The Relationship of Serum Calcium to Shell Weight and Other Criteria in Hens Laying a Low or High Incidence of Shell-Less Eggs

The Relationship of Serum Calcium to Shell Weight and Other Criteria in Hens Laying a Low or High Incidence of Shell-Less Eggs

The Relationship of Serum Calcium to Shell Weight and Other Criteria in Hens Laying a Low or High Incidence of Shell-Less Eggs R. LENNARDS and D. A. R...

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The Relationship of Serum Calcium to Shell Weight and Other Criteria in Hens Laying a Low or High Incidence of Shell-Less Eggs R. LENNARDS and D. A. ROLAND, SR. Poultry Science Department and J. A. McGUIRE Research Data Analysis, Alabama Agricultural Experiment Station, Auburn University, Alabama 36849

ABSTRACT Experiments were conducted to determine the relationship of serum calcium to shell weight and other criteria. Blood samples for calcium analysis were taken at oviposition in Experiments 1 and 2 from hens fed a 3.5% calcium diet. In Experiment 3, blood was taken at various intervals from hens laying a high or low incidence of shell-less eggs. These hens were fed a control diet or various calcium-deficient diets throughout a 45-day period. No relationship was found between serum calcium and shell weight^oregg weight. Hens laying a high incjdencejof shell-less eggs showed no decrease in serum calcmnToFegg production whenTed a .5_8,^^25^0^07% ca]cium_diet. However, these criteria were reduced in heriiTaying~a low incidence of shell-less eggs. It was concluded that the normal variation in serum calcium is not related to the hen's ability to produce eggshell. The mechanism of_action_resp^onsible for cessation of lay when control hens wfre ,ffd a raHum-def"'*"*"'' Hipr appparpH nnf tn function as it does in hens laving a high incidence of shelMesj_eggs. (Key words: serum calcium, shell weight, shell quality, oviposition, dietary calcium) 1981 Poultry Science 60:2501-2505

INTRODUCTION H e r t e l e n d y and Taylor ( 1 9 6 1 ) and Roland et al. ( 1 9 7 3 ) have s h o w n serum calcium t o be related t o shell quality and q u a n t i t y w h e n hens were fed a calcium-deficient diet. However, m o r e recently Sloan et al. ( 1 9 7 4 ) f o u n d n o relationship b e t w e e n serum calcium and egg specific gravity (shell quality) w h e n hens were fed a d e q u a t e calcium diets. T h e a m o u n t of shell deposited o n t h e egg m a y or m a y n o t have any relationship t o t h e quality of shell p r o d u c e d because of variation in egg size ( R o l a n d , 1 9 7 9 ) . F o r e x a m p l e , an egg with a 4 g shell could have a b e t t e r shell quality t h a n an egg with a 6 g shell d e p e n d i n g on t h e relative size of each egg. A l t h o u g h research t o relate serum calcium t o egg shell quality has been c o n d u c t e d , n o w o r k has been d o n e t o relate serum calcium t o t h e q u a n t i t y of shell deposited. T h e q u a n t i t y of shell deposited o n t h e egg varies from 3 t o 7 g a n d t h e average serum calcium level a m o n g p r o d u c i n g hens varies from a p p r o x i m a t e l y 2 0 t o 30 mg% (Taylor, 1 9 7 0 ) . Since t h e shell consists of a p p r o x i m a t e l y 4 0 % calcium and all calcium reaches t h e shell gland via t h e b l o o d , it

would seem likely t h a t some relationship could exist b e t w e e n serum calcium level and t h e q u a n t i t y of shell d e p o s i t e d . This s t u d y was c o n d u c t e d t o establish w h e t h e r or n o t a relationship exists b e t w e e n serum calcium and q u a n t i t y of shell d e p o s i t e d . In order t o o b t a i n a b e t t e r understanding of t h e relationship b e t w e e n serum calcium, shell weight, and p r o d u c t i o n , these criteria were also studied in h e n s laying a high o r low incidence of shell-less eggs w h e n fed diets containing various levels of calcium.

MATERIALS AND METHODS T h r e e e x p e r i m e n t s were c o n d u c t e d in this s t u d y . Single C o m b White Leghorns (SCWL), 53 and 73 weeks of age, were used in E x p e r i m e n t s 1 and 2 , respectively. Criteria studied were egg weight, shell plus m e m b r a n e weight, specific gravity, serum calcium, a n d t i m e of oviposition. Individually caged h e n s were fed a commercialt y p e corn-soy layer diet containing 16% p r o tein, 1 2 7 7 kcal M E / k g , and 3.5% calcium. Blood samples of 3 cc per hen were t a k e n from

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(Received for publication January 28, 1980)

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LENNARDS ET AL. TABLE 1. Coefficients of determination (R*) between various criteria of laying hens (Experiment 1)

Criteria

Oviposition time

Egg weight

Shell weight

Serum calcium

Egg weight Shell weight Serum calcium Specific gravity

.001 .035 .067 .180

.224 (.0001) .012 (.21) .001 (.67)

.001 (.77) .356 (.0001)

.048 (.01)

(.22)* (.03) (.002) (.0001)

values in parentheses represent probability of R2 = 0.

TABLE 2. Coefficients of determination (R1) between various criteria of laying hens (Experiment 2)

Criteria

Oviposition time

Egg weight Shell weight Serum calcium Specific gravity

.0001 .032 .037 .031

(.90) a (.03) (.02) (.03)

Egg weight

Shell weight

Serum calcium

.237 (.001) .017 (.12) .008 (.27)

.002 (.62) .562 (.0001)

.0002 (.87)

Values in parentheses represent probability of R2 = 0.

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a total of 135 hens (Experiment 1) and 150 The time chosen for decreasing dietary calcium hens (Experiment 2) by anterior heart puncture was dependent upon the results as the experiat the time of oviposition — between 0800 and ment progressed. When it became apparent that 1630 hr. Egg weight, specific gravity, and shell the hens laying a high incidence of shell-less weight values were obtained from each egg eggs were not responding to the calciumcollected. Specific gravity was determined in deficient diet as were the hens producing a low graded sodium chloride solutions ranging from incidence of shell-less eggs, dietary-calcium 1.060 to 1.100 in increments of .005 units. levels were further decreased. All diets were isoSerum calcium determinations were made using caloric and isonitrogenous. Samples of 3 cc of an atomic absorption spectrophotometer. blood were taken from all hens on days 3, 7, 14, 20, 28, 35, and 45 at approximately 1 pm In Experiment 3, 60 SCWL hens, 84 weeks of age, were selected from a larger population. each day by anterior heart puncture from Thirty hens were selected for laying a highjnci- which serum calcium levels were determined. Criteria measured were serum calcium and egg dence of hard-shelled eggs (hard-shell hens) with no shell-less eggs_Qyj*r rhp piwirmc i o production. days. The other J0_ hens were selected for Coefficients of determination and standard 1 aying a high~7ncid~enre of shell-less eggs (sh ell - errors were calculated according to standard less hensj_QT soft-shelled eggs over the- previous procedures (Snedecor, 1956). 10 days. The technique of Roland (1977) was used for determining extent of shell-less eggs. RESULTS AND DISCUSSION At the start of the experiment, 15 hens from each group were fed a commercial-type cornThe results of these studies (Experiments 1 soy diet containing 3.5% calcium and 16% and 2) indicated that no correlation existed protein while the remaining 15 hens from each between egg weight and oviposition time group were fed a .58% calcium diet. The dietary (Tables 1 and 2). Shell weight was positively calcium levels were decreased as the experiment correlated to oviposition time and egg weight. progressed as indicated in Tables 3, 4, and 5. Egg specific gravity was positively correlated

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Total egg production of hens laying a low incidence of shell-less eggs and fed the 3.5% calcium diet for the first 9 days and the .25% calcium diet from days 10 to 45 decreased from 79 to 27% within 39 to 45 days (Table 4). Thin-shelled egg production increased from 3 to 31% within 18—24 days and then slightly decreased while hard-shelled egg production fell § from 76% to a low of 2% within 25 to 31 days. In the other group of hard-shell hens (Table 5) fed the .58% calcium diet during days 1 to 28 and the .07% calcium diet during days 29 to 42, egg production declined from 68 to 24% within 42 days. Hard-shell egg production fell from 62 to 0% within 42 days, and at this time hens were laying only thin shelled eggs. In comparison to the change in production \ of hens laying mostly hard-shell eggs, little or j no change in egg production of hens laying a J high incidence of shell-less eggs was observed \x\J

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to oviposition time and shell weight but egg specific gravity was not correlated to egg weight. Serum calcium was positively correlated to egg specific gravity in Experiment 1 but not in Experiment 2. Serum calcium was not correlated to shell weight in either experiment. These results indicated that there was no relationship between serum calcium and quantity of shell deposited tor hens~fed a 3.5% cakiurn_diejL_. In Experiment 3, comparison of serum calcium levels of the hard-shell hens fed a 3.5 or .58% calcium diet showed a 6.5 mg% reduction in serum calcium within 3 days of feeding the .58% calcium diet (Table 3). By day 7, the difference in serum calcium levels between these two groups was 11.3 mg%. Feeding the .58% caIcium_diet__to_h£ns v laying a high" incidence pt thell-lpw pffp;<: for 7 days caused no change in serum calcium (Table 3) as" was observed in hens laying a low incidence of shell-less eggs. Since no change in serum calcium level was noted, shell-less hens being fed the 3.5% calcium diet were changed to a .25% calcium diet on day 10. After 18 days of consuming the .25% calcium diet, essentially no change was observed in the serum calcium level of hens laying a high incidence of shellless eggs, which remained at 28.5 mg% on day 28 (Table 3). On day 29, shell-less hens being fed the .58% Ca diet were fed a .07% calcium diet. However, after 17 days, hens laying a high incidence of shell-less eggs and fed the .07% cal cium diet still showed no change in serum calcium level (Table 3).

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LENNARDS ET AL. TABLE 4. Hard-shell (HS), thin-sbell (TS), and shell-less (SL) egg production of hens laying either a low (hardshell) or high incidence of shell-less eggs (Experiment 3) % Production Days Criteria

1-10

11-17

18-24

25-31

32-38

39-45

Hard-shell

HS TS Total

76 + 4° 3 ±2 79 ± 3

54 + 4 10 ± 2 64 ± 4

4+ 2 31 ± 5 35 ± 5

2 +1 20 ± 8 22 ± 8

13 + 5 27 + 6 40 ± 6

6±4 21 ± 5 27 + 8

Shell-less

HS SL Total

1 ±1 57 ± 8 58 ± 8

3 +3 48 ± 7 51 + 7

52 ± 8 52 + 8

64 + 9 64 ± 9

1 ±1 56 + 8 57 ± 8

51+9 51 ± 9

a

Hens fed a 3..5% Ca diet from days 1 to 9 and a .25% Ca diet from days :10 to 45.

b

Mean ± SEM

either dietary treatment group as indicated by Tables 4 and 5. Hens laying a high incidence of shell-less eggs and fed the 3.5% calcium diet for 9 days followed by the .25% calcium diet for the remainder of the experiment maintained egg production at a 55% average over the experimental period (Table 4). Hens laying a high incidence of shell-less eggs and fed the .58% calcium diet followed by the .07% calcium diet maintained an average of 57% production throughout the experimental period (Tables). It was concluded that under the conditions of these experiments no relationship exists between the quantity of calcium in serum and

shell weight or egg weight. Also, the calcium requirement for yolk formation was very low (.58% calcium or lower), since the hens laying a high incidence of shell-less eggs were able to maintain up to 60% production for at least 42 days when fed the various calcium-deficient diets. The mechanism of action responsible for the cessation of lay when hens laying a low incidence of shell-less eggs wese fed a calciumdeficient diet is not known. However, it appears that^ such a mechanism was not_junctiohlng in hens laylng^aTi^_jn^ia^c£_rf_^hell-less eggs, since egg production and serum calcium of these hens were not affected by the same dietary level of calcium_deficiency.

TABLE 5. Hard-shell (HS), thin-shell (TS), and shell-less (SL) egg production of hens laying either a low (hard-shell) or high incidence of shell-less eggs (Experiment 3) % Production Days Group

Criteria

1-7

8-14

15-21

22-28

29-35

36-42

Hard-shell

HS TS Total

62 ± 4 ° 6±2 68 + 4

17± 5 20 ± 7 37 + 9

15±6 24+7 39 ± 7

19+5 30 + 7 49 + 5

1± 1 29 ± 7 30 ± 8

0 24 ± 10 24+ 10

Shell-less

HS SL Total

0 49 + 3 49 ± 3

0 54 ± 4 54 ± 4

0 73 ± 6 73 ± 6

0 65 ± 6 65 ± 6

0 60 ± 8 60 ± 8

0 42+7 42+7

Hens fed a .58% Ca diet during days 1 to 28 and a .07% Ca diet during days 29 to 42. b

Mean + SEM.

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SERUM CALCIUM VERSUS SHELL WEIGHT REFERENCES Hertelendy, F., and T. G. Taylor, 1961. Changes in blood calcium associated with egg shell calcification in domestic fowl. 1. Changes in total calcium. Poultry Sci. 40:108-114. Roland, D. A., Sr., 1977. An efficient method and procedure for determining the incidence of uncollectable eggs. Poultry Sci. 5 6 : 1 3 2 7 1328. Roland, D. A., Sr., 1979. Factors influencing shell quality of aging hens. Poultry Sci. 58:774— 777. Roland, D. A., Sr., D. R. Sloan, H. R. Wilson, and R.

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H. Harms, 1973. Influence of dietary calcium deficiency on yolk and serum calcium, yolk and organ weights and other selected production criteria of the pullet. Poultry Sci. 52:2220— 2225. Sloan, D. R., D. A. Roland, Sr., and R. H. Harms, 1974. Circadian rhythms of serum calcium in hens and the relationship of serum calcium to shell quality. Poultry Sci. 53:2003-2009. Snedecor, G. W., 1956. Statistical methods. 5th ed. Iowa State University Press, Ames, IA. Taylor, T. G., 1970. How an eggshell is made. Sci. Am. 222:88-95. Downloaded from http://ps.oxfordjournals.org/ at Purdue University Libraries ADMN on June 10, 2015