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Group Title: Bulletin University of Florida. Agricultural Experiment Station
Title: The effects of feeding various levels and sources of phosphorus to laying hens
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 Material Information
Title: The effects of feeding various levels and sources of phosphorus to laying hens
Series Title: Bulletin 644 ; University of Florida. Agricultural Experiment Station
Physical Description: 22 p. : ; 23 cm.
Language: English
Creator: Harms, R. H ( Robert Henry ), 1923-
Douglas, Carroll Reece, 1932-
Waldroup, P. W ( Park WIlliam ), 1937-
Publisher: University of Florida Agricultural Experiment Station
Place of Publication: Gainesville, Fla.
Publication Date: December, 1961
Copyright Date: 1961
 Subjects
Subject: Chickens -- Feeding and feeds   ( lcsh )
Phosphorus in animal nutrition   ( lcsh )
Phosphates   ( lcsh )
Calcium in animal nutrition   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: R.H. Harms, C.R. Douglas and P.W. Waldroup.
Bibliography: Includes bibliographical references (p. 22).
General Note: Cover title.
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Bibliographic ID: UF00026851
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: ltuf - AEN9790
oclc - 18343230
alephbibnum - 000929026

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THE EFFECTS OF FEEDING VARIOUS

LEVELS AND SOURCES OF

PHOSPHORUS TO LAYING HENS



R. H. HARMS, C. R. DOUGLAS and P. W. WALDROUP
Department of Poultry Science









UNIVERSITY OF FLORIDA 0 AGRICULTURAL EXPERIMENT STATIONS 0 GAINESVILLE
Bulletin 644 J. R. BECKENBACH, Director December, 1961












TABLE OF CONTENTS
Page

INTRODUCTION .......... ... ..................................... ....... ......... 3

EXPERIMENT NO. 1: A COMPARISON OF THREE SOURCES OF PHOSPHORUS
FOR LAYING HENS IN FLOOR PENS .............................. 4
Procedure: -..... ----.... ----. ......---------- ..-.-------.. ----..----... 4
Results: --------...... .....-...-------....--......-.- .........---.---. 5

EXPERIMENT NO. 2: A COMPARISON OF VARIOUS LEVELS OF THREE
SOURCES OF PHOSPHORUS FOR LAYING HENS IN
FLOOR PENS ......--......... --.. --.. -- ...--......-.... 7
Procedure: ----.... -----..... ........... ---.....---.... ----- -....-...-- ...... 7
Results: .....----....... ..--- .. .... ..----..- ------------ ........-. .....-- 8

EXPERIMENT NO. 3: A COMPARISON OF VARIOUS LEVELS OF SOFT PHOS-
PHATE AND DEFLUORINATED PHOSPHATE FOR HENS
IN FLOOR PENS ...........- ------.. .--------.....-...... 10
Procedure: .-..---. -----...--------- --- ....----... -------........--------.. 10
Results: -...- .....---- ..------- ----... .---........----------..... 10

EXPERIMENT NO. 4: A COMPARISON OF VARIOUS LEVELS OF PHOSPHORUS
FOR HENS IN CAGES ...........---......... ....-------...... 11
Procedure: ..-....-..-- ...-- ..-- -..------- --- --- ... ..------ -.......... 11
Results: ....- ....----- --. ........--.--....-.-- .--- .. --- ... .......... ... 12

EXPERIMENT NO. 5: EFFECT OF FEEDING VARIOUS LEVELS OF CALCIUM
AND PHOSPHORUS TO HENS IN CAGES ..........--........ 13
Procedure: .....--..--...--. -----.... --- ....... ......... ..----------- 13
Results: -.....---...... ------...--- ...-- .... ...... ...-- ..---- ....... 15

EXPERIMENT NO. 6: EFFECT OF FEEDING VARIOUS LEVELS OF SOFT PHOS-
PHATE AND DEFLUORINATED PHOSPHATE WITH TWO
CALCIUM LEVELS TO HENS IN CAGES .......---............... 16
Procedure: .. -...---...-----.............. ........... ..... ...... .. .. --- .....-- 16
Results: .............. --.... ---.--. .-----.----... .. ....- .....-- .-------- 17

DISCUSSION: .-...-..... ---.......--...---...- .. --..... ... ----..-.....- ...--- 18

SUMMARY: --........--. ---- --- --......-----....... .....------....- 20

ACKNOWLEDGMENTS --...... ............ ...... ........... ..........- ..... --- .-..-- 21

REFERENCES ..............------ ..------ ...-- ....--- ..... ..................-------- 21










THE EFFECTS OF FEEDING VARIOUS LEVELS AND
SOURCES OF PHOSPHORUS TO LAYING HENS

R. H. HARMS, C. R. DOUGLAS 1 and P. W. WALDROUP
Department of Poultry Science

INTRODUCTION
The need for supplemental phosphorus in the diet of chickens
has been determined. Although the exact requirement for the
laying hen has not been determined, the Na final Research Coun-
cil (1960) recommends that the feed conta 0.6 percent phos-
phorus.
A review of the literature reveals there is no general agree-
ment concerning the level of phosphorus required by the laying
hen. Miller and Bearse (1934), Norris et al. (1934), and Evans
et al. (1944) indicated that the phosphorus requirement of the
laying hen was approximately 0.80 percent of the diet. How-
ever, Massengale and Platt (1930) and Gillis et al. (1953) re-
ported the requirement to be near 0.50 percent of the diet.
O'Rourke et al. (1954) found that a level of 0.30 percent
phosphorus supported normal egg production when a semi-puri-
fied diet was used. In a later report these workers (O'Rourke
et al., 1955) found that a practical diet containing 0.43 percent
phosphorus supported normal egg production.
Pepper et al. (1958) reported that phosphorus supplements
could not be assayed with laying hens fed diets of natural in-
gredients, since hens do not require supplemental inorganic phos-
phorus. Baruah et al. (1960) reported that collodial phosphate
could be used as a source of phosphorus for the laying hen.
Experiments reported in this bulletin were conducted to eval-
uate soft phosphate, dicalcium phosphate and defluorinated phos-
phate as a source of phosphorus for the laying hen, and to deter-
mine the hen's requirement for phosphorus with a corn-soy-
bean meal type diet.

1Present address: Florida State Hatcheries, Inc., Gainesville, Florida.








4 Florida Agricultural Experiment Stations

A COMPARISON OF VARIOUS LEVELS OF THREE SOURCES
OF PHOSPHORUS FOR LAYING HENS IN FLOOR PENS

EXPERIMENT 1 (1957-58)

Procedure.-Five pens of 78 Single Comb White Leghorn pul-
lets per pen and 5 pens of 57 New Hampshire pullets per pen
were used in this experiment. The pullets were reared on range,
and before housing had reached an egg production rate of 20 and
30 percent, respectively, for the New Hampshires and White
Leghorns. The White Leghorn pullets were placed at random
into pens on the north side of the laying house and the New
Hampshires were randomly placed in pens on the south side of
the laying house.

TABLE 1.-COMPOSITION OF BASAL DIETS.

Ingredients Exp. 1 Exp. 2, 3 & 4 Exp. 5 & 6

(Lbs/cwt)

Yellow corn -.......... ........ --...... ....---.... 64.9 68.0 69.8
Animal fat ........----------.... --. ---...... .. -- 1.0 1.0
Soybean meal (44% protein) ............ 18.9 -
Soybean meal (50% protein) .........-..... --19.5 1 20.4
Dehydrated alfalfa meal (17% protein) 5.0 i 5.0 i 3.0
Menhaden fish meal (60% protein) .. 2.5 -
Iodized salt ...-...-..-- ... -- ..------- .... 0.4 0.4 1 0.4
Micro-ingredients* ....-- ...... .......-..---..... 0.5 0.5 0.5
Ground limestone--- .....-.... -- ...... ..---- ..-.- -- 5.6 4.9
Variable ingredients** ............-...-- .... -- 7.8 -
Methionine hydroxy analogue calcium 4 gms.

Supplies per pound of diet: 1996 I.U. vitamin A, 646 LC U. vitamin Da, 6 meg. vitamin
B1, 2 mg. riboflavin, 4 mg. ca. pantothenate, 9 mg. niacin, 90 mg. choline chloride, 2.5 I.U.
vitamin E, 0.5 mg. menadione sodium bisulfite and 0.08 gms. Mn. S04.
** Included phosphate source to furnish 0.45% phosphorus and sufficient ground limestone
for diet to contain 2.30 percent calcium. Remainder consisted of corn and soybean meal so
that diets contained 17 percent protein.

Each floor contained 240 square feet of floor space which
allowed approximately 3 square feet for each of the White Leg-
horn pullets, and slightly in excess of 4 square feet for each of








The Effects of Feeding Phosphorus to Laying Hens 5

the New Hampshire pullets. Wood shavings were used as litter.
Each pen was equipped with one bell-type automatic waterer,
2 4-foot feed troughs, and 12 individual nests.
The composition of the basal diet used in this experiment
is shown in Table 1. This diet was modified to form 5 experi-
mental treatments as shown in Table 2, by using various sources
and combinations of phosphorus supplements. Experimental
diets were kept iso-nitrogenous by varying the amount of corn
and soybean meal used in the diet. No attempt was made to
keep diets iso-caloric since this would have entailed the use of
animal fat, and it was felt that fat might alter the level of phos-
phorus required by the hen.
Daily collections of eggs were made and the total number of
eggs per pen was recorded. At the end of each 28-day period2
rate of egg production and pounds of feed required to produce
a dozen eggs were calculated. Rate of egg production was cal-
culated on a hen day basis.
At approximately bi-monthly intervals the specific gravity of
all eggs produced for three successive days was determined. How-
ever, for this presentation only the average of the specific gravity
for all eggs measured is given. This experiment was conducted
for a period of 10 months.
Results.-Source of supplemental phosphorus in the diet of
New Hampshire pullets did not affect rate of egg production
(Table 2). However, a wide variation in rate of egg production
was found when White Leghorn pullets were fed these experi-
mental diets. As the level of soft phosphate was increased in
the diet of White Leghorn pullets, a reduction in rate of egg pro-
duction was obtained. The lowest rate of egg production was
obtained with the pullets receiving the diet containing soft phos-
phate as the sole source of supplemental phosphorus. Since
replicate pens of each breed were not fed the experimental diets,
significance of differences between the experimental treatments
could not be measured.
As the level of soft phosphate was increased in the diet of the
White Leghorn pullets, the amount of feed required to produce
a dozen eggs was increased (Table 2). However, when the same
diets were given to the New Hampshire pullets no difference was
found in the amount of feed required to produce a dozen eggs.
It should be pointed out that when soft phosphate was included

SFor convenience of presentation in this bulletin the 28-day period will
be referred to as a month.








6 Florida Agricultural Experiment Stations

in the diet the energy content of the feed was decreased, which
partially accounts for the difference in feed efficiency.
The mortality for the entire ten month laying period was
13.25 percent (Table 2). This ranged from 7.4 to 18.9 percent
for the New Hampsire pullets and from 9.8 to 15.2 percent for
the White Leghorn pullets. This mortality was in the normal
range of expectancy for this number of groups of pullets, there-
fore, it would be concluded that the source of supplemental phos-
phorus did not affect mortality of the pullets.

TABLE 2.-RATE OF EGG PRODUCTION, FEED EFFICIENCY, MORTALITY AND
SPECIFIC GRAVITY OF EGGS FROM PULLETS FED DIETS CONTAINING VARIOUS
SUPPLEMENTAL PHOSPHATE SOURCES (EXPERIMENT 1).

Supplemental Egg Lbs feed/ Mortali- Sp. gravity
phosphorus source Breed prod. doz eggs ty (%) of eggs
I I _____ ____I ____I
Defluorinated phosphate N.H.* 43.8 7.02 16.7
W.L.** 54.1 4.88 15.2
Av. 48.9 5.95 16.0 1.0798

Dicalcium phosphate ....... N.H. 43.0 7.12 18.9
W.L. 60.8 4.50 9.8
Av. 51.9 5.81 14.4 1.0788

Soft phosphate -....--.....-- N.H. 45.2 7.19 13.0
W.L. 44.3 5.96 10.2
Av. 44.8 6.58 11.6 1.0785

40% Defluorinated N.H. 44.8 7.21 14.8
phosphate and 60% W.L. 51.0 5.30 15.2
soft phosphate ............. Av. 47.9 6.26 15.0 1.0793

70% Defluorinated N.H. 43.7 7.08 7.4
phosphate and 30% W.L. 53.2 5.03 11.4
soft phosphate .............. ) Av. 48.5 6.06 9.4 1.0802
N. H. Indicates one pen of 57 New Hampshire pullets.
** W. L. Indicates one pen of 78 Single Comb White Leghorn pullets.

Thickness of egg shells, measured as specific gravity of eggs,
was not significantly affected by source of supplemental phos-
phorus (Table 2). Specific gravity of eggs from birds in all
treatments declined as the laying year progressed. This was
expected since it has been shown that thickness of egg shell
decreased as laying year progresses. The interaction of diets
X period did not approach statistical significance, indicating that
none of the phosphorus supplements was more effective than
others in preventing this decline in egg shell thickness.








The Effects of Feeding Phosphorus to Laying Hens 7


A COMPARISON OF VARIOUS LEVELS OF THREE SOURCES
OF PHOSPHORUS FOR LAYING HENS IN FLOOR PENS

EXPERIMENT 2 (1958-59)
Procedure.-Twenty pens, each containing 39 commercial egg
production type pullets (Hy-line 934A) per pen, were used in
this experiment. These pullets were reared in confinement and
were "full-fed" a grower diet containing 17 percent protein and
945 Calories of productive energy per pound of feed. This
grower diet contained approximately 1.2 percent calcium and
0.7 percent total phosphorus. The pullets were moved into the
laying house at 161 days of age at which time they were ran-
domly assorted into the 20 pens.
All pullets were intraocularly vaccinated for bronchitis and
Newcastle disease at one day of age and again at 12 weeks of
age. At 8 weeks of age, pullets received fowl pox vaccination
by the wing web method. Birds were "dubbed" at 1 day of age
and "debeaked" at 8 weeks of age.
Each floor pen contained 120 square feet of floor space, which
allowed approximately 3 square feet for each pullet. Wood
shavings were used as litter. Each pen was equipped with one
bell-type automatic waterer, 1 4-foot feed trough, and 9 indivi-
dual nests.
The composition of the basal diet used in this experiment
is shown in Table 1. This basal diet was modified to form the
other 9 experimental treatments as shown in Table 3. These
experimental diets included the use of 3 levels of phosphorus
derived from 3 sources. It also included a positive control con-
taining 3 percent fish meal. This positive control diet was in-
cluded to test whether the "all vegetable" basal diet would sup-
port a maximum rate of egg production. The calcium content
of the experimental diets was maintained at 2.3 percent by vary-
ing the amount of ground limestone in the diet in order to com-
pensate for the additional calcium furnished by the phosphorus
supplement. All experimental diets contained approximately 17
percent protein and 945 Calories of productive energy per pound
of feed. This level of protein and energy was maintained by vary-
ing the amount of corn, animal fat, and soybean meal in the
diets.
Egg production and feed efficiency calculations were identical
to the procedure followed in Experiment 1.








8 Florida Agricultural Experiment Stations

At approximately bi-monthly intervals, the specific gravity
of all eggs laid for two successive days was determined. How-
ever, for this presentation only average specific gravity of all
eggs measured is given. All birds were weighed at the end of
the tenth month at which time the experiment was terminated.
Statements of probability in this experiment and the remain-
ing experiments are based on the analysis of variance accord-
ing to Snedecor (1956).

TABLE 3.-RATE OF EGG PRODUCTION, FEED EFFICIENCY, MORTALITY, BODY
WEIGHT AND SPECIFIC GRAVITY OF EGGS FROM PULLETS FED DIETS CON-
TAINING VARIOUS LEVELS AND SOURCES OF PHOSPHORUS (EXPERIMENT 2).

Supple. P [Egg Prod. i Lbs. feed I Mortality Body wt. Sp. gravity
Level Source (%) doz eggs I (%) (gms) of eggs

None ............... 65.9 3.98 12.8 1795 1.0786
.03 S* .......----- 71.9 3.71 7.7 1790 1.0786
.03 DF** --..... 71.7 3.72 6.4 1765 1.0772
.03 DCt ......... 66.5 3.92 17.9 1763 1.0789
.09 S -........-...... 67.5 3.89 11.5 1780 1.0777
.09 DF .......... 71.9 3.76 9.0 1791 1.0791
.09 DC .........---- 69.3 3.88 12.8 1764 1.0787
.35 S ......-........ 63.6 4.15 10.2 1656 1.0742
.35 DF .----............ 74.7 3.60 7.7 1847 1.0790
.25 DF + ---....... 72.6 3.71 10.2 1829 1.0789
3% fish meal -

Indicates supplemental phosphorus from soft phosphate.
** Indicates supplemental phosphorus from defluorinated phosphate.
t Indicates supplemental phosphorus from dicalcium phosphate.

Results.-The basal diet, which contained 0.34 percent phos-
phorus, did not support maximum rate of egg production (Table
3). The addition of 0.03 percent phosphorus to the diet from
either of the 3 sources resulted in improving rate of egg pro-
duction by approximately 4 percent. The pullets receiving 0.03
percent supplemental phosphorus from dicalcium phosphate did
not lay at a rate comparable to pullets receiving diets contain-
ing this level of phosphorus from other sources. This lowered








The Effects of Feeding Phosphorus to Laying Hens 9

rate of egg production can be explained by the excessive mor-
tality of birds in this pen. No explanation can be given for this
high rate in mortality; however, since pullets were allowed to
remain in the pen until they died it would partially explain the
lowered rate of egg production. When the level of supplemental
phosphorus was increased to 0.09 percent, the rate of egg pro-
duction was not increased. However, when the level of sup-
plemental phosphorus from defluorinated phosphate was in-
creased to 0.35 percent of the diet, an improvement in rate of
egg production was observed. When the level of supplemental
phosphorus was increased to 0.35 percent from soft phosphate,
a reduction in rate of egg production was obtained. Rate of egg
production from this group was 2.3 percent less than obtained
from feeding the basal diet.
Considerable differences were observed among the groups of
hens in the amount of feed required to produce a dozen eggs
(Table 3). However, it is felt that these differences in feed utili-
zation were primarily due to the differences in rate of egg pro-
duction of the hens and not due to difference in the composition
of the feed.
Mortality for the various experimental lots during the 10
month laying period ranged from 6.4 percent to 17.9 percent
(Table 3). Due to the variation between replicates, these differ-
ences were not found to be significant. The over-all mortality
for the entire group was approximately one percent per month
which was considered to be normal except for high mortality
with the group receiving 0.03 percent supplemental phosphorus
from the dicalcium phosphate.
Specific gravity of eggs from hens receiving the diet con-
taining the high level of soft phosphate was significantly lower
than that of eggs from hens receiving any of the other experi-
mental diets (Table 3). No significant differences in specific
gravity were detected between the other 9 experimental groups.
Body weight of the hens at the termination of the experi-
ment is shown in Table 3. Although no significant differences
in body weight were found among groups of hens on the various
diets, some trends were evident. Body weight of the hens re-
ceiving 0.35 percent supplemental phosphorus from soft phos-
phate was 109 grams lighter than any other group of hens. The
other 2 groups of hens receiving diets containing 0.35 percent
phosphorus from defluorinated phosphorus and defluorinated
phosphorus plus fish meal were the heaviest birds in the test.







10 Florida Agricultural Experiment Stations

The addition of fish meal to the laying diet did not signifi-
cantly affect the performance of the pullets as shown in Table
3. In fact, rate of production was decreased by 2.1 percent and
the amount of feed required to produce a dozen eggs was in-
creased by 0.11 pounds per dozen eggs when fish meal was added
to the diet. It should be pointed out that when fish meal was
added the diet was adjusted for total protein, methionine, energy,
phosphorus and calcium content.

A COMPARISON OF VARIOUS LEVELS OF SOFT
PHOSPHATE AND DEFLUORINATED PHOSPHATE
FOR HENS IN FLOOR PENS
EXPERIMENT 3 (1959-60)
Procedure.-Eighteen pens, each containing 36 commercial
egg production type pullets (Hy-line 934A), were used in this
experiment. The vaccination and growing program followed
in Experiment 2 were used for the pullets involved in this ex-
periment. The pullets were housed in floor pens under condi-
tions similar to those used in experiment 2.
The composition of the basal diet is shown in Table 1. This
diet was modified to give 8 treatments as indicated in Table 4.
The protein and energy level of these diets were maintained
constant by varying the amount of corn, animal fat, and soy-
bean meal. The calcium content of all diets was maintained
at 2.3 percent by varying the amount of ground limestone.
Egg production and feed efficiency calculations were identical
to procedures followed in Experiment 1. Since level or source
of supplemental phosphorus had not consistently been shown
to affect specific gravity of eggs, this measurement was not
obtained with these pullets. This experiment was terminated
at the end of 11 months.
Results.-The basal diet containing 0.34 percent total phos-
phorus did not support maximum rate of egg production (Table
4). The addition of 0.05 percent phosphorus from defluorinated
phosphate resulted in improving rate of egg production by ap-
proximately 6 percent. A further increase in the level of
phosphorus did not result in a further increase in rate of egg
production.
When the diet was supplemented with phosphorus from
soft phosphate, production was not equal to that observed from
diets with similar phosphorus content from defluorinated phos-








The Effects of Feeding Phosphorus to Laying Hens 11

phate. Poorest performance was observed with the group re-
ceiving the diet containing 0.20 percent phosphorus from soft
phosphate. The rate of egg production on this diet was less
than that observed from feeding the basal diet containing no
supplemental phosphorus.
A considerable reduction in the amount of feed required to
produce a dozen eggs was observed when the basal diet was sup-
plemented with 0.05 percent phosphorus from defluorinated phos-
phate (Table 4). When higher levels of supplemental phosphorus
were added, no further improvement was observed in feed utili-
zation. A portion of this improvement in feed utilization could
be attributed to the higher rate of egg production of the hens
receiving the diet supplemented with phosphorus since an im-
proved rate of lay will result in improved feed utilization. When
the diet was supplemented with phosphorus from soft phosphate
the utilization of feed was not as good as from diets containing
similar levels of phosphate from defluorinated phosphate.
Mortality for the various experimental lots during the 11
month laying period ranged from 2.8 to 16.7 percent. No signi-
ficant differences were detected in mortality between the various
groups.

A COMPARISON OF VARIOUS LEVELS OF PHOSPHORUS
FOR HENS IN CAGES

EXPERIMENT 4 (1959-60)
Procedure.-Forty-eight groups, each containing 5 commer-
cial egg production type pullets (Hy-line 934A) maintained in
individual cages, were used in this experiment. The growing
program was the same as followed in Experiment 2. The pullets
were placed in individual cages at 21 weeks of age at which
time the experiment was begun.
The composition of the basal diet is shown in Table 1. This
basal diet was modified by the addition of different levels of phos-
phorus from defluorinated phosphate to form 5 other experi-
mental treatments as shown in Table 4. When these levels of
defluorinated phosphate were added to the basal diet, adjust-
ments were made in the amount of ground limestone in order
to maintain the calcium content of the diet at 2.3 percent. The
level of animal fat was adjusted in order to maintain the energy
content of the diets at 945 Calories of productive energy per
pound of feed.








12 Florida Agricultural Experiment Stations

Daily collections of eggs were made and production records
for individual hens were kept. Rate of egg production was
calculated on a hen day basis. At the end of each 28 day period,
the amount of feed required to produce a dozen eggs was cal-
culated. This experiment was terminated at the end of the
tenth month.

TABLE 4.-RATE OF EGG PRODUCTION, FEED EFFICIENCY AND MORTALITY
OF PULLETS MAINTAINED IN CAGES AND ON THE FLOOR RECEIVING DIETS
CONTAINING VARIOUS LEVELS OF PHOSPHORUS (EXPERIMENTS 3 AND 4).

Supple. P % Egg prod. Lbs feed/doz eggs % Mortality
L'vel Source Floor Cage Floor Cage Floor Cage

(exp. 3) (exp.4) (exp.3) (exp.4) (exp. 3) (exp.4)
None 67.5 56.4 3.90 4.79 8.3 50.0
.05 D* 73.8 64.8 3.69 4.36 4.2 55.0
.05 S** 67.6 -3.85 16.7
.10 D 74.4 67.5 3.66 3.88 2.8 30.0
.15 D 71.2 66.2 3.74 4.21 6.9 30.0
.15 S 69.0 3.78 5.6 -
.20 D 74.4 63.9 3.61 4.47 11.2 20.0
.20 S 66.4 -3.96 9.6
.25 D 71.5 68.1 3.77 4.22 5.5 20.0

Indicates supplemental phosphorus from defluorinated phosphate.
** Indicates supplemental phosphorus from soft phosphate.

Results.-Rate of egg production was improved when the
basal diet was supplemented with 0.05 percent phosphorus from
defluorinated phosphate (Table 4). This improvement of 10
percent approached the 5 percent level of probability when the
entire laying period was considered. When production was con-
sidered for the last 5 months of the laying period a significant
difference was found between the production for the pullets re-
ceiving the basal diet and the pullets receiving the diets contain-
ing supplemental phosphorus. Increasing the level of phos-
phorus above the 0.05 percent level resulted in a slight improve-
ment in rate of egg production. However, production of the
group receiving the 0.05 percent phosphorus was as good as
that group receiving the 0.20 percent phosphorus. The highest








The Effects of Feeding Phosphorus to Laying Hens 13

rate of egg production was obtained with the group receiving
the diet supplemented with 0.25 percent phosphorus.
Feed utilization was associated very closely with the rate of
egg production for the birds in this experiment. A substantial
reduction in the amount of feed required to produce a dozen
eggs was obtained when the diet was supplemented with 0.05
percent phosphorus. No further improvement in utilization of
feed was noted when additional phosphorus was added to the
diet.
Fifty percent of the birds died in the group which received
the basal diet and 55 percent died in the group receiving the diet
supplemented with 0.05 percent phosphorus. Significantly fewer
birds died when the diet was supplemented with 0.10 percent
phosphorus, and a further reduction in mortality was observed
when the level of supplemental phosphorus was increased to
0.20 and 0.25 percent of the diet. The birds receiving diets
containing low levels of phosphorus developed leg weakness and
were unable to stand for several days prior to death. Many
of these birds played two to three eggs after this leg weakness
occurred.

EFFECT OF FEEDING VARIOUS LEVELS OF CALCIUM
AND PHOSPHORUS TO HENS IN CAGES

EXPERIMENT 5 (1960-61)
Procedure.-The calcium level was maintained at 2.3 percent
in the first 4 experiments, therefore, in view of recent reports
that egg shell quality could be greatly improved by feeding
higher levels of calcium (Petersen et al, 1960 and Harms and
Waldroup, 1961) it seemed desirable to determine whether these
increased calcium levels would alter the phosphorus require-
ments of the laying hen.
Forty-eight groups, each containing 5 commercial egg pro-
duction type pullets (Hy-line 934A) maintained in individual
cages, were used in this experiment. These pullets were grown
on a program similar to that used in Experiment 2, and were
placed in cages at 23 weeks of age at which time the experiment
was begun.
The composition of the basal diet, containing 2.0 percent cal-
cium and 0.345 percent phosphorus, is shown in Table 1. This
diet was modified by the addition of defluorinated phosphate
and ground limestone to form 11 other experimental treatments








TABLE 5.-RATE OF EGG PRODUCTION, FEED EFFICIENCY, THICKNESS OF EGG SHELLS, AND MORTALITY OF PULLETS WHEN FED
VARIOUS LEVELS OF CALCIUM AND PHOSPHORUS (EXPERIMENT 5).
I Egg Shell Thickness
Dietary Treatment |c Egg Prod. J(mm x 1000)
(mo. of lay) Lbs. feed/ mo. of lay Mortality
Ca Supplemental P* doz. egg (%)
%/ % 0-3 4-6 7-9 0-9 3 6 9

2.0 None 66.4 53.4 32.4 53.7 4.78 298 255 265 65.0
0.05 67.8 58.2 33.4 56.5 4.35 315 280 290 50.0
0.10 73.6 58.3 41.9 60.4 4.07 290 301 275 60.0
0.45 71.3 68.9 64.6 68.1 3.88 317 282 269 35.0
All 69.8 59.7 43.1 59.7 4.27 305 279 275 52.5

3.75 None 77.0 63.6 45.1 63.6 4.10 338 314 310 45.0
0.05 82.7 77.0 64.0 74.9 3.63 341 317 318 25.0
0.10 84.6 81.8 64.6** 77.0** 3.60** 336 308 310** 17.0**
S 0.45 84.4 80.6 65.3 77.1 3.56 329 295 315 5.0
All 82.2 75.8 59.7 73.2** 3.72** 336 308 313** 23.0**

5.50 None 78.9 62.2 42.7 65.4 3.94 347 331 352 70.0
0.05 81.1 79.8 65.2 75.4 3.41 349 318 328 5.0
,, 0.10 77.8 74.9 64.8 74.3 3.44 354 324 314 15.0
0.45 80.3 79.8 71.3 77.1 3.58 335 326 315 15.0
S All 79.5 74.2 61.0 73.1 3.59 346 324 327 26.3

All None 74.1 59.8 40.0 60.9 4.27 327 300 309 60.0 Q
0.05 77.2 71.7 54.2 68.9 3.80 335 305 312 30.0
S 0.10 78.7 71.7 57.1 70.6** 3.70** 326 311 299** 30.7**
,, 0.45 78.6 76.4 67.1 74.1 3.67 327 301 300 18.3
S All 77.1 69.9 54.6 68.6** 3.86** 329 303 305** 34.8**
Basal diet contained 0.345% phosphorus supplied from plant sources, remainder furnished by defluorinated phosphate.
** Pullets receiving the diet containing 0.445% P and 3.75% Ca were terminated at the end of the sixth month. Missing values calculated accord-
ing to the procedure as outlined by Snedecor (1956).








The Effects of Feeding Phosphorus to Laying Hens 15

as shown in Table 5. The factorial design included 3 levels of
total calcium (2.0, 3.75, and 5.50 percent) and 4 levels of total
phosphorus (0.345, 0.395, 0.445 and 0.80 percent). The amount
of yellow corn, soybean meal and animal fat was varied in the
experimental diets in order to keep them iso-caloric and iso-
nitrogenous.
Daily collections of eggs were made and production records
were kept for individual hens, however, rate of egg production
is reported on a hen-day basis. At monthly intervals, thickness
of shell of 1 egg was measured from each pullet that was lay-
ing. Measurements were made at the equatorial plane of the
egg with a Starrett rachet-stop micrometer calibrated in mili-
meters. This experiment was terminated at the end of the
ninth month.
Results.-Increasing either the level of calcium or phos-
phorus in the diet resulted in significantly increasing rate of
egg production (Table 5). Supplementing the basal diet, which
contained 0.345 percent phosphorus, with 0.05 percent phos-
phorus resulted in improving rate of egg production by an
average of approximately 8 percent when all levels of calcium
were considered. Further increases in the level of supplemental
phosphorus gave an improved rate of egg production.
Increasing the calcium content from 2 to 3.75 percent over
all levels of phosphorus resulted in significantly increasing rate
of egg production. Rate of egg production was comparable for
the groups of hens receiving the diets containing 3.75 and 5.0
percent calcium. The calcium X phosphorus interaction as meas-
ured by rate of egg production was not statistically significant.
As the level of supplemental phosphorus was increased the
amount of feed required to produce a dozen eggs was signifi-
cantly decreased (Table 5). Also feed utilization was signifi-
cantly improved when the level of total calcium was increased
from 2.0 to 3.75 percent. A further increase in calcium content
did not affect feed utilization. These differences in feed utiliza-
tion are not considered to be meaningful since rate of egg pro-
duction varied greatly among the various groups, therefore,
these differences are primarily attributed to differences in rate
of egg production.
Thickness of egg shells was not influenced by the level of
phosphorus in the diet (Table 5). Increasing the level of cal-
cium from 2 to 3.75 percent resulted in significantly increasing
thickness of egg shells. A further improvement in egg shells







16 Florida Agricultural Experiment Stations

was noted when the calcium level was increased from 3.75 to
5 percent. The calcium X phosphorus interaction as measured
by egg shell thickness was not statistically significant. Thick-
ness of egg shells declined as the laying year progressed, how-
ever, there were no significant interactions between months of
lay and calcium or phosphorus level.
When the level of phosphorus in the diet was increased mor-
tality of pullets was significantly reduced (Table 5). Mortality
of pullets was significantly lowered when they received diets con-
taining 3.75 or 5.0 percent calcium. The interaction of calcium
X phosphorus, as measured by mortality, was not statistically
significant.

EFFECT OF FEEDING VARIOUS LEVELS OF SOFT
PHOSPHATE AND DEFLUORINATED PHOSPHATE
WITH TWO CALCIUM LEVELS TO HENS
IN CAGES
EXPERIMENT 6 (1961)
Procedure.-Results of the first 3 experiments indicated that
soft phosphate could be satisfactorily used to furnish low levels
of phosphorus in laying hen diets, however, supplementing the
diet with high levels of soft phosphate resulted in lowering rate
of egg production. This reduction in rate of egg production
could not be explained on the basis of the low availability of
phosphorus in the soft phosphate since a higher rate of egg
production was obtained with diets containing lower levels of
phosphorus.
Based on a report by Watts and Miner (1959) that the cal-
cium in soft phosphate is less available than that from dicalcium
phosphate, it was suspected that the difference of performance
of hens receiving diets with low and high levels of soft phos-
phate might be explained on the difference in available calcium
in the different diets. This experiment was conducted to study
this hypothesis.
Fifty-two groups, each containing 5 commercial egg produc-
tion type pullets (Hy-line 934A), maintained in individual cages,
were used in this experiment. These pullets had been in pro-
duction for approximately 6 months when the experiment was
begun. They had been receiving the basal diet (Table 1) sup-
plemented with ground limestone and defluorinated phosphate
(2.3% calcium and 0.75% total phosphorus).








The Effects of Feeding Phosphorus to Laying Hens 17

The basal diet (Table 1) was modified to form 12 other experi-
mental diets as shown in Table 6. The amount of corn, soybean
meal and animal fat was adjusted in order to maintain a constant
energy level of 968 Calories of productive energy per pound of
diet, and a level of 17 percent protein.

TABLE 6.-RATE OF EGG PRODUCTION, FEED EFFICIENCY, EGG SHELL THICK-
NESS AND MORTALITY OF PULLETS WHEN FED VARIOUS LEVELS OF PHOS-
PHORUS FROM SOFT PHOSPHATE AND DEFLUORINATED PHOSPHATE WITH
TWO LEVELS OF CALCIUM (EXPERIMENT 6).

Dietary Treatment IEgg Prod. Lbs. feed/I Shell Thick. Mortality
Ca Supplemental P % doz. egg 3rd mo. %
% __ Source I ____(mmx1000)_

2.0 None 0* 53.5 4.37 270 65.0
DF** 0.05 56.5 4.10 256 30.0
DF 0.10 64.6 3.81 236 10.0
DF 0.45 70.6 3.46 265 10.0
st 0.05 47.8 4.27 260 25.0
S 0.10 53.2 3.73 293 5.0
S 0.45 37.6 5.20 259 10.0
3.75 None 0* 59.3 3.71 259 15.0
DF 0.05 66.2 3.48 251 10.0
DF 0.45 69.6 3.44 299 10.0
S 0.05 63.2 3.56 322 15.0
S 0.10 71.0 3.07 313 5.0
S 0.45 72.7 3.45 305 5.0

Con ained 0.345% phosphorus from p'ant sources.
** Indicates supplemental phosphorus from defluorinated phosphate.
SIndicates supplemental phosphorus from soft phosphate.

Daily collections of eggs were made and production records
were kept for individual hens, however, rate of egg production
is reported on a hen-day basis. Thickness of egg shell was
measured at monthly intervals. Due to the high rate of mor-
tality this experiment was terminated at the end of the third
month.
Results.-Increasing the level of dietary phosphorus or cal-
cium resulted in an increased rate of egg production (Table 6).







18 Florida Agricultural Experiment Stations

Although rate of production was slightly higher for birds receiv-
ing diets containing defluorinated phosphate than for birds receiv-
ing diets containing soft phosphate, this difference was not statis-
tically significant. Increasing the level of supplemental phos-
phorus increased rate of egg production in all groups except for
those groups receiving supplemental soft phosphate with 2.0
percent dietary calcium. This resulted in a statistically signifi-
cant interaction of calcium X phosphorus source. As expected,
rate of egg production was significantly improved by increasing
the calcium level from 2.0 to 3.75 percent. The calcium X phos-
phorus interaction was not statistically significant.
Utilization of feed (Table 6) was closely associated with rate
of egg production. Therefore, differences in amount of feed
required to produce a dozen eggs were primarily due to differ-
ences in rate of egg production.
Increasing the level of calcium from 2.0 to 3.75 percent re-
sulted in significantly increasing egg shell thickness (Table 6).
The phosphorus content of the diet did not significantly affect
shell thickness, and the calcium X phosphorus interaction was
not significant. The calcium X phosphorus source interaction,
as measured by egg shell thickness, was not significant. How-
ever, at the end of the first 28-day period hens receiving the diet
containing 0.45 percent supplemental phosphorus from soft
phosphate with 2.0 percent calcium produced eggs with thinner
shells than other groups receiving comparable levels of calcium
(0.266 vs. 0.310 mm.).
Mortality of pullets was decreased by increasing the dietary
level of either calcium or phosphorus.

DISCUSSION
The phosphorus requirement of hens maintained in floor
pens fed a corn-soybean type diet appeared to be approximately
0.40 percent of the diet. Maximum rate of egg production was
obtained in Experiment 3 when the phosphorus content of the
diet was 0.39 percent (Table 4); however, in Experiment 2 an
improvement in rate of egg production was obtained from in-
creasing the level of phosphorus above 0.43 percent (Table 3).
It would appear that the phosphorus requirement for hens main-
tained in cages is higher than 0.40 percent. The basal diet,
supplemented with 0.05 (0.39 percent total) percent phosphorus
from defluorinated phosphate, supported a fair rate of egg pro-








The Effects of Feeding Phosphorus to Laying Hens 19

duction with birds maintained in cages; however, a high rate
of mortality was obtained on this feed (Tables 4, 5, 6). It was
felt that the rate of egg production in these experiments was
not a true indication of the adequacy of phosphorus in the diet
since mortality greatly influenced this, as it is suspected that
birds with the higher requirements died in the early part of the
experiment. Therefore, the adequacy of the phosphorus did not
have an opportunity to express itself as indicated by lowered
rate of egg production for this group. It should also be pointed
out that the greatest depression in rate of egg production for
those birds maintained in cages came after they had been in
production for 6 months. Length of test may account for a
portion of the variation in phosphorus requirement previously
reported for the laying hen.
Dicalcium phosphate and defluorinated phosphate may be
satisfactorily used to furnish levels as high as 0.35 percent sup-
plemental phosphorus for the laying hen when the diet contains
at least 2.25 percent calcium (Tables 2, 3, and 4). These ex-
periments also indicate that soft phosphate may be satisfactorily
used to furnish low levels of supplemental phosphorus at this
level of calcium. Feeding of high levels of soft phosphate at a
calcium level of 2.25 percent or less resulted in lowering the
rate of egg production, and increasing the amount of feed re-
quired to produce a dozen eggs. This reduction of performance
of hens with the high levels of soft phosphate could not be ex-
plained on the basis of the low availability of phosphorus in the
soft phosphate since a higher rate of production was obtained
with the diets containing a lower level of phosphorus. It is
assumed that these hens receiving the high levels of soft phos-
phate were suffering from a calcium deficiency, since compar-
able levels of soft phosphate gave good performance when the
level of calcium was increased to 3.75 percent (Table 6). The
results from Experiment 6 agree with the results of Baruah et al.
(1960) who reported that two-thirds of the phosphorus in the
laying mash could be supplied by soft phosphate. That calcium
availability is a factor to be considered when evaluating soft
phosphate as a source of phosphorus for poultry agrees with the
report of Watts and Miner (1959), who found that calcium is
less available in soft phosphate than in dicalcium phosphate.
Therefore, the decreased performance obtained with the diets
containing high levels of soft phosphate in Experiments 2, 3,
and 4 may be attributed to a deficiency of calcium rather than







20 Florida Agricultural Experiment Stations

a deficiency of phosphorus. The fact that these diets were
deficient in calcium is substantiated by the report of Durham
et al. (1960) who states that in diets supplemented with soft
phosphate, the calcium requirement is in excess of 2.25 per-
cent. The fact that the New Hampshire pullets in Experiment
1 (Table 2) were able to maintain maximum rate of egg pro-
duction with diets containing high levels of soft phosphate,
whereas, the White Leghorns receiving the diets containing
high levels of soft phosphate performed at a lower rate of pro-
duction, indicated that calcium was the limiting factor, and
that the availability of phosphorus was not the cause for the
decreased rate of egg production. This would point out the neces-
sity of increasing the calcium level of the diet when soft phos-
phate was used in order to compensate for the lowered avail-
ability of the calcium in the supplement.
The calcium-phosphorus ratio does not appear to be critical
in diets for laying hens. Feeding extremely high levels of cal-
cium (5.5 percent) or phosphorus (0.80 percent total phosphorus)
when the other mineral was deficient did not appear to alter
the performance of the hen (Tables 5 and 6). These data would
indicate that the laying hen does not react the same as the chick
to varying the calcium-phosphorus ratio, as it has been shown
that widening the calcium-phosphorus ratio with low levels of
phosphorus will decrease growth rate of chicks (Vandepopuliere
et al., 1961). Therefore, varying the level of either of these
minerals in a practical laying diet would not alter the require-
ment for the other mineral.
The corn-soybean type diet employed in Experiments 2
through 6 appears to be adequate for assessing the phosphorus
requirement of the laying hen and should be adequate for com-
paring the relative values of different supplemental phosphorus
sources for laying hens. The results obtained with this basal
diet also indicate that this diet will support a maximum rate of
egg production, and may be used in evaluating the protein and
amino acid requirements of the laying hen as well as evaluating
the phosphorus requirement.

SUMMARY
Six experiments were conducted to evaluate the phosphorus
requirement of the laying hen, and to compare the relative value
of dicalcium phosphate, defluorinated phosphate and soft phos-
phate as sources of phosphorus for the laying hen.








The Effect of Feeding Phosphorus to Laying Hens 21

Results from these experiments indicate that: (1) An "all
vegetable" diet containing 0.34 percent total phosphorus was
deficient in phosphorus for the laying hen. This basal diet may
be used for measuring the phosphorus requirement of the laying
hen and for comparing the feeding value of various sources
of supplemental phosphorus. (2) A level of approximately 0.40
percent phosphorus was required for the commercial egg pro-
duction type pullet maintained in floor pens and fed a corn-soy-
bean meal type diet. The requirement of hens maintained in
cages appeared to be in excess of this level, and may be near
0.60 percent of the diet. (3) The phosphorus content of the
diet did not affect egg shell quality as measured by specific
gravity of eggs or thickness of egg shells. (4) Defluorinated
phosphate, dicalcium phosphate, and soft phosphate were found
to be satisfactory sources of phosphorus for the laying hen.
However, the inclusion of high levels of soft phosphate in the
diet with total calcium levels of 2.25 percent or less resulted
in a reduction in egg production. It is concluded that this
reduction in rate of egg production was not attributed to the
lowered availability of the phosphorus, but was caused by a
calcium deficiency resulting from the lowered availability of
calcium in the soft phosphate. (5) Calcium-phosphorus ratios,
within the range studied in these experiments, did not affect the
performance of the hen when measured by rate of egg produc-
tion or thickness of egg shells.

ACKNOWLEDGMENTS
This work was supported in part by a grant-in-aid from the
Soft Phosphate Research Institute, Inc., and Smith-Douglass
Co.
The authors are indebted to the following for furnishing
these materials: The Soft Phosphate Research Institute for the
soft phosphate; International Minerals Co. for the dicalcium
phosphate; The Smith-Douglass Co. for the defluorinated phos-
phate; Chas. Pfizer & Co. for the vitamin A and B vitamins;
Abbott Laboratories for the menadione sodium bisulfite; and
Distillation Products for the vitamin E.

REFERENCES
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of phosphorus from defluorinated and collodial phosphate by chicks and
laying hens. Poultry Sci. 39:843-849.









22 Florida Agricultural Experiment Stations

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EVANS, R. J., J. S. CARVER and A. W. BRANDT, 1944. The influence of
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