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Dietary Phosphorus Needs of Laying Hens1
Dietary Phosphorus Needs of Laying Hens1 W. J. OWINGS, J. L. SELL and S. L. BALLOUN Department of Animal Science, Iowa State University, Ames, Iowa 50011 (Received for publication April 22, 1977)
Poultry Science 56:2056-2060, 1977
There is considerable u n c e r t a i n t y a b o u t t h e p h o s p h o r u s (P) r e q u i r e m e n t s of t h e laying h e n . T h e National Research Council ( 1 9 7 1 ) recomm e n d e d a dietary P level of 0.6% and indicated t h a t a p o r t i o n of this P should be in organic form. V o h r a et al. ( 1 9 7 4 ) reviewed t h e literat u r e and suggested t h a t 0.4% P in laying hen rations was a d e q u a t e b u t gave n o indication as t o sources of t h e P. Since Pepper et al. ( 1 9 5 9 ) reported t h a t rations containing 0.38% P, all of plant origin with 0 . 1 1 % as n o n - p h y t i n P, were a d e q u a t e for laying hens, several papers have been published indicating t h a t t h e h e n ' s P requirement is less t h a n t h a t r e c o m m e n d e d b y t h e National Research Council ( 1 9 7 1 ) (Pepper et al. 1 9 6 9 ; H u n t a n d C h a n c e y , 1 9 7 0 ; and S u m m e r s et al., 1 9 7 6 ) . However, Waldroup et al. ( 1 9 6 7 ) , Garlich et al. ( 1 9 7 5 ) and Garlich and Parkhurst ( 1 9 7 6 ) f o u n d t h a t levels of 0.34 t o 0.44% P were n o t satisfactory for maintaining high rates of egg p r o d u c t i o n and health of t h e hens. T h e research r e p o r t e d h e r e was c o n d u c t e d t o
'Journal Paper No. J-8811 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa. Project No. 1984.
d e t e r m i n e t h e influence of relatively l o w P levels o n laying hen performance and t o o b t a i n m o r e definitive information a b o u t t h e P req u i r e m e n t s of t h e h e n . METHODS AND MATERIALS T w o different commercial strains were used in t h e t w o e x p e r i m e n t s . T h e hens were k e p t in wire laying hen cages (25 X 4 5 cm.), t w o hens per cage, and were given feed and water ad lib. through t h e e x p e r i m e n t s . Experiment 1. Each of three ration treatm e n t s was assigned t o five experimental units, and each e x p e r i m e n t a l u n i t consisted of four cages containing eight hens 22 weeks of age. T h e ration t r e a t m e n t s were comprised of three levels of P. T h e ingredient composition of t h e low-P, basal ration A is s h o w n in Table 1. O n a calculated basis, this ration contained 0.42% total P (TP), 0.19% available P ( A P as nonp h y t i n P) and 0.09% inorganic P (IP). T h e remaining t w o ration t r e a t m e n t s were o b t a i n e d by substituting defluorinated rock p h o s p h a t e (18% P) for corn t o increase t h e dietary P level b y i n c r e m e n t s of 0.09%. T h e trial was conducted for 1 4 0 days. Egg p r o d u c t i o n , feed c o n s u m p t i o n , m o r t a l i t y a n d egg weight d a t a were recorded.
2056
Downloaded from http://ps.oxfordjournals.org/ at University of Bath, Library on June 19, 2015
ABSTRACT Two experiments were conducted with commercial strain, White Leghorn laying hens, kept in wire cages, to determine the effect of low dietary phosphorus (P) levels on production characteristics. In experiment 1, rations that contained 0.19, 0.28 or 0.37% available P (AP) were fed to 22 week old hens. The total (TP) and inorganic (IP) levels of these rations were 0.42, 0.51, 0.60% and 0.09, 0.18, 0.27%, respectively. All dietary P levels supported a high rate of egg production during the 140-day trial. Ration treatments did not affect feed consumption, feed efficiency or average egg weight. Mortality, however, was slightly higher for hens fed 0.19% AP. The second experiment utilized 47 week old hens of a different strain. A basal ration containing 0.10% AP (0.30% TP all from plant sources) was used as one ration treatment. Three additional treatments were obtained by including defluorinated rock phosphate in the diet to supply 0.09, 0.18 or 0.27% IP. Egg production by hens fed 0.10% AP decreased markedly within four weeks, while egg production by hens fed 0.19% or more AP (0.09% or more IP) continued at a high rate throughout the 56-day trial. Hens fed 0.10% AP also lost considerable body weight and suffered a relatively high death loss. Feed consumption and femur ash were not affected significantly by dietary P. The results indicated that relatively low dietary P levels can fulfill the laying hen's requirement for egg production provided that about 0.19% or more AP is present in the ration. To maintain livability, as well, the AP requirement may be at least 0.28%.
LAYING HEN PHOSPHORUS REQUIREMENT
2057
TABLE 1 .—Ingredient composition of rations used in experiment 1 (Basal A) and experiment 2 (Basal B) Ingredient
Basal A
Basal B 0
0—
0.192 A v a i l a b l
(% of the ration)
Calculated analysis Inorganic P Available P Total P
70 20 7.5 1.0 0.5 0.5 0.5
0.09 0.19 0.42
72.3 18.0 8.0 0.7 0.5 0.5
-
-9
0.28Z A v a i l a b l
x- -
- -X
0.37Z A v a i l a b l
FIG. 1. Influence of dietary phosphorus on rate of egg production—experiment 2.
0.10 0.30
1
Provided the following per kg. of ration: vitamin A 8,000 I.U.j vitamin D 3 1500 I.U.; vitamin B , 2 5 Mg.; riboflavin 5 mg.; pantothenic acid 5 mg.; niacin 15 mg.; choline 325 mg.; and methionine hydroxy analogue 500 mg. 2 Provided the following per kg. of ration: sodium chloride 4.6 g.; manganese 66 mg.; zinc 25 mg.; iron 18 mg.; copper 3 mg.; iodine 1.3 mg.;and cobalt0.28 mg.
Experiment 2. The second experiment was conducted to determine whether the laying hen required any inorganic P in the ration at all. Basal ration B, presented in Table 1, contained
0.30% TP and 0.10% AP but no IP. Three additional ration treatments were obtained by substituting increments of defluorinated rock phosphate for corn. The IP level of the rations was increased by 0.09, 0.18 and 0.27%. Each ration treatment was fed to four experimental units of eight hens each. The hens were 47 weeks of age at the start of the experiment. Egg production, feed consumption, mortality and egg weight data were recorded during the 56-day experiment. Changes in body weight during the experiment were also measured, and the percentage of ash in the fat-free, moisturefree femur was determined at the end of the trial. Thickness of the shells of all eggs produced on the first and last day of the experi-
TABLE 2.—Influence of dietary phosphorus on egg production, feed consumption, feed per dozen eggs, egg weight and mortality — experiment 1 Ration phosphorus, %
Hen-day egg prod., %
Hen-day feed cons., g.
Feed/doz. eggs, kg.
Av. egg weight, g.
Mortality n/40
Inorganic — 0.09 Available - 0.19 Total - 0.42
83.1
104.3
1.52
56.9
9/40
Inorganic — 0.18 Available - 0.28 Total - 0 . 5 1
85.5
106.5
1.50
57.1
5/40
Inorganic — 0.27 Available- 0.37 Total - 0.60
78.6
103.1
1.58
56.4
3/40
5.2
3.6
0.12
1.3
1
Standard error of the means.
Downloaded from http://ps.oxfordjournals.org/ at University of Bath, Library on June 19, 2015
Corn Soybean meal (48% protein) Ground oyster shell Soy oil Vitamin premix 1 Salt premix 2 Defluor. rock phosphate
0- -
2058
W. J. OWINGS, J. L. SELL AND S. L. BALLOUN
ment was also measured. Analyses of varinace were conducted according to methods outlined by Snedecor and Cochran (1971). RESULTS
The average femur ash of hens fed no IP was slightly lower than that of other treatments. The highest level of ash was found in femurs of hens fed 0.18% IP (0.28% AP and 0.48% TP), but there were no significant differences among
DISCUSSION Generally, the data show that relatively low levels of dietary P will support egg production by hens. In both experiments, levels of 0.09% IP (0.19% AP and 0.39% TP) in rations sustained a high rate of efficiency egg production. The results also demonstrated that a ration containing no IP, 0.10% AP and 0.30% TP was not satisfactory for laying hens. For the most part, the data agree with the findings of Pepper et al. (1959) and Pepper et al. (1969) and Hunt and Chancey (1970) in the low levels of P can fulfill die hen's requirement. Pepper et al. (1959) and Pepper et al. (1969) also reported that the P requirement of hens could be fulfilled by rations in which all P was of plant origin. This was not substantiated in the current study. The data presented here indicate that hens require about 0.19—0.20% AP, some of which should be of inorganic origin. Waldroup et al. (1967) also found that approximately 0.19% AP was required by hens, but Summers et al. (1976) suggested that 0.25 to 0.35% AP should be present in laying hen rations. In contrast to the present findings, Garlich et al. (1975) reported that hens fed 0.227% AP (0.39% TP) were unable to maintain normal weight gains and femur density. Garlich and Parkhurst (1976) also found that mortality among hens fed a ration with 0.205% AP (0.44% TP) was excessive, although rate of hen-day egg production was maintained. It should be noted that hens used in the Garlich and Parkhurst (1976) research were in their second cycle of egg production. In the current study, relatively high mortality was observed also when the AP level was only 0.10%. Increasing the AP level to 0.19% with the older hens in experiment two reduced mortality, while in experiment one with younger hens of a different strain, mortality among hens fed 0.19% AP was higher than with AP levels of 0.28% or 0.37%. The data presented herein show that the P requirement as listed by the National Research Council (1971) is higher than necessary to
Downloaded from http://ps.oxfordjournals.org/ at University of Bath, Library on June 19, 2015
Experiment 1. Feeding rations that ranged from 0.19% AP (0.42% TP and 0.09% IP) to 0.42% AP (0.60% TP and 0.27% IP) had no significant effect on rate of egg production, hen-day feed consumption, average egg weight or efficiency of feed utilization (Table 2). Experiment 2. There were no significant ration treatment effects on egg production parameters for the first three weeks of the experiment. However, egg production by hens fed the ration with no IP (0.10% AP and 0.30% TP) decreased markedly during the fourth week (Fig. 1). Rate of egg production by this treatment group contined to decrease through week six, and was significantly (P<0.025) less than that of other treatment groups from week four through eight. Hens fed rations supplemented with 0.09% or more IP maintained egg production throughout the trial. Hen-day feed consumption during the experiment was not affected significandy by P level of the ration (Table 3). Hens fed the ration with no IP lost a noticeable amount of weight, while hens fed rations with added IP underwent little weight change. There were no significant differences among ration treatment groups with respect to average thickness of eggshell at the start of the experiment. By the end of the trial, however, eggs produced by hens fed the ration with no IP had thinner shells than those of other treatment groups. Eggshells produced by hens fed the highest P level had relatively thin shells, although the mean for this treatment group did not differ significantly from those of the remaining ration treatments. There seemed to be an inverse relationship between average egg weight and shell thickness. Hens fed the lowest and highest P levels produced larger eggs than hens fed the intermediate P levels, and eggs from these hens also had the thinnest shells. Therefore, it seems that dietary P may not have exerted a direct effect on shell thickness but may have influenced this parameter indirectly via rate of egg production and (or) egg size.
treatments. Mortality of hens fed the ration with no IP was markedly higher than that of any other treatment group. The mortality occurred primarily during the last three weeks of the experiment and presumably was related to the development of P deficiency.
0.016
105.7
4.7
Inorganic - 0.27 Available - 0 . 3 7 Total-0.57
2
1
0.328
101.5
0.326
Standard error of the means.
Means not followed by same superscript letter differ significantly (P<0.05).
20
+36"
0.324
Inorganic - 0.18 Available - 0.28 Total - 0.48
-5*
103.1
Inorganic - 0.09 Available - 0.19 Total-0.39
0.338
56.6 a b
59.3a
0.352*b
0.318 a b
1.1
55.0 b
0.3 7 2 b
0.020
58.5 a b
Av. egg at 8 wks
0.29 5 a
Shell thickness, mm. 8 wks. Start
105.4
-173 b l
Change in body wt., g.
Inorganic — none Available-0.10 Total - 0 . 3 0
Phosphorus, %
Hen-day feed cons., g.
TABLE 3 .—Influence of dietary phosphorus on feed consumption, body weight, shell thick femur ash and mortality — experiment 2
rom http://ps.oxfordjournals.org/ at University of Bath, Library on June 19, 2015
2060
W. J. OWINGS, J. L. SELL AND S. L. BALLOUN
support egg production providing that the TP present in laying hen rations is comprised of at least 0.19% AP. The data also suggest that approximately 0.28% AP may be needed to reduce mortality. ACKNOWLEDGMENT The assistance of Albert Kagan, Gary Johnson and Wayne White, Department of Animal Science, is gratefully acknowledged.
Downloaded from http://ps.oxfordjournals.org/ at University of Bath, Library on June 19, 2015
REFERENCES Garlich, J. D., R. L. James and J. B. Ward, 1975. Effects of short term phosphorus deprivation on laying hens. Poultry Sci. 54:1193-1199. Garlich, J. D., and C. R. Parkhurst, 1976. Phosphorus for laying hens. Feedstuffs 48( 1): 3 7. Hunt, J. R., and H. W. R. Chancey, 1970. Influence of dietary phosphorus on shell quality. Brit. Poultry Sci. 11:259-267. National Research Council, National Academy of
Sciences, Washington, D.C., 1971. Nutrient Requirements of Domestic Animals. I. Nutrient Requirements of Poultry. 6th revised edition. Pepper, W. F., S. J. Slinger, J. D. Summers and G. C. Ashton, 1959. On the phosphorus requirements of chickens for egg production and hatchability. Can. J. Anim. Sci. 39:182-192. Pepper, W. F., J. D. Summers, E. T. Moran and H. S. Bayley, 1969. The influence of steam pelleting on the utilization of phosphorus by the laying hen. Poultry Sci. 48:1055-1060. Snedecor, G. W., and W. G. Cochran, 1971. The Iowa State University Press, Ames, Iowa. Summers, J. D., R. Grandhi and S. Leeson, 1976. Calcium and phosphorus requirements of the laying hens. Poultry Sci. 55:402-413. Vohra, P., F. H. Kratzer and L. C. Norris, 1974. Phosphorus levels for poultry feeds. Feedstuffs 46(8):44-45. Waldroup, P. W., C. F. Simpson, B. L. Damron and R. H. Harms, 1967. The effectiveness of plant and inorganic phosphorus in supporting egg production in hens and hatchability and bone development in chick embryo. Poultry Sci. 46:659—664.
Poultry Science 56:2056-2060, 1977
There is considerable u n c e r t a i n t y a b o u t t h e p h o s p h o r u s (P) r e q u i r e m e n t s of t h e laying h e n . T h e National Research Council ( 1 9 7 1 ) recomm e n d e d a dietary P level of 0.6% and indicated t h a t a p o r t i o n of this P should be in organic form. V o h r a et al. ( 1 9 7 4 ) reviewed t h e literat u r e and suggested t h a t 0.4% P in laying hen rations was a d e q u a t e b u t gave n o indication as t o sources of t h e P. Since Pepper et al. ( 1 9 5 9 ) reported t h a t rations containing 0.38% P, all of plant origin with 0 . 1 1 % as n o n - p h y t i n P, were a d e q u a t e for laying hens, several papers have been published indicating t h a t t h e h e n ' s P requirement is less t h a n t h a t r e c o m m e n d e d b y t h e National Research Council ( 1 9 7 1 ) (Pepper et al. 1 9 6 9 ; H u n t a n d C h a n c e y , 1 9 7 0 ; and S u m m e r s et al., 1 9 7 6 ) . However, Waldroup et al. ( 1 9 6 7 ) , Garlich et al. ( 1 9 7 5 ) and Garlich and Parkhurst ( 1 9 7 6 ) f o u n d t h a t levels of 0.34 t o 0.44% P were n o t satisfactory for maintaining high rates of egg p r o d u c t i o n and health of t h e hens. T h e research r e p o r t e d h e r e was c o n d u c t e d t o
'Journal Paper No. J-8811 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa. Project No. 1984.
d e t e r m i n e t h e influence of relatively l o w P levels o n laying hen performance and t o o b t a i n m o r e definitive information a b o u t t h e P req u i r e m e n t s of t h e h e n . METHODS AND MATERIALS T w o different commercial strains were used in t h e t w o e x p e r i m e n t s . T h e hens were k e p t in wire laying hen cages (25 X 4 5 cm.), t w o hens per cage, and were given feed and water ad lib. through t h e e x p e r i m e n t s . Experiment 1. Each of three ration treatm e n t s was assigned t o five experimental units, and each e x p e r i m e n t a l u n i t consisted of four cages containing eight hens 22 weeks of age. T h e ration t r e a t m e n t s were comprised of three levels of P. T h e ingredient composition of t h e low-P, basal ration A is s h o w n in Table 1. O n a calculated basis, this ration contained 0.42% total P (TP), 0.19% available P ( A P as nonp h y t i n P) and 0.09% inorganic P (IP). T h e remaining t w o ration t r e a t m e n t s were o b t a i n e d by substituting defluorinated rock p h o s p h a t e (18% P) for corn t o increase t h e dietary P level b y i n c r e m e n t s of 0.09%. T h e trial was conducted for 1 4 0 days. Egg p r o d u c t i o n , feed c o n s u m p t i o n , m o r t a l i t y a n d egg weight d a t a were recorded.
2056
Downloaded from http://ps.oxfordjournals.org/ at University of Bath, Library on June 19, 2015
ABSTRACT Two experiments were conducted with commercial strain, White Leghorn laying hens, kept in wire cages, to determine the effect of low dietary phosphorus (P) levels on production characteristics. In experiment 1, rations that contained 0.19, 0.28 or 0.37% available P (AP) were fed to 22 week old hens. The total (TP) and inorganic (IP) levels of these rations were 0.42, 0.51, 0.60% and 0.09, 0.18, 0.27%, respectively. All dietary P levels supported a high rate of egg production during the 140-day trial. Ration treatments did not affect feed consumption, feed efficiency or average egg weight. Mortality, however, was slightly higher for hens fed 0.19% AP. The second experiment utilized 47 week old hens of a different strain. A basal ration containing 0.10% AP (0.30% TP all from plant sources) was used as one ration treatment. Three additional treatments were obtained by including defluorinated rock phosphate in the diet to supply 0.09, 0.18 or 0.27% IP. Egg production by hens fed 0.10% AP decreased markedly within four weeks, while egg production by hens fed 0.19% or more AP (0.09% or more IP) continued at a high rate throughout the 56-day trial. Hens fed 0.10% AP also lost considerable body weight and suffered a relatively high death loss. Feed consumption and femur ash were not affected significantly by dietary P. The results indicated that relatively low dietary P levels can fulfill the laying hen's requirement for egg production provided that about 0.19% or more AP is present in the ration. To maintain livability, as well, the AP requirement may be at least 0.28%.
LAYING HEN PHOSPHORUS REQUIREMENT
2057
TABLE 1 .—Ingredient composition of rations used in experiment 1 (Basal A) and experiment 2 (Basal B) Ingredient
Basal A
Basal B 0
0—
0.192 A v a i l a b l
(% of the ration)
Calculated analysis Inorganic P Available P Total P
70 20 7.5 1.0 0.5 0.5 0.5
0.09 0.19 0.42
72.3 18.0 8.0 0.7 0.5 0.5
-
-9
0.28Z A v a i l a b l
x- -
- -X
0.37Z A v a i l a b l
FIG. 1. Influence of dietary phosphorus on rate of egg production—experiment 2.
0.10 0.30
1
Provided the following per kg. of ration: vitamin A 8,000 I.U.j vitamin D 3 1500 I.U.; vitamin B , 2 5 Mg.; riboflavin 5 mg.; pantothenic acid 5 mg.; niacin 15 mg.; choline 325 mg.; and methionine hydroxy analogue 500 mg. 2 Provided the following per kg. of ration: sodium chloride 4.6 g.; manganese 66 mg.; zinc 25 mg.; iron 18 mg.; copper 3 mg.; iodine 1.3 mg.;and cobalt0.28 mg.
Experiment 2. The second experiment was conducted to determine whether the laying hen required any inorganic P in the ration at all. Basal ration B, presented in Table 1, contained
0.30% TP and 0.10% AP but no IP. Three additional ration treatments were obtained by substituting increments of defluorinated rock phosphate for corn. The IP level of the rations was increased by 0.09, 0.18 and 0.27%. Each ration treatment was fed to four experimental units of eight hens each. The hens were 47 weeks of age at the start of the experiment. Egg production, feed consumption, mortality and egg weight data were recorded during the 56-day experiment. Changes in body weight during the experiment were also measured, and the percentage of ash in the fat-free, moisturefree femur was determined at the end of the trial. Thickness of the shells of all eggs produced on the first and last day of the experi-
TABLE 2.—Influence of dietary phosphorus on egg production, feed consumption, feed per dozen eggs, egg weight and mortality — experiment 1 Ration phosphorus, %
Hen-day egg prod., %
Hen-day feed cons., g.
Feed/doz. eggs, kg.
Av. egg weight, g.
Mortality n/40
Inorganic — 0.09 Available - 0.19 Total - 0.42
83.1
104.3
1.52
56.9
9/40
Inorganic — 0.18 Available - 0.28 Total - 0 . 5 1
85.5
106.5
1.50
57.1
5/40
Inorganic — 0.27 Available- 0.37 Total - 0.60
78.6
103.1
1.58
56.4
3/40
5.2
3.6
0.12
1.3
1
Standard error of the means.
Downloaded from http://ps.oxfordjournals.org/ at University of Bath, Library on June 19, 2015
Corn Soybean meal (48% protein) Ground oyster shell Soy oil Vitamin premix 1 Salt premix 2 Defluor. rock phosphate
0- -
2058
W. J. OWINGS, J. L. SELL AND S. L. BALLOUN
ment was also measured. Analyses of varinace were conducted according to methods outlined by Snedecor and Cochran (1971). RESULTS
The average femur ash of hens fed no IP was slightly lower than that of other treatments. The highest level of ash was found in femurs of hens fed 0.18% IP (0.28% AP and 0.48% TP), but there were no significant differences among
DISCUSSION Generally, the data show that relatively low levels of dietary P will support egg production by hens. In both experiments, levels of 0.09% IP (0.19% AP and 0.39% TP) in rations sustained a high rate of efficiency egg production. The results also demonstrated that a ration containing no IP, 0.10% AP and 0.30% TP was not satisfactory for laying hens. For the most part, the data agree with the findings of Pepper et al. (1959) and Pepper et al. (1969) and Hunt and Chancey (1970) in the low levels of P can fulfill die hen's requirement. Pepper et al. (1959) and Pepper et al. (1969) also reported that the P requirement of hens could be fulfilled by rations in which all P was of plant origin. This was not substantiated in the current study. The data presented here indicate that hens require about 0.19—0.20% AP, some of which should be of inorganic origin. Waldroup et al. (1967) also found that approximately 0.19% AP was required by hens, but Summers et al. (1976) suggested that 0.25 to 0.35% AP should be present in laying hen rations. In contrast to the present findings, Garlich et al. (1975) reported that hens fed 0.227% AP (0.39% TP) were unable to maintain normal weight gains and femur density. Garlich and Parkhurst (1976) also found that mortality among hens fed a ration with 0.205% AP (0.44% TP) was excessive, although rate of hen-day egg production was maintained. It should be noted that hens used in the Garlich and Parkhurst (1976) research were in their second cycle of egg production. In the current study, relatively high mortality was observed also when the AP level was only 0.10%. Increasing the AP level to 0.19% with the older hens in experiment two reduced mortality, while in experiment one with younger hens of a different strain, mortality among hens fed 0.19% AP was higher than with AP levels of 0.28% or 0.37%. The data presented herein show that the P requirement as listed by the National Research Council (1971) is higher than necessary to
Downloaded from http://ps.oxfordjournals.org/ at University of Bath, Library on June 19, 2015
Experiment 1. Feeding rations that ranged from 0.19% AP (0.42% TP and 0.09% IP) to 0.42% AP (0.60% TP and 0.27% IP) had no significant effect on rate of egg production, hen-day feed consumption, average egg weight or efficiency of feed utilization (Table 2). Experiment 2. There were no significant ration treatment effects on egg production parameters for the first three weeks of the experiment. However, egg production by hens fed the ration with no IP (0.10% AP and 0.30% TP) decreased markedly during the fourth week (Fig. 1). Rate of egg production by this treatment group contined to decrease through week six, and was significantly (P<0.025) less than that of other treatment groups from week four through eight. Hens fed rations supplemented with 0.09% or more IP maintained egg production throughout the trial. Hen-day feed consumption during the experiment was not affected significandy by P level of the ration (Table 3). Hens fed the ration with no IP lost a noticeable amount of weight, while hens fed rations with added IP underwent little weight change. There were no significant differences among ration treatment groups with respect to average thickness of eggshell at the start of the experiment. By the end of the trial, however, eggs produced by hens fed the ration with no IP had thinner shells than those of other treatment groups. Eggshells produced by hens fed the highest P level had relatively thin shells, although the mean for this treatment group did not differ significantly from those of the remaining ration treatments. There seemed to be an inverse relationship between average egg weight and shell thickness. Hens fed the lowest and highest P levels produced larger eggs than hens fed the intermediate P levels, and eggs from these hens also had the thinnest shells. Therefore, it seems that dietary P may not have exerted a direct effect on shell thickness but may have influenced this parameter indirectly via rate of egg production and (or) egg size.
treatments. Mortality of hens fed the ration with no IP was markedly higher than that of any other treatment group. The mortality occurred primarily during the last three weeks of the experiment and presumably was related to the development of P deficiency.
0.016
105.7
4.7
Inorganic - 0.27 Available - 0 . 3 7 Total-0.57
2
1
0.328
101.5
0.326
Standard error of the means.
Means not followed by same superscript letter differ significantly (P<0.05).
20
+36"
0.324
Inorganic - 0.18 Available - 0.28 Total - 0.48
-5*
103.1
Inorganic - 0.09 Available - 0.19 Total-0.39
0.338
56.6 a b
59.3a
0.352*b
0.318 a b
1.1
55.0 b
0.3 7 2 b
0.020
58.5 a b
Av. egg at 8 wks
0.29 5 a
Shell thickness, mm. 8 wks. Start
105.4
-173 b l
Change in body wt., g.
Inorganic — none Available-0.10 Total - 0 . 3 0
Phosphorus, %
Hen-day feed cons., g.
TABLE 3 .—Influence of dietary phosphorus on feed consumption, body weight, shell thick femur ash and mortality — experiment 2
rom http://ps.oxfordjournals.org/ at University of Bath, Library on June 19, 2015
2060
W. J. OWINGS, J. L. SELL AND S. L. BALLOUN
support egg production providing that the TP present in laying hen rations is comprised of at least 0.19% AP. The data also suggest that approximately 0.28% AP may be needed to reduce mortality. ACKNOWLEDGMENT The assistance of Albert Kagan, Gary Johnson and Wayne White, Department of Animal Science, is gratefully acknowledged.
Downloaded from http://ps.oxfordjournals.org/ at University of Bath, Library on June 19, 2015
REFERENCES Garlich, J. D., R. L. James and J. B. Ward, 1975. Effects of short term phosphorus deprivation on laying hens. Poultry Sci. 54:1193-1199. Garlich, J. D., and C. R. Parkhurst, 1976. Phosphorus for laying hens. Feedstuffs 48( 1): 3 7. Hunt, J. R., and H. W. R. Chancey, 1970. Influence of dietary phosphorus on shell quality. Brit. Poultry Sci. 11:259-267. National Research Council, National Academy of
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