Full text of DOI:10.1093/japr/12.3.264

2003 Poultry Science Association, Inc.
Egg Production, Fertility, and
Hatchability of Breeder Hens
Receiving Dietary Phytase
1
W. D. Berry, J. B. Hess, R. J. Lien, and D. A. Roland
Department of Poultry Science, Alabama Agricultural Experiment Station,
Auburn University, Auburn, Alabama 36849-5416
Primary Audience: Broiler Breeder Managers, Nutritionists, Researchers
SUMMARY
An experiment was conducted to determine whether supplemental dietary phytase could support
egg production, egg shell quality, fertility, and hatchability in broiler breeder hens on a diet with
marginal available phosphorus. During the production period, 27 to 60 wk of age, individually
caged broiler breeder hens were fed four diets with two available phosphorus (AP) concentrations
(0.1 and 0.3%) and two phytase levels [0 and 300 phytase units (FTU)/kg]. Phytase increased
overall hen-day egg production by 9.8%, as compared with hens consuming a low phosphorus diet
without added phytase. Addition of phytase significantly reduced hen mortality regardless of
AP levels. Phytase improved bone mineral content and bone density of hens at both AP levels.
Supplemental phytase had no significant effect on egg weight or egg specific gravity. The results
suggest the possibility of a detrimental interaction of phytase with the 0.1 AP level on hatchability.
Key words: broiler breeder hen, phytase, phytate phosphorus
2003 J. Appl. Poult. Res. 12:264–270
EP, EW, and feed intake, whereas an additional
increase in either P or phytase produced no fur-
ther benefit in performance [3]. Addition of phy-
tase at 300 FTU/kg to diets containing 0.1% AP
DESCRIPTION OF PROBLEM
In an effort to reduce phosphorus in poultry
waste, diets for commercial egg laying flocks
and broilers have been formulated with reduced
levels of inorganic phosphate and supplemented
with phytase to increase phosphorus availability.
Addition of 200 to 300 phytase units (FTU)/kg
(0.3% total P) corrected P-deficiency in EP, EW,
egg specific gravity (ESG), and decreased mor-
tality of 21- to 39-wk laying hens [4].
Little information is available about the re-
sponse of broiler breeder hens to supplemental
dietary phytase. The current study was con-
ducted to determine whether broiler breeder hens
would respond to supplemental phytase in a
manner similar to Leghorns.
[
1] to diets containing 0.1% available phospho-
rus (AP) has been demonstrated to satisfy the P
requirement of Leghorn laying hens. Supple-
mentation of diets containing 0.12% AP (0.33%
total P) with 200 to 2,000 FTU phytase/kg were
found to support normal 24- to 52-wk egg pro-
duction (EP), egg weight (EW), feed intake (FI),
and tibia weight in commercial layers [2]. Phy-
tase supplementation at 200 FTU/kg to a basal
diet (no added P) was enough to maintain normal
MATERIALS AND METHODS
Four hundred Ross 308 [5] broiler breeder
females were reared to 21 wk of age in a com-
mercial light-proof pullet rearing facility. Man-
1
To whom correspondence should be addressed: berrywd@acesag.auburn.edu.

BERRY ET AL.: PHYTASE FOR BREEDER HENS
265
TABLE 1. Composition of diets
Diet
Ingredient
1
2
3
4
(%)
Corn
69.81
21.58
0.36
1.09
4.16
2.00
0.41
0.25
0.25
0.10
0.00
69.74
21.58
0.39
1.09
4.15
2.00
0.41
0.25
0.25
0.10
0.05
70.72
21.51
0.00
0.00
4.77
2.00
0.41
0.25
0.25
0.10
0.00
70.65
21.51
0.03
0.00
4.76
2.00
0.41
0.25
0.25
0.10
0.05
Soybean meal (48% protein)
Poultry oil
Dibasic calcium phosphate
Calcium carbonate
Hard shellA
Salt
B
Vitamin premix
Mineral premixC
DL-Methionine
Natuphos 5000
Calculated analysis
Protein
Calcium
Available P
Total P
15.94
2.75
0.30
0.52
15.94
2.75
0.30
0.52
15.98
2.75
0.10
0.32
15.98
2.75
0.10
0.32
ME, kcal/kg
2,919
2,919
2,919
2,919
ALarge-partical calcium carbonate (passing through US mesh #4 and retained by mesh # 6). Supplied by Franklin Industrial
minerals, Lowell, FL.
B
3
Vitamin premix provided per kilogram of finished feed: vitamin A, 7,350 IU; vitamin D , 2,200 ICU; vitamin E, 8 IU;
riboflavin, 5.5 mg; d-pantothenic acid, 13.0 mg; niacin, 36 mg; choline, 500 mg; vitamin B12, 0.02 mg; menadione, 2 mg;
folic acid, 0.5 mg; thiamine mononitrate, 1.0 mg; pyridoxine, 2.2 mg; d-biotin, 0.05 mg.
C
Mineral premix provided in mg/kg of finished feed: Cu, 6.0; Fe, 54.8; I, 1.0; Mn, 65.3; Se, 0.3; Zn, 55.
agement and feeding during rearing followed
the primary breeder’s guidelines for this strain.
Daylength was maintained at 8 h light from 3
wk of age until transfer to the breeder house.
The birds were transferred at 21 wk of age to
individual layer cages in a curtain-sided house.
Each cage was equipped with nipple waterers
and a trough feeder. Day length was increased
at that time to 14 h light to photostimulate the
birds. Daylength was further increased to 15 h
at the beginning of wk 22, and to 16 h at the
beginning of wk 24. From 21 wk of age onward,
the hens were fed four diets in a factorial ar-
rangement with two levels of AP (0.1 and 0.3%)
and phytase (0 and 300 FTU/kg; Table 1). All
diets were isocaloric (2,919 ME/kg), isonitro-
genous (15.9% CP), and contained 2.75% Ca.
The four treatments were arranged into random-
ized complete blocks, with 10 replicates of 10
hens each. Each hen was provided with a mea-
sured amount of feed based on maintaining hen
BW at the target BW recommended in the man-
agement guide for Ross 308 hens. Hens were
individually fed 106 g per hen per day at 21 wk
per hen each week until 30 wk of age (151 g
per bird per day, 33.3 lb/100). After 30 wk,
feed allocations were based on maintaining the
average BW of “control” (0.3 AP group without
phytase) hens on the growth curve in the primary
breeder management guide. As it turned out,
feed amounts were essentially constant after 30
wk of age. To 52 wk of age, these feed alloca-
tions were less than the amounts listed in the
management guide. Feed allocations to the hens
were slightly above the management guide rec-
ommendations after 52 wk of age. Water was
consumed ad libitum.
Body weights of all hens were recorded ev-
ery 4 wk. Mortality was recorded as it occurred.
Egg production was tabulated weekly. Egg
weight and ESG were determined from a 3-
day collection of eggs every 4 wk. Egg specific
gravity was determined using a series of saline
solutions (1.060 to 1.100 incremented by 0.005).
Fertility was determined at 39 and 49 wk of
age. All hens from each treatment group were
inseminated twice in 3 d with pooled broiler
breeder semen. Eggs were collected from the
third through twelfth day following insemination
(23.3 lb/100), increasing by approximately 5 g

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JAPR: Research Report
TABLE 2. Mean hen-day egg production during early (27 to 36 wk), middle (37 to 46 wk), and late production (47
to 60 wk) of broiler breeder hens fed diets containing two levels of available phosphorus (AP) and phytase
AP
%)
Phytase
(FTU/kg)
(
Early
Mid
Late
Overall
50.37b
0
0
0
0
.1
.1
.3
.3
0
300
0
59.84b
52.47b
40.14b
ab
ab
ab
ab
62.67
64.16
66.74
1.37
58.64
60.46
46.29
48.01
55.33
56.94
a
a
ab
ab
ab
300
64.12a
2.13
51.49a
1.55
60.19a
1.51
SEM
Probability
ANOVA
AP
Phytase
AP × phytase
0.037
0.180
0.098
0.010
0.065
0.017
0.001
0.035
0.001
0.001
0.043
0.002
a,b
Means within the same column with different superscripts differ significantly (P ≤ 0.05).
and incubated. Upon hatching of the chicks, un-
hatched eggs were broken out and examined to
determine the number of infertile eggs. Hatch-
ability was calculated as hatchability of fertile
eggs. Tibias were removed from 20 hens per
treatment at termination of the study and ana-
lyzed for bone mineral content (BMC) and bone
density (BD) using a Norland 2780 bone densi-
tometer [6]. Bone measures were made by sin-
gle-photon absorptiometry from an I125 source
the 0.1 AP hens that received no phytase. These
results suggest that even the 0.3 AP level may
have been limiting for EP in the caged breeders
in this study that were unable to consume feces
and litter to obtain or “recycle” phosphorus as
would birds in floor pen trials. This type of phos-
phorus recycling has been shown to provide
enough additional dietary P to significantly af-
fect egg shell quality [10, 11]. Besides direct
effects of AP and phytase, other factors such
as differences in gut microflora or variation in
activity of endogenous phosphatases [12] may
contribute to the effects of AP and phytase on
EP. As stated by Summers [13] and Roland and
Gordon [14], accurately determining P require-
ment in poultry is a difficult task, as puzzling
results are often encountered due to numerous
interacting factors.
Body weight for each of the treatment groups
tended to be below the management guide rec-
ommendations for this strain prior to wk 56 (Fig-
ure 1). This was due to the investigators’ reluc-
tance to increase feed allotments too quickly for
fear of rapid weight gains once the birds were
placed in cages. However, during the course of
production, BW were not significantly different
among the treatments (Table 3).
[7].
Data were subjected to analysis of variance
using general linear models procedures [8] with
pooled cages of each replication as an experi-
mental unit. The model included replication, AP,
phytase, and interaction of AP and phytase. Per-
centage egg production, fertility, hatchability,
and mortality were arcsine-transformed prior
to analysis.
RESULTS AND DISCUSSION
There is little published information about
effectiveness of phytase on performance of
broiler breeder hens. Wilson and Harms [9] dem-
onstrated that broiler breeder hens in floor pens,
fed diets containing 610 to 750 mg total P daily,
did not show differences in 24- to 64-wk EP,
EW, and ESG. In the present study, egg produc-
tion tended to be lower in hens receiving the 0.1
AP (780 mg total P, 450 mg AP) as compared
with hens receiving the 0.3 AP diet (Table 2).
Phytase supplementation tended to increase EP
in both the 0.1 and 0.3 AP diet hens. Hens receiv-
ing both 0.3 AP and phytase supplementation
had significantly higher EP as compared with
Overall EP of the highest producing groups
in this study (77%, Figure 2) was below the
expected peak EP (84%) listed in the manage-
ment guide. It is likely that keeping the birds
lighter than the target weight restricted their EP.
Lower EP would obviously reduce the hen’s
demand for phosphorus and other minerals.
Lower demand for phosphorus in these hens

BERRY ET AL.: PHYTASE FOR BREEDER HENS
267
FIGURE 1. Mean body weight of broiler breeder hens when fed diets containing two levels of available phosphorus
AP) and phytase.
(
would be mitigated to some extent because the
caged birds in this study were unable to obtain
phosphorus from consuming litter.
Total average hen-day EP increased as the
apparent availability of phosphorus increased.
Overall (wk 27 to 60) hen-day EP tended to
increase with increased AP or phytase (Table
ited the lowest overall EP and the 0.3 AP, 300
FTU phytase group had the highest EP (9.8%
difference). Average EP for the 27 to 60 wk
production period was 5.7% higher in the 0.3
AP group as compared with the 0.1 AP birds.
Average EP for the 27 to 60 wk production
period was 4.1% higher with phytase than with-
out added phytase.
2
), and these factors interacted to significantly
increase EP at the 0.3 AP and 300 unit phytase
level. The 0.1 AP, 0 FTU phytase group exhib-
Analysis of EP as early (27 to 36 wk), middle
(37 to 46 wk), and late production (47 to 60 wk)
TABLE 3. Mean egg weight (EW), egg specific gravity (ESG), combined 39 through 49 wk fertility (FERT) and
hatchability of fertile eggs (HATCH), BW gain (GAIN), and mortality (MORT), bone mineral content (BMC), and
bone density (BD) of Ross broiler breeder hens after feeding diets containing two levels of available phosphorus
(AP) and phytase
AP
Phytase
(FTU /kg)
EW
(g)
FERT
(%)
HATCH
(%)
GAIN
(g)
MORT
(%)
BMC
(g/cm )
BD
(g/cm )
A
2
2
(%)
ESG
0
0
0
0
.1
.1
.3
.3
0
300
0
63.5
64.0
64.1
64.3
1.3
1.085
1.085
1.084
1.084
0.0012
79.6
76.6
79.8
82.1
2.3
84.2a
1,660
1,628
1,634
1,508
68
17.0a
0.307b
0.340c
0.372b
b
b
ab
71.9
9.0
11.0
5.0
0.325
0.318
85.3a
85.0a
5.6
ab
b
0.367
bc
b
0.349a
0.018
0.399a
0.024
300
SEM
5.0
Probability
ANOVA
AP
Phytase
AP × phytase
0.37
0.50
0.78
0.09
0.61
0.67
0.45
0.92
0.47
0.01
0.01
0.02
0.13
0.11
0.33
0.12
0.03
0.75
0.14
0.04
0.58
0.04
0.02
0.10
a–c
Means in the same column with differing superscripts differ significantly (P ≤ 0.05).
A
Phytase units.

268
JAPR: Research Report
FIGURE 2. Mean weekly egg production of broiler breeder hens when fed diets containing two levels of available
phosphorus (AP) and phytase.
indicated that EP tended to increase with the
apparent AP level from early in production (Ta-
ble 2). This effect became more pronounced later
in production. The interaction of AP and phytase
supplementation became significant during mid-
dle production and remained so during late pro-
duction.
The demands of a high rate of EP in commer-
cial layers limit BW gain or may result in weight
loss, even though the hens are fed free choice.
Clearly EP in commercial layers can outstrip the
hen’s resources and ability to take in nutrients
and energy. Studies of phytase supplementation
of commercial layer diets have demonstrated a
gain in BW in addition to an increase in EP
[2, 15]. Increased nutrient availability due to
phytase supplementation improved the ability
of commercial layers to meet the demands of
increased EP with less depletion of body re-
serves, thus allowing increased BW. Broiler
breeder hens have a much lower rate of lay and
start producing eggs at a higher BW. Moreover,
broiler breeder hens gain weight during produc-
tion. Therefore, broiler breeder hens should have
greater body reserves while their EP puts less
demand on reserves and nutrient uptake. It was
expected that phytase supplementation would
increase weight gain of the breeder hens during
production. Unexpectedly, phytase-supple-
mented hens in the present study gained BW at
a reduced rate, in comparison with the hens that
did not receive phytase, although the differences
in weight gain were not significant overall. Im-
These results suggest that 0.1% AP was sig-
nificantly limiting for EP, whereas 0.3 AP tended
to be limiting for EP in caged breeders in this
study. Phytase supplementation improved EP at
both levels of AP. This effect became more pro-
nounced later in production. Increasing egg size,
decreasing bone reserves, and impaired nutrient
uptake with aging were likely contributors to
this effect, while decreasing EP would have been
a mitigating factor. It is difficult to predict how
the birds would have responded to larger feed
allotments. More feed would have provided
more P to the hens. However, assuming that
feed increases were based on increased EP with
control of BW gain, then the additional resources
would have been allocated to EP. In that case, the
overall effects may not have been significantly
different from what was observed in the pres-
ent study.

BERRY ET AL.: PHYTASE FOR BREEDER HENS
proved nutrient availability may have allowed
269
No published information is available about
for increased EP by the phytase-supplemented
hens; however, without the ability to increase
food intake due to controlled feeding, BW did
not increase as quickly as that of the hens with
lower EP. The lower BW, in turn, may have
directly improved laying persistency. A more
intriguing possibility is that there may be an
interaction between AP (and/or other nutrients)
and energy that favors the allocation of resources
to EP over weight gain.
The trend towards reduced mortality in the
phytase supplemented hens is consistent with the
results of studies in layers [4, 16] and broilers.
Mortality was significantly reduced in hens re-
ceiving phytase, as compared with the 0.1 AP
hens that did not receive phytase. Hens on the
the influence of phytase on the hatchability of
eggs in commercial layers or broiler breeders.
The results of this study indicate that, within
the levels of phosphorus fed, fertility in broiler
breeders is not sensitive to dietary AP (Table
3). For this reason, differences in fertility due
to phytase would not be expected, and none
was observed. Hatchability, like fertility, did not
appear to be sensitive to AP levels as fed in this
experiment. Hens on 0.1% AP without phytase
were able to package sufficient resources for
embryonic development. It is possible that
higher EP would have consumed resources at
a rate that would have resulted in insufficient
phosphorus for the production of viable em-
bryos. The results do suggest the possibility of
a detrimental interaction of phytase with the 0.1
AP level on hatchability. This was an intriguing
result and may be the effect of phytase interac-
tions with the uptake of other nutrients such as
iron. However, to date, similar studies currently
underway by the authors have not reproduced
this effect.
0
.3 AP diet without phytase had a mortality rate
intermediate to that of the 0.1 AP hens and the
phytase-supplemented hens. Mortality of hens
from 27 to 60 wk of age was reduced by an
average of 7% due to the addition of phytase
(Table 3).
In the current study, EW (Table 3) did not
differ between AP and phytase levels, which is
consistent with results from commercial layers
Addition of phytase increased BMC and BD,
regardless of dietary P levels (Table 3). This is
consistent with results obtained in studies of
commercial layers [15] and broilers [17]. Histo-
logical observations of tibial bones in phytase-
supplemented broilers demonstrated increased
width of cartilaginous and proliferative zones,
increased density of trabecular bone, and im-
proved mineralization of cartilage and bone
cells [17].
[15]. However, in the same study of commercial
layers, phytase increased ESG. In the present
study, ESG was not affected by AP or phytase.
Leghorns have lower feed intake and higher EP,
so it is possible that commercial layers could
be more responsive to phytase supplementation
than broiler breeder hens fed diets with marginal
or subnormal P level.
CONCLUSIONS AND APPLICATIONS
1. Supplementing breeder hen diets with phytase at 300 FTU/kg in a diet containing 0.1% available
phosphorus is sufficient to support EP in broiler breeders.
2
3
4
. Egg production was increased by phytase supplementation with no decrease in EW or ESG.
. Phytase supplementation decreased mortality regardless of available phosphorus levels.
. Phytase supplementation can replace added inorganic phosphate in breeder diets down to the
0.1% available phosphorus level with an increase in livability and egg production.
REFERENCES AND NOTES
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Acknowledgments
The authors thank the U.S. Poultry & Egg Association for provid-
ing financial support for the this project and the BASF Corporation
for donation of the phytase.
1
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