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Egg Shell Quality
Egg Shell Quality. 1. Effect of Dietary Manipulations of Protein, Amino Acids, Energy, and Calcium in Aged Hens on Egg Weight, Shell Weight, Shell Quality, and Egg Production D. A. ROLAND, SR. Poultry Science Department, Agricultural Experiment Station, Auburn University, Auburn, Alabama 36830 (Received for publication August 24, 1979)
1980 Poultry Science 59:2038-2046
INTRODUCTION
During the past 50 years numerous experiments have been conducted in an attempt to solve the shell quality problem. Although the cause of poor shell quality was not known, much of this research was based on the assumption that a failure in calcium metabolism occurred as the hen aged. However, recent results suggested that the aged hen's ability to absorb calcium and mobilize skeletal calcium in the process of shell calcification was just as good as that of the young hen, and that the amount of shell deposited does not decrease as the hen ages but remains fairly constant or increases slighdy (Roland et al., 1975, 1978; Roland, 1979). They stated that shell quality declined with hen age due to a continued increase in egg size which forced the constant amount of shell to be spread thinner. The above studies suggested that if egg size in old hens could be reduced or held constant without reducing shell deposition, the decline in shell quality with hen age could be prevented.
Although age at first egg, body size, feed, water, ambient temperature, drugs and disease CFowler, 1972) are known to affect egg size, the influence of protein on egg size is probably the most documented with at least 75 articles published within the past 20 years. Although there is considerable disagreement as to the protein requirement, ranging from 11 to 19% (Thayer et al, 1974; Reid, 1976), most of these studies indicated that egg weight is directly related to the protein content of the diet. However, only a few of the 75 articles used shell quality as a criterion (Hochreich et al., 1958; Deaton and Quisenberry, 1965; Smith, 1967; Gardner and Young, 1972) widt none reporting an improvement in shell quality (specific gravity) as egg size decreased. The following studies were conducted in an attempt to reduce egg size in older hens by dietary manipulation of protein, amino acids, energy, and calcium while maintaining die amount of shell deposited on the egg, thereby improving shell quality.
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ABSTRACT Sixteen dietary treatments (including four protein, four energy, and eight calcium levels) were fed to 560 aged hens for 8 weeks in an attempt to improve shell quality by reducing egg weight without reducing shell deposition. Decreasing the dietary protein from 20 to 11.5% in isocaloric diets resulted in a decrease in egg weight, shell weight, and serum calcium. No improvement in egg specific gravity and no adverse effect on egg production and feed consumption were noted. The response of hens to the 16 or 13.5% protein diet was similar to that of the hens fed the 20% protein diet. Increasing the dietary calcium level from 3 to 4.25% did not prevent the decline in shell weight. Exaggerating the protein deficiency by increasing the dietary energy level from 2.42 to 3.30 kcal ME/g in graded increments and calcium from 2.56 to 4.94%, respectively, also did not prevent the decline in shell weight as egg weight decreased. Body weight decreased as the protein level decreased. Percent yolk increased while percent shell and albumin decreased as egg size decreased. Within 3 weeks after returning the hens to the control feed (16% protein), there was no significant difference in egg weight, shell weight, or feed consumption. It was concluded that reducing egg size by dietary manipulation of protein, amino acids, energy, and calcium also reduced shell deposition, thus preventing any improvement in shell quality; and that the dietary protein level can be reduced to as low as 11.5% in old hens for at least 1 to 2 months prior to hen disposal without any adverse affect on production. (Key words: egg weight, egg shell quality, amino acids, protein, calcium, energy, aged hens)
EGG SHELL QUALITY AND PRODUCTION VS. NUTRIENT LEVEL AND EGG WEIGHT PROCEDURE
Experiment 2. This experiment was as Experiment 1 except that all hens received diets containing 4.25% calcium instead of 3.00%. Experiment 3. Experiment 3 was similar to Experiment 1 except that the energy contents of the 20, 16, 13.5, and 11.5% protein diets were 2.42, 2.84, 3.06, and 3.30 kcal ME/g, respectively. The calcium level of the diets were 2.56, 3.00, 3.23, and 3.49%, respectively. Experiment 4. This experiment was conducted as Experiment 3 except that the calcium levels of the 20, 16, 13.5, and 11.5% protein diets were 3.63, 4.25, 4.58, and 4.94%, respectively. The calcium levels were adjusted in Experiments 3 and 4 to equalize calcium intake among birds (approximately 3 g for Experiment 3 and 4.25 for Experiment 4). Because hens eat to satisfy their energy requirements, increasing or decreasing the energy level of the diet should exaggerate the deficiency or excess protein condition, and decrease or increase egg weight even further. For example, the energy content of the 2.84 kcal ME/g diet was increased to 3.30 kcal ME/g. This reduced the amount of feed consumed by approximately 14% making the 11.5% protein diet equivalent to 10%. Although these studies were conducted simultaneously, they are divided into four
experiments for simplicity in writing the results and discussion section. Diets 2 and 10 were the same treatments as were diets 6 and 14 (Table 1). Calcium in serum was determined using an atomic absorption spectrophotometer. The calculated dietary composition for all diets are presented in Table 1. The methionine plus cystine levels were maintained at minimum level of .53% in all diets except the 11.5 % protein diet in which they were .42, .42, .41, and .40% for Experiments 1, 2, 3, and 4, respectively. Prior to this study the hens had been fed a commerical type corn-soy diet containing approximately 17% protein. Data from each experiment were subjected to an analysis of variance and the multiple range test of Duncan (1955) as modified by Kramer (1956) was used to identify significant treatment differences. RESULTS AND DISCUSSION
In Experiment 1 the change in egg weight was directly related to the protein content of the diet (Table 2). Decreasing the dietary protein from 16 to 11.5% significantly reduced egg weight within 8 weeks. Although increasing the dietary protein level from 16 to 20% did not significantly increase egg weight, the change in egg weight was significandy greater for hens fed the 20% protein diet compared to that of hens fed the 13.5 or 11.5% protein diets. Similar effects were observed in Experiment 2 except that within 4 weeks egg weight was significandy reduced for hens fed the 11.5% protein diet. Increasing the dietary calcium level from 3.00 to 4.25% had no influence on egg weight. When the energy level of the diet was increased from 2.84 to 3.3 kcal ME/g in the 11.5% protein diet, the change in egg weight was 38% greater in Experiment 3 than in Experiment 1 and 95% greater in Experiment 4 than in Experiment 2. This indicated that increasing the energy content of the 11.5% protein diet exaggerated tiie protein deficiency. When the dietary protein level was reduced from 16 to 11.5%, egg weight was significantly reduced within 4 weeks in Experiment 4 and within 6 weeks in Experiment 3. The numerical change in shell weight was directly related to the protein content of the diet (Table 3). Decreasing the dietary protein from 16 to 11.5% significantly reduced shell weight within 8 weeks _n Experiments 1 and 2. Increasing the dietary protein from 16 to 20% or decreasing the dietary protein from 16 to 13.5%
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Experiment I. One hundred and sixty individually caged Babcock hens 14.5 months in lay were randomly divided into 4 equal groups and fed diets containing 20, 16, 13.5, or 11.5% protein for 8 weeks during August and September. The diets contained 2.84 kcal ME/g, 3.00% calcium, and .65% phosphorus. Egg weight, shell weight, and specific gravity were determined on eggs laid during a 4-day period prior to initiation of the experiment and at 2-week intervals thereafter. Body weight was determined both at the beginning and at termination of the experiment. Egg production and feed consumption were also determined. At the end of 8 weeks, blood was drawn by anterior heart puncture from 20 hens per treatment; yolk weight and interval between oviposition were determined on eggs laid during a 5-day period. The hens were returned to the control diet (16% protein) and feed consumption, egg weight, shell weight, and specific gravity were determined at 2 or 3-week intervals for 6 weeks.
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2040
ROLAND, SR. TABLE 1. Composition of dietary treatments'3 Experiment 2
Experim ent 1
Proteinb Metab. energy Calcium
2
3
4
5
6
7
8
20.00 2838.00 3.00
16.00 2838.00 3.00
13.50 2828.00 3.00
11.50 2838.00 3.00
20.00 2838.00 4.25
16.00 2838.00 4.25
11.50 2838.00 4.25
.33 .65
.28 .54 .83
.28 .54 .85
1.01 1.71
.22 .42 .51 .75 .47 .14 .58
.33 .64
.65 .22 .81
.31 .53 .64 .90 .55 .18 .68
13.50 2838.00 4.25 . .31
1.40
1.20
1.04
.48
.38
.32
1.73 1.01 1.01
1.48 .77 .82
Met
Met + Cys. Lysine Arginine Threonine Tryptophan Phe. Phe. + Tyr.
1.13 1.44
Leucine Isoleucine Valine
.22 .42 .51 .75 .47 .15 .58
1.39
1.19
1.04
.27
.48
.38
.32
.27
1.32
1.18
1.45
1.30
1.17
.63 .69
.52 .59
1.70 1.02 1.01
.78 .81
.64 .69
.52 .59
1.11
.81 .28
His
1.01 1.70
.65 .22 .81
.53 .66 .91 .55 .18 .68
1.15 1.45
1.12
.81 .29
Experimenl : 3
Protein" Metab. energy Calcium Met
Met + Cys. Lysine Arginine Threonine Tryptophan Phe. Phe. + Tyr. His
Leucine Isoleucine Valine
Experiment 4
9
10
11
12
13
14
15
16
20.00 2420.00 2.56
16.00 2838.00 3.00
13.50 3058.00 3.23
11.50 3300.00 3.49
20.00 2420.00 3.63
16.00 2838.00 4.25
13.50 3058.00 4.58
11.50 3300.00 4.94
.33 .65
.28 .54 .83
.28 .54 .85
1.01 1.70
.22 .41 .53 .76 .47 .15 .58
.33 .65
.65 .22 .81
.31 .53 .66 .91 .55 .18 .68
1.40
1.19
1.03
.48
.38
.32
1.71 1.01 1.01
1.48 .77 .82
1.14 1.44 .81 .28
1.11
1.01 1.70
.65 .22 .81
.31 .53 .68 .92 .55 .18 .60
.21 .40 .56 .77 .47 .15 .58
1.39
1.18
1.02
.28
.48
.38
.32
.28
1.30
1.14
1.45
1.26
1.10
.64 .69
.53 .59
1.71 1.01 1.01
.78 .81
.65 .69
.54 .59
1.14 1.44 .81 .28
1.12
All diets contained .14% Na, .21% Cl, 2.5% alfalfa meal, .65% total phosphorus, and .5% micromix. Corn, soybean meal, dicalcium phosphate, limestone, poultry fat, DL-methionine, and sand varied in the diets depending upon the above specifications. The micromix added at the rate of 227 g/wt supplies the following per kilogram of finished feed: vitamin A, 7,339 USPU; vitamin D 3 , 2,200 ICU; vitamin E, 8.0 IU; menadione dimethypyrimidnol bisulfite, 2.0 mg; riboflavin, 5.5 mg; pantothenic acid, 13.0 mg; niacin, 36; choline, 499; vitamin B 1 2 , .02 mg; folic acid, .5 mg; thiamine, 1.0 mg; pyridoxine, 2.2 mg; ethoxyquin, 125 mg; manganese, 65.0; iodine, 1.0 mg; iron, 55 mg; copper, 6.0 mg; zinc, 55 mg; cobalt, .20 mg. All units are percent except metabolizable energy which is expressed as kcal/kg.
had no significant influence on shell weight in Experiments 1 or 2. Increasing the dietary calcium level from 3.00 to 4.25% did not prevent the decline in shell weight as egg weight declined. When the energy level was increased, as protein content of the diet decreased (Experiments 3 and 4), the influence on shell weight was very similar to that of the hens in Experiments 1 and 2. Increasing
the calcium level in Experiment 4 also did not prevent the decline in shell weight as egg size decreased. Decreasing the dietary protein level below 16% did not significantly improve egg specific gravity (shell quality) in Experiments 1 or 2 (Table 4). Hens fed the 11.5% protein diets (Experiment 1) had a significantly lower egg specific gravity at the end of 2 weeks compared
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ROLAND, SR. TABLE 4. Egg specific gravity as influenced by protein (Prot), calcium (Ca), and energy (ME)
Experiment
Specific gravity (weeks)
Treatment Prot
Ca
ME
4
6
8
Average
1.078 a 1.079 a 1.077 a 1.077 a 1.076 a 1.079 a 1.077 a 1.078 a 1.077t>c 1.079 a b c 1.076 c 1.081 a 1.077t>c 1.079 a b c 1.080 ab 1.078 a b c
1.079 a 1.080 a 1.079 a 1.077 a 1.079 a 1.080 a 1.078 a 1.079 a
1.077 a 1.078 a 1.076 a 1.077 a 1.077 a 1.077 a 1.077 a 1.075 a
1.078 a 1.079 a 1.078 a 1.077 a 1.078 a 1.079 a 1.078 a 1.078 a
1.078 ab 1.080 ab 1.076 b 1.083 a 1.078 b 1.080 ab 1.081 a b 1.080 ab
1.077 a b 1.078 a 1.073 b 1.080 a 1.077 ab 1.077 ab 1.078 a b 1.077 a b
1.078 a b 1.079 a b 1.076 b 1.081 a 1.078 a b 1.079 a b 1.080 a 1.078 a b
(%)
<%)
(kcal/g)
1 1 1 1 2 2 2 2
20.0 16.0 13.5 11.5 20.0 16.0 13.5 11.5
3.00 3.00 3.00 3.00 4.25 4.25 4.25 4.25
2.84 2.84 2.84 2.84 2.84 2.84 2.84 2.84
1.080 ab 1.081 a 1.079 ab 1.077b 1.079 ab 1.081 a 1.079 ab 1.079 ab
3 3 3 3 4 4 4 4
20.0 16.0 13.5 11.5 20.0 16.0 13.5 11.5
2.56 3.00 3.23 3.49 3.63 4.25 4.58 4.94
2.42 2.84 3.06 3.30 2.42 2.84 3.06 3.30
1.079 a 1.081 a 1.078 a 1.081 a 1.080 a 1.081 a 1.082 a 1.079 a
' ' Values followed by different letters in the same column within Experiments 1 and 2 or Experiments 3 and 4 are significantly different (P<.05).
significant influence on egg specific gravity, there was a trend for the average specific gravity of eggs from hens fed the 20% protein diet to be numerically lower than that of hens fed the 16% protein diet in all four experiments. The average egg production during the 8-week experiment was not significantly influenced by dietary treatments in Experiments 1 or 2 but was in Experiments 3 and 4 (Table 5). Although egg production during the first 4 weeks of Experiments 2, 3, and 4 was not significantly influenced, egg production was significantly influenced during the 6- and 8week test period. When the protein content of the diet was reduced from 16 to 11.5% and energy increased from 2.84 to 3.30 kcal ME/g in Experiments 3 and 4, egg production was significantly reduced within 6 weeks in both experiments. Increasing the dietary calcium level from 3.00 to 4.25% or to equivalent levels had no significant influence on egg production. The dietary treatments used in Experiment 1 did not significantly influence feed consumption during any of the biweekly test periods; however, decreasing the dietary protein from 16 to 11.5% significantly reduced the feed consumed during the experiment (Table 6). Decreasing the dietary protein from 16 to 11.5% in Experiment 2 had no significant influence on feed con-
sumption. The feed consumption of hens in Experiments 3 and 4 was directly related to the energy content of the diet. In Experiment 3, the hens ability to regulate feed intake according to the energy level of the diet was demonstrated, since the average feed consumption of hens receiving each energy level was significantly different from the others. The energy consumed per hen per day varied little, ranging from 281 to 294 kcal ME. Although hens are reported to be able to regulate their protein intake when given access to multiple isocaloric diets containing various levels of protein (Holcombe et al, 1976), the hens in these studies appeared to have no tendency to overconsume energy to increase protein consumption. The grams of protein consumed per hen per day in Experiments 3 and 4 ranged from 9.8 to 22.5. Since the hens in Experiments 1 and 2 were consuming approximately 100 g of feed per hen in each treatment, the percent dietary protein levels and actual grams of protein consumed per day were very similar. Serum calcium was significantly decreased when the dietary protein level was reduced from 16 to 11.5% in Experiments 1 and 2 (Table 7). Increasing the calcium level from 3 to 4.25% had no significant influence on serum calcium. It has been reported (Sloan et al., 1974) that serum calcium levels in hens were
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EGG SHELL QUALITY AND PRODUCTION VS. NUTRIENT LEVEL AND EGG WEIGHT
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TABLE 5. Egg production as influenced by protein (Prot), calcium (Ca), and energy (ME) Experiment
Egg production (weeks)
Treatment Prot
Ca
ME
2
4
6
8
Average
(%)
20.0 16.0 13.5 11.5 20.0 16.0 13.5 11.5
3.00 3.00 3.00 3.00 4.25 4.25 4.25 4.25
(kcal/kg) 2.84 2.84 2.84 2.84 2.84 2.84 2.84 2.84
69.3 a 70.5 a 73.0 a 67.9 a 69.6 a 70.4 a 70.5 a 69.5 a
74.4 a 68.9 a b 74.6 a 67.7 a b 64.8b 72.3 a b 66.4 a b 68.6 a b
67.2 a b 66.8 a b 66.4 a b 60.9 a b 66.3ab 70.4 a 59.5 b 60.0 b
54.9 a b 55.7 a b 60.4 a b 60.1ab 60.5 a b 65.3 a 57.5 a b 50.2 b
67.0 a 65.5 a 68.6 a 64. l a 65.3 a 69.6 a 63.5 a 62.1 a
3 3 3 3 4 4 4 4
20.0 16.0 13.5 11.5 20.0 16.0 13.5 11.5
2.56 3.00 3.23 3.49 3.63 4.25 4.58 4.94
2.42 2.84 3.06 3.30 2.42 2.84 3.06 3.30
64.5 b 70.5 a b 67.0b 65.7b 66.8b 70.4 a b 73.0 a b 77.7 a
66.6 a 68.9 a 67.3 a 65.0 a 69.8 a 72.3 a 71.8 a 73.0 a
67.3 a 66.8 a 60.7 a 50.lb 63.4 a 70.4 a 62.3 a 50.9 b
56.3 a b 55.7 a b 50.5 a b c 37.6 c d 48.2abc 65.3 a 58.0 a b 34.1 d
63.7 a b 65.5ab 61.4abc 54.6 C 62.1abc 69.6 a 66.3ab 58.9bc
a ' '""Values followed by different letters in the same column with Experiments 1 and 2 or Experiments 3 and 4 are significantly different (P<.05).
n o t related t o egg specific gravity. Hens producing eggs with a high specific gravity h a d n o greater serum calcium levels than hens producing eggs with a low specific gravity. However, t h e results of E x p e r i m e n t s 1 a n d 2 revealed t h a t die quantity of calcium in serum m a y be
related t o t h e quality of shell secreted b y an individual hen. Since egg weight decreased as shell weight declined, egg specific gravity w o u l d remain t h e same, t h u s losing any relationship of serum calcium t o egg specific gravity (shell quality). T h e dietary t r e a t m e n t s used in Ex-
TABLE 6. Feed consumption as influenced by protein (Prot), calcium (Ca), and energy (ME) Experiment
Feed consumption (weeks)
Treatment Prot
Ca
ME
2
4
(%)
(%)
1 1 1 1 2 2 2 2
20.0 16.0 13.5 11.5 20.0 16.0 13.5 11.5
3.00 3.00 3.00 3.00 4.25 4.25 4.25 4.25
(kcal/g) 2.84 2.84 2.84 2.84 2.84 2.84 2.84 2.84
100.6b 109.6 a b 109.5 a b 100.3 b 107.4 a b 111.5a 104. l a b 107.7 a b
105.3 a b 102.3 a b 102.6 a b 97.8 b 103.7 a b 109.9 a 99.0 a b 101.3 a b
3 3 3 3 4 4 4 4
20.0 16.0 13.5 11.5 20.0 16.0 13.5 11.5
2.56 3.00 3.23 3.49 3.63 4.25 4.58 4.94
2.42 2.84 3.06 3.30 2.42 2.84 3.06 3.30
107.9 a b c 109.6 a b c 101.5c 104.9bc 115.3a 111.5 a b 106.1 a b c 111.2 a b
112.9 a 102.3 b c 96.9 c d 85.4 e 115.2 a 109.9 a b 100.7C 90.6 d e
6
• (g/hen/day) 104.5 a 112.2 a 104.9 a 99.6 a 106.8 a 107.4 a 99.7 a 110.8 a 121.3 a 112.2 a b 95.2 d 83.6 e 116.1 a b 107.4 b c 98.8 c d 82.0 e
Average
8
87.8 a b 91.0 a b 85.6 a b 83.3 b 91.0 a b 94.8 a 86.8 a b 83.1 b
99.8abc 103.4 a b 100.5 a b c 95.2abc 102.2 a b c 105.9 a 97.4bc 100.7 a bc
102.2 a 91.0b 81.5c 66.1d 100.1 a b 94.8 a b 75.9C 57.7 d
111.1* 103.4b 94.3C 85.0 d 112.4 a 105.9 a b 95.4C 85.4 d
3 h p n £
> ' > > Values followed by different letters in the same column with Experiments 1 and 2 or Experiments 3 and 4 are significantly different (P-C.05).
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(%) 1 1 1 1 2 2 2 2
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ROLAND, SR. TABLE 7. Serum calcium and change in body weight as influenced by dietary protein Prot), calcium (Ca), and energy (ME) Change
Experiment
Treatment Prot
Ca
ME
Serum calcium
body weight
(%)
(kcal/g)
(mg/lOOml)
(g)
20.0 16.0 13.5 11.5 20.0 16.0 13.5 11.5
3.00 3.00 3.00 3.00 4.25 4.25 4.25 4.25
2.84 2.84 2.84 2.84 2.84 2.84 2.84 2.84
25.8 a b 26.3 a 24.7ab 22.2t> 24.8 a b 26.5 a 27.1 a 22.5 b
-36a -62a -108ab -168bc -72a -44a -112ab -208C
3 3 3 3 4 4 4 4
20.0 16.0 13.5 11.5 20.0 16.0 13.5 11.5
2.56 3.00 3.23 3.49 3.63 4.25 4.58 4.94
2.42 2.84 3.06 3.30 2.42 2.84 3.06 3.30
25.02 26.3 a 24.4 a 23.8 a 23.3 a 26.5 a 26.2 a 24.8 a
-42a -62a -128ab -162b -67a -44a -105ab -251c
a,b,c Values followed by different letters in the same column within Experiments 1 and 2 or 3 and 4 are significantly different (P<.05).
periments 3 and 4 had no significant influence on serum calcium. Reducing the dietary protein level from 16 to 11.5% significantly increased the change in body weight (Table 7). Increasing the calcium level of the diet from 3.00 to 4.25% had no influence on hen weight. The results of Experiments 3 and 4 were similar to that of 1 and 2 except that increasing the dietary calcium level from 3.49% (equivalent to 3.00%) to 4.94% (equivalent to 4.25%) significantly decreased body weight. This may have been because of the slightly lower percentage of methionine plus cystine level in the 4.94% calcium diet (Experiment 4) compared to that in the 3.49% calcium diet (Experiment 3). Most of the decrease in egg weight produced by reducing the dietary protein from 16 to 11.5% was due to a reduction in the secretion of albumen (Experiments 1 to 4, Table 8). For example, in Experiment 4 egg weight decreased 7.36 g with 70% (5.18 g) due to a decrease in albumen weight and 19% and 11% was due to a decrease in yolk weight and shell weight, respectively. However, when the loss in shell, albumen, and yolk weights were divided by die original weight, the respective percent decreases
in shell weight and albumen weight were approximately the same (14.72% and 12.85%) and the percentage decrease in yolk was only about one-half as great (7.23%). The dietary treatments used in Experiments 1 to 4 had no significant influence on intervals between oviposition times. This suggested that the decrease in shell deposited on eggs from hens fed the 11.5% protein diets was not due to a decrease in the time the egg stays in the reproductive tract but to a decrease in the rate of shell deposition. The average interval between oviposition times of eggs laid before 1200 hr or after 1200 hr was 26.08 hr vs. 28.31 hr, respectively, and was significandy different (P<.01). Reducing the dietary protein from 16 to 11.5% and increasing the energy content of the diet from 2.84 to 3.30 kcal ME/g significandy reduced the percentage of eggs laid before 1200 hr (Experiments 3 and 4, Table 8). Within 3 weeks after all hens were returned to the diet containing 16% protein, 3.00% calcium and 2.84 kcal ME/g, the decrease in egg weight and shell weight between hens previously fed the 16 and 11.5% protein diets had disappeared. Within 2 weeks there were no significant differences in feed consumption
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(%) 1 1 1 1 2 2 2 2
EGG SHELL QUALITY AND PRODUCTION VS. NUTRIENT LEVEL AND EGG WEIGHT
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TABLE 8. Yolk weight,1 albumin weight, and ovipostion time as influenced by dietary protein (Prot), calcium (Ca), and energy (ME)
Experiment
Prot
Ca
ME
(%>
(kcal/g)
20.0 16.0 13.5 11.5 20.0 16.0 13.5 11.5
3.00 3.00 3.00 3.00 4.25 4.25 4.25 4.25
2.84 2.84 2.84 2.84 2.84 2.84 2.84 2.84
3 3 3 3 4 4 4 4
20.0 16.0 13.5 11.5 20.0 16.0 13.5 11.5
2.56 3.00 3.23 3.49 3.63 4.25 4.58 4.94
2.42 2.84 3.06 3.30 2.42 2.84 3.06 3.30
% Eggs laid after 1200 hr
Albumen weight
40.8 a 38.9 a b 39.2 a b 36.3 C 39.8 a b 40.3a 39.4 a b 38.lbc
58.6 a 66.4 a 54.2 a 50.8 a 62.3 a 52.2 a 60.6 a 59.6 a
41.4 a 33.6 a 45.8 a 49.2 a 37.7 a 47.8 a 39.4 a 40.4 a
38.9 a 38.9 a 39.5 a 36.4b 39.5 a 40.3a 39.1 a 35.lb
57.2 a 66.4 a 54.7 a b 38.3bc 54.0 a b 52.2 a b 51.5 a b 33.3 C
42.8 C 33.6 C 45.3bc 61.7ab 46.0bc 47.8bc 48.5bc 66.7 a
{a\
18.9 a b 18.7*b 18.9 a b 18.4b 19.6 a 18.9 a b 19.2 a b 18.5b 18.6 a b 18.7 a b 19.0 a 18.3ab 18.4 a b 18.9 a 18.7 a b 17.6b
(g)
' ' Values followed by different letters in the same column within Experiments 1 and 2 or 3 or 4 are significantly different (P<.05). 1 Egg weight and shell weight data are shown in Table 1.
between treatments in Experiments 1, 2, and 3. In Experiment 4, however, feed consumption and egg production were still significantly lower after 4 weeks for hens fed the 11.5% protein diet when compared to that of hens fed the 16% protein diet. The results of these studies demonstrated that no improvement in shell quality occurs when egg size is reduced by the dietary manipulations of protein, energy, and calcium used in these experiments, because the amount of shell deposited decreased at a rate equal to or greater than the rate of decrease in either albumen or yolk. Since the quantity of shell deposited on the egg after 3 months of lay remains fairly constant or increased very slightly (Roland, 1979), it is believed that the increase in egg size above that achieved at approximately 3 months of lay does not influence the quality of shell deposited. However, the significant decrease in the amount of shell deposited as egg size decreased indicates a definite adverse effect of decreasing egg size on shell deposition. These studies do not preclude the possibility that reducing egg size by other methods would not have the same effect on the
quantity of shell deposited. Although no improvement occurred in egg specific gravity as egg size decreased, the reduction in egg size could have a beneficial effect on reducing egg breakage. The larger the egg the more likely it is to break during handling. Forty-five percent of total breakage occurs in extra large eggs while only 27.7% occurs in large eggs (Bramhall et ai, 1973). Reducing the dietary protein from 16 to 11.5% reduced egg weights (5.01 g) significantly more for hens laying extra large and jumbo eggs prior to the treatments than for those hens laying eggs in the large or smaller egg categories (2.36 g). The results also suggest the the protein content of the diet of hens laying approximately 70% can be reduced to as low as 11.5% in commercial-type corn-soy diets containing 2.84 kcal ME/g, .42% methionine plus cystine, and .52% lysine for at least 1 to 2 months prior to hen disposal without adversely affecting egg production. This could result in substantial savings in feed cost, since it is well below the protein and sulfur amino acid requirement as stated by the NRC (1977) and also below
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(%) 1 1 1 1 2 2 2 2
Yolk weight
% Eggs laid before 1200 hr
2046
ROLAND, SR.
protein and a m i n o acid levels typically fed t o commercial layers. REFERENCES
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Bramhall, E. L., M. H. Swanson, and G. Johnston, 1973. Egg shell damage during handling. Poultry Dig. 32:12-13. Deaton, J. W., and J. H. Quisenberry, 1965. Effects of dietary protein level on performance of four commercial egg production stocks. Poultry Sci. 44:936-942. Duncan, D. B., 1955. Multiple range and multiple F tests. Biometrics 11:1—42. Fowler, C.J.S., 1972. How management can affect egg size. Shaver Focus 2:1—2. Gardner, F. A., and L. L. Young, 1972. The influence of dietary protein and energy levels on the protein and lipid content of the hen's egg. Poultry Sci. 51:994-997. Hochreich, H. J., C. R. Douglas, I. H. Kidd, and R. H. Harms, 1958. The effect of dietary protein and energy levels upon production of Single Comb White Leghorn hens. Poultry Sci. 37:949-953. Holcombe, D. J., D. A. Roland, Sr., and R. H. Harms, 1976. The ability of hens to regulate protein intake when offered a choice of diets containing different levels of protein. Poultry Sci. 55: 1731-1737. Kramer, C. Y., 1956. Extension of multiple range test
to group means with unequal numbers of replication. Biometrics 12:307-310. National Research Council, 1977. Nutrient requirements of poultry, 7th rev. ed. Nat. Acad. Sci. Washington, DC. Reid, B. L., 1976. Estimated daily protein requirements of laying hens. Poultry Sci. 55:1641-1645. Roland, D. A., Sr., 1979. Factors influencing shell quality of aging hens. Poultry Sci. 58:774-777. Roland, D. A., Sr., C. E. Putnam, and R. L. Hilburn, 1978. The influcence of age on ability of hens to maintain egg shell calcification when stressed with inadequate dietary calcium. Poultry Sci. 57:1616-1621. Roland, D. A., Sr., D. R. Sloan, and R. H. Harms, 1975. The ability of hens to maintain calcium deposition in the egg shell and egg yolk as the hen ages. Poultry Sci. 54:1720-1723. 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. Smith, R. E., 1967. The utilization of poultry diets containing high, low and intermediate levels of protein of identical amino acid pattern. Poultry P.-i. 46:730-735. Thayer, R. H., G. E. Hubbell, J. A. Kasbohm, R. D. Morrison, and C. E. Nelson, 1974. Daily protein intake requirement of laying hens. Poultry Sci. 53:354-364.
1980 Poultry Science 59:2038-2046
INTRODUCTION
During the past 50 years numerous experiments have been conducted in an attempt to solve the shell quality problem. Although the cause of poor shell quality was not known, much of this research was based on the assumption that a failure in calcium metabolism occurred as the hen aged. However, recent results suggested that the aged hen's ability to absorb calcium and mobilize skeletal calcium in the process of shell calcification was just as good as that of the young hen, and that the amount of shell deposited does not decrease as the hen ages but remains fairly constant or increases slighdy (Roland et al., 1975, 1978; Roland, 1979). They stated that shell quality declined with hen age due to a continued increase in egg size which forced the constant amount of shell to be spread thinner. The above studies suggested that if egg size in old hens could be reduced or held constant without reducing shell deposition, the decline in shell quality with hen age could be prevented.
Although age at first egg, body size, feed, water, ambient temperature, drugs and disease CFowler, 1972) are known to affect egg size, the influence of protein on egg size is probably the most documented with at least 75 articles published within the past 20 years. Although there is considerable disagreement as to the protein requirement, ranging from 11 to 19% (Thayer et al, 1974; Reid, 1976), most of these studies indicated that egg weight is directly related to the protein content of the diet. However, only a few of the 75 articles used shell quality as a criterion (Hochreich et al., 1958; Deaton and Quisenberry, 1965; Smith, 1967; Gardner and Young, 1972) widt none reporting an improvement in shell quality (specific gravity) as egg size decreased. The following studies were conducted in an attempt to reduce egg size in older hens by dietary manipulation of protein, amino acids, energy, and calcium while maintaining die amount of shell deposited on the egg, thereby improving shell quality.
2038
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ABSTRACT Sixteen dietary treatments (including four protein, four energy, and eight calcium levels) were fed to 560 aged hens for 8 weeks in an attempt to improve shell quality by reducing egg weight without reducing shell deposition. Decreasing the dietary protein from 20 to 11.5% in isocaloric diets resulted in a decrease in egg weight, shell weight, and serum calcium. No improvement in egg specific gravity and no adverse effect on egg production and feed consumption were noted. The response of hens to the 16 or 13.5% protein diet was similar to that of the hens fed the 20% protein diet. Increasing the dietary calcium level from 3 to 4.25% did not prevent the decline in shell weight. Exaggerating the protein deficiency by increasing the dietary energy level from 2.42 to 3.30 kcal ME/g in graded increments and calcium from 2.56 to 4.94%, respectively, also did not prevent the decline in shell weight as egg weight decreased. Body weight decreased as the protein level decreased. Percent yolk increased while percent shell and albumin decreased as egg size decreased. Within 3 weeks after returning the hens to the control feed (16% protein), there was no significant difference in egg weight, shell weight, or feed consumption. It was concluded that reducing egg size by dietary manipulation of protein, amino acids, energy, and calcium also reduced shell deposition, thus preventing any improvement in shell quality; and that the dietary protein level can be reduced to as low as 11.5% in old hens for at least 1 to 2 months prior to hen disposal without any adverse affect on production. (Key words: egg weight, egg shell quality, amino acids, protein, calcium, energy, aged hens)
EGG SHELL QUALITY AND PRODUCTION VS. NUTRIENT LEVEL AND EGG WEIGHT PROCEDURE
Experiment 2. This experiment was as Experiment 1 except that all hens received diets containing 4.25% calcium instead of 3.00%. Experiment 3. Experiment 3 was similar to Experiment 1 except that the energy contents of the 20, 16, 13.5, and 11.5% protein diets were 2.42, 2.84, 3.06, and 3.30 kcal ME/g, respectively. The calcium level of the diets were 2.56, 3.00, 3.23, and 3.49%, respectively. Experiment 4. This experiment was conducted as Experiment 3 except that the calcium levels of the 20, 16, 13.5, and 11.5% protein diets were 3.63, 4.25, 4.58, and 4.94%, respectively. The calcium levels were adjusted in Experiments 3 and 4 to equalize calcium intake among birds (approximately 3 g for Experiment 3 and 4.25 for Experiment 4). Because hens eat to satisfy their energy requirements, increasing or decreasing the energy level of the diet should exaggerate the deficiency or excess protein condition, and decrease or increase egg weight even further. For example, the energy content of the 2.84 kcal ME/g diet was increased to 3.30 kcal ME/g. This reduced the amount of feed consumed by approximately 14% making the 11.5% protein diet equivalent to 10%. Although these studies were conducted simultaneously, they are divided into four
experiments for simplicity in writing the results and discussion section. Diets 2 and 10 were the same treatments as were diets 6 and 14 (Table 1). Calcium in serum was determined using an atomic absorption spectrophotometer. The calculated dietary composition for all diets are presented in Table 1. The methionine plus cystine levels were maintained at minimum level of .53% in all diets except the 11.5 % protein diet in which they were .42, .42, .41, and .40% for Experiments 1, 2, 3, and 4, respectively. Prior to this study the hens had been fed a commerical type corn-soy diet containing approximately 17% protein. Data from each experiment were subjected to an analysis of variance and the multiple range test of Duncan (1955) as modified by Kramer (1956) was used to identify significant treatment differences. RESULTS AND DISCUSSION
In Experiment 1 the change in egg weight was directly related to the protein content of the diet (Table 2). Decreasing the dietary protein from 16 to 11.5% significantly reduced egg weight within 8 weeks. Although increasing the dietary protein level from 16 to 20% did not significantly increase egg weight, the change in egg weight was significandy greater for hens fed the 20% protein diet compared to that of hens fed the 13.5 or 11.5% protein diets. Similar effects were observed in Experiment 2 except that within 4 weeks egg weight was significandy reduced for hens fed the 11.5% protein diet. Increasing the dietary calcium level from 3.00 to 4.25% had no influence on egg weight. When the energy level of the diet was increased from 2.84 to 3.3 kcal ME/g in the 11.5% protein diet, the change in egg weight was 38% greater in Experiment 3 than in Experiment 1 and 95% greater in Experiment 4 than in Experiment 2. This indicated that increasing the energy content of the 11.5% protein diet exaggerated tiie protein deficiency. When the dietary protein level was reduced from 16 to 11.5%, egg weight was significantly reduced within 4 weeks in Experiment 4 and within 6 weeks in Experiment 3. The numerical change in shell weight was directly related to the protein content of the diet (Table 3). Decreasing the dietary protein from 16 to 11.5% significantly reduced shell weight within 8 weeks _n Experiments 1 and 2. Increasing the dietary protein from 16 to 20% or decreasing the dietary protein from 16 to 13.5%
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Experiment I. One hundred and sixty individually caged Babcock hens 14.5 months in lay were randomly divided into 4 equal groups and fed diets containing 20, 16, 13.5, or 11.5% protein for 8 weeks during August and September. The diets contained 2.84 kcal ME/g, 3.00% calcium, and .65% phosphorus. Egg weight, shell weight, and specific gravity were determined on eggs laid during a 4-day period prior to initiation of the experiment and at 2-week intervals thereafter. Body weight was determined both at the beginning and at termination of the experiment. Egg production and feed consumption were also determined. At the end of 8 weeks, blood was drawn by anterior heart puncture from 20 hens per treatment; yolk weight and interval between oviposition were determined on eggs laid during a 5-day period. The hens were returned to the control diet (16% protein) and feed consumption, egg weight, shell weight, and specific gravity were determined at 2 or 3-week intervals for 6 weeks.
2039
2040
ROLAND, SR. TABLE 1. Composition of dietary treatments'3 Experiment 2
Experim ent 1
Proteinb Metab. energy Calcium
2
3
4
5
6
7
8
20.00 2838.00 3.00
16.00 2838.00 3.00
13.50 2828.00 3.00
11.50 2838.00 3.00
20.00 2838.00 4.25
16.00 2838.00 4.25
11.50 2838.00 4.25
.33 .65
.28 .54 .83
.28 .54 .85
1.01 1.71
.22 .42 .51 .75 .47 .14 .58
.33 .64
.65 .22 .81
.31 .53 .64 .90 .55 .18 .68
13.50 2838.00 4.25 . .31
1.40
1.20
1.04
.48
.38
.32
1.73 1.01 1.01
1.48 .77 .82
Met
Met + Cys. Lysine Arginine Threonine Tryptophan Phe. Phe. + Tyr.
1.13 1.44
Leucine Isoleucine Valine
.22 .42 .51 .75 .47 .15 .58
1.39
1.19
1.04
.27
.48
.38
.32
.27
1.32
1.18
1.45
1.30
1.17
.63 .69
.52 .59
1.70 1.02 1.01
.78 .81
.64 .69
.52 .59
1.11
.81 .28
His
1.01 1.70
.65 .22 .81
.53 .66 .91 .55 .18 .68
1.15 1.45
1.12
.81 .29
Experimenl : 3
Protein" Metab. energy Calcium Met
Met + Cys. Lysine Arginine Threonine Tryptophan Phe. Phe. + Tyr. His
Leucine Isoleucine Valine
Experiment 4
9
10
11
12
13
14
15
16
20.00 2420.00 2.56
16.00 2838.00 3.00
13.50 3058.00 3.23
11.50 3300.00 3.49
20.00 2420.00 3.63
16.00 2838.00 4.25
13.50 3058.00 4.58
11.50 3300.00 4.94
.33 .65
.28 .54 .83
.28 .54 .85
1.01 1.70
.22 .41 .53 .76 .47 .15 .58
.33 .65
.65 .22 .81
.31 .53 .66 .91 .55 .18 .68
1.40
1.19
1.03
.48
.38
.32
1.71 1.01 1.01
1.48 .77 .82
1.14 1.44 .81 .28
1.11
1.01 1.70
.65 .22 .81
.31 .53 .68 .92 .55 .18 .60
.21 .40 .56 .77 .47 .15 .58
1.39
1.18
1.02
.28
.48
.38
.32
.28
1.30
1.14
1.45
1.26
1.10
.64 .69
.53 .59
1.71 1.01 1.01
.78 .81
.65 .69
.54 .59
1.14 1.44 .81 .28
1.12
All diets contained .14% Na, .21% Cl, 2.5% alfalfa meal, .65% total phosphorus, and .5% micromix. Corn, soybean meal, dicalcium phosphate, limestone, poultry fat, DL-methionine, and sand varied in the diets depending upon the above specifications. The micromix added at the rate of 227 g/wt supplies the following per kilogram of finished feed: vitamin A, 7,339 USPU; vitamin D 3 , 2,200 ICU; vitamin E, 8.0 IU; menadione dimethypyrimidnol bisulfite, 2.0 mg; riboflavin, 5.5 mg; pantothenic acid, 13.0 mg; niacin, 36; choline, 499; vitamin B 1 2 , .02 mg; folic acid, .5 mg; thiamine, 1.0 mg; pyridoxine, 2.2 mg; ethoxyquin, 125 mg; manganese, 65.0; iodine, 1.0 mg; iron, 55 mg; copper, 6.0 mg; zinc, 55 mg; cobalt, .20 mg. All units are percent except metabolizable energy which is expressed as kcal/kg.
had no significant influence on shell weight in Experiments 1 or 2. Increasing the dietary calcium level from 3.00 to 4.25% did not prevent the decline in shell weight as egg weight declined. When the energy level was increased, as protein content of the diet decreased (Experiments 3 and 4), the influence on shell weight was very similar to that of the hens in Experiments 1 and 2. Increasing
the calcium level in Experiment 4 also did not prevent the decline in shell weight as egg size decreased. Decreasing the dietary protein level below 16% did not significantly improve egg specific gravity (shell quality) in Experiments 1 or 2 (Table 4). Hens fed the 11.5% protein diets (Experiment 1) had a significantly lower egg specific gravity at the end of 2 weeks compared
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1
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2042
ROLAND, SR. TABLE 4. Egg specific gravity as influenced by protein (Prot), calcium (Ca), and energy (ME)
Experiment
Specific gravity (weeks)
Treatment Prot
Ca
ME
4
6
8
Average
1.078 a 1.079 a 1.077 a 1.077 a 1.076 a 1.079 a 1.077 a 1.078 a 1.077t>c 1.079 a b c 1.076 c 1.081 a 1.077t>c 1.079 a b c 1.080 ab 1.078 a b c
1.079 a 1.080 a 1.079 a 1.077 a 1.079 a 1.080 a 1.078 a 1.079 a
1.077 a 1.078 a 1.076 a 1.077 a 1.077 a 1.077 a 1.077 a 1.075 a
1.078 a 1.079 a 1.078 a 1.077 a 1.078 a 1.079 a 1.078 a 1.078 a
1.078 ab 1.080 ab 1.076 b 1.083 a 1.078 b 1.080 ab 1.081 a b 1.080 ab
1.077 a b 1.078 a 1.073 b 1.080 a 1.077 ab 1.077 ab 1.078 a b 1.077 a b
1.078 a b 1.079 a b 1.076 b 1.081 a 1.078 a b 1.079 a b 1.080 a 1.078 a b
(%)
<%)
(kcal/g)
1 1 1 1 2 2 2 2
20.0 16.0 13.5 11.5 20.0 16.0 13.5 11.5
3.00 3.00 3.00 3.00 4.25 4.25 4.25 4.25
2.84 2.84 2.84 2.84 2.84 2.84 2.84 2.84
1.080 ab 1.081 a 1.079 ab 1.077b 1.079 ab 1.081 a 1.079 ab 1.079 ab
3 3 3 3 4 4 4 4
20.0 16.0 13.5 11.5 20.0 16.0 13.5 11.5
2.56 3.00 3.23 3.49 3.63 4.25 4.58 4.94
2.42 2.84 3.06 3.30 2.42 2.84 3.06 3.30
1.079 a 1.081 a 1.078 a 1.081 a 1.080 a 1.081 a 1.082 a 1.079 a
' ' Values followed by different letters in the same column within Experiments 1 and 2 or Experiments 3 and 4 are significantly different (P<.05).
significant influence on egg specific gravity, there was a trend for the average specific gravity of eggs from hens fed the 20% protein diet to be numerically lower than that of hens fed the 16% protein diet in all four experiments. The average egg production during the 8-week experiment was not significantly influenced by dietary treatments in Experiments 1 or 2 but was in Experiments 3 and 4 (Table 5). Although egg production during the first 4 weeks of Experiments 2, 3, and 4 was not significantly influenced, egg production was significantly influenced during the 6- and 8week test period. When the protein content of the diet was reduced from 16 to 11.5% and energy increased from 2.84 to 3.30 kcal ME/g in Experiments 3 and 4, egg production was significantly reduced within 6 weeks in both experiments. Increasing the dietary calcium level from 3.00 to 4.25% or to equivalent levels had no significant influence on egg production. The dietary treatments used in Experiment 1 did not significantly influence feed consumption during any of the biweekly test periods; however, decreasing the dietary protein from 16 to 11.5% significantly reduced the feed consumed during the experiment (Table 6). Decreasing the dietary protein from 16 to 11.5% in Experiment 2 had no significant influence on feed con-
sumption. The feed consumption of hens in Experiments 3 and 4 was directly related to the energy content of the diet. In Experiment 3, the hens ability to regulate feed intake according to the energy level of the diet was demonstrated, since the average feed consumption of hens receiving each energy level was significantly different from the others. The energy consumed per hen per day varied little, ranging from 281 to 294 kcal ME. Although hens are reported to be able to regulate their protein intake when given access to multiple isocaloric diets containing various levels of protein (Holcombe et al, 1976), the hens in these studies appeared to have no tendency to overconsume energy to increase protein consumption. The grams of protein consumed per hen per day in Experiments 3 and 4 ranged from 9.8 to 22.5. Since the hens in Experiments 1 and 2 were consuming approximately 100 g of feed per hen in each treatment, the percent dietary protein levels and actual grams of protein consumed per day were very similar. Serum calcium was significantly decreased when the dietary protein level was reduced from 16 to 11.5% in Experiments 1 and 2 (Table 7). Increasing the calcium level from 3 to 4.25% had no significant influence on serum calcium. It has been reported (Sloan et al., 1974) that serum calcium levels in hens were
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2
EGG SHELL QUALITY AND PRODUCTION VS. NUTRIENT LEVEL AND EGG WEIGHT
2043
TABLE 5. Egg production as influenced by protein (Prot), calcium (Ca), and energy (ME) Experiment
Egg production (weeks)
Treatment Prot
Ca
ME
2
4
6
8
Average
(%)
20.0 16.0 13.5 11.5 20.0 16.0 13.5 11.5
3.00 3.00 3.00 3.00 4.25 4.25 4.25 4.25
(kcal/kg) 2.84 2.84 2.84 2.84 2.84 2.84 2.84 2.84
69.3 a 70.5 a 73.0 a 67.9 a 69.6 a 70.4 a 70.5 a 69.5 a
74.4 a 68.9 a b 74.6 a 67.7 a b 64.8b 72.3 a b 66.4 a b 68.6 a b
67.2 a b 66.8 a b 66.4 a b 60.9 a b 66.3ab 70.4 a 59.5 b 60.0 b
54.9 a b 55.7 a b 60.4 a b 60.1ab 60.5 a b 65.3 a 57.5 a b 50.2 b
67.0 a 65.5 a 68.6 a 64. l a 65.3 a 69.6 a 63.5 a 62.1 a
3 3 3 3 4 4 4 4
20.0 16.0 13.5 11.5 20.0 16.0 13.5 11.5
2.56 3.00 3.23 3.49 3.63 4.25 4.58 4.94
2.42 2.84 3.06 3.30 2.42 2.84 3.06 3.30
64.5 b 70.5 a b 67.0b 65.7b 66.8b 70.4 a b 73.0 a b 77.7 a
66.6 a 68.9 a 67.3 a 65.0 a 69.8 a 72.3 a 71.8 a 73.0 a
67.3 a 66.8 a 60.7 a 50.lb 63.4 a 70.4 a 62.3 a 50.9 b
56.3 a b 55.7 a b 50.5 a b c 37.6 c d 48.2abc 65.3 a 58.0 a b 34.1 d
63.7 a b 65.5ab 61.4abc 54.6 C 62.1abc 69.6 a 66.3ab 58.9bc
a ' '""Values followed by different letters in the same column with Experiments 1 and 2 or Experiments 3 and 4 are significantly different (P<.05).
n o t related t o egg specific gravity. Hens producing eggs with a high specific gravity h a d n o greater serum calcium levels than hens producing eggs with a low specific gravity. However, t h e results of E x p e r i m e n t s 1 a n d 2 revealed t h a t die quantity of calcium in serum m a y be
related t o t h e quality of shell secreted b y an individual hen. Since egg weight decreased as shell weight declined, egg specific gravity w o u l d remain t h e same, t h u s losing any relationship of serum calcium t o egg specific gravity (shell quality). T h e dietary t r e a t m e n t s used in Ex-
TABLE 6. Feed consumption as influenced by protein (Prot), calcium (Ca), and energy (ME) Experiment
Feed consumption (weeks)
Treatment Prot
Ca
ME
2
4
(%)
(%)
1 1 1 1 2 2 2 2
20.0 16.0 13.5 11.5 20.0 16.0 13.5 11.5
3.00 3.00 3.00 3.00 4.25 4.25 4.25 4.25
(kcal/g) 2.84 2.84 2.84 2.84 2.84 2.84 2.84 2.84
100.6b 109.6 a b 109.5 a b 100.3 b 107.4 a b 111.5a 104. l a b 107.7 a b
105.3 a b 102.3 a b 102.6 a b 97.8 b 103.7 a b 109.9 a 99.0 a b 101.3 a b
3 3 3 3 4 4 4 4
20.0 16.0 13.5 11.5 20.0 16.0 13.5 11.5
2.56 3.00 3.23 3.49 3.63 4.25 4.58 4.94
2.42 2.84 3.06 3.30 2.42 2.84 3.06 3.30
107.9 a b c 109.6 a b c 101.5c 104.9bc 115.3a 111.5 a b 106.1 a b c 111.2 a b
112.9 a 102.3 b c 96.9 c d 85.4 e 115.2 a 109.9 a b 100.7C 90.6 d e
6
• (g/hen/day) 104.5 a 112.2 a 104.9 a 99.6 a 106.8 a 107.4 a 99.7 a 110.8 a 121.3 a 112.2 a b 95.2 d 83.6 e 116.1 a b 107.4 b c 98.8 c d 82.0 e
Average
8
87.8 a b 91.0 a b 85.6 a b 83.3 b 91.0 a b 94.8 a 86.8 a b 83.1 b
99.8abc 103.4 a b 100.5 a b c 95.2abc 102.2 a b c 105.9 a 97.4bc 100.7 a bc
102.2 a 91.0b 81.5c 66.1d 100.1 a b 94.8 a b 75.9C 57.7 d
111.1* 103.4b 94.3C 85.0 d 112.4 a 105.9 a b 95.4C 85.4 d
3 h p n £
> ' > > Values followed by different letters in the same column with Experiments 1 and 2 or Experiments 3 and 4 are significantly different (P-C.05).
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(%) 1 1 1 1 2 2 2 2
2044
ROLAND, SR. TABLE 7. Serum calcium and change in body weight as influenced by dietary protein Prot), calcium (Ca), and energy (ME) Change
Experiment
Treatment Prot
Ca
ME
Serum calcium
body weight
(%)
(kcal/g)
(mg/lOOml)
(g)
20.0 16.0 13.5 11.5 20.0 16.0 13.5 11.5
3.00 3.00 3.00 3.00 4.25 4.25 4.25 4.25
2.84 2.84 2.84 2.84 2.84 2.84 2.84 2.84
25.8 a b 26.3 a 24.7ab 22.2t> 24.8 a b 26.5 a 27.1 a 22.5 b
-36a -62a -108ab -168bc -72a -44a -112ab -208C
3 3 3 3 4 4 4 4
20.0 16.0 13.5 11.5 20.0 16.0 13.5 11.5
2.56 3.00 3.23 3.49 3.63 4.25 4.58 4.94
2.42 2.84 3.06 3.30 2.42 2.84 3.06 3.30
25.02 26.3 a 24.4 a 23.8 a 23.3 a 26.5 a 26.2 a 24.8 a
-42a -62a -128ab -162b -67a -44a -105ab -251c
a,b,c Values followed by different letters in the same column within Experiments 1 and 2 or 3 and 4 are significantly different (P<.05).
periments 3 and 4 had no significant influence on serum calcium. Reducing the dietary protein level from 16 to 11.5% significantly increased the change in body weight (Table 7). Increasing the calcium level of the diet from 3.00 to 4.25% had no influence on hen weight. The results of Experiments 3 and 4 were similar to that of 1 and 2 except that increasing the dietary calcium level from 3.49% (equivalent to 3.00%) to 4.94% (equivalent to 4.25%) significantly decreased body weight. This may have been because of the slightly lower percentage of methionine plus cystine level in the 4.94% calcium diet (Experiment 4) compared to that in the 3.49% calcium diet (Experiment 3). Most of the decrease in egg weight produced by reducing the dietary protein from 16 to 11.5% was due to a reduction in the secretion of albumen (Experiments 1 to 4, Table 8). For example, in Experiment 4 egg weight decreased 7.36 g with 70% (5.18 g) due to a decrease in albumen weight and 19% and 11% was due to a decrease in yolk weight and shell weight, respectively. However, when the loss in shell, albumen, and yolk weights were divided by die original weight, the respective percent decreases
in shell weight and albumen weight were approximately the same (14.72% and 12.85%) and the percentage decrease in yolk was only about one-half as great (7.23%). The dietary treatments used in Experiments 1 to 4 had no significant influence on intervals between oviposition times. This suggested that the decrease in shell deposited on eggs from hens fed the 11.5% protein diets was not due to a decrease in the time the egg stays in the reproductive tract but to a decrease in the rate of shell deposition. The average interval between oviposition times of eggs laid before 1200 hr or after 1200 hr was 26.08 hr vs. 28.31 hr, respectively, and was significandy different (P<.01). Reducing the dietary protein from 16 to 11.5% and increasing the energy content of the diet from 2.84 to 3.30 kcal ME/g significandy reduced the percentage of eggs laid before 1200 hr (Experiments 3 and 4, Table 8). Within 3 weeks after all hens were returned to the diet containing 16% protein, 3.00% calcium and 2.84 kcal ME/g, the decrease in egg weight and shell weight between hens previously fed the 16 and 11.5% protein diets had disappeared. Within 2 weeks there were no significant differences in feed consumption
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(%) 1 1 1 1 2 2 2 2
EGG SHELL QUALITY AND PRODUCTION VS. NUTRIENT LEVEL AND EGG WEIGHT
2045
TABLE 8. Yolk weight,1 albumin weight, and ovipostion time as influenced by dietary protein (Prot), calcium (Ca), and energy (ME)
Experiment
Prot
Ca
ME
(%>
(kcal/g)
20.0 16.0 13.5 11.5 20.0 16.0 13.5 11.5
3.00 3.00 3.00 3.00 4.25 4.25 4.25 4.25
2.84 2.84 2.84 2.84 2.84 2.84 2.84 2.84
3 3 3 3 4 4 4 4
20.0 16.0 13.5 11.5 20.0 16.0 13.5 11.5
2.56 3.00 3.23 3.49 3.63 4.25 4.58 4.94
2.42 2.84 3.06 3.30 2.42 2.84 3.06 3.30
% Eggs laid after 1200 hr
Albumen weight
40.8 a 38.9 a b 39.2 a b 36.3 C 39.8 a b 40.3a 39.4 a b 38.lbc
58.6 a 66.4 a 54.2 a 50.8 a 62.3 a 52.2 a 60.6 a 59.6 a
41.4 a 33.6 a 45.8 a 49.2 a 37.7 a 47.8 a 39.4 a 40.4 a
38.9 a 38.9 a 39.5 a 36.4b 39.5 a 40.3a 39.1 a 35.lb
57.2 a 66.4 a 54.7 a b 38.3bc 54.0 a b 52.2 a b 51.5 a b 33.3 C
42.8 C 33.6 C 45.3bc 61.7ab 46.0bc 47.8bc 48.5bc 66.7 a
{a\
18.9 a b 18.7*b 18.9 a b 18.4b 19.6 a 18.9 a b 19.2 a b 18.5b 18.6 a b 18.7 a b 19.0 a 18.3ab 18.4 a b 18.9 a 18.7 a b 17.6b
(g)
' ' Values followed by different letters in the same column within Experiments 1 and 2 or 3 or 4 are significantly different (P<.05). 1 Egg weight and shell weight data are shown in Table 1.
between treatments in Experiments 1, 2, and 3. In Experiment 4, however, feed consumption and egg production were still significantly lower after 4 weeks for hens fed the 11.5% protein diet when compared to that of hens fed the 16% protein diet. The results of these studies demonstrated that no improvement in shell quality occurs when egg size is reduced by the dietary manipulations of protein, energy, and calcium used in these experiments, because the amount of shell deposited decreased at a rate equal to or greater than the rate of decrease in either albumen or yolk. Since the quantity of shell deposited on the egg after 3 months of lay remains fairly constant or increased very slightly (Roland, 1979), it is believed that the increase in egg size above that achieved at approximately 3 months of lay does not influence the quality of shell deposited. However, the significant decrease in the amount of shell deposited as egg size decreased indicates a definite adverse effect of decreasing egg size on shell deposition. These studies do not preclude the possibility that reducing egg size by other methods would not have the same effect on the
quantity of shell deposited. Although no improvement occurred in egg specific gravity as egg size decreased, the reduction in egg size could have a beneficial effect on reducing egg breakage. The larger the egg the more likely it is to break during handling. Forty-five percent of total breakage occurs in extra large eggs while only 27.7% occurs in large eggs (Bramhall et ai, 1973). Reducing the dietary protein from 16 to 11.5% reduced egg weights (5.01 g) significantly more for hens laying extra large and jumbo eggs prior to the treatments than for those hens laying eggs in the large or smaller egg categories (2.36 g). The results also suggest the the protein content of the diet of hens laying approximately 70% can be reduced to as low as 11.5% in commercial-type corn-soy diets containing 2.84 kcal ME/g, .42% methionine plus cystine, and .52% lysine for at least 1 to 2 months prior to hen disposal without adversely affecting egg production. This could result in substantial savings in feed cost, since it is well below the protein and sulfur amino acid requirement as stated by the NRC (1977) and also below
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(%) 1 1 1 1 2 2 2 2
Yolk weight
% Eggs laid before 1200 hr
2046
ROLAND, SR.
protein and a m i n o acid levels typically fed t o commercial layers. REFERENCES
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Bramhall, E. L., M. H. Swanson, and G. Johnston, 1973. Egg shell damage during handling. Poultry Dig. 32:12-13. Deaton, J. W., and J. H. Quisenberry, 1965. Effects of dietary protein level on performance of four commercial egg production stocks. Poultry Sci. 44:936-942. Duncan, D. B., 1955. Multiple range and multiple F tests. Biometrics 11:1—42. Fowler, C.J.S., 1972. How management can affect egg size. Shaver Focus 2:1—2. Gardner, F. A., and L. L. Young, 1972. The influence of dietary protein and energy levels on the protein and lipid content of the hen's egg. Poultry Sci. 51:994-997. Hochreich, H. J., C. R. Douglas, I. H. Kidd, and R. H. Harms, 1958. The effect of dietary protein and energy levels upon production of Single Comb White Leghorn hens. Poultry Sci. 37:949-953. Holcombe, D. J., D. A. Roland, Sr., and R. H. Harms, 1976. The ability of hens to regulate protein intake when offered a choice of diets containing different levels of protein. Poultry Sci. 55: 1731-1737. Kramer, C. Y., 1956. Extension of multiple range test
to group means with unequal numbers of replication. Biometrics 12:307-310. National Research Council, 1977. Nutrient requirements of poultry, 7th rev. ed. Nat. Acad. Sci. Washington, DC. Reid, B. L., 1976. Estimated daily protein requirements of laying hens. Poultry Sci. 55:1641-1645. Roland, D. A., Sr., 1979. Factors influencing shell quality of aging hens. Poultry Sci. 58:774-777. Roland, D. A., Sr., C. E. Putnam, and R. L. Hilburn, 1978. The influcence of age on ability of hens to maintain egg shell calcification when stressed with inadequate dietary calcium. Poultry Sci. 57:1616-1621. Roland, D. A., Sr., D. R. Sloan, and R. H. Harms, 1975. The ability of hens to maintain calcium deposition in the egg shell and egg yolk as the hen ages. Poultry Sci. 54:1720-1723. 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. Smith, R. E., 1967. The utilization of poultry diets containing high, low and intermediate levels of protein of identical amino acid pattern. Poultry P.-i. 46:730-735. Thayer, R. H., G. E. Hubbell, J. A. Kasbohm, R. D. Morrison, and C. E. Nelson, 1974. Daily protein intake requirement of laying hens. Poultry Sci. 53:354-364.