. This gain was due to decreased production, since it has been observed by Miller and Bearse (1937) that a hen produces eggs with a higher albumen index when she is laying only a few eggs than when she is in heavy production.
INFLUENCE OF DIETARY FACTORS ON EGG SHELL QUALITY. II. CALCIUM
SUMMARY Laying Single Comb White Leghorn hens kept in laying cages were fed 11 different diets containing levels of 1.0, 1.5, 2.5, 3.0, and 3.5 percent calcium. The phosphorus levels of these diets were 0.6, 0.8, or 1.0 percent, and the vitamin D content was 60 A.O.A.C. chick units per 100 grams of diet. Hens receiving 3.0 percent calcium in the diet gave more satisfactory results than those receiving higher or lower levels when egg shell thickness was used as the criterion. However, a level of 2.5 percent calcium allowed as satisfactory production as one of 3.0 percent. Production and egg shell quality were considerably decreased when the dietary calcium level was reduced to 1.0 percent. Many hens receiving this level of calcium withdrew calcium from the bones till the bones were so soft that they would not support the weight of the birds. REFERENCES
Berg, L. R., 1941. The effect of varying levels of calcium intake on the calcium balance, shell thickness, and blood calcium level of White Leghorn pullets. Thesis, Kansas State College of Agriculture and Applied Science. Carver, J. S., E. I. Robertson, D. Brazie, R. II. Johnson, and J. L. St. John, 1934. The vitamin D requirements of chickens. Wash. Agr. Expt. Sta., Bull. 299:5-40. Collier, P., 1892. Oyster shells as food for laying hens. New York Agr. Expt. Sta., Bull. 38:1-10. Common, R. H., 1938. Observations on the mineral metabolism of pullets. III. J. Agr. Sci. 28:347-66. Common, R. H., and R. W. Hale, 1941. Observations on the mineral metabolism of pullets. VI. The mobilization of body calcium for shell formation. J. Agr. Sci. 31:415-437. Deobald, H. J., E. J.'Lease, E. B. Hart, and J. G. Halpin, 1936. Studies on the calcium metabolism in laying hens. Poultry Sci. IS :179-18S. Evans, R. J., J. S. Carver, and A. W. Brant, 1944. The influence of dietary factors on egg shell quality. I. Phosphorus. Poultry Sci. 23 :9-15. Gutowska, M. S., and R. T. Parkhurst, 1942. Studies in mineral nutrition of laying hens. II.
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difference between 3.5 and 3.0 percent was not statistically significant. Three percent calcium is a higher level than other workers have found necessary to maintain high production. It will be observed that 3.0 percent calcium did not give any better production than lower levels; therefore, 2.5 percent may be considered as satisfactory for production, while 3.0 percent is necessary for the production of thicker egg shells. In this connection Berg (1941) observed that a 3.0 percent level of calcium caused an increase in shell thickness during the relatively short period of his experiment. Gutowska and Parkhurst (1942) fed Rhode Island Red pullets for six months on diets containing 2.35, 2.77, and 3.95 percent calcium. They observed no significant differences in egg shell breaking strength or egg weight between the different levels. The 3.95 percent level gave a decrease in production. Several investigators have pointed out that the hen has an unusually great capacity to metabolize calcium. Morgan, Mitchell, Ringrose, and Lease (1942) observed a 32 percent loss of body calcium from one hen during six weeks of production on a 2.4 percent level of dietary calcium. Morgan and Mitchell (1938) observed that the ability of the hen to utilize calcium was an individual characteristic. Deobald, Lease, Hart, and Halpin (1936) and Common (1938) also noted a withdrawal of body calcium for egg shell formation. Common and Hale (1941) and Tyler (1940) differentiated between two types of bone calcium, the "residual" calcium having the higher Ca:P ratio and being mobilized for egg shell formation. It is evident, however, that in our experiment not only the "residual" calcium but considerable of the structural calcium also was mobilized for egg shell formation by some of the hens receiving 0.5 and 1.0 percent dietary calcium.
41
42
BOOK REVIEWS chicks and laying hens. Pa. Agr. Expt. Sta., Bull. 334. Norris, L. C , G. F. Heuser, A. T. Ringrose, and H. S. Wilgus, Jr., 1934. Studies of the calcium requirements of laying hens. Poultry Sci. 13 :308309. Titus, H. W., T. C. Byerly, N. R. Ellis, and R. B. Nestler, 1937. Effect of calcium and phosphorus content of the diet of chickens on egg production and hatchability. Poultry Sci. 16:118. Titus, H. W., 1939. Practical nutritive requirements of poultry. Yearbook of Agriculture, 1939, 818. Tyler, C , 1940. Calcium and phosphorus metabolism in relation to the chemical structure of bone. I. Experiments with laying birds. Biochem. J. 34:202-212.
Book Reviews Ewing, W. Ray. Handbook of Poultry Nutrition (second edition). South Pasadena, California: W. R. Ewing, 1943. 1,245 pages, 118 figures. Price $10.00. The second edition of this outstanding; text contains 400 pages more than the first edition. It has been more completely illustrated also, the first edition containing 68'< figures whereas this edition has 118 figures. A large part of the increase in the size of' the text is due to the inclusion of the resultsi of new research. Many sections have beeni entirely rewritten because of new discoveries. Others have been expanded and some: entirely new topics have been included. Typical of new topics worthy of separate; chapters in this edition are those discussingI "Biotin" and "Wartime construction off poultry feed formulas." This edition contains six new chapters. Much of the material included in these new? chapters was incorporated in the "Miscellaneous" chapter in the first edition. Thee use of additional illustrations has aided materially in helping the reader to recognizee many of the nutritional disorders.—D.R.M.
Thompson, Willard C , and John Bird. The Home Poultry Flock. New York, New York: W. W. Norton & Company, Inc., 1943. 144 pages, 25 figures. Price $2.00. This small book, comprising 10 chapters, presents in an easily read form the essential details of caring for a home poultry flock. The general pattern of this text is somewhat similar to other texts reviewed in recent months but in many respects the approach is quite different. The reviewer observed a tendency to discuss some topics which have little application to a small home flock; for illustration, the presentation of several different rations, each adapted to a different purpose. Of the seven rations offered to the reader, none would conform to present day feeding restrictions and even though the rations did conform the reviewer would question the advisability of home mixing for a flock of 15 to 20 hens, especially such rations as a broiler finishing mash or special fattening mash. In many other places in the text there is evidence of large flock planning.—D. R. M.
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Excess of calcium in the diet. Poultry Sci. 21:321-328. Miller, M. W., and G. E. Bearse, 1937. Protein supplements for laying hens. Wash. Agr. Expt. Sta., Bull. 347 :S-16. Mitchell, H. H., and F. J. McClure, 1937. Mineral nutrition of farm animals. National Research Council, Bull. 99:127. Morgan, C. L., and J. H. Mitchell, 1938. The calcium and phosphorus balance of laying hens. Poultry Sci. 17:99-104. Morgan, C. L., J. H. Mitchell, R. C. Ringrose, and E. J. Lease, 1942. The study of calcium metabolism in the laying hen by the comparative slaughter method. Poultry Sci. 21:212-215. Murphy, R. R., J. E. Hunter, and H. C. Knandel, 1936. The vitamin D requirements of growing