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Dietary Calcium Levels in Pre-Lay and Lay Diets in Leghorn Pullets
Dietary Calcium Levels in Pre-Lay and Lay Diets in Leghorn Pullets P . C. MILLER ' AND M. L . SUNDE
Department of Poultry Science, University of Wisconsin, Madison, Wisconsin 53706 (Received for publication January 13, 1975)
POULTRY SCIENCE 54: 1856-1867, 1975
INTRODUCTION
F
ROM eight to 18 weeks of age, the requirements for calcium and phosphorus in growing chickens are 0.8 and 0.4% respectively (National Research Council, 1971). These figures are based on research using growth and bone development (Hart et al., 1930; Taylor and Moore, 1954, 1958; Twining et al., 1965; and Mraz, 1972) as the criteria and not subsequent lay performance. Several workers (see reviews by Anderson, 1966, 1967; Meyer et al., 1971; and Hurwitz and Bar, 1971) have studied the carry-over influence of the pre-lay calcium and phosphorus levels on lay performance but only Berg et
1. Present address: Technical Services Department, Shaver Poultry Breeding Farms, Box 400, Cambridge, Ontario, Canada NIR 5V9. Research supported by the College of Agricultural and Life Sciences, University of Wisconsin, Madison, Wisconsin.
al. (1947, 1964) have reported on the interaction of the pre-lay diets with lay diets on shell quality. Using pullet diets of 0.7, 0.9, 1.1, 2.0 and 3.0% calcium and lay diets of 1.0, 1.7, 2.1, 2.5 and 2.9% calcium, Berg et al. (1947, 1964) found no apparent interaction based on shell quality. The effects of various calcium levels in the lay period on egg production and shell quality have been extensively studied (Evan et al., 1955; Kienholz and McPherron, 1964; Mehring, 1965; Reddy et al., 1968; and others) but no research has been reported involving bone mineralization through a complete lay period. Only Meyer et al. (1971) have studied bone mineralization through the lay period based on the pre-lay treatments. The relationship between the rate of production and shell quality has been studied by several workers, but with conflicting results. Anderson (1966) found a negative relationship between eggs per bird with egg shell
1856
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ABSTRACT Four experiments over a period of four years with 1350 first-year pullets were designed to determine the influence of the calcium and phosphorus levels in the pre-lay diets on the growing birds and on their subsequent performance. Several dietary calcium levels in the lay period were studied, as well as the interaction between the pre-lay and lay diets. During the growing phase the pullets fed 3.0% calcium and 0.4% phosphorus had significantly (P < 0.05) lower body weight at 20 weeks of age than the pullets in the other pre-lay treatments. Feed consumption and feed efficiency were also adversely affected by this treatment, and sexual maturity was significantly (P < 0.05) delayed. Early lay mortality from this treatment was evident. On the basis of egg production, egg weight, shell deformation and percent poorly shelled eggs (PSE) at point-of-lay, the pre-lay diets did not influence lay performance nor was there an interaction between any combination of pullet and lay diets. As the calcium levels of the lay diets increased, egg production, feed consumption and shell rigidity increased. The 1.5% calcium level did not maintain bone mineralization as compared to the 3.0 and 4.5% calcium levels. It was noted that shell quality on the basis of PSE and deformation does not begin to deteriorate immediately after the onset of production. In fact there is a short period of time where the egg shells improve and then there is a gradual decline in shell rigidity. The layers fed the lay diet containing 1.5% calcium produced eggs weighing an average of 57.4 g. This was significantly (P < 0.05) lower than the eggs of the 2.3, 3.0 or 4.5% calcium fed groups which produced eggs weighing 59.1, 58.6 and 59.4 g. respectively.
2884 16.1 0.61 0.67 2880 16.1 0.66 0.96
2838 16.0 0.66 1.53
2840 15.8 0.41 3.00
2827 15.7 0.70 3.02
2849 16.2 0.99 2.91
2704 15.8 0.97 4.51
100.0
100.0 100.0
100.0
7.3 0.5 0.5
—
16.0 3.0 5.0 2.5 8.7 0.5 0.5 16.0 3.0 5.0 2.5 4.5 0.5 0.5
18.3 3.0 2.0 1.5 6.2 0.5 0.5
19.7 3.0 1.0
— —
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9 63.8
8 68.0
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6 68.0
'Premix supplied per kg. of diet: 6000 I.U., vitamin A; 500 I.C.U., vitamin D 3 ; 2 mg., riboflavin; 5 mg., calcium pantothenate; 10 mg., niacin; 251 mg., choline; 3 I.U., vitamin E; 123 mg., manganese oxide; 0.5 g., D,L-methionine; 0.005 mg., vitamin B 1 2 ; and 240 mg., Zoamix.
2900 15.8 0.41 0.61
100.0
100.0
2917 15.9 0.41 0.42
100.0
1.0 0.5 0.5
0.5 0.5 0.5
Chemical composition M.E. (kcal./kg.) Protein (calculated) Phosphorus (calculated) Calcium (calculated)
100.0
100.0
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56.0 13.5 5.0 14.0 3.0 5.0 0.5 2.0 0.5 0.5
56.0 15.0 5.0 14.0 3.0 5.0 0.5 0.5 0.5 0.5
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Corn Corn and cob meal Wheat bran Soybean meal (44% protein) Alfalfa meal (17% protein) Meat scrap (50% protein) Dicalcium phosphate Limestone, ground Iodized salt Premix'
3
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TABLE 1.—Percentage composition of pre-lay diets
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4 1-4 C 67.7 12.5 3.0 3.0 1 2.0 1.0 9.8 0.5
3 1-4 C 67.2 12.0 3.0 3.0 1 2.0 1.0 5.8 0.5
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composition of lay diets
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Chemical composition 15.6 15.3 15.9 15.9 17.0 15.9 15.9 Protein (calculated) 0.65 0.68 0.69 0.61 0.63 0.69 0.69 Phosphorus (calculated) 2.79 2.53 2.66 2.98 4.49 2.25 1.51 Calcium (calculated) *C—Cage; F—Floor; C—Pullet treatment stratified in cage Experiment 4. 1 Meat scrap in Experiment 4. 2 Defluorinated rock phosphate. 'Ground oat hulls in Experiment 4. 4 Premix supplied per kg. of diet: 0.3 g., D,L-methionine; 1060 I.C.U., vitamin D 3 ; 1000 I.U., vitamin A; 3.5 mg., riboflavin; 110 mg., manganese oxide; and 44 mg., choline. 5 Premix supplied per kg. of diet: 0.5 g., D,L-methionine; 880 I.C.U., vitamin D 3 ; 4000 I.U., vitamin A; 3.1 mg., riboflavin; 100 mg., manganese oxide; and 22 mg., erythromycin. 6 Premix supplied per kg. of diet: 0.5 g., D,L-methionine: 1170 I.C.U., vitamin D 3 ; 4400 I.U., vitamin A; 2.4 mg., riboflavin; 100 mg.. manganese oxide; and 22 mg., erythromycin.
Corn Soybean meal (44% protein) Meat scrap (50% protein) Fish meal (60% protein) Alfalfa meal (17% protein) Dicalcium phosphate Calcium source Iodized salt Ground oats Oat mill by-product3 Premix
Experiment Facility*
TABLE 2.—Percentage
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1859
CALCIUM L E V E L FOR LAYERS
thickness but Perek and Snapir (1970) indicated no significant correlation between egg numbers and shell quality. This research was conducted to study the interaction of several pre-lay diets (varying in calcium and phosphorus levels) with several types of lay diets (varying in levels, sources and forms of calcium). Special emphasis was placed on the influence of the pullet calcium level upon subsequent bone mineralization and shell quality at different lay calcium levels.
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MATERIALS AND METHODS
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Egg Production Phase. In all four experiments each of the eight floor pens contained 40 birds. The experimental birds were equally stratified across each pen. The calcium source used was ground limestone unless otherwise stated. In some lots free choice coarse limestone, coarse dolomitic limestone or oyster shell were provided. The description of each experiment will include the floor test and cage test during the lay period. Experiment 1: Pre-lay diets 4 and 5 were fed to a total of 96 birds until housing at 19 weeks in the floor pens. In addition to the lay diet number 5 (Table 2), three pens received coarse dolomitic limestone, coarse limestone or coarse oyster shell, and the other four pens received the previous four treat-
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Growing Phase. Over a period of four years a total of 1350 eight-week-old commercial strain cross pullets (Leghorn type) were given diets containing various levels of calcium and phosphorus (Table 1). Of the 1350 birds at eight weeks of age, 1178 were used in the egg production phase. The birds received: feed and water ad lib., 2200 sq. cm. of floor space per bird, deep litter floor covering, and natural lighting. Mortality, body weight, feed consumption, and feed conversion data were compiled from eight weeks of age to time of housing.
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P. C. MILLER AND M. L. SUNDE
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ments plus granite grit. The lay diet, calcium source and granite grit were fed ad lib. For the cage test, pre-lay diets three, four, five and eight were fed to 72 birds. At 17 weeks these birds were placed in individual cages to create 12 groups of six birds each and a 4 x 3 factorial design. The lay diets one, two and three were fed at first egg. Experiment 2: For the floor test, pre-lay diets four and five were fed to 145 birds until housing at 19 weeks. The methods and procedure of Experiment 2 for the cage test was identical to that of Experiment 1 cage test, with the exception that housing was at 19 weeks of age. Experiment 3: Diets three, four and seven were fed during the rearing period. Housing in the floor pens of the 160 birds was at 20 weeks and the lay diet (number 6) was used with additional calcium free choice. The four rearing diets of Experiments 1 and 2 (cage test) were used for the 96 birds. Four lay diets (one, two, three and four) were used thus creating a 4 x 4 factorial design. Lay diets were fed at first egg and housing was at 20 weeks. Experiment 4: All nine pre-lay diets were fed to 320 pullets which were equally stratified across the eight pens. For the cage layer test the 4 x 4 design of Experiment 3 was used. In addition, there were 120 birds fed pre-lay diets one, two, four, six, eight and nine and then stratified across the same five treatments as described for the floor test above. Both the experimental lay rations and water were supplied ad lib. Fourteen hours of light were provided per day with incandescent plus natural light for the floor and fluorescent light for the cages. Each pullet had 1100 and 2100 sq. cm. for the individual cages and floor pens respectively. The floor birds were trapnested and maintained on deep wood shavings. The following data were obtained on all birds: livability; daily egg production; body
CALCIUM L E V E L FOR LAYERS
RESULTS AND DISCUSSION Performance During the Growing Phase. The data (Table 3) indicate no difference in mortality but the diet of 3.0% calcium and 0.4% phosphorus (a ratio of 7.5-1) in Experiment 4 definitely reduced the body weight to 20 weeks of age, feed efficiency and feed consumption as compared to the standard diet (1.0% calcium, 0.7% phosphorus). Body weights for the other treatments varying in Ca:P ratio from 1:1-4.5-1, were not different,
2. Marius, N. V. Fabriek en Magazijn Van Wetenschappelijke Instrumenten, Utrecht, Hollantl.
but there appears to have been a consistent increase in feed consumption per bird and feed consumption per unit of gain in the birds fed the higher calcium diets (3.0 and 4.5%). Performance During the Laying Phase. The analysis of variance following the procedure of Harvey (1960) within experiments gave no indication that the pre-lay diets influenced egg production, egg weight, or shell quality (Table 4). The highest level of poorly shelled eggs (5.6%) and deformation (0.0164 mm.) was from the pullets fed a pre-lay diet of 1.5% calcium. This was not significantly different (P > 0.05) from the other treatments but apparent differences were consistent within each experiment and the results agree with Meyer et al. (1971) who reported the highest incidence of shell-less and broken eggs from the 1.5% calcium developer diet as compared to the 0.4, 0.7, 0.9 and 1.2% calcium diets. In the experiment presented here the levels of 3.0 and 4.5% calcium with adequate phosphorus did not result in a higher rate of mortality as compared to the much lower calcium levels. The pre-lay diet containing 3.0% calcium and 0.4% phosphorus delayed sexual maturity which is in agreement with the findings of Young et al. (1964). The floor birds on this diet matured at 188 days which was significantly different (P < 0.01) from diets three, four and five. The corresponding value of 169 days for cage birds was significantly different (P < 0.05) from diets one and four. During the lay period, this same group gained more weight (673 g.) than the other groups (Table 3). Mortality was also the highest (21.6%) from this group. This mortality occurred in the early (9 of 12 dead died before 36 weeks of age) stages of production and was caused by visceral gout (4), nephritis (1), leucosis (3), and one undetermined. The use of this pullet diet in another experiment not reported here has apparently also caused high early mortality (3/50 vs. 0/55 for the
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weight at various ages; age at first egg; egg weight and shell rigidity. Eggs produced by caged birds were inspected at point-of-lay and classified poorly shelled eggs (PSE) if they were checked, cracked, leakers, broken or soft-shelled. The non-stratified cage birds made it possible to obtain feed consumption data every 28 days. Egg shell deformation, on the vertical axis, was taken under a 500 g. load using the Marius apparatus. 2 In cage Experiment 1, two days of eggs per week were deformed whereas in all other experiments one day's eggs pe1 week were tested. Egg weights were takei. once per 28-day period for the floor Experiments 2, 3 and 4 and cage Experiment 4 involving the six stratified pullet diets, but all eggs deformed were weighed in the other experiments. Bone mass measurements using a modified Cameron-Sorenson scanning apparatus (Meyer et al., 1968) were made on birds in the cage experiments. Data were summarized from 20 to 68 weeks or from 24 to 68 weeks on a per bird basis (hen-housed, hen-day, and/or hen-survivor) and / o r on a lot per period basis. Arcsin transformation and Duncan's multiple range test (Steel and Torrie, 1960) were utilized when appropriate.
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controls) and low body weight (1330 g. vs. 1532 g. for the controls at 20 weeks of age). Excessive pullet and/or lay mortality was reported by Young et al. (1964) and Young and Shane (1970) using a 3.0% calcium and 0.4% phosphorus pre-lay diet, but earlier Young et al. (1962) found excessive lay mortality due to salpingitis from a 1.4% calcium, 0.7% phosphorus pullet diet. The 1.5% calcium, 0.7% phosphorus diet in these experiments gave the lowest (8.1%) mortality. Meyer et al. (1971) reported that mortality was unaffected by the pre-laying calcium level of 0.4, 0.7, 0.9, 1.2 and 1.5% calcium with 0.55% phosphorus. It has been noted above that the only pre-lay diet adversely affecting lay performance was the 3.0% calcium and 0.4% phosphorus which increased lay mortality. Apparently the low phosphorus level in combination with a high calcium-phosphorus ratio is a detrimental combination in a pre-lay diet and not just simply high levels of calcium or low levels of phosphorus. On the basis of egg production, % poorly shelled eggs, deformation, egg weight and final body weight there was no significant (P > 0.01) interaction between the pre-lay and lay diets. Only two F values of 49 were significant at the 0.05 level of probability— again indicating no important interaction between pullet diets three, four, five and eight and lay calcium levels of 1.5, 2.3, 3.0 or 4.5% nor between any pullet diet. Various Calcium Levels for the Laying Hen. There also was no interaction between the pullet and lay calcium levels but there were some noteworthy differences among the lay diets varying in calcium levels (Table 5). As the calcium level increased, there was an increase in egg production; however, only in Experiments 1 and 3 did the 1.5% calcium level produce significantly (P < 0.05) fewer eggs than the other calcium levels. Reddy et al. (1968) reported a decrease in egg pro-
Downloaded from http://ps.oxfordjournals.org/ at UCSF Library on April 12, 2015
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Egg weight'
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p. C. MILLER AND M. L. SUNDE
1863
CALCIUM LEVEL FOR LAYERS
< 0.05) by the 1.5% calcium level as compared to the 4.5% calcium diet in three of the four experiments. This has not been reported by other workers. Mortality was highest (16.7%) in the 1.5% calcium group and although the final body weight did not reflect poor body uniformity it was apparent at each weighing that there were large variations in body weight within the 1.5% treatment. The observation was made that those birds that laid at a high rate depleted their body stores while those that modified their production rate downward, put on weight and appeared quite healthy. Several birds in the 1.5% calcium diet died of cage layer osteoporosis. Poorly Shelled Eggs. A plot of the % poorly shelled eggs (PSE) per lay treatment against each four-week period of time (Fig. 1) shows: 4.3% PSE during the first period (20-24 weeks of age); a decline for two or three periods; and then a gradual increase to about 60 weeks of age. Finally, a very sharp rise in the % PSE occurred which corresponded to warm climatic conditions. Previous workers on shell quality have noted a gradual increase in shell damage from the start of lay (Jenkins and Taylor, 1960; Pope et al., 1960), but only a few have reported large quantities of PSE or high deformation during the first month of production. Portsmouth (1973) and Miller
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duction at levels of 4.3 and 5.1% calcium, but the decreases did not occur at the 4.5% level used in the present study, which is in agreement with the findings of Mehring (1965), and Hurwitz and Bornstein (1966). In each of the four experiments the hens fed the 4.5% calcium diet produced from five to 11 more eggs per hen than the 3.0% calcium level. The average difference was 8 eggs per hen (Table 5). The hens fed the 3.0% calcium level produced from seven to 16 more eggs than those fed the 2.3% calcium level. The differences in feed consumption are small and probably reflect more the increase in the mineral content of the diet than anything else. In three out of four experiments the hens fed the 1.5% calcium diet consumed less feed than the hens fed the 4.5% calcium diet. Contrary to the findings of Kienholz and McPherron (1964), Mehring (1965), and Hurwitz and Bornstein (1966) the dietary calcium level of 4.5% did not depress feed consumption nor egg weight as compared to the 3.0% calcium diet. As expected, decreased production generally results in poorer feed conversion. Feed conversion per dozen eggs was improved significantly (P < 0.05) with 4.5% calcium in all four experiments and with 3.0% calcium in three out of four experiments as compared to the 1.5% calcium level. The feed conversions from both the 1.5 and 2.3% calcium diets were inferior to the feed conversions of the 3.0 and 4.5% calcium diets. This is in disagreement with Bragg and Stephenson (1964) who reported no difference in feed conversion after feeding 2.3, 2.8, 3.3 or 3.8% calcium. As reported by many workers (Evans et al., 1944; Sullivan and Kingan, 1962; Mehring, 1965; Mathers et al., 1971; and Gerry and Bird, 1967) egg shell quality as measured by rigidity was significantly (P < 0.05) decreased with 1.5 and 2.3% calcium as compared to higher calcium levels. Egg weight was depressed significantly (P
1864
P. C. MILLER AND M. L. SUNDE
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and Sunde (1975) reported that the % PSE declines slightly during the first four weeks of production and then increases. Stillmak and Sunde (1971) and Miller and Sunde (1975) found that shell quality measured by deformation did not immediately decline in all groups of birds after the onset of production. As indicated in the graph, the difference in the % PSE between the 2.3, 3.0 and 4.5% calcium diets is slight. The 1.5% calcium diet obviously produced a high number of PSE in proportion to the total production. Most of these eggs were checked or cracked—not soft-shelled as might be expected. A plot of shell deformation against each four-week period of time (Fig. 2) shows that there is an increase in shell rigidity with normal diets (3.0 and 4.5% calcium) for about four weeks of production and then a gradual decline in shell quality. About 50% of all groups of birds showed this increase in shell rigidity between periods one and two, whereas between periods 11 and 12 (64 to 68 weeks of age), 75% of all groups of birds showed a decrease in rigidity. It is of interest that the hens receiving 2.3% calcium had very acceptable rigidity values during the last three periods of production.
FIG. 3. Bone mineralization from first egg in Experiment 1. age (Fig. 3) indicates that the birds fed a pre-lay diet of 1.0% calcium did not maintain skeletal makeup through the egg production cycle as well as those birds fed the 0.7, 1.5 or 3.0% calcium diets but these differences are nonsignificant (P > 0.05). No apparent distinction in BMM existed among the other pre-lay calcium levels during the lay period. These findings do not parallel those of Meyer et al. (1971) who concluded that of the 0.4 and 1.2% pre-lay calcium groups, the higher level had a considerably higher BMM through the lay period. The difference between his 0.4 and the 0.7% calcium level of this study may be the cause of the nonagreement in findings. The pre-lay by lay interaction on the basis
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FIG. 4. Bone mineralization from first egg in Experiment 2.
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FIG. 2. Shell deformation from 20 weeks of age for all cage experiments combined.
CALCIUM LEVEL FOR LAYERS
of BMM did not exist but the level of the calcium in the lay diet influenced bone mineralization during the production phase. The 1-5% calcium did not maintain skeletal integrity. The 3.0% calcium diet gave, through all three experiments, less BMM than the 4.5% calcium diet (Fig. 4) although nonsignificant (P > 0.05). In Experiments 1 and 3, the birds put on the 3.0% calcium lay diet had the higher bone mass at first egg.
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The positive correlation between EN and mean EW is in agreement with Quinn (1963) who found a positive genotypic and phenotypic relationship. There is also a significant positive relationship between shell deformation and % poorly shelled eggs, but this relationship is not as great as would be expected. It has been noticed that on a lot per period basis a distinct relationship between deformation and poor shell quality is commonly lost. A significant correlation between bone mineral mass (BMM) and egg shell deformation may make it possible to use this as an index of selection so that birds that would produce breakage resistant eggs can be identified with a single BMM measurement rather than test eggs for shell quality over an extended period of time. The correlation
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Correlations Between Criteria of Performance. The simple correlation (Table 6) between a variety of lay performance criteria appears to indicate mean shell deformation is independent of mean egg weight (EW) and egg number (EN). This is contrary to the findings of Anderson (1966) who showed that there was a highly significant negative regression of eggs per bird on egg shell thickness but the present report is in agreement with Richards and Staley (1967) who reported a positive correlation of .06 between deformation/unit load and egg weight and Perek and Snapir (1970) who indicated that there was no significant correlation between shell quality and production rate.
1866
P. C. MILLER AND M. L. SUNDE
mineral stores and then utilizing the stores for the production of sound shells. Further research must be done to resolve the question as to which of the two theories is correct, keeping in mind the possible distinctions in mineralization based on breeds and/or strains. Both theories may be correct. It is conceivable that the correlation goes from negative to positive as egg production increases, and that there is a threshhold point which separates the low producer (i.e. heavy breed) from the higher producer (i.e. light breed). ACKNOWLEDGMENT The authors wish to thank the Cosmic Medicine Laboratory for supplying the iodine 125 source used in taking the bone mass scans. Appreciation is also extended to Dr. Robert Miller, Merck and Co. for the niacin, riboflavin, and pantothenate and to Don Gray, Dow Chemical Co. for the Zoamix. REFERENCES Anderson, D. L., 1966. Pre-laying nutritional and environmental factors in the performance of the adult fowl. 1. Adaptation of litter-reared Single Comb White Leghorn females to different calcium and phosphorus levels. Poultry Sci. 45: 67-75. Anderson, D. L., 1967. Pre-laying nutritional and environmental factors in the performance of the adult fowl. 2. Influence of environment on the calcium requirement and adaptation of Single Comb White Leghorn females. Poultry Sci. 46: 52-63. Berg, L. R., G. E. Bearse and L. H. Merrill, 1964. The calcium and phosphorus requirements of White Leghorn pullets from 8 to 21 weeks. Poultry Sci. 43: 885-896. Berg, L. R., G. E. Bearse and V. L. Miller, 1947. The effect of the pre-laying level of calcium on the performance of White Leghorn pullets. Poultry Sci. 26: 463-468. Bragg, D. B., and E. L. Stephenson, 1964. The use of radioactive tracer in studying the effect of different levels of calcium and vitamin D, and season on egg shell quality and performance of White Leghorn hens. Poultry Sci. 43: 1304. Evans, J. R., J. S. Caver and A. W. Brant, 1944. The influence of dietary factors on egg shell quality.
Downloaded from http://ps.oxfordjournals.org/ at UCSF Library on April 12, 2015
of BMM with deformation at 68 weeks of age shows a possible relationship. In Experiments 1, 2 and 3 there were significant negative correlations of .31, .51 and .28 respectively. A more practical type of index for selection would be to use BMM at an early age such as at first egg. The negative correlation between BMM at first egg and subsequent deformation is not significantly different (P > 0.05) from zero when using the combined data of birds from all lay calcium levels, but within each calcium level there were both negative and positive correlations. A test of the relationship between BMM and deformation could be a selection process based on BMM and/or deformation. A limited test of this hypothesis was possible using heavy breed birds. These birds were provided by Goher and McGibbon (1974) after they had been selected on the basis of shell deformation for three generations. Thirty-nine birds randomly selected from the two lines of the third generation were scanned and the mean shell deformation per bird was computed from one day's eggs per week for 49 weeks. These lines had very distinct deformations and BMM, but with a positive correlation of 0.48. The line with 30.6 bone mass units had a high mean deformation of 0.0182 mm. as compared to the line with 27.3 bone mass units and a mean deformation of 0.0154 mm. The highly significant positive correlation of 0.48 agrees with the correlation of Experiment 3 date at first egg. This would indicate the possibility (Theory 1) that the birds which produced eggs of low shell rigidity have deposited minerals into the skeleton, hence the large BMM, but do not have the capability to remove the stored minerals. The negative relationship found in Experiments 1, 2 and 3 at 68 weeks would indicate birds with the higher BMM, are producing eggs of the highest shell rigidity. These birds are very possibly (Theory 2) building up
CALCIUM L E V E L FOR LAYERS
and shell weights in White Leghorns and White Rock hens. Brit. Poultry. Sci. 11: 133-145. Pope, C. W., A. W. Watts, E. Williams and C. C. Bronson, 1960. The effect of length of time in production and stage of egg production on certain egg quality measurements and blood constituents of laying hens. Poultry Sci. 39: 1427-1431. Portsmouth, J. I., 1973. The timing of the change from growers' to layers' ration: Its effect on egg production with particular reference to shell quality. 4th European Poultry Conf., London, pp. 29-34. Quinn, J. P., 1963. Estimates of some genetic parameters of egg quality. Poultry Sci. 42: 792-793. Reddy, C. V., P. E. Sanford and R. E. Clegg, 1968. Influence of calcium in laying hens on shell quality and interior quality of eggs. Poultry Sci. 47: 10771083. Richards, J. F., and L. M. Staley, 1967. The relationship between crushing strength, deformation and other physical measurements of the hen's egg. Poultry Sci. 46: 430-438. Steel, R. G. D., and J. H. Torrie, 1960. Principles and Procedures of Statistics with Special References to Biological Sciences. McGraw-Hill Book Co., Inc., New York, New York. Stillmak, S. J., and M. L. Sunde, 1971. The use of high magnesium limestone in the diet of the laying hen. 1. Egg production. Poultry Sci. 50: 553-564. Sullivan, T. W., and J. R. Kingan, 1962. Effect of dietary calcium level, calcium lactate and ascorbic acid on the egg production of S.C.W.L. hens. Poultry Sci. 41: 1596-1602. Taylor, T. G., and J. H. Moore, 1954. Skeletal depletion in hens laying on a low calcium diet. Brit. J. Nutr. 8: 112-124. Taylor, T. G. and J. H. Moore, 1958. The effect of high and low levels of dietary inorganic phosphate on the pre-laying storage of calcium and phosphorus and on the composition of the medullary and cortical bone in pullets. Brit. J. Nutr. 12: 35-42. Twining, P. F., R. J. Lillie, E. J. Robel and C. A. Denton, 1965. Calcium and phosphorus requirements of broiler chickens. Poultry Sci. 44: 283-296. Young, R. J., C. C. Calbert and D. T. Hopkins, 1962. Calcium nutrition of replacement pullets and laying hens. Proc. Cornell Nutr. Conf., pp. 138-143. Young, R. J., M. C. Nesheim, I. D. Desai and M. L. Scott, 1964. The effect of high dietary calcium on growing pullets and the performance of laying hens. Proc. Cornell Nutr. Conf., pp. 45-49. Young, R. J., and S. M. Shane, 1970. The effects of calcium and phosphorus levels in the diet on the development of nephrosis and parathyroid activity of replacement pullets. Proc. Georgia Nutr. Conf., pp. 1-14.
Downloaded from http://ps.oxfordjournals.org/ at UCSF Library on April 12, 2015
II. Calcium. Poultry Sci. 23: 36-42. Gerry, R. W., and F. H. Bird, 1967. The performance of Red x Rock sex links as affected by calcium levels in their growing and laying hens. Poultry Sci. 46: 1264. Goher, N. E., and W. H. McGibbon, 1974. Biomedical study of the variability of shell deformation. Poultry Sci. 53: 1928-1929. Hart, E. B., H. T. Scott, O. L. Kline and J. G. Halpin, 1930. The calcium-phosphorus ratio in the nutrition of growing chicks. Poultry Sci. 9: 296-306. Harvey, W. R., 1960. Least squares analysis of data with unequal subclass numbers. U.S.D.A. ARS-208. Hurwitz, S.,andA. Bar, 1971. The effect of pre-laying mineral nutrition on the development, performance and mineral metabolism of pullets. Poultry Sci. 50: 1044-1055. Hurwitz, S., and S. Bornstein, 1966. The effect of high dietary calcium on the performance of laying hens fed rations on varying energy levels. Poultry Sci. 45: 805-809. Jenkins, N. K., and C. Taylor, 1960. Changes in egg shell thickness and white and yolk weight and composition over a period of a year. J. Agr. Sci. 55: 323-331. Kienholz, E. W., and T. A. McPherron, 1964. The effect of some dietary supplements upon caged hen performance while heat stressed. Poultry Sci. 43: 1334. Mathers, J. W., M. Longstaff and R. Hill, 1971. The influence on shell formation of the pre-laying period for which a low-manganese diet is given. Brit. Poultry Sci. 12: 179-185. Mehring, A. L., Jr., 1965. Effect of level of dietary calcium on broiler-type laying chickens. Poultry Sci. 44: 240-248. Meyer, G. B„ S. W. Babcockand M. L. Sunde, 1968. An accurate in vivo technique for measuring bone mineral mass in chickens. J. Nutr. 96: 195-205. Meyer, G. B., S. W. Babcock and M. L. Sunde, 1971. Effect of various prelaying levels of dietary calcium upon subsequent performance in chickens. Poultry Sci. 50: 536-547. Miller, P. C , and M. L. Sunde, 1975. The effect of various particle sizes of oyster shell and limestone on performance of laying Leghorn pullets. Poultry Sci: 54: 1422-1433. Mraz, F. R., 1972. Influence of pre-lay dietary calcium upon tibial 45 Ca uptake in 20 week old pullets. Poultry Sci. 51: 1058-1059. National Research Council Publication, 1971. Nutrient Requirements of Poultry. 6th ed., Washington, D.C. Perek, M., and N. Snapir, 1970. Interrelationship between shell quality and egg production and eggs
1867
Department of Poultry Science, University of Wisconsin, Madison, Wisconsin 53706 (Received for publication January 13, 1975)
POULTRY SCIENCE 54: 1856-1867, 1975
INTRODUCTION
F
ROM eight to 18 weeks of age, the requirements for calcium and phosphorus in growing chickens are 0.8 and 0.4% respectively (National Research Council, 1971). These figures are based on research using growth and bone development (Hart et al., 1930; Taylor and Moore, 1954, 1958; Twining et al., 1965; and Mraz, 1972) as the criteria and not subsequent lay performance. Several workers (see reviews by Anderson, 1966, 1967; Meyer et al., 1971; and Hurwitz and Bar, 1971) have studied the carry-over influence of the pre-lay calcium and phosphorus levels on lay performance but only Berg et
1. Present address: Technical Services Department, Shaver Poultry Breeding Farms, Box 400, Cambridge, Ontario, Canada NIR 5V9. Research supported by the College of Agricultural and Life Sciences, University of Wisconsin, Madison, Wisconsin.
al. (1947, 1964) have reported on the interaction of the pre-lay diets with lay diets on shell quality. Using pullet diets of 0.7, 0.9, 1.1, 2.0 and 3.0% calcium and lay diets of 1.0, 1.7, 2.1, 2.5 and 2.9% calcium, Berg et al. (1947, 1964) found no apparent interaction based on shell quality. The effects of various calcium levels in the lay period on egg production and shell quality have been extensively studied (Evan et al., 1955; Kienholz and McPherron, 1964; Mehring, 1965; Reddy et al., 1968; and others) but no research has been reported involving bone mineralization through a complete lay period. Only Meyer et al. (1971) have studied bone mineralization through the lay period based on the pre-lay treatments. The relationship between the rate of production and shell quality has been studied by several workers, but with conflicting results. Anderson (1966) found a negative relationship between eggs per bird with egg shell
1856
Downloaded from http://ps.oxfordjournals.org/ at UCSF Library on April 12, 2015
ABSTRACT Four experiments over a period of four years with 1350 first-year pullets were designed to determine the influence of the calcium and phosphorus levels in the pre-lay diets on the growing birds and on their subsequent performance. Several dietary calcium levels in the lay period were studied, as well as the interaction between the pre-lay and lay diets. During the growing phase the pullets fed 3.0% calcium and 0.4% phosphorus had significantly (P < 0.05) lower body weight at 20 weeks of age than the pullets in the other pre-lay treatments. Feed consumption and feed efficiency were also adversely affected by this treatment, and sexual maturity was significantly (P < 0.05) delayed. Early lay mortality from this treatment was evident. On the basis of egg production, egg weight, shell deformation and percent poorly shelled eggs (PSE) at point-of-lay, the pre-lay diets did not influence lay performance nor was there an interaction between any combination of pullet and lay diets. As the calcium levels of the lay diets increased, egg production, feed consumption and shell rigidity increased. The 1.5% calcium level did not maintain bone mineralization as compared to the 3.0 and 4.5% calcium levels. It was noted that shell quality on the basis of PSE and deformation does not begin to deteriorate immediately after the onset of production. In fact there is a short period of time where the egg shells improve and then there is a gradual decline in shell rigidity. The layers fed the lay diet containing 1.5% calcium produced eggs weighing an average of 57.4 g. This was significantly (P < 0.05) lower than the eggs of the 2.3, 3.0 or 4.5% calcium fed groups which produced eggs weighing 59.1, 58.6 and 59.4 g. respectively.
2884 16.1 0.61 0.67 2880 16.1 0.66 0.96
2838 16.0 0.66 1.53
2840 15.8 0.41 3.00
2827 15.7 0.70 3.02
2849 16.2 0.99 2.91
2704 15.8 0.97 4.51
100.0
100.0 100.0
100.0
7.3 0.5 0.5
—
16.0 3.0 5.0 2.5 8.7 0.5 0.5 16.0 3.0 5.0 2.5 4.5 0.5 0.5
18.3 3.0 2.0 1.5 6.2 0.5 0.5
19.7 3.0 1.0
— —
— —
— —
9 63.8
8 68.0
— —
7 68.0
6 68.0
'Premix supplied per kg. of diet: 6000 I.U., vitamin A; 500 I.C.U., vitamin D 3 ; 2 mg., riboflavin; 5 mg., calcium pantothenate; 10 mg., niacin; 251 mg., choline; 3 I.U., vitamin E; 123 mg., manganese oxide; 0.5 g., D,L-methionine; 0.005 mg., vitamin B 1 2 ; and 240 mg., Zoamix.
2900 15.8 0.41 0.61
100.0
100.0
2917 15.9 0.41 0.42
100.0
1.0 0.5 0.5
0.5 0.5 0.5
Chemical composition M.E. (kcal./kg.) Protein (calculated) Phosphorus (calculated) Calcium (calculated)
100.0
100.0
—
—
— 0.5 0.5
56.0 13.5 5.0 14.0 3.0 5.0 0.5 2.0 0.5 0.5
56.0 15.0 5.0 14.0 3.0 5.0 0.5 0.5 0.5 0.5
56.0 15.0 5.5 15.0 3.0 4.0 0.5
57.0 15.0 4.0 18.0 3.0 1.0
5
Diet
57.5 15.0 4.0 18.0 3.0 1.0
4
Corn Corn and cob meal Wheat bran Soybean meal (44% protein) Alfalfa meal (17% protein) Meat scrap (50% protein) Dicalcium phosphate Limestone, ground Iodized salt Premix'
3
1
Ingredient
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TABLE 1.—Percentage composition of pre-lay diets
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67.0 11.5 3.0 3.0 1 2.0 1.0 1.9 0.5 9.6 0.5 4 100.0
4 1-4 C 67.7 12.5 3.0 3.0 1 2.0 1.0 9.8 0.5
3 1-4 C 67.2 12.0 3.0 3.0 1 2.0 1.0 5.8 0.5
1 1-4 C
2 1-4 C 67.1 11.7 3.0 3.0' 2.0 1.0 3.9 0.5
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composition of lay diets
100.5
0.3 s
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—
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100.0
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—
7 4 F,C 73.3 12.5 6.0
0.5 6
6 2,3 F 73.3 12.5 3.0 3.0 2.0 0.5 2 4.7 0.5
Chemical composition 15.6 15.3 15.9 15.9 17.0 15.9 15.9 Protein (calculated) 0.65 0.68 0.69 0.61 0.63 0.69 0.69 Phosphorus (calculated) 2.79 2.53 2.66 2.98 4.49 2.25 1.51 Calcium (calculated) *C—Cage; F—Floor; C—Pullet treatment stratified in cage Experiment 4. 1 Meat scrap in Experiment 4. 2 Defluorinated rock phosphate. 'Ground oat hulls in Experiment 4. 4 Premix supplied per kg. of diet: 0.3 g., D,L-methionine; 1060 I.C.U., vitamin D 3 ; 1000 I.U., vitamin A; 3.5 mg., riboflavin; 110 mg., manganese oxide; and 44 mg., choline. 5 Premix supplied per kg. of diet: 0.5 g., D,L-methionine; 880 I.C.U., vitamin D 3 ; 4000 I.U., vitamin A; 3.1 mg., riboflavin; 100 mg., manganese oxide; and 22 mg., erythromycin. 6 Premix supplied per kg. of diet: 0.5 g., D,L-methionine: 1170 I.C.U., vitamin D 3 ; 4400 I.U., vitamin A; 2.4 mg., riboflavin; 100 mg.. manganese oxide; and 22 mg., erythromycin.
Corn Soybean meal (44% protein) Meat scrap (50% protein) Fish meal (60% protein) Alfalfa meal (17% protein) Dicalcium phosphate Calcium source Iodized salt Ground oats Oat mill by-product3 Premix
Experiment Facility*
TABLE 2.—Percentage
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1859
CALCIUM L E V E L FOR LAYERS
thickness but Perek and Snapir (1970) indicated no significant correlation between egg numbers and shell quality. This research was conducted to study the interaction of several pre-lay diets (varying in calcium and phosphorus levels) with several types of lay diets (varying in levels, sources and forms of calcium). Special emphasis was placed on the influence of the pullet calcium level upon subsequent bone mineralization and shell quality at different lay calcium levels.
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Egg Production Phase. In all four experiments each of the eight floor pens contained 40 birds. The experimental birds were equally stratified across each pen. The calcium source used was ground limestone unless otherwise stated. In some lots free choice coarse limestone, coarse dolomitic limestone or oyster shell were provided. The description of each experiment will include the floor test and cage test during the lay period. Experiment 1: Pre-lay diets 4 and 5 were fed to a total of 96 birds until housing at 19 weeks in the floor pens. In addition to the lay diet number 5 (Table 2), three pens received coarse dolomitic limestone, coarse limestone or coarse oyster shell, and the other four pens received the previous four treat-
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Growing Phase. Over a period of four years a total of 1350 eight-week-old commercial strain cross pullets (Leghorn type) were given diets containing various levels of calcium and phosphorus (Table 1). Of the 1350 birds at eight weeks of age, 1178 were used in the egg production phase. The birds received: feed and water ad lib., 2200 sq. cm. of floor space per bird, deep litter floor covering, and natural lighting. Mortality, body weight, feed consumption, and feed conversion data were compiled from eight weeks of age to time of housing.
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P. C. MILLER AND M. L. SUNDE
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ments plus granite grit. The lay diet, calcium source and granite grit were fed ad lib. For the cage test, pre-lay diets three, four, five and eight were fed to 72 birds. At 17 weeks these birds were placed in individual cages to create 12 groups of six birds each and a 4 x 3 factorial design. The lay diets one, two and three were fed at first egg. Experiment 2: For the floor test, pre-lay diets four and five were fed to 145 birds until housing at 19 weeks. The methods and procedure of Experiment 2 for the cage test was identical to that of Experiment 1 cage test, with the exception that housing was at 19 weeks of age. Experiment 3: Diets three, four and seven were fed during the rearing period. Housing in the floor pens of the 160 birds was at 20 weeks and the lay diet (number 6) was used with additional calcium free choice. The four rearing diets of Experiments 1 and 2 (cage test) were used for the 96 birds. Four lay diets (one, two, three and four) were used thus creating a 4 x 4 factorial design. Lay diets were fed at first egg and housing was at 20 weeks. Experiment 4: All nine pre-lay diets were fed to 320 pullets which were equally stratified across the eight pens. For the cage layer test the 4 x 4 design of Experiment 3 was used. In addition, there were 120 birds fed pre-lay diets one, two, four, six, eight and nine and then stratified across the same five treatments as described for the floor test above. Both the experimental lay rations and water were supplied ad lib. Fourteen hours of light were provided per day with incandescent plus natural light for the floor and fluorescent light for the cages. Each pullet had 1100 and 2100 sq. cm. for the individual cages and floor pens respectively. The floor birds were trapnested and maintained on deep wood shavings. The following data were obtained on all birds: livability; daily egg production; body
CALCIUM L E V E L FOR LAYERS
RESULTS AND DISCUSSION Performance During the Growing Phase. The data (Table 3) indicate no difference in mortality but the diet of 3.0% calcium and 0.4% phosphorus (a ratio of 7.5-1) in Experiment 4 definitely reduced the body weight to 20 weeks of age, feed efficiency and feed consumption as compared to the standard diet (1.0% calcium, 0.7% phosphorus). Body weights for the other treatments varying in Ca:P ratio from 1:1-4.5-1, were not different,
2. Marius, N. V. Fabriek en Magazijn Van Wetenschappelijke Instrumenten, Utrecht, Hollantl.
but there appears to have been a consistent increase in feed consumption per bird and feed consumption per unit of gain in the birds fed the higher calcium diets (3.0 and 4.5%). Performance During the Laying Phase. The analysis of variance following the procedure of Harvey (1960) within experiments gave no indication that the pre-lay diets influenced egg production, egg weight, or shell quality (Table 4). The highest level of poorly shelled eggs (5.6%) and deformation (0.0164 mm.) was from the pullets fed a pre-lay diet of 1.5% calcium. This was not significantly different (P > 0.05) from the other treatments but apparent differences were consistent within each experiment and the results agree with Meyer et al. (1971) who reported the highest incidence of shell-less and broken eggs from the 1.5% calcium developer diet as compared to the 0.4, 0.7, 0.9 and 1.2% calcium diets. In the experiment presented here the levels of 3.0 and 4.5% calcium with adequate phosphorus did not result in a higher rate of mortality as compared to the much lower calcium levels. The pre-lay diet containing 3.0% calcium and 0.4% phosphorus delayed sexual maturity which is in agreement with the findings of Young et al. (1964). The floor birds on this diet matured at 188 days which was significantly different (P < 0.01) from diets three, four and five. The corresponding value of 169 days for cage birds was significantly different (P < 0.05) from diets one and four. During the lay period, this same group gained more weight (673 g.) than the other groups (Table 3). Mortality was also the highest (21.6%) from this group. This mortality occurred in the early (9 of 12 dead died before 36 weeks of age) stages of production and was caused by visceral gout (4), nephritis (1), leucosis (3), and one undetermined. The use of this pullet diet in another experiment not reported here has apparently also caused high early mortality (3/50 vs. 0/55 for the
Downloaded from http://ps.oxfordjournals.org/ at UCSF Library on April 12, 2015
weight at various ages; age at first egg; egg weight and shell rigidity. Eggs produced by caged birds were inspected at point-of-lay and classified poorly shelled eggs (PSE) if they were checked, cracked, leakers, broken or soft-shelled. The non-stratified cage birds made it possible to obtain feed consumption data every 28 days. Egg shell deformation, on the vertical axis, was taken under a 500 g. load using the Marius apparatus. 2 In cage Experiment 1, two days of eggs per week were deformed whereas in all other experiments one day's eggs pe1 week were tested. Egg weights were takei. once per 28-day period for the floor Experiments 2, 3 and 4 and cage Experiment 4 involving the six stratified pullet diets, but all eggs deformed were weighed in the other experiments. Bone mass measurements using a modified Cameron-Sorenson scanning apparatus (Meyer et al., 1968) were made on birds in the cage experiments. Data were summarized from 20 to 68 weeks or from 24 to 68 weeks on a per bird basis (hen-housed, hen-day, and/or hen-survivor) and / o r on a lot per period basis. Arcsin transformation and Duncan's multiple range test (Steel and Torrie, 1960) were utilized when appropriate.
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controls) and low body weight (1330 g. vs. 1532 g. for the controls at 20 weeks of age). Excessive pullet and/or lay mortality was reported by Young et al. (1964) and Young and Shane (1970) using a 3.0% calcium and 0.4% phosphorus pre-lay diet, but earlier Young et al. (1962) found excessive lay mortality due to salpingitis from a 1.4% calcium, 0.7% phosphorus pullet diet. The 1.5% calcium, 0.7% phosphorus diet in these experiments gave the lowest (8.1%) mortality. Meyer et al. (1971) reported that mortality was unaffected by the pre-laying calcium level of 0.4, 0.7, 0.9, 1.2 and 1.5% calcium with 0.55% phosphorus. It has been noted above that the only pre-lay diet adversely affecting lay performance was the 3.0% calcium and 0.4% phosphorus which increased lay mortality. Apparently the low phosphorus level in combination with a high calcium-phosphorus ratio is a detrimental combination in a pre-lay diet and not just simply high levels of calcium or low levels of phosphorus. On the basis of egg production, % poorly shelled eggs, deformation, egg weight and final body weight there was no significant (P > 0.01) interaction between the pre-lay and lay diets. Only two F values of 49 were significant at the 0.05 level of probability— again indicating no important interaction between pullet diets three, four, five and eight and lay calcium levels of 1.5, 2.3, 3.0 or 4.5% nor between any pullet diet. Various Calcium Levels for the Laying Hen. There also was no interaction between the pullet and lay calcium levels but there were some noteworthy differences among the lay diets varying in calcium levels (Table 5). As the calcium level increased, there was an increase in egg production; however, only in Experiments 1 and 3 did the 1.5% calcium level produce significantly (P < 0.05) fewer eggs than the other calcium levels. Reddy et al. (1968) reported a decrease in egg pro-
Downloaded from http://ps.oxfordjournals.org/ at UCSF Library on April 12, 2015
Poorly shelled eggs'
Egg weight'
Deform ation' (0.001 mm.)
p. C. MILLER AND M. L. SUNDE
1863
CALCIUM LEVEL FOR LAYERS
< 0.05) by the 1.5% calcium level as compared to the 4.5% calcium diet in three of the four experiments. This has not been reported by other workers. Mortality was highest (16.7%) in the 1.5% calcium group and although the final body weight did not reflect poor body uniformity it was apparent at each weighing that there were large variations in body weight within the 1.5% treatment. The observation was made that those birds that laid at a high rate depleted their body stores while those that modified their production rate downward, put on weight and appeared quite healthy. Several birds in the 1.5% calcium diet died of cage layer osteoporosis. Poorly Shelled Eggs. A plot of the % poorly shelled eggs (PSE) per lay treatment against each four-week period of time (Fig. 1) shows: 4.3% PSE during the first period (20-24 weeks of age); a decline for two or three periods; and then a gradual increase to about 60 weeks of age. Finally, a very sharp rise in the % PSE occurred which corresponded to warm climatic conditions. Previous workers on shell quality have noted a gradual increase in shell damage from the start of lay (Jenkins and Taylor, 1960; Pope et al., 1960), but only a few have reported large quantities of PSE or high deformation during the first month of production. Portsmouth (1973) and Miller
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duction at levels of 4.3 and 5.1% calcium, but the decreases did not occur at the 4.5% level used in the present study, which is in agreement with the findings of Mehring (1965), and Hurwitz and Bornstein (1966). In each of the four experiments the hens fed the 4.5% calcium diet produced from five to 11 more eggs per hen than the 3.0% calcium level. The average difference was 8 eggs per hen (Table 5). The hens fed the 3.0% calcium level produced from seven to 16 more eggs than those fed the 2.3% calcium level. The differences in feed consumption are small and probably reflect more the increase in the mineral content of the diet than anything else. In three out of four experiments the hens fed the 1.5% calcium diet consumed less feed than the hens fed the 4.5% calcium diet. Contrary to the findings of Kienholz and McPherron (1964), Mehring (1965), and Hurwitz and Bornstein (1966) the dietary calcium level of 4.5% did not depress feed consumption nor egg weight as compared to the 3.0% calcium diet. As expected, decreased production generally results in poorer feed conversion. Feed conversion per dozen eggs was improved significantly (P < 0.05) with 4.5% calcium in all four experiments and with 3.0% calcium in three out of four experiments as compared to the 1.5% calcium level. The feed conversions from both the 1.5 and 2.3% calcium diets were inferior to the feed conversions of the 3.0 and 4.5% calcium diets. This is in disagreement with Bragg and Stephenson (1964) who reported no difference in feed conversion after feeding 2.3, 2.8, 3.3 or 3.8% calcium. As reported by many workers (Evans et al., 1944; Sullivan and Kingan, 1962; Mehring, 1965; Mathers et al., 1971; and Gerry and Bird, 1967) egg shell quality as measured by rigidity was significantly (P < 0.05) decreased with 1.5 and 2.3% calcium as compared to higher calcium levels. Egg weight was depressed significantly (P
1864
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and Sunde (1975) reported that the % PSE declines slightly during the first four weeks of production and then increases. Stillmak and Sunde (1971) and Miller and Sunde (1975) found that shell quality measured by deformation did not immediately decline in all groups of birds after the onset of production. As indicated in the graph, the difference in the % PSE between the 2.3, 3.0 and 4.5% calcium diets is slight. The 1.5% calcium diet obviously produced a high number of PSE in proportion to the total production. Most of these eggs were checked or cracked—not soft-shelled as might be expected. A plot of shell deformation against each four-week period of time (Fig. 2) shows that there is an increase in shell rigidity with normal diets (3.0 and 4.5% calcium) for about four weeks of production and then a gradual decline in shell quality. About 50% of all groups of birds showed this increase in shell rigidity between periods one and two, whereas between periods 11 and 12 (64 to 68 weeks of age), 75% of all groups of birds showed a decrease in rigidity. It is of interest that the hens receiving 2.3% calcium had very acceptable rigidity values during the last three periods of production.
FIG. 3. Bone mineralization from first egg in Experiment 1. age (Fig. 3) indicates that the birds fed a pre-lay diet of 1.0% calcium did not maintain skeletal makeup through the egg production cycle as well as those birds fed the 0.7, 1.5 or 3.0% calcium diets but these differences are nonsignificant (P > 0.05). No apparent distinction in BMM existed among the other pre-lay calcium levels during the lay period. These findings do not parallel those of Meyer et al. (1971) who concluded that of the 0.4 and 1.2% pre-lay calcium groups, the higher level had a considerably higher BMM through the lay period. The difference between his 0.4 and the 0.7% calcium level of this study may be the cause of the nonagreement in findings. The pre-lay by lay interaction on the basis
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FIG. 2. Shell deformation from 20 weeks of age for all cage experiments combined.
CALCIUM LEVEL FOR LAYERS
of BMM did not exist but the level of the calcium in the lay diet influenced bone mineralization during the production phase. The 1-5% calcium did not maintain skeletal integrity. The 3.0% calcium diet gave, through all three experiments, less BMM than the 4.5% calcium diet (Fig. 4) although nonsignificant (P > 0.05). In Experiments 1 and 3, the birds put on the 3.0% calcium lay diet had the higher bone mass at first egg.
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The positive correlation between EN and mean EW is in agreement with Quinn (1963) who found a positive genotypic and phenotypic relationship. There is also a significant positive relationship between shell deformation and % poorly shelled eggs, but this relationship is not as great as would be expected. It has been noticed that on a lot per period basis a distinct relationship between deformation and poor shell quality is commonly lost. A significant correlation between bone mineral mass (BMM) and egg shell deformation may make it possible to use this as an index of selection so that birds that would produce breakage resistant eggs can be identified with a single BMM measurement rather than test eggs for shell quality over an extended period of time. The correlation
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Correlations Between Criteria of Performance. The simple correlation (Table 6) between a variety of lay performance criteria appears to indicate mean shell deformation is independent of mean egg weight (EW) and egg number (EN). This is contrary to the findings of Anderson (1966) who showed that there was a highly significant negative regression of eggs per bird on egg shell thickness but the present report is in agreement with Richards and Staley (1967) who reported a positive correlation of .06 between deformation/unit load and egg weight and Perek and Snapir (1970) who indicated that there was no significant correlation between shell quality and production rate.
1866
P. C. MILLER AND M. L. SUNDE
mineral stores and then utilizing the stores for the production of sound shells. Further research must be done to resolve the question as to which of the two theories is correct, keeping in mind the possible distinctions in mineralization based on breeds and/or strains. Both theories may be correct. It is conceivable that the correlation goes from negative to positive as egg production increases, and that there is a threshhold point which separates the low producer (i.e. heavy breed) from the higher producer (i.e. light breed). ACKNOWLEDGMENT The authors wish to thank the Cosmic Medicine Laboratory for supplying the iodine 125 source used in taking the bone mass scans. Appreciation is also extended to Dr. Robert Miller, Merck and Co. for the niacin, riboflavin, and pantothenate and to Don Gray, Dow Chemical Co. for the Zoamix. REFERENCES Anderson, D. L., 1966. Pre-laying nutritional and environmental factors in the performance of the adult fowl. 1. Adaptation of litter-reared Single Comb White Leghorn females to different calcium and phosphorus levels. Poultry Sci. 45: 67-75. Anderson, D. L., 1967. Pre-laying nutritional and environmental factors in the performance of the adult fowl. 2. Influence of environment on the calcium requirement and adaptation of Single Comb White Leghorn females. Poultry Sci. 46: 52-63. Berg, L. R., G. E. Bearse and L. H. Merrill, 1964. The calcium and phosphorus requirements of White Leghorn pullets from 8 to 21 weeks. Poultry Sci. 43: 885-896. Berg, L. R., G. E. Bearse and V. L. Miller, 1947. The effect of the pre-laying level of calcium on the performance of White Leghorn pullets. Poultry Sci. 26: 463-468. Bragg, D. B., and E. L. Stephenson, 1964. The use of radioactive tracer in studying the effect of different levels of calcium and vitamin D, and season on egg shell quality and performance of White Leghorn hens. Poultry Sci. 43: 1304. Evans, J. R., J. S. Caver and A. W. Brant, 1944. The influence of dietary factors on egg shell quality.
Downloaded from http://ps.oxfordjournals.org/ at UCSF Library on April 12, 2015
of BMM with deformation at 68 weeks of age shows a possible relationship. In Experiments 1, 2 and 3 there were significant negative correlations of .31, .51 and .28 respectively. A more practical type of index for selection would be to use BMM at an early age such as at first egg. The negative correlation between BMM at first egg and subsequent deformation is not significantly different (P > 0.05) from zero when using the combined data of birds from all lay calcium levels, but within each calcium level there were both negative and positive correlations. A test of the relationship between BMM and deformation could be a selection process based on BMM and/or deformation. A limited test of this hypothesis was possible using heavy breed birds. These birds were provided by Goher and McGibbon (1974) after they had been selected on the basis of shell deformation for three generations. Thirty-nine birds randomly selected from the two lines of the third generation were scanned and the mean shell deformation per bird was computed from one day's eggs per week for 49 weeks. These lines had very distinct deformations and BMM, but with a positive correlation of 0.48. The line with 30.6 bone mass units had a high mean deformation of 0.0182 mm. as compared to the line with 27.3 bone mass units and a mean deformation of 0.0154 mm. The highly significant positive correlation of 0.48 agrees with the correlation of Experiment 3 date at first egg. This would indicate the possibility (Theory 1) that the birds which produced eggs of low shell rigidity have deposited minerals into the skeleton, hence the large BMM, but do not have the capability to remove the stored minerals. The negative relationship found in Experiments 1, 2 and 3 at 68 weeks would indicate birds with the higher BMM, are producing eggs of the highest shell rigidity. These birds are very possibly (Theory 2) building up
CALCIUM L E V E L FOR LAYERS
and shell weights in White Leghorns and White Rock hens. Brit. Poultry. Sci. 11: 133-145. Pope, C. W., A. W. Watts, E. Williams and C. C. Bronson, 1960. The effect of length of time in production and stage of egg production on certain egg quality measurements and blood constituents of laying hens. Poultry Sci. 39: 1427-1431. Portsmouth, J. I., 1973. The timing of the change from growers' to layers' ration: Its effect on egg production with particular reference to shell quality. 4th European Poultry Conf., London, pp. 29-34. Quinn, J. P., 1963. Estimates of some genetic parameters of egg quality. Poultry Sci. 42: 792-793. Reddy, C. V., P. E. Sanford and R. E. Clegg, 1968. Influence of calcium in laying hens on shell quality and interior quality of eggs. Poultry Sci. 47: 10771083. Richards, J. F., and L. M. Staley, 1967. The relationship between crushing strength, deformation and other physical measurements of the hen's egg. Poultry Sci. 46: 430-438. Steel, R. G. D., and J. H. Torrie, 1960. Principles and Procedures of Statistics with Special References to Biological Sciences. McGraw-Hill Book Co., Inc., New York, New York. Stillmak, S. J., and M. L. Sunde, 1971. The use of high magnesium limestone in the diet of the laying hen. 1. Egg production. Poultry Sci. 50: 553-564. Sullivan, T. W., and J. R. Kingan, 1962. Effect of dietary calcium level, calcium lactate and ascorbic acid on the egg production of S.C.W.L. hens. Poultry Sci. 41: 1596-1602. Taylor, T. G., and J. H. Moore, 1954. Skeletal depletion in hens laying on a low calcium diet. Brit. J. Nutr. 8: 112-124. Taylor, T. G. and J. H. Moore, 1958. The effect of high and low levels of dietary inorganic phosphate on the pre-laying storage of calcium and phosphorus and on the composition of the medullary and cortical bone in pullets. Brit. J. Nutr. 12: 35-42. Twining, P. F., R. J. Lillie, E. J. Robel and C. A. Denton, 1965. Calcium and phosphorus requirements of broiler chickens. Poultry Sci. 44: 283-296. Young, R. J., C. C. Calbert and D. T. Hopkins, 1962. Calcium nutrition of replacement pullets and laying hens. Proc. Cornell Nutr. Conf., pp. 138-143. Young, R. J., M. C. Nesheim, I. D. Desai and M. L. Scott, 1964. The effect of high dietary calcium on growing pullets and the performance of laying hens. Proc. Cornell Nutr. Conf., pp. 45-49. Young, R. J., and S. M. Shane, 1970. The effects of calcium and phosphorus levels in the diet on the development of nephrosis and parathyroid activity of replacement pullets. Proc. Georgia Nutr. Conf., pp. 1-14.
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II. Calcium. Poultry Sci. 23: 36-42. Gerry, R. W., and F. H. Bird, 1967. The performance of Red x Rock sex links as affected by calcium levels in their growing and laying hens. Poultry Sci. 46: 1264. Goher, N. E., and W. H. McGibbon, 1974. Biomedical study of the variability of shell deformation. Poultry Sci. 53: 1928-1929. Hart, E. B., H. T. Scott, O. L. Kline and J. G. Halpin, 1930. The calcium-phosphorus ratio in the nutrition of growing chicks. Poultry Sci. 9: 296-306. Harvey, W. R., 1960. Least squares analysis of data with unequal subclass numbers. U.S.D.A. ARS-208. Hurwitz, S.,andA. Bar, 1971. The effect of pre-laying mineral nutrition on the development, performance and mineral metabolism of pullets. Poultry Sci. 50: 1044-1055. Hurwitz, S., and S. Bornstein, 1966. The effect of high dietary calcium on the performance of laying hens fed rations on varying energy levels. Poultry Sci. 45: 805-809. Jenkins, N. K., and C. Taylor, 1960. Changes in egg shell thickness and white and yolk weight and composition over a period of a year. J. Agr. Sci. 55: 323-331. Kienholz, E. W., and T. A. McPherron, 1964. The effect of some dietary supplements upon caged hen performance while heat stressed. Poultry Sci. 43: 1334. Mathers, J. W., M. Longstaff and R. Hill, 1971. The influence on shell formation of the pre-laying period for which a low-manganese diet is given. Brit. Poultry Sci. 12: 179-185. Mehring, A. L., Jr., 1965. Effect of level of dietary calcium on broiler-type laying chickens. Poultry Sci. 44: 240-248. Meyer, G. B„ S. W. Babcockand M. L. Sunde, 1968. An accurate in vivo technique for measuring bone mineral mass in chickens. J. Nutr. 96: 195-205. Meyer, G. B., S. W. Babcock and M. L. Sunde, 1971. Effect of various prelaying levels of dietary calcium upon subsequent performance in chickens. Poultry Sci. 50: 536-547. Miller, P. C , and M. L. Sunde, 1975. The effect of various particle sizes of oyster shell and limestone on performance of laying Leghorn pullets. Poultry Sci: 54: 1422-1433. Mraz, F. R., 1972. Influence of pre-lay dietary calcium upon tibial 45 Ca uptake in 20 week old pullets. Poultry Sci. 51: 1058-1059. National Research Council Publication, 1971. Nutrient Requirements of Poultry. 6th ed., Washington, D.C. Perek, M., and N. Snapir, 1970. Interrelationship between shell quality and egg production and eggs
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