Full text of DOI:10.1093/japr/11.1.34

2002 Poultry Science Association, Inc.
A DEMONSTRATION OF
P
OSTPELLET
HYTASE TO
IETS
A
PPLICATION OF
D
RY
P
B
ROILER
D
1
F. W. EDENS, C. R. PARKHURST, P. R. FERKET, and G. B. HAVENSTEIN
Department of Poultry Science, North Carolina State University,
Raleigh, NC 27695-7635
Telephone: (919) 515-2649
FAX: (919) 515-2625
e-mail: fwedens@mindspring.com
A. E. SEFTON
Alltech Biotechnology Center, Alltech, Inc.,
3031 Catnip Hill Pike, Nicholasville, KY 40356
Primary Audience: Nutritionists, Production Managers, Feed Mill Managers, Researchers
SUMMARY
A comparison of performance and P reduction in litter and manure from broilers fed rations
with and without phytase enzyme was made with chickens reared on litter or in cages. Low-activity
phytase supplemented as a dry powder to mash diets did not affect performance, but litter P
accumulation was decreased 14 to 21% in the finisher phase. Manure P content of broilers in
cages was reduced 14 to 19% during the starter and grower phases. Liquid phytase applied
postpelleting to diets with 0.5% total P (0.3% available P) reduced litter P accumulation (14 to
1
9%) and reduced manure P content in starter, grower, and finisher phases of the study. Phosphorus
content in raw manure was decreased by 55% during the finisher phase. Feed conversions of
broilers in cages and on conventional litter-covered floors were improved significantly with
postpellet application of liquid phytase. Feed conversion improvement was greater in birds in
cages. Postpellet application of dry phytase was shown to be feasible based upon performance and
reduction in litter P accumulation. Feed conversions were improved by 7 to 8 points (P < 0.05)
when compared to those of birds given a normal P level (0.72% total P) diet without phytase.
Litter P accumulation was reduced between 20.5 and 28.5% with dry phytase applied postpelleting.
With liquid phytase applied postpelleting, litter P accumulation was reduced 26.6%. These
reductions in litter P content represent about 4 lb of P per ton of litter.
Key words: broiler, phytase, postpellet, application, phosphorus, litter, manure
2002 J. Appl. Poult. Res. 11:34–45
exceeds the amount that can be used by crops
and other plants. Phosphorus and N in animal
manure often are applied to land, and excessive
levels can be subject to leaching into and pollut-
ing ground and surface water. If manure is ap-
plied to course-textured, permeable soils, such
as that found in the coastal plains, rapid water
D
ESCRIPTION OF
P
ROBLEM
On a regional and national level, disposal
of manure and litter from poultry production
facilities is a critical issue because the total P
(tP) being produced in some production areas
1
To whom correspondence should be addressed.

EDENS ET AL.: DRY PHYTASE APPLICATION
35
filtration allows for vertical and subsurface
movement of P (principally inorganic and to a
lesser degree organic P [1]) and N into ground
and surface water systems [2]. Concerns raised
by some environmental activist groups about
potential over-application of nutrients have led
to considerable debate about the appropriate ap-
plication of manure and litter. The Water Quality
Improvement Act of 1998 and the Nutrient Man-
agement Practices Act of 1998 in the State of
Maryland mandate that all feeds for monogastric
animals must be supplemented with a phytase
enzyme or other additives that reduce P in animal
wastes. These laws require that this supplemen-
tation be done to the maximum extent that is
commercially and biologically feasible. Other
states may follow this precedent.
M
ATERIALS AND
M
ETHODS
ANIMAL WELFARE
This project was approved and conducted
under the supervision of the North Carolina State
University Animal Care and Use Committee,
which has adopted Animal Care and Use Guide-
lines governing all animal use in experimental
procedures.
ANIMALS AND HUSBANDRY
Four separate experiments were conducted.
In each experiment, Arbor Acres × Arbor Acres
sex-linked, slow-feathering, high-yielding males
were used. After the hatchling chicks had been
sexed, chicks were assigned randomly to groups
of 40 for weighing and placement into each pen.
The ambient temperature at placement was
Poultry manure P can be significantly re-
duced by reducing dietary inorganic P and sup-
3
2°C. At 7-d intervals after placement, ambient
temperature was reduced by 4°C until a final
minimum ambient temperature of 24°C was
reached and maintained until the end of the ex-
periment (42 d). Upper limits on the ambient
temperature were not set but were allowed to
fluctuate with the daily maximum. The photope-
riod at placement was set at 24 h for the first 5
d, and thereafter, the photoperiod was set at
plementing the diets with a microbial phytase
3, 4, 5]. Significant reductions in caged layer
[
manure P content has been reported to be be-
tween 16 and 38%, but these manure P reduc-
tions cannot be achieved without reductions in
the concentration of inorganic P (P ) that is nor-
i
mally supplemented to the diet [3, 4, 5, 6, 7, 8,
9
]. Similarly, decreased P excretion in phytase-
supplemented market turkeys has been reported
10]. Fecal P reductions from laying hens, mar-
23 h light:1 h darkness. Feed and water were
[
provided ad libitum.
ket turkeys, broilers and swine have been re-
ported when feeds were supplemented with phy-
tase enzymes [3, 11, 12, 13, 14].
HOUSING
In Experiments 1 and 2, a 2 × 4 factorially
arranged, completely randomized experimental
design was used to test the effects of phytase
on male broiler chickens reared in replicate pens
in conventional litter-covered floor pens and rep-
licate pens in cage rows in the Broilermatic cage-
rearing system [15, 16]. There were 40 chickens
in each of the 64 pens (e.g., 8 rows of 8 cages
with 320 birds per cage row) in the Broilermatic
cage-rearing system, and 40 chickens in each of
the 32 pens in the conventional broiler house.
With this design, a total of 3,840 broiler chickens
was used. A total of 1,280 chickens was housed
in the conventional house and 2,560 were as-
signed to the Broilermatic cage-rearing system.
Experiments 3 and 4 were conducted to ad-
dress the use of postpelleting dry phytase vs.
liquid phytase application. This phase of the in-
vestigation was conducted in the conventional
There is no question about the efficacy of
phytase use in feeds for poultry and swine. Nev-
ertheless, due to cost and application difficulties,
there is resistance from the animal industries to
use this technology. Several reasons prevail, but
they most often focus on the cost of using post-
pelleting, liquid phytase application and the cost
of liquid phytase. If the feasibility of using
postpellet application of dry phytase could be
demonstrated, poultry growers could benefit
from reduced cost of enzyme, the positive effects
of phytase usage on performance, and decreased
P levels in manure and litter, thereby allowing
them to spread more litter per acre of land. Thus,
the objective of this investigation was to com-
pare the efficacy of postpellet liquid phytase
application and postpellet dry phytase applica-
tion in broiler chickens.

36
JAPR: Research Report
TABLE 1. Composition of North Carolina Agricultural Research Service basal broiler diets
INGREDIENTS AS A PERCENTAGE OF DIET COMPOSITION
INGREDIENT
Starter
Grower
Finisher
Corn
59.08
26.95
0.70
0.70
3.49
7.98
0.18
0.07
0.40
0.20
0.20
0.05
0.04
68.61
19.30
0.70
0.80
1.80
8.00
0.04
0.09
0.20
0.20
0.20
0.05
0.04
76.62
15.38
0.40
Soybean meal (48%)
Limestone
Dicalcium phosphate (22% Ca, 18.7% P)A
Poultry fat
Poultry meal
DL-Methionine
Lysine-HCl
NaCl
Choline chloride
6.79
0.05
0.30
0.20
0.20
0.05
0.04
B
Minerals (TM-90)
VitaminsC (NCSU-90)
Selenium premix (0.02% Se)
ABasal diets were modified to provide 0.5, 0.4, or 0.3% available inorganic P (P
i
) in the control diet by manipulating the
i
amount of dicalcium phosphate in the diets for the phytase studies. The Ca:available P was also modified to yield 2:1 in
the diets in the phytase studies.
B
Trace mineral (TM-90) premix provided in milligrams per kilogram of diet: manganese, 120; zinc, 120; iron, 80; copper,
10; iodine, 2.5; cobalt, 1.0. Selenium premix as sodium selenite was provided to each diet at a level to assure a concentration
of 0.15 ppm.
C
Vitamin premix (NCSU-90) provided per kilogram of diet: vitamin A, 6,600 IU; cholecalciferol, 2,000 IU; vitamin E, 33
IU; vitamin B12, 19.8 µg; riboflavin, 6.6 mg; niacin, 55 mg; pantothenic acid, 11 mg; vitamin K, 2 mg; folic acid, 1.1 mg;
thiamine, 2 mg; pyridoxine, 4 mg; biotin, 126 mg.
housing environment described above. As pre-
viously described, after chicks had been sexed,
females were assigned randomly and were
weighed in groups of 40 birds. They were then
placed in one of 36 floor pens containing five
inches of blended fresh and used litter. A total
of 1,440 chicks was used in each of Experiments
dietary treatments for each of the starter, grower,
and finisher diets as described in Table 3. The
dietary treatments consisted of the following:
starter, grower, and finisher treatments (1) con-
trol, (2) negative control (6 lb corn oil per 1,000
lb applied postpelleting and 0.2% decrease in
tP), (3) phytase and 0.2% decrease in tP, and
(4) phytase and 0.2% decrease in tP + oil spray.
The finisher diets in all four experiments had no
supplemental P, but phytase was retained in the
phytase treatment groups. The recommended
3
and 4. Feed and water were provided ad libi-
tum, and ambient temperatures were maintained
as described above.
DIETS
[17] dietary Ca and available P (aP) for broiler
starter, grower, and finisher diets are 1.0% Ca
and 0.45% aP, 0.9% Ca and 0.35% aP, and 0.8%
Ca and 0.30 aP, respectively. Broiler starter,
grower, and finisher diets were analyzed by the
North Carolina Department of Agriculture’s
Food and Drug Protection Division Forage Test-
ing Laboratory in Raleigh, NC, and the Ca and
tP concentrations are shown in Tables 2 and 3.
Basal diets without supplemental P contained
roughly 0.21% tP.
The broilers were given North Carolina Ag-
ricultural Research Service diets (Table 1) on
the following schedule: starter diet: 3,177 kcal
ME/kg, 22.5% crude protein (available to 18 d
of age); grower diet: 3,168 kcal ME/kg, 19.5%
crude protein (18 to 35 d of age); and finisher
diet: 3,160 kcal ME/kg, 17.4% crude protein (35
to 42 d of age). In Experiments 1 and 2, there
were four dietary treatments for each of the
starter, grower, and finisher diets, consisting of
(
1) negative control, (2) phytase control, (3) phy-
PHYTASE
tase test 1 with a 0.1% reduction in tP, and (4)
phytase test 2 with 0.2% reduction in tP. These
treatments are described in Table 2. In Experi-
ment 3 and Experiment 4, there also were four
Allzyme phytase [18] is an enzyme prepara-
tion derived from a solid-state fermentation pro-
cess with Aspergillus niger, and in addition to

EDENS ET AL.: DRY PHYTASE APPLICATION
37
TABLE 2. Calculated dietary Ca, total P, available P, and analyzed phytase distribution of treatments among
Experiments 1 (dry phytase mixed into mash) and 2 (liquid phytase sprayed onto pellets)
EXPERIMENT 1 FEEDS
Grower
EXPERIMENT 2 FEEDS
Grower
TREATMENT
Starter
Finisher
Starter
Finisher
Negative control
Ca, %
Total P, %
1.00
0.72
0.52
0
1.00
0.72
0.52
0
0.46
0.41
0.21
0
1.00
1.00
0.72
0.52
0
0.46
0.41
0.21
0
0.72
0.52
0
Available P, %
A
Phytase, PTU /kg
Phytase control
Ca, %
Total P, %
Available P, %
Phytase, PTU/kg
1.00
0.72
0.52
1.00
0.72
0.52
0.46
0.41
0.21
1.00
0.72
0.52
1.00
0.72
0.52
0.46
0.41
0.21
1,240
1,240
1,240
10,478
10,478
10,478
Phytase test 1
Ca, %
Total P, %
Available P, %
Phytase, PTU/kg
0.80
0.62
0.42
0.80
0.62
0.42
0.46
0.41
0.21
0.80
0.62
0.42
0.80
0.62
0.42
0.46
0.41
0.21
1,240
1,240
1,240
10,478
10,478
10,478
Phytase test 2
Ca, %
Total P, %
Available P, %
Phytase, PTU/kg
0.60
0.52
0.32
0.60
0.52
0.32
0.46
0.41
0.21
0.60
0.52
0.32
0.60
0.52
0.32
0.46
0.41
0.21
1,240
1,240
1,240
10,478
10,478
10,478
A
PTU = phytase units.
the phytase enzyme, there are several additional
side-enzyme activities that include cellulase,
protease, xylanase, and acid phosphatase [19].
In Experiment 1, phytase was dry-blended into
Diets 2, 3 and 4, and activity was determined
by chemical analysis to be 1,240 phytase units
lots. During the bagging process, a total of 20
different 1-lb samples were collected randomly
and were sealed in plastic bags until analyzed
for phytase activity by biochemists at Alltech
Biotechnology Center [18]. Phytase activity was
determined chemically to be 11,500 PTU/kg.
(
PTU)/kg, an activity that is roughly 10.7% the
ASSESSMENT OF DIETARY PHYTASE
INFLUENCE ON PERFORMANCE
recommended activity, in all three diets. In Ex-
periment 2, due to susceptibility of the enzyme
to degrade at the temperatures necessary for pel-
leting (82°C), it was applied postpelleting as a
liquid onto Diets 2, 3 and 4, and activity was
determined by chemical analysis to be 10,478
PTU/kg, an activity that is roughly 91.1% the
recommended activity, in all three diets. In Ex-
periments 3 and 4, postpelleting dry phytase ap-
plication was accomplished as follows: diets
were pelleted at 82 C and were run through the
cooling tower. The pellets were then returned to
a horizontal ribbon blender where one operator
dusted the dry phytase over the blending pellets,
and a second operator sprayed corn oil over the
pellets. Complete blending for postpelleting dry
phytase application required approximately 1
min. The pellets were then moved to the dispens-
ing bin where the feed was bagged in 40-lb
The influences of dietary phytase on serum
concentration of P and total Ca, weight gain,
i
feed conversion, livability, and manure and litter
P were determined in each of the four experi-
ments. Phosphorus was determined on the basis
of pounds per ton in the litter and on the basis
of grams tP per kilogram of dry matter intake
in manure in Experiment 1 and 2. In Experiments
3 and 4, accumulation of P was determined on
the basis of pounds per ton of litter. Litter sam-
ples were collected prior to placement of birds
in each of the experiments so that a baseline litter
P level could be determined. Blood sampling for
determination of serum P [20] and total Ca [21]
i
was done at 21 and 42 d of age; fecal P was
determined weekly on fresh feces collected from
belts under the cages in the Broilermatic cage-

38
JAPR: Research Report
TABLE 3. Calculated dietary Ca, total P, Available P, and analyzed phytase distribution of treatments among
Experiments 3 and 4 (dry phytase applied post pelleting)
EXPERIMENT 3 FEEDS
Grower
EXPERIMENT 4 FEEDS
Grower
TREATMENTS
Starter
Finisher
Starter
Finisher
Control
Ca, %
Total P, %
Available P, %
1.00
0.72
0.52
0
1.00
0.72
0.52
0
0.46
0.41
0.21
0
1.00
0.72
0.52
0
1.00
0.72
0.52
0
0.46
0.41
0.21
0
A
Phytase, PTU /kg
Oil spray, %
0
0
0
0
0
0
Negative control
Calcium, %
Total P, %
Available P, %
Phytase, PTU/kg
Oil spray, %
0.60
0.52
0.32
0
0.60
0.52
0.32
0
0.46
0.41
0.21
0
0.60
0.52
0.32
0
0.60
0.52
0.32
0
0.46
0.41
0.21
0
0.6
0.6
0.6
0.6
0.6
0.6
Phytase Test 1
Ca, %
Total P, %
Available P, %
Phytase, PTU/kg
Oil spray, %
0.60
0.52
0.32
0.60
0.52
0.32
0.46
0.41
0.21
0.60
0.52
0.32
0.60
0.52
0.32
0.46
0.41
0.21
11,500
11,500
11,500
0
11,500
11,500
11,500
0
0
0
0
0
Phytase Test 2
Ca, %
Total P, %
Available P, %
Phytase, PTU/kg
Oil spray, %
0.60
0.52
0.32
0.60
0.52
0.32
0.46
0.41
0.21
0.60
0.52
0.32
0.60
0.52
0.32
0.46
0.41
0.21
11,500
0.6
11,500
0.6
11,500
0.6
11,500
0.6
11,500
0.6
11,500
0.6
A
PTU = phytase units.
rearing system and in litter that was collected
from 10 random sites within each sampled pen
in the conventional house. An AOAC-certified
commercial laboratory [22] was used to analyze
the litter and manure for P by colorimetric
analysis.
Analyses of variance were conducted for
each parameter, and the level of significance was
set at P ≤ 0.05, depending upon the F values
generated by the GLM procedure. When differ-
ences among treatments were found, the means
were separated by least-significant difference
procedures of SAS software [23]. Percentage
data were converted to arc sins and analyzed
with the GLM procedure of SAS software [23].
phytase in mash feed) and Experiment 2 (a win-
ter study with liquid phytase sprayed onto post-
pelleted feed), phytase supplementation had
minimal effects on 42-d BW of broilers grown
in cages or in conventional housing (Table 4).
However, there was a seasonal effect with win-
ter-grown broilers having a heavier BW. In Ex-
periment 2, there was a housing effect on BW
with broilers in the conventional litter-covered
floor pens showing a slight advantage. In young
broiler chickens, a phytase product, different
from that used in this study, was associated with
improved digestibility of amino acids [24]. Kor-
negay [25] did not find improved BW in broilers
fed a finisher diet with phytase from 3 to 7 wk
of age. However, McKnight [26] summarized
the work of several scientific studies and re-
ported that the use of phytase reversed the nega-
R
ESULTS AND
D
ISCUSSION
PHYTASE AND PERFORMANCE
tive impact of reducing dietary P supplementa-
i
Mixed results have been observed with re-
gard to BW response of broilers fed phytase. In
Experiment 1 (a late summer study with dry
tion, which appeared to be the condition in this
study as well. Qian et al. [27] reported that broil-
ers fed very low levels of dietary P had depressed

EDENS ET AL.: DRY PHYTASE APPLICATION
39
TABLE 4. Influence of phytase applied dry in broiler mash (experiment 1) or as a liquid to postpelleted broiler
feeds (Experiment 2) on production parameters of chickens reared in conventional litter-covered floor pens and
cage environments (Broilermatic cage system)
BODY WEIGHTB (kg)
FCR
MORTALITY (%)
HOUSINGA
DIET
Exp. 1C
2.09a
Exp. 2
Exp. 1
Exp. 2
Exp. 1
Exp. 2
2.28b
2.25b
2.31b
1.73b
1.81b
1.82
ab
2.66a
2.81a
5.32
ab
Broilermatic
Cage
(1) 0.5% P
(2) 0.5% P + phytase
3) 0.4% P + phytase
4) 0.3% P + phytase
ab
ab
ab
2.01
1.98
1.97
1.84
5.79
ab
b
ab
a
b
(
(
1.74
1.81
2.03
4.07
ab
ab
1.78b
1.72c
2.03a
2.04c
7.82a
2.34
ab
2.40a
2.06a
1.86a
2.19a
Conventional
Litter floor
(1) 0.5% P
(2) 0.5% P + phytase
3) 0.4% P + phytase
4) 0.3% P + phytase
SEM
2.00
1.96
1.92
2.01
ab
ab
2.05a
1.87a
1.56a
ab
2.34
5.94
b
a
a
ab
a
9.07a
(
(
2.40
2.04
1.84
2.10
ab
2.41a
0.04
2.01a
0.02
1.80b
0.02
2.10a
0.73
ab
6.57
0.06
1.02
a–c
Within a column, means with unlike superscripts differ significantly (P < 0.05).
A
B
n = 640 birds per treatment in the Broilermatic cage system and 320 birds per treatment in the conventional house.
Body weights were based on average pen weights for each treatment group.
C
Exp. = experiment; FCR = feed conversion ratio.
weight gain, and even with an excess activity
of supplemental phytase, weight gain was not
equivalent to controls with NRC-recommended
P levels [17] in their diets. However, this reduced
weight gain, even with phytase, was related to
the ratio of dietary Ca to total aP in the diet.
Calcium:tP (Ca:tP ) ratios greater than 1.5 were
associated with reduced weight gain [27].
all treatment groups with the best FCR in groups
with the lowest levels of available P . In Experi-
i
ment 1, which was a summer study with tunnel
ventilation in the cage house but not in the con-
ventional house, the overall FCR in the cage
facility was improved by 28 points in compari-
son to the conventional house. In Experiment 2,
which was a winter study with relatively even
temperatures and ventilation in both facilities,
the overall FCR in the cage facility was im-
proved by only 4 points in comparison to the
conventional house. In this study, the improved
FCR in broilers given Allzyme phytase was con-
sistent with observations made when broilers
were given another phytase enzyme, Natuphos
[2, 23]. In Experiment 1, there were no differ-
ences among treatment mortality rates. Yet in
Experiment 2, in the cage facility, there was a
tendency for phytase supplementation to reduce
mortality, which resulted in an environment ×
phytase interaction (P < 0.05).
In Experiments 3 and 4, dry phytase was
applied postpelleting. The data shown in Table
5 indicate that this method of phytase application
to feed had no adverse effect on BW. Further-
more, it appeared that the use of an oil spray to
facilitate adherence of the dry phytase to the
pellets was not necessary, if BW was used as a
criterion of efficacy. Nevertheless, reduction of
tP from 0.72 to 0.52% without phytase supple-
mentation resulted in birds with smaller body
weights (significant in Experiment 4), which was
In Experiments 1 and 2, the Ca:tP ratios for
Diets 1, 2, 3, and 4 were 1.43, 1.43, 1.33, and
1
.20, respectively, for starter and grower feeds,
but in the finisher feed, the Ca:tP ratios were all
.12. Nevertheless, broilers in the conventional
1
house demonstrated slight reductions in BW
when they were given 0.5 or 0.4% aP diets with
supplemental phytase, but broilers given a 0.3%
aP diet with supplemental phytase had 6-wk BW
that was slightly greater than controls given the
0
.5% aP diet without supplemental phytase. In
the conventional house, it was possible that the
broilers were engaging in coprophagy and were
obtaining additional nutrients that were unavail-
able to the birds in the cage rearing facility.
In Experiment 1, feed conversion ratios
(FCR) within rearing environment were not af-
fected significantly by phytase supplementation
to the diets, but in Experiment 2, in both housing
environments, phytase supplementation to diets
with lower P concentrations resulted in im-
i
proved FCR. However, there was a clear trend
in cages and conventional houses that showed
an improving FCR with addition of phytase in

40
JAPR: Research Report
TABLE 5. Influence of dry phytase applied to postpelleted broiler feeds (Experiments 3 and 4) on production
parameters of broiler chickens reared in conventional litter-covered floor pens
BODY WEIGHTA (kg)
FCR
MORTALITY (%)
TREATMENT
Exp. 3B
Exp. 4
2.20a
Exp. 3
Exp. 4
Exp. 3
Exp. 4
a
1.86b
1.91a
1.86b
1.89a
2.24a
1.39a
4.17a
1.96a
0
0
0
0
.72% tP, no oil spray, no phytase
.52% tP, oil spray, no phytase
.52% tP, no oil spray, phytase
.52% tP, oil spray, phytase
2.18
2.13
2.18
2.17
a
b
2.15
a
ab
c
bc
a
a
2.19
1.82
1.84
3.61
2.50
a
a
1.83c
0.01
1.82c
0.01
1.96a
1.42
1.94a
0.82
2.22
SEM
0.03
0.02
a–c
Within a column, means with unlike superscripts differ significantly (P < 0.05).
A
B
Body weights are based on average pen weights for each treatment group.
Exp. = experiment; FCR = feed conversion ratio; tP = total P.
consistent with observations made earlier [27].
Yet on a practical basis, an average of a 0.1-lb
depression in BW of birds given a low-aP diet
is highly significant, as it would require approxi-
mately one additional day for growout to the
same body weight. The postpellet application of
dry phytase to diets containing 0.52% tP (0.3%
aP) corrected this problem.
Experiment 1 and 2 (Table 6). Serum total Ca
concentrations were also not affected by phytase
supplementation in the feed in which the Ca
levels were decreased along with P . The Ca:aP
i
ratios were maintained at 2:1 for each of the
experimental diets in this study, but serum Ca:Pi
ratios at 21 d of age ranged between 1.02 and
1.26 in Experiment 1 and between 1.16 and 1.44
in Experiment 2. This finding was not a depar-
ture from ratios normally reported [28] even
Reduction of tP in the diets used in these
experiments without supplementation of phytase
resulted in a significant increase in FCR (Table
though values for serum Ca and P were elevated
i
5). However, FCR for those diets with reduced
at 21 d of age in this study. At 42 d of age, the
tP and with dry phytase applied postpelleting
were improved significantly compared to the
control (0.72% tP, no oil spray, no phytase diet
and 0.52% tP, no oil spray diet). These results
were consistent with the results from Experiment
serum Ca and P concentrations were lower than
i
those found at 21 d of age, and this finding might
have been a reflection of lower dietary levels of
aP and Ca in the finisher diets. The higher serum
Ca and P concentrations associated with the
i
2
, in which liquid phytase was applied postpel-
phytase treatment of the finisher diets is an im-
portant observation. There was a very low di-
etary aP level in the basal finisher formulation,
and the provision of phytase in the diet appar-
ently catalyzed the hydrolysis of phytate P, re-
sulting in increased P for absorption and less for
leting and with observations made by other sci-
entists working with phytase [4, 26].
Mortality was not influenced by the phytase
treatment. Therefore, if BW and FCR are to be
used as criteria for efficacy of dry phytase ap-
plied to postpelleted feed, one must conclude
that this method of application is effective in
overcoming the negative effects of simply reduc-
ing tP in diets as a means to reduce fecal P.
elimination in feces. Serum Ca:P ratios at 42 d
i
of age were higher than at 21 d of age and ranged
between 1.04 and 1.70 in Experiment 1 and be-
tween 1.41 and 1.86 in Experiment 2, suggesting
that there was freeing of these minerals from
phytate in the feed.
PHYTASE INFLUENCE ON SERUM CA
AND P CONCENTRATIONS
i
The data in Table 7 indicate that postpel-
leting application of dry phytase had no adverse
Serum concentrations of P and total Ca are
i
presented in Table 6. Phytase and lower dietary
levels of aP did not cause a decrease in serum
Pi levels at either 21 or 42 d of age. To the
contrary, there was evidence at 42 d of age in
the lowest aP treatment that phytase supplemen-
effects on serum P
21 d of age in Experiments 3 and 4, serum P
in phytase-treated groups were not different
from the control diet (0.72% tP). In Experiment
4, the 0.52% tP group was found to have signifi-
and Ca concentrations. At
i
i
tation had actually elevated serum P in both
cantly lower serum P concentrations than the
i
i

EDENS ET AL.: DRY PHYTASE APPLICATION
41
TABLE 6. Influence of phytase applied dry in broiler mash (Experiment 1; Exp. 1) or as a liquid to postpelleted
broiler feeds (Experiment 2; Exp. 2) on serum inorganic phosphorus (P ) and total Ca concentrations in chickens
i
reared in conventional litter-covered floor pens and cage environments (Broilermatic cage system)
SERUM CONCENTRATION (mg/dL)
3
Wk
6 Wk
P
i
Ca
P
i
Ca
HOUSINGA
Cage
DIETB
0.5% aP
Exp. 1
Exp. 2
Exp. 1
9.0c
Exp. 2
Exp. 1
Exp. 2
5.5b
Exp. 1
Exp. 2
b
bc
bc
ab
b
bc
b
d
8.4c
8.3
7.7
8.0
7.6
7.8
8.1
7.9
9.2
5.3
5.5
c
bc
11.2a
6.2a
b
7.8c
7.4c
10.8a
0
0
0
.5% aP + phytase
.4% aP + phytase
.3% aP + phytase
9.7
9.9
5.8
bc
b
ab
a
b
a
10.6
6.1
5.8
10.6
ab
ab
9.3c
6.1a
b
bc
10.4a
8.7
10.1
5.8
8.0
Floor
ab
c
9.0c
5.4b
5.7b
9.2a
bc
0
0
0
0
.5% aP
9.1a
7.4c
10.1
9.2
8.7
ab
bc
bc
ab
b
b
b
.5% aP + phytase
.4% aP + phytase
.3% aP + phytase
8.6
9.1
9.6
7.8
8.6
7.9
9.4
5.8
5.8
5.9
6.2
8.5
9.2
a
a
10.6a
10.1b
ab
ab
ab
b
8.7
9.4
a
b
b
bc
6.0a
0.2
6.6a
0.3
7.8c
b
9.8
9.2
9.3
SEM
0.3
0.2
0.3
0.3
0.2
0.4
a–d
Within a column, means with unlike superscripts differ significantly (P < 0.05).
B
B
n = 20 for each treatment mean in both the Broilermatic cage system and in the conventional house.
NRC dietary requirement of 0.45% available P (aP) and 1.0% Ca in starter; 0.35% aP and 0.8% Ca in grower; 0.3% aP
i
and 0.6% Ca in finisher.
0.52% tP, no oil spray, phytase group; a similar
tase supplementation increased the serum P con-
i
condition that was not statistically significant
was observed in Experiment 3. At 42 d of age in
Experiment 3, there were no differences among
centrations to a control level or even exceeded
the control level. The reason for this response
is that supplemental phytase in the finisher diet
facilitated hydrolysis of phytate P making more
P available for absorption. At 21 and 42 d of
age, serum total Ca concentrations were not af-
fected by lower tP levels in the diet, and supple-
mentation with phytase did not alter that condi-
tion. Nevertheless, at 42 d of age, there was a
nonsignificant tendency for those birds given
phytase treatment to have a slightly higher serum
total Ca concentration.
treatment groups for serum P even though the
i
Pi concentrations in the phytase-treated groups
were numerically higher than the two non-sup-
plemented groups. In Experiment 4 at 42 d of
age, serum P concentrations in the 0.72% tP
i
group was significantly less than the P in the
i
two phytase-treated groups.
Generally, low aP in the finisher diet caused
i
a depression in serum P concentrations, but phy-
i
i
TABLE 7. Influence of dry phytase applied to postpelleted feeds (Experiments 3 and 4) on serum inorganic P (P )
and total Ca concentrations in broilers reared in conventional litter-covered floor pensA
SERUM CONCENTRATIONS (mg/dL)
3
Wk
6 Wk
P
i
Ca
P
i
Ca
DIET
Exp. 3
Exp 4
Exp. 3
Exp. 4
Exp. 3
Exp. 4
6.9b
Exp. 3
Exp. 4
a
ab
b
10.3a
10.8a
11.0a
10.6a
7.2a
7.3a
8.4a
8.6a
10.6a
10.7a
0
0
0
0
.72% tP, no oil spray, no phytase
.52% tP, oil spray, no phytase
.52% tP, no oil spray, phytase
.52% tP, oil spray, phytase
8.1
7.6
7.9
8.1
7.4
6.8
7.9
7.4
0.2
a
ab
7.2
7.4
a
a
a
a
a
a
a
a
10.5
11.8
7.7
9.0
11.1
a
ab
10.1a
1.3
10.9a
1.1
7.7a
0.2
7.5a
0.2
9.0a
1.2
11.4a
1.4
SEM
0.2
a,b
Within a column, means with unlike superscripts differ significantly (P < 0.05).
Exp. = experiment; tP = total P.
A

42
JAPR: Research Report
TABLE 8. Effect of low phytase activity applied in starter, grower, and finisher mash diets on changes in litter P
A
content in a conventional house and raw manure P content from birds in a cage facility
LITTER
Grower
MANURE
Grower
TREATMENT
Starter
100.0a
Finisher
Starter
Finisher
100.0a
a
100.0a
100.0a
85.9b
78.9b
2.7
100.0a
95.9a
95.2a
85.9b
2.9
100.0a
94.3a
92.3a
80.6b
2.7
NRC
NRC + phytase
100.0
a
a
a
96.6
102.4
104.3
107.2
94.1
a
a
107.1a
104.7a
2.8
0
0
.4% aP + phytase
.3% aP + phytase
99.1
a
a
97.4
SEM
2.2
2.4
a,b
Within a column, means with unlike superscripts differ significantly (P < 0.05).
A
All cells are expressed as a percentage of the NRC basal diet (set to an equivalent of 100%) without added phytase.
These data for serum P and total Ca were
consistent with the data from Experiment 2. The
results suggest that even when tP is at 0.52%
phytase was hydrolyzing some phytate P and Ca
that caused a slight increase in serum concen-
trations.
i
(
0.32% aP), the phytase can hydrolyze sufficient
In Experiment 2, liquid phytase was applied
postpelleting, and the activity of the phytase was
applied at a rate chemically determined to be
91.1% of the recommended activity level. In this
experiment, when tP was reduced in the diet and
phytase was supplemented, there was signifi-
cantly less P in litter and manure (Table 9).
Reduced litter and manure P was most evident
in those groups that had been fed diets with 0.3%
aP. Reductions in litter and manure P content
were apparent in all three feeding regimes
(starter, grower, and finisher). Phytase-associ-
ated reductions in litter ranged between 15 and
19%, whereas in the raw manure from the cage
facility, P was reduced between 12 and 18% in
the 0.4% aP-fed birds and in the 0.3% aP diets
the range was between 25 and 55%.
phytate P to meet the needs of broiler chickens.
In fact, if one uses serum P as an indicator of
efficacy of the enzyme in the feed, it might be
concluded that 0.32% aP is excessive in the diet
because phytase, liquid or dry applied postpel-
i
leting, was sufficient to maintain serum P at a
i
control level. Serum total Ca was not affected
significantly by the phytase treatment, but it was
interesting to note the numerically higher serum
total Ca levels at 42 d of age in the phytase
treated broilers. Higher serum P and total Ca
concentrations can be related to improved bone
ash in chickens.
i
PHYTASE INFLUENCE ON P CONTENT
IN RAW MANURE AND LITTER
In Experiments 3 and 4, phytase was applied
dry to postpelleted feeds. In both experiments,
significant decreases in litter P accumulation
were determined at the end of the study (Table
10). Reductions in litter P under birds fed the
phytase diet without oil spray were between 28.5
and 20.5% in Experiments 3 and 4, respectively.
Similarly, in Experiments 3 and 4, litter P under
birds fed the phytase diet with oil spray was
reduced between 22.9 and 23.1%, respectively.
There was no difference between Experiments
3 and 4 for the phytase-associated reduction in
litter P. These data compared favorably with the
results obtained in Experiment 2 when a liquid
phytase was applied to feed postpelleting. In
Experiment 2, the 0.3% aP diet was comparable
with the phytase diets in Experiments 3 and 4.
In Experiment 2, a 26.1% reduction in litter P
The phytase activity added to diets in Experi-
ment 1 was about 10% of the recommended
activity. Therefore, it was not very surprising to
find that the amount of P in litter and manure
was not very different from that found in litter
and manure from control birds (Table 8). How-
ever, in the cage facility, phytase supplementa-
tion resulted in significantly lower P content in
the 0.3% aP diet during feeding of starter and
grower feeds. During the feeding of finisher feed
there was significantly less P accumulation in
the litter under birds fed a 0.3% aP diet. These
reductions in litter and manure P are not due
entirely to the phytase activity in the finisher
feeds but may simply reflect the lower levels
of P in the diets. Nevertheless, even with the
inadequate phytase activity in the finisher feed,
serum P and Ca concentrations suggest that the

EDENS ET AL.: DRY PHYTASE APPLICATION
43
TABLE 9. Effect of liquid phytase activity applied postpelleting in starter, grower, and finisher diets on changes in
litter P content in the conventional house and raw manure P content from birds in the cage facilityA
LITTER
Grower
MANURE
Grower
TREATMENTA
Starter
Finisher
100.0a
Starter
Finisher
a
a
100.0a
91.0a
100.0a
97.8a
100.0a
101.0a
NRC
NRC + phytase
100.0
107.9
100.0
a
a
a
100.9
103.1
b
b
100.7a
85.7b
2.4
b
b
b
0
0
.4% aP + phytase
.3% aP + phytase
92.3
92.8
82.1
88.0
84.6
c
c
74.6c
2.0
74.9c
2.2
45.0c
2.9
81.2
82.4
SEM
2.1
2.2
a–c
Within a column, means with unlike superscripts differ significantly (P < 0.05).
A
B
All cells are expressed as a percentage of the NRC basal diet (set to an equivalent of 100%) without added phytase.
aP = available P.
was determined at 42 d of age, similar to the
observations made in Experiments 3 and 4.
Therefore, it appears that application of dry phy-
tase to postpelleted feeds can be accomplished
with results comparable with results associated
with liquid phytase application postpelleting.
The efficacy of phytase use in feeds to de-
crease litter P can be variable. A 30% P reduction
in poultry manure was reported in early studies
with a microbial phytase [3, 4, 5]. Later, it was
reported that a 38% reduction in laying hen ma-
nure P could be achieved with microbial phytase
fecal P from laying hens fed P at 80 or 60% of
i
the NRC requirements [6]. The same phytase
enzyme has been shown to reduce manure P in
market turkeys [10]. Fecal P reductions from
laying hens [4], market turkeys [10], and broilers
given the phytase used in the current study were
similar to the fecal P reductions found in pigs
[3], layers [11, 12], and broilers [13, 14] given
another phytase feed supplement.
At the termination of these studies, litter P
accumulation was reduced by 20.5 to 28.5% in
pens containing broilers given the diet with 0.5%
tP (0.3% aP) and supplemental phytase. Similar
reductions in litter P accumulation were not ob-
tained with dietary tP at 0.6% (0.4% aP) or
higher. Qian et al. [27] reported that phytase,
[9]. In 21-d-old broilers, the availability of di-
etary P could be increased up to 65% by means
of supplemental dietary phytase while reducing
fecal P by 50% [3]. The phytase used in the
current study yielded significant 16 and 25%
reductions in fecal P, similar to reductions in
vitamin D , and Ca:tP ratios are important fac-
3
tors in degrading phytate P and improving di-
TABLE 10. Comparison of the influence of postpellet application of dry phytase (Experiments 3 and 4) and postpellet
application of liquid phytase (Experiment 2) on the accumulation of P in pine wood shavings litterA under 6-wk-
old broiler chickens
Exp. 2
Exp. 3
Exp. 4
TREATMENTSB
Litter P (lb/t) Control (%) Litter P (lb/t) Control (%) Litter P (lb/t) Control (%)
0
.72% tP, no oil spray,
no phytase (control)
.52% tP, oil spray, no phytase
.52% tP, phytase, no oil spray
.52% tP, phytase, oil spray
18.0
17.3
12.9
13.9
1.4
100.0a
15.6
14.4
12.4
12.0
1.1
100.0a
a
a
0
0
0
−3.73
−5.1
−20.5b
b
b
−28.5b
−22.9
−23.1
SEM
a
a
a
b
NRC (0.7% tP, control)
NRC + phytase (0.7% tP)
13.8
14.6
14.0
10.2
1.2
100.0
+5.8
+1.5
0
0
.4% aP + phytase (0.6% tP)
.3% aP + phytase (0.5% tP)
−26.1
SEM
a,b
Within a column, means with unlike superscripts differ significantly (P < 0.05).
n = 9 for each cell mean.
A
B
tP = total P; Exp. = experiment.

44
JAPR: Research Report
etary P and Ca use in broilers. Dietary Ca in
excess of 1.25% [29] can precipitate phytate
as an insoluble Ca-phytate in the intestine and
inhibit release of phytate P by phytase [30, 31,
crease in phytate digestibility [34]. It has been
noted that low levels of dietary P result in in-
creased activity of intestinal phytase in chicks
[
30, 35], explaining the observations made by
Edwards [33] and Van der Klis and Versteegh
7, 8]. Therefore, an increase in endogenous in-
32], but in this study dietary Ca was 1% or less.
[
However, it has been demonstrated that broiler
chickens have the ability to degrade phytate P
as they approach market age [7, 8, 33]. The
digestibility of phytate P can increase from 31%
at 14 d of age to 38.2% at 25 d of age in broilers
testinal phytase in response to decreased dietary
P (0.6% tP; 0.4% aP) and supplemental dietary
phytase activity might have liberated phytate Ca
that was sufficiently high to precipitate Ca-phy-
tate. Thus, when dietary tP is higher than 0.5%,
even with phytase supplemented to the diet, litter
P accumulation may be higher than expected.
[
7, 8]. At low levels of dietary P , phytate P
i
becomes more available due to an adaptive in-
C
ONCLUSIONS AND
A
PPLICATIONS
1
. The use of phytase at less than recommended activities does not reduce fecal P when dietary
tP is high, but it is possible to reduce fecal P at the expense of performance if there is low tP
in the diet.
2
3
4
5
6
. Feed conversions are improved significantly with the use of properly formulated diets with
adequate phytase activity.
. Dry phytase applied to postpelleted broiler feeds resulted in significant reductions in litter P
accumulation comparable to the reductions associated with postpellet liquid phytase application.
. It is feasible to apply dry phytase postpelleting; revenue savings can be realized due to reduced
costs of purchasing and shipping liquid phytase.
. Use of dry phytase applied postpelleting provides for a safety factor associated with the bacteri-
cidal effect of high pelleting temperature.
. Dry phytase is more stable than liquid phytase and requires less warehouse space for storage.
R
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