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Nutritional Investigations with Turkey Hens1
604
J. H. WOLFCXRD, R. K. RINGER, T. H. COLEMAN AND H. C. ZINDEL
performance of breeding turkeys. Poultry Sci. 20: 395-401. Simpson, G. G., A. Roe and R. C. Lewontin, 1960. Quantitative Zoology. Revised ed. Harcourt, Brace and Company, New York. Whitson, D., S. J. Marsden and H. W. Titus, 1944. A comparison of the performance of four varie-
ties of turkeys during the breeding season. Poultry Sci. 23: 314-320. Wolford, J. H., R. K. Ringer, T. H. Coleman and H. C. Zindel, 1962. Body weight and egg production of turkeys as influenced by lighting regime during growing and subsequent laying period. Michigan Agr. Expt. Quart. Bull. 45: 506-517.
4. QUANTITATIVE REQUIREMENT FOR CALCIUM L. S. JENSEN, H. C. SAXENA AND J. MCGINNIS Department of Poultry Science, Washington State University, Pullman (Received for publication August 27, 1962)
B
ECAUSE all-inclusive diets are now commonly used for turkeys, quantitative information on the nutrient requirements is greatly needed in formulating optimum levels in practical rations. Apparently no published information is available on the calcium requirement of turkey breeder hens. The National Research Council (1960) recommended a level of 2.25%. An experiment was conducted to estimate this requirement and the results are reported here.
experimental diets were fed in crumbled form, and granite grit was supplied ad libitum. The diets were formulated to contain 1, 1.75, 2.5, and 3.25% calcium. Each diet was fed to three pens. Records on egg production, feed consumption, fertility, and hatchability were kept. All sound eggs of normal size laid were held in a 55°F. room and were incubated every two weeks. Eggs were candled at TABLE 1.—Composition of experimental diets Experimental diets Ingredients
PROCEDURE
One hundred and twenty Broad Breasted Bronze hens were randomly distributed into 12 pens of 10 hens each. Each pen was provided with one male, and all males were rotated from pen to pen weekly. Shavings were used for litter and the litter was not changed during the experiment. The hens were provided with 14 hours of light daily at 26 weeks of age, at which time they were also given the experimental rations. Composition of experimental diets is shown in Table 1. All 1 Scientific Paper No. 2268, Washington Agricultural Experiment Stations, Pullman. Project 715.
Yellow corn, ground Soybean oil meal (50% protein) Fish meal, herring Dehydrated alfalfa Brewers' yeast Salt, iodized Limestone, ground Dicalcium phosphate Vitamin mix a Trace mineral mix" Calculation: Protein, % Calcium, % Phosphorus, % Chemical estimation: 0 Calcium, % a
1
2
3
4
%
%
%
%
74.0
72.0
69.0
67.1
13.0 2.5 5.0 2.5 0.5 1.3 1.2
13.0 2.5 5.0 2.5 0.5 3.3 1.2
14.0 2.5 5.0 2.5 0.5 5.3 1.2
14.0 2.5 5.0 2.5 0.5 7.2 1.2
+ +
+ +
+ +
+ +
16 1.0 0.6
16 1.75 0.6
16 2.50 0.6
16 3.25 0.6
1.76
2.58
3.16
0.95
Supplied the following r e r kilogram of diet: vitamin A, 8,800 I.U.; vitamin D 3 , 1,100 I.C.U.; vitamin E, 22 I.U.; riboflavin, 4.4 mg.; Ca-pantothenate, 17.6 mg.; and ethoxyquin, 12.5 mg. b Supplied the following mg. per kilogram of diet: manganese, 50.0; iron, 50.0; copper, 5.0; cobalt, 0.5; iodine, 1.5; and zinc, 50.0. o Analyzed by the A.O.A.C. method (1960).
Downloaded from http://ps.oxfordjournals.org/ at Lahore University of Management Sciences on May 9, 2015
Nutritional Investigations with Turkey Hens 1
CALCIUM
605
REQUIREMENT
CALCIUM _ Sbeil Color
.
SCORE ....
*mrf^-:-, - ;.
v
i»
f
•
I1
>
3 FIG. 1. Samples of eggs representing the three color classifications used in obtaining a color index.
the 10th day of incubation. D a t a for fertility and hatchability of fertile eggs do not include the first six weeks of production, because the eggs candled out at the 10th day were not broken to clearly distinguish between infertiles and early deads. Twenty poults hatching from each pen every two weeks were placed on a practical turkey starter ration and kept for two weeks to determine the effect of maternal diets on growth and viability. Samples of shells were also measured for thickness by use of a micrometer. After the experiment began, a marked difference in shell color was observed. Therefore, an arbitrary color scoring scale of 1 to 3 was developed, with 1 being almost white and 3 being dark and typical of most Broad Breasted Bronze turkey eggs (Fig. 1). Two times during the experiment, the ash of egg contents from the different treatments was analyzed spectrographically (semi-quantitative method). The egg contents were removed from the shell, homogenized, lyophilized, and ashed at 600°C. The contents of one sample of eggs from the different treatments were analyzed for calcium by the A.O.A.C. method (1960).
The experiment was started October 12, 1961 and terminated April 26, 1962. RESULTS
R a t e of egg production was definitely depressed at the 1% level of calcium (Table 2). Increasing the level above 1.75, however, did not further improve egg production. Shell thickness also was definitely lowered by the 1.0% level of calcium. A larger number of lightly colored eggs was observed on the lowest level of calcium, as shown by the lower shell color score. Maximal feed efficiency was observed with the 1.75% calcium level and decreased slightly as the calcium level was increased. This was anticipated, as no a t t e m p t was made to make the T A B L E 2.—Effect of calcium level on egg production, shell thickness, shell color and feed efficiency Dietary calcium level. % 1.0 Egg production, % Feed efficiency, lb feed/egg Gm. C a intake/egg Shell thickness, mm. Shell color score 1
37.4 1.64 7.4 .325 1.86
1.75
2.5
3.25
53.9*
56.0*
54.8*
1.20 13.6 .372 2.5
1.26 18.6 .380 2.5
1.18 9.4 .371 2.5
1 Score 1-3, 1 for very light, 2 for medium and 3 for dark eggshell color (Fig. 1). •Significantly different (P<0.05) from the 1.0% calcium level.
Downloaded from http://ps.oxfordjournals.org/ at Lahore University of Management Sciences on May 9, 2015
t
606
L. S. J E N S E N , H. C. SAXENA AND J.
TABLE 3.—Effect
MCGINNIS
of calcium level on fertility, hatchability of fertile eggs and growth and viability of offspring Dietary calcium level, %
Total eggs set % Fertility % Hatchability Av. 2 wk. poult w t , gm.±S.E. % poult mortality
1.0
1.75
2.5
3.25
1,089 81.3 71.2 196 + 3.65 6.4
1,725 86.4 71.6 194 + 3.56 5.6
1,866 89.8 62.6* 195 + 2.71 6.4
1,799 87.4 59.7* 199 + 2.82 5.7
* Significantly different (P<0.05) from the 1.0 and 1.75% calcium levels.
Spectrographic analysis (semi-quantitative) of the egg content failed to reveal any significant trend of the mineral elements in relation to dietary calcium level. Determination of the calcium content in-
TABLE 4.—Effect of calcium level on embryonic •mortality at different periods during incubation Dietary calcium level, % 1.0
1.75
2.5
3.25
Early dead, % (0-10 days)
13.0
13.3
18.2
21.6
Late dead, % (10-28 days)
10.8
9.7
13.0
13.9
5.7
6.0
6.0
4.6
Pips, %
dicated an increased percentage as the dietary calcium level was elevated. DISCUSSION Results of this experiment show t h a t the calcium requirement for maximal performance of turkey breeders is in the neighborhood of 1.75% of the diet. Because the calcium requirement, as a percentage of the ration, is markedly affected by climatic conditions, size of the bird, energy level of the diet, rate of egg production, and other factors; a requirement expressed in terms of calcium intake per egg may be more meaningful in applying these results to various conditions. Results indicated t h a t an intake of approximately 9.4 grams per egg gave optimal results. I t should be remembered, however, t h a t the birds were on litter and t h a t there probably was some reingestation of excreted calcium. Wilhelm, Robertson and Rhian (1941) reported that a deficiency of vitamin D in Broad Breasted Bronze turkey hens markedly reduced color and spotting of the eggs. A similar observation was made here with a calcium deficiency, indicating t h a t the results of the previous workers were probably due to a reduced calcium absorption caused by the vitamin D deficiency. An interesting observation in this experiment was the depression of hatchability with the two highest levels of calcium (2.5 and 3.25%). The reason for this depression is not readily apparent. I t is
Downloaded from http://ps.oxfordjournals.org/ at Lahore University of Management Sciences on May 9, 2015
experimental diets isocaloric. Optimum performance, based on all criteria used, was obtained with the groups of birds consuming approximately 9.4 grams of calcium per egg (1.75% calcium level). No significant effect on fertility was observed (Table 3). Hatchability of fertile eggs was not affected by the low level of calcium, but the two highest levels of calcium significantly ( P < 0 . 0 5 ) depressed hatchability. The majority of increased embryonic deaths caused by higher calcium levels occurred during the first 10 days of incubation (Table 4) with many of these occurring during the first 24 hours of incubation. No difference was observed in the number of pips (Table 4). There was no difference in growth rate or mortality of offspring to two weeks of age (Table 3).
607
CALCIUM REQUIREMENT
Perhaps a higher level of calcium ions in the egg contents somehow interfered with the normal development of embryos during the first few days of incubation. Titus et al. (1937) reported that high calcium depressed hatchability in chickens, but this work was probably complicated by marginal levels of manganese and riboflavin in the rations used at that time. Gutowska and Parkhurst (1942) did not observe any effect of high calcium levels on hatchability. Berg et al. (1962a) observed a marked effect of calcium level on hatchability and early chick mortality in young breeders (30% lay). When the peak production was reached, however, no effect of calcium level on hatchability or chick viability was found. The depression in hatchability of turkeys persisted throughout the breeding season. Therefore, a species difference between chickens and turkeys in response to high calcium diets is apparent. Further work is necessary to reveal the mechanism of depression of hatchability in turkeys by high dietary calcium levels.
SUMMARY
An experiment was conducted with Broad Breasted Bronze turkey hens to investigate the quantitative requirement for calcium. Four levels (1.0, 1.75, 2.5, and 3.25%) of calcium were fed to turkey hens for 28 weeks. Optimal performance was obtained with 1.75% calcium in the diet, or an average intake of 9.4 grams per egg. Higher levels of dietary calcium (2.5 and 3.25%) depressed hatchability. No effect was observed, however, on the growth and viability of turkey poults raised to 2 weeks of age. Shell color was markedly affected by the low calcium diet. REFERENCES Association of Official Agricultural Chemists, 1962. Official Methods of Analysis, 9th Ed., Washington, D. C. Berg, L. R., G. E. Bearse and L. H. Merrill, 1962a. Effect of calcium level of the developing and laying ration on hatchability of eggs and on viability and growth rate of progeny of young pullets. Poultry Sci. 41: 1328-1335. Berg, L. R., G. E. Bearse and L. H. Merrill, 1962b. Evidence for a high zinc requirement of pullets at the onset of egg production. Poultry Sci. 42: 1627. Davis, G. K., 1959. Effects of high calcium intake on the absorption of other nutrients. Federation Proc. 18: 1119-1123. Gutowska, M. S., and R. T. Parkhurst, 1942. Studies in mineral nutrition of laying hens. II. Excess of calcium in the diet. Poultry Sci. 21: 321-328. Kienholz, E. W., D. E. Turk, M. L. Sunde and W. G. Hoekstra, 1961. Effects of zinc deficiency in the diets of hens. J. Nutrition, 75: 211-221. National Research Council, 1960. Nutrient requirements of domestic animals. No. 1. Nutrient requirements for poultry. Titus, H. W., T. C. Byerly, N. R. Ellis and R. B. Nestler, 1937. Effect of the calcium and phosphorus content of the diet of chickens on egg production and hatchability. Poultry Sci. 16: 118-128. Wilhelm, L. A., E. I. Robertson and M. Rhian, 1941. The effect of the level of vitamin D on egg production and hatchability of Bronze turkey hens. Poultry Sci. 20: 565-569.
Downloaded from http://ps.oxfordjournals.org/ at Lahore University of Management Sciences on May 9, 2015
well known that high dietary calcium levels interfere with the utilization of manganese, zinc and other mineral elements (Davis, 1959). Kienholz et al. (1961) and Berg et al. (1962b) have recently shown that high calcium levels interfere with zinc utilization in chicken breeder pullets. In the present work, however, rations were supplemented with 50 p.p.m. zinc and 50 p.p.m. manganese to add to that already present in the natural ingredients. Furthermore, no embryonic zinc and manganese deficiency symptoms such as abnormal feather development and chondodystrophy were observed in the embryos or the poults after hatching. Spectrographic analysis of the egg contents also failed to reveal any definite change of any of the mineral elements detected by this method in relation to dietary calcium level.
J. H. WOLFCXRD, R. K. RINGER, T. H. COLEMAN AND H. C. ZINDEL
performance of breeding turkeys. Poultry Sci. 20: 395-401. Simpson, G. G., A. Roe and R. C. Lewontin, 1960. Quantitative Zoology. Revised ed. Harcourt, Brace and Company, New York. Whitson, D., S. J. Marsden and H. W. Titus, 1944. A comparison of the performance of four varie-
ties of turkeys during the breeding season. Poultry Sci. 23: 314-320. Wolford, J. H., R. K. Ringer, T. H. Coleman and H. C. Zindel, 1962. Body weight and egg production of turkeys as influenced by lighting regime during growing and subsequent laying period. Michigan Agr. Expt. Quart. Bull. 45: 506-517.
4. QUANTITATIVE REQUIREMENT FOR CALCIUM L. S. JENSEN, H. C. SAXENA AND J. MCGINNIS Department of Poultry Science, Washington State University, Pullman (Received for publication August 27, 1962)
B
ECAUSE all-inclusive diets are now commonly used for turkeys, quantitative information on the nutrient requirements is greatly needed in formulating optimum levels in practical rations. Apparently no published information is available on the calcium requirement of turkey breeder hens. The National Research Council (1960) recommended a level of 2.25%. An experiment was conducted to estimate this requirement and the results are reported here.
experimental diets were fed in crumbled form, and granite grit was supplied ad libitum. The diets were formulated to contain 1, 1.75, 2.5, and 3.25% calcium. Each diet was fed to three pens. Records on egg production, feed consumption, fertility, and hatchability were kept. All sound eggs of normal size laid were held in a 55°F. room and were incubated every two weeks. Eggs were candled at TABLE 1.—Composition of experimental diets Experimental diets Ingredients
PROCEDURE
One hundred and twenty Broad Breasted Bronze hens were randomly distributed into 12 pens of 10 hens each. Each pen was provided with one male, and all males were rotated from pen to pen weekly. Shavings were used for litter and the litter was not changed during the experiment. The hens were provided with 14 hours of light daily at 26 weeks of age, at which time they were also given the experimental rations. Composition of experimental diets is shown in Table 1. All 1 Scientific Paper No. 2268, Washington Agricultural Experiment Stations, Pullman. Project 715.
Yellow corn, ground Soybean oil meal (50% protein) Fish meal, herring Dehydrated alfalfa Brewers' yeast Salt, iodized Limestone, ground Dicalcium phosphate Vitamin mix a Trace mineral mix" Calculation: Protein, % Calcium, % Phosphorus, % Chemical estimation: 0 Calcium, % a
1
2
3
4
%
%
%
%
74.0
72.0
69.0
67.1
13.0 2.5 5.0 2.5 0.5 1.3 1.2
13.0 2.5 5.0 2.5 0.5 3.3 1.2
14.0 2.5 5.0 2.5 0.5 5.3 1.2
14.0 2.5 5.0 2.5 0.5 7.2 1.2
+ +
+ +
+ +
+ +
16 1.0 0.6
16 1.75 0.6
16 2.50 0.6
16 3.25 0.6
1.76
2.58
3.16
0.95
Supplied the following r e r kilogram of diet: vitamin A, 8,800 I.U.; vitamin D 3 , 1,100 I.C.U.; vitamin E, 22 I.U.; riboflavin, 4.4 mg.; Ca-pantothenate, 17.6 mg.; and ethoxyquin, 12.5 mg. b Supplied the following mg. per kilogram of diet: manganese, 50.0; iron, 50.0; copper, 5.0; cobalt, 0.5; iodine, 1.5; and zinc, 50.0. o Analyzed by the A.O.A.C. method (1960).
Downloaded from http://ps.oxfordjournals.org/ at Lahore University of Management Sciences on May 9, 2015
Nutritional Investigations with Turkey Hens 1
CALCIUM
605
REQUIREMENT
CALCIUM _ Sbeil Color
.
SCORE ....
*mrf^-:-, - ;.
v
i»
f
•
I1
>
3 FIG. 1. Samples of eggs representing the three color classifications used in obtaining a color index.
the 10th day of incubation. D a t a for fertility and hatchability of fertile eggs do not include the first six weeks of production, because the eggs candled out at the 10th day were not broken to clearly distinguish between infertiles and early deads. Twenty poults hatching from each pen every two weeks were placed on a practical turkey starter ration and kept for two weeks to determine the effect of maternal diets on growth and viability. Samples of shells were also measured for thickness by use of a micrometer. After the experiment began, a marked difference in shell color was observed. Therefore, an arbitrary color scoring scale of 1 to 3 was developed, with 1 being almost white and 3 being dark and typical of most Broad Breasted Bronze turkey eggs (Fig. 1). Two times during the experiment, the ash of egg contents from the different treatments was analyzed spectrographically (semi-quantitative method). The egg contents were removed from the shell, homogenized, lyophilized, and ashed at 600°C. The contents of one sample of eggs from the different treatments were analyzed for calcium by the A.O.A.C. method (1960).
The experiment was started October 12, 1961 and terminated April 26, 1962. RESULTS
R a t e of egg production was definitely depressed at the 1% level of calcium (Table 2). Increasing the level above 1.75, however, did not further improve egg production. Shell thickness also was definitely lowered by the 1.0% level of calcium. A larger number of lightly colored eggs was observed on the lowest level of calcium, as shown by the lower shell color score. Maximal feed efficiency was observed with the 1.75% calcium level and decreased slightly as the calcium level was increased. This was anticipated, as no a t t e m p t was made to make the T A B L E 2.—Effect of calcium level on egg production, shell thickness, shell color and feed efficiency Dietary calcium level. % 1.0 Egg production, % Feed efficiency, lb feed/egg Gm. C a intake/egg Shell thickness, mm. Shell color score 1
37.4 1.64 7.4 .325 1.86
1.75
2.5
3.25
53.9*
56.0*
54.8*
1.20 13.6 .372 2.5
1.26 18.6 .380 2.5
1.18 9.4 .371 2.5
1 Score 1-3, 1 for very light, 2 for medium and 3 for dark eggshell color (Fig. 1). •Significantly different (P<0.05) from the 1.0% calcium level.
Downloaded from http://ps.oxfordjournals.org/ at Lahore University of Management Sciences on May 9, 2015
t
606
L. S. J E N S E N , H. C. SAXENA AND J.
TABLE 3.—Effect
MCGINNIS
of calcium level on fertility, hatchability of fertile eggs and growth and viability of offspring Dietary calcium level, %
Total eggs set % Fertility % Hatchability Av. 2 wk. poult w t , gm.±S.E. % poult mortality
1.0
1.75
2.5
3.25
1,089 81.3 71.2 196 + 3.65 6.4
1,725 86.4 71.6 194 + 3.56 5.6
1,866 89.8 62.6* 195 + 2.71 6.4
1,799 87.4 59.7* 199 + 2.82 5.7
* Significantly different (P<0.05) from the 1.0 and 1.75% calcium levels.
Spectrographic analysis (semi-quantitative) of the egg content failed to reveal any significant trend of the mineral elements in relation to dietary calcium level. Determination of the calcium content in-
TABLE 4.—Effect of calcium level on embryonic •mortality at different periods during incubation Dietary calcium level, % 1.0
1.75
2.5
3.25
Early dead, % (0-10 days)
13.0
13.3
18.2
21.6
Late dead, % (10-28 days)
10.8
9.7
13.0
13.9
5.7
6.0
6.0
4.6
Pips, %
dicated an increased percentage as the dietary calcium level was elevated. DISCUSSION Results of this experiment show t h a t the calcium requirement for maximal performance of turkey breeders is in the neighborhood of 1.75% of the diet. Because the calcium requirement, as a percentage of the ration, is markedly affected by climatic conditions, size of the bird, energy level of the diet, rate of egg production, and other factors; a requirement expressed in terms of calcium intake per egg may be more meaningful in applying these results to various conditions. Results indicated t h a t an intake of approximately 9.4 grams per egg gave optimal results. I t should be remembered, however, t h a t the birds were on litter and t h a t there probably was some reingestation of excreted calcium. Wilhelm, Robertson and Rhian (1941) reported that a deficiency of vitamin D in Broad Breasted Bronze turkey hens markedly reduced color and spotting of the eggs. A similar observation was made here with a calcium deficiency, indicating t h a t the results of the previous workers were probably due to a reduced calcium absorption caused by the vitamin D deficiency. An interesting observation in this experiment was the depression of hatchability with the two highest levels of calcium (2.5 and 3.25%). The reason for this depression is not readily apparent. I t is
Downloaded from http://ps.oxfordjournals.org/ at Lahore University of Management Sciences on May 9, 2015
experimental diets isocaloric. Optimum performance, based on all criteria used, was obtained with the groups of birds consuming approximately 9.4 grams of calcium per egg (1.75% calcium level). No significant effect on fertility was observed (Table 3). Hatchability of fertile eggs was not affected by the low level of calcium, but the two highest levels of calcium significantly ( P < 0 . 0 5 ) depressed hatchability. The majority of increased embryonic deaths caused by higher calcium levels occurred during the first 10 days of incubation (Table 4) with many of these occurring during the first 24 hours of incubation. No difference was observed in the number of pips (Table 4). There was no difference in growth rate or mortality of offspring to two weeks of age (Table 3).
607
CALCIUM REQUIREMENT
Perhaps a higher level of calcium ions in the egg contents somehow interfered with the normal development of embryos during the first few days of incubation. Titus et al. (1937) reported that high calcium depressed hatchability in chickens, but this work was probably complicated by marginal levels of manganese and riboflavin in the rations used at that time. Gutowska and Parkhurst (1942) did not observe any effect of high calcium levels on hatchability. Berg et al. (1962a) observed a marked effect of calcium level on hatchability and early chick mortality in young breeders (30% lay). When the peak production was reached, however, no effect of calcium level on hatchability or chick viability was found. The depression in hatchability of turkeys persisted throughout the breeding season. Therefore, a species difference between chickens and turkeys in response to high calcium diets is apparent. Further work is necessary to reveal the mechanism of depression of hatchability in turkeys by high dietary calcium levels.
SUMMARY
An experiment was conducted with Broad Breasted Bronze turkey hens to investigate the quantitative requirement for calcium. Four levels (1.0, 1.75, 2.5, and 3.25%) of calcium were fed to turkey hens for 28 weeks. Optimal performance was obtained with 1.75% calcium in the diet, or an average intake of 9.4 grams per egg. Higher levels of dietary calcium (2.5 and 3.25%) depressed hatchability. No effect was observed, however, on the growth and viability of turkey poults raised to 2 weeks of age. Shell color was markedly affected by the low calcium diet. REFERENCES Association of Official Agricultural Chemists, 1962. Official Methods of Analysis, 9th Ed., Washington, D. C. Berg, L. R., G. E. Bearse and L. H. Merrill, 1962a. Effect of calcium level of the developing and laying ration on hatchability of eggs and on viability and growth rate of progeny of young pullets. Poultry Sci. 41: 1328-1335. Berg, L. R., G. E. Bearse and L. H. Merrill, 1962b. Evidence for a high zinc requirement of pullets at the onset of egg production. Poultry Sci. 42: 1627. Davis, G. K., 1959. Effects of high calcium intake on the absorption of other nutrients. Federation Proc. 18: 1119-1123. Gutowska, M. S., and R. T. Parkhurst, 1942. Studies in mineral nutrition of laying hens. II. Excess of calcium in the diet. Poultry Sci. 21: 321-328. Kienholz, E. W., D. E. Turk, M. L. Sunde and W. G. Hoekstra, 1961. Effects of zinc deficiency in the diets of hens. J. Nutrition, 75: 211-221. National Research Council, 1960. Nutrient requirements of domestic animals. No. 1. Nutrient requirements for poultry. Titus, H. W., T. C. Byerly, N. R. Ellis and R. B. Nestler, 1937. Effect of the calcium and phosphorus content of the diet of chickens on egg production and hatchability. Poultry Sci. 16: 118-128. Wilhelm, L. A., E. I. Robertson and M. Rhian, 1941. The effect of the level of vitamin D on egg production and hatchability of Bronze turkey hens. Poultry Sci. 20: 565-569.
Downloaded from http://ps.oxfordjournals.org/ at Lahore University of Management Sciences on May 9, 2015
well known that high dietary calcium levels interfere with the utilization of manganese, zinc and other mineral elements (Davis, 1959). Kienholz et al. (1961) and Berg et al. (1962b) have recently shown that high calcium levels interfere with zinc utilization in chicken breeder pullets. In the present work, however, rations were supplemented with 50 p.p.m. zinc and 50 p.p.m. manganese to add to that already present in the natural ingredients. Furthermore, no embryonic zinc and manganese deficiency symptoms such as abnormal feather development and chondodystrophy were observed in the embryos or the poults after hatching. Spectrographic analysis of the egg contents also failed to reveal any definite change of any of the mineral elements detected by this method in relation to dietary calcium level.