Download Effect of Bird Cage Space and Dietary Metabolizable Energy Level

Effect of Bird Cage Space and Dietary Metabolizable Energy Level
on Production Parameters in Laying Hens1
M. A. Jalal,* S. E. Scheideler,†2 and D. Marx‡
*PO Box 34, Dahiyet El-Amir Rashed, Amman 11831, Jordan; †Department of Animal Science, University of Nebraska,
Lincoln 68583-0908; and ‡Department of Statistics, 342C Hardin Hall,
University of Nebraska, Lincoln 68583-0963
except for body weight change. Hens housed at 516 cm2/
hen and fed 2,800 kcal of ME/kg exhibited the greatest
weight change, which was significantly (P < 0.05) greater
than those fed other levels of ME at the same cage space.
Hens housed at 690 cm2/hen had significantly (P < 0.05)
greater ME efficiency of egg production than hens housed
at other cage spaces. Hens fed the diet with 2,900 kcal of
ME/kg had significantly (P < 0.001) greater ME digestibility compared with those fed 2,800 or 2,580 kcal of ME/
kg with differences of 107 and 118 kcal of ME/kg, respectively. There were no significant effects of ME levels observed except ME digestibility, and no significant effects
of cage space allowance on egg weight, hen weight, bone
ash, or maintenance energy intake. It is evident that decreasing the number of birds per cage and increasing cage
space allowance per hen had an overall positive effect
on performance.
ABSTRACT A study was conducted to assess the effects
of varying cage spaces on a commercial laying hen strain
fed differing levels of dietary metabolizable energy (ME)
for 15 wk. Four cage space allowances (342, 413, 516, and
690 cm2/hen) were combined with 3 levels of dietary ME
(2,800, 2,850, and 2,900 kcal of ME/kg) in a 4 × 3 factorial
arrangement. Each treatment was assigned to 6 replicate
cages for a total of 72 cages in randomized complete block
design. Feed intake and metabolizable energy intake were
significantly (P < 0.01) greater for hens housed at 690
cm2/hen compared with those housed at 413 and 342
cm2/hen, but not those housed at 516 cm2/hen, across
all dietary ME levels. Egg production and egg mass were
significantly (P < 0.001) improved for hens housed at 690
cm2/ hen in contrast to other cage spaces and across all
energy levels. There were no interaction effects of ME
levels on laying hen performance at varying cage space
Key words: cage space, laying hen, metabolizable energy
2006 Poultry Science 85:306–311
has been reported to lower egg production (EP), egg
weight (EW), and feed intake (FI), and increase mortality
(Marks et al., 1970; Bell, 1981; Roush et al., 1984; Sandoval
et al., 1991). Differing diets were not used in these studies
to determine whether there was an interaction between
diet and caging space.
Only a few researchers have investigated the interaction of cage space and diet on performance of laying
hens. Jackson and Waldrup (1988) reported that increased
dietary nutrient space helped overcome the effects of limited feeder space associated with crowded cages, but the
influence was minimal when shallow cages were used.
Owings et al. (1967) found that decreased EP caused by
decreasing cage space was partially overcome by increased dietary protein, but Brake and Peebles (1992) detected no effects of increased dietary lysine on performance with decreased cage space. Carew et al. (1976,
1980) concluded that increasing the dietary energy level
of White Leghorn hens did not reverse the downward
trend in EP associated with decreased hen cage space.
In 2001, United Egg Producers (Atlanta, GA) put forth
new animal welfare guidelines that recommend a cage
INTRODUCTION
Modern-day egg producers have attempted to increase
net income by utilizing available housing facilities at maximum capacity. Currently, commercial layer operations
tend to maximize the number of birds per cage, consequently decreasing cage space allowance per bird (Hester
and Wilson, 1986). Producers reduce bird space with the
assumption that an increase in total egg production per
housing unit increases profit and offsets the negative effects of crowding (Adams and Craig, 1985). This perception, however, started to change in the decade with animal
welfare issues receiving more publicity (Anderson et
al., 1995).
Cage space effects on the performance of commercial
laying hens are well documented. Decreased cage space
2006 Poultry Science Association, Inc.
Received May 5, 2005.
Accepted October 21, 2005.
1
Published with the approval of the Director as Paper Number 14504,
Journal Series, Nebraska Agricultural Research Division.
2
Corresponding author: [email protected]
306
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BIRD CAGE SPACE AND DIETARY METABOLIZABLE ENERGY
space of 432 cm2/hen for small White Leghorn hens compared with the current industry practice of 336 to 348
cm2/hen. If cage space changes, then the energy requirement of the laying hen may change. New research needs
to be conducted to test the effects of cage on energy needs
of the laying hen.
The objective of our study was to evaluate the effects
of varying cage space and dietary ME levels on energy
requirement and production parameters of White Leghorn laying hens.
MATERIALS AND METHODS
Experimental Design
Four cage space allowances (342, 413, 516, and 690 cm2/
bird) were assigned to Hy-Line W-36 (Hy-Line International, West Des Moines, IA) White Leghorn hens from
20 to 35 wk of age. The hens were beak trimmed at 10 d
of age using a precision trimming technique. Each cage
space allowance was combined with 3 levels of dietary
ME (2800, 2850, and 2900 kcal/kg) in a 3 × 4 factorial
arrangement. Each treatment was randomly allotted to 6
replicate cages (total of 72 cages). Individual cages were
designated as experimental units and had varying numbers of hens; 3 (690 cm2/hen), 4 (516 cm2/hen), 5 (413
cm2/hen), or 6 (342 cm2/hen) for a total of 324 hens.
Experimental cage dimensions were 40.6 × 50.8 cm in a
stacked-deck manure belt system (manufactured by
Chore-Time, Milford, IN) consisting of the 3 rows (12
cages per row) on each side. Stainless steel feeder troughs
with a feeder depth of 13.5 cm were used, providing
feeder space of 6.70, 5.0, 4.0, and 3.33 cm/hen for 3, 4, 5,
and 6 hens/cage, respectively, and watering equipment
consisted of nipple drinkers (1/cage). The experimental
design was a randomized complete block design with 6
blocks and 12 cages per block. A block constituted 1 row
of 12 cages with 3 blocks on each side of the layer unit.
The hens were fed treatment diets for a period of 15 wk
from 20 to 35 wk of age.
Diets
The experimental diets were formulated according to
the recommendations of the breeder’s manual (Hy-Line
International) and to meet National Research Council
(1994) nutrient requirements of laying hens. The diets
were standard corn-soybean meal diets formulated to be
isonitrogenous and to contain 4.00% Ca and 0.42% nonphytate phosphorus (Table 1). The intermediate ME diet
was mixed by blending equal quantities of high and low
ME diets. Dietary samples were collected from each batch
of diet formulated, sieved through a 1-mm screen,
ground, and stored for analysis of gross energy (GE), Ca,
P, Cr, and N. The N content in the diets was multiplied
by 6.25 to obtain protein content in the diets. Calcium
and P were determined by procedures established by the
Association of Official Analytical Chemists (AOAC, 1984).
Dietary and fecal Cr were determined according to the
1
Table 1. Diet composition
Ingredients
High ME
Low ME
(%)
Corn
Soybean meal2
Wheat middlings
Tallow
Limestone
Dicalcium phosphate
Salt
DL-Methionine
Lysine
Vitamin premix3
Mineral premix4
Calculated nutrient composition5
ME, kcal/kg
Protein, %
TSAA, %
Lysine, %
Ca, %
Nonphytate P, %
Total P, %
Analyzed nutrient composition6
ME, kcal/kg
Protein, %
Ca, %
Total P, %
60.53
23.33
—
4.25
9.39
1.70
0.40
0.19
0.06
0.08
0.08
58.71
21.47
4.92
3.00
9.40
1.66
0.40
0.19
0.09
0.08
0.08
2,900
17.20
0.73
0.85
4.00
0.42
0.63
2,800
17.20
0.73
0.85
4.00
0.42
0.63
3,097
15.73
3.97
0.68
2,979
16.14
4.28
0.70
1
Intermediate ME diet was mixed by blending equal quantities of
high and low ME diets.
2
Soybean meal incorporated into the diet was high protein (48% CP)
soybean meal.
3
Vitamin premix: vitamin A, 6,600 IU; vitamin D3, 2,805 IU; vitamin
E, 10 IU; vitamin K, 2 mg; riboflavin, 4.4; pantothenic acid, 6.6 mg;
niacin, 24.4 mg; choline, 110 mg; vitamin B7, 8.8 mg/kg.
4
Mineral premix: Mn, 88 mg; Cu, 66 mg; Fe, 8.5 mg; Zn, 88 mg; Se,
0.30 mg/kg.
5
ME values for ingredients used diet formulation were based on
values in NRC (1994).
6
Analyzed nutrient composition for intermediate diet was: 2,990 kcal
of ME/kg, 15.75% CP, 4.40% Ca, 0.69% total P.
procedure of Williams et al. (1962) using atomic absorption spectrophotometry. Dietary and fecal N were determined using the Kjeldahl method as established by the
Association of Official Analytical Chemists (AOAC, 1984).
Dietary and fecal GE were determined using a Parr adiabatic oxygen bomb calorimeter.
Parameters Measured
Feed intake and EP were recorded daily. Hens were
given ad libitum access to feed. Egg production was calculated on a hen-day basis. Egg mass (EM) was calculated
by multiplying egg weight by EP. The ME intake (kcal/
hen per d) was calculated by multiplying nitrogen-corrected digestible ME content of the diet by daily feed
intake.
Egg weight was measured weekly on 1 d of egg production. Hens were weighed individually at the start of the
trial and every other week thereafter until the end of the
trial at 20, 22, 24, 26 28, 30, 32, 34, and 35 wk of age.
Maintenance ME requirements were calculated by subtracting ME requirements for production from ME intake
according to the following equation (Peguri and Coon,
1989, 1991):
308
JALAL ET AL.
maintenance = MEn intake − (2.86 × EM) − 6.00
× BWC + mean BW
main effects of diet, space, and their interaction. The following model statement was used:
where maintenance = maintenance ME (kcal of MEn/kg
of BW), BWC = body weight change (g/hen per d), BW =
mean BW (g), and MEn = nitrogen-corrected ME intake
(kcal/hen per d).The ME efficiency of egg production
(MEEP) was calculated according to an equation from
Emmans and Charles (1977):
Yijkl = ␮ + Rl + αi + βj + αβij + εijkl
where Yijk = measured response, ␮ = overall mean, Rl =
block effect, αi = diet effect, βj = cage space effect, αβij =
interaction between diet and cage space, and εijkl = residual error.
MEEP = EM × 1.66/MEn
RESULTS
where EM = egg mass output (g/hen per d). The factor
1.66 represents the average energetic equivalent of egg
weight as (kcal/g) egg (NRC, 1981).
Hen mortality was recorded daily during the course of
the experiment. Production parameters such as FI and
EP were corrected for hen mortalities.
Cage space had a significant (P < 0.05) effect on FI of
laying hens (Table 2). Hens housed at 690 cm2/hen had
greater FI than those housed at 342 and 413 cm2/hen, but
not those housed at 516 cm2/hen, across all dietary ME
levels. A similar effect was observed with ME intake,
as hens housed at 690 cm2/hen significantly (P < 0.05)
consumed 15.69 and 20.06 more kcal/hen per d than those
housed at 342 and 413 cm2/hen, respectively (Table 2).
There were no significant effects of dietary ME level on
feed or ME intakes.
Egg production was significantly (P < 0.05) affected by
cage space (Table 2). Hens housed at 690 cm2/hen had
greater EP in contrast to those housed at other bird cage
spaces across all dietary ME levels. Egg mass followed
the same trend as EP.
Egg weight was not significantly affected by dietary
ME level or cage space (Table 2). Hens fed the highest
ME levels and those housed at 690 cm2/hen laid the
largest eggs, across dietary ME levels and cage spaces, respectively.
There were no significant effects of diet or cage space
on average hen weight (Table 2). There was a significant
(P < 0.05) diet × cage space interaction on BW change
(Table 2). Hens fed the high ME diet and housed at 342
cm2/hen had significantly greater BW change than those
housed at 413 cm2/hen, but not those housed at 516 and
690 cm2/hen. Hens fed the intermediate ME diet and
housed at 413 cm2/hen had significantly greater BW
change than those housed at 342 cm2/hen, but not those
housed at other space allowances. Hens fed the low ME
diet exhibited the greatest BW change when housed at
516 cm2/hen, and their BW change was significantly
greater than those housed at 413 cm2/hen, but not greater
than those housed at 342 and 690 cm2/hen.
There were no significant effects of dietary ME, cage
space, or their interaction on bone ash percentage (Table 2).
Maintenance energy intake was not significantly affected by either dietary ME or cage space (Table 3). Reducing the number of birds per cage did not appear to increase ME requirement with extra space available for activity. However, MEEP was significantly (P < 0.05)
affected by cage space (Table 3). Hens housed at 690 cm2/
hen had greater MEEP compared with hens housed at
other spaces and across all diets.
Digestible AMEn was significantly affected by dietary
ME level in the diet (Table 3). Hens fed high ME had
ME Digestibility
At the end of the trial, chromic oxide (Cr2O3) was added
to all diets as an analytical marker for nutrient digestibility at a rate of 0.25% of the diet and fed for 5 d. Representative fecal samples were collected from each pen on the
last day of Cr2O3 feeding to determine GE, N, and Cr
content of feces. The fecal samples were freeze-dried,
sieved through a 1-mm screen to remove feathers,
ground, and packed in plastic bags for storage before
analysis.
The following equation was used for calculation of
AME digestibility (Scott et al., 1976):
% AME digestibility = 100 − [(dietary Cr/fecal Cr
× fecal GE/dietary GE) × 100]
The value of AME was corrected for N retention (Hill
and Anderson, 1958). The retained n value was multiplied
by 8.22 kcal/g and subtracted from AME value. The corrected AME is referred to as AMEn (N-corrected apparent ME).
Bone Ash
At 35 wk of age, 6 hens from each treatment were killed
by cervical dislocation and their tibias removed. The tibial
bones were boiled to remove any traces of flesh. Tibias
were solvent-extracted to remove fat, and then dried and
ashed at 600°C for 48 h to determine bone ash percentage.
Methods used were approved by the institutional animal
care and use committee at the University of NebraskaLincoln.
Statistical Analyses
Data were analyzed using the mixed model analysis
from SAS software (Proc Mixed, 2001; SAS Institute, Inc.,
Cary, NC) for a randomized complete block design with
a 3 × 4 factorial arrangement. The data were tested for
309
BIRD CAGE SPACE AND DIETARY METABOLIZABLE ENERGY
Table 2. Layer production data: feed intake, ME intake, egg production, egg weight, and egg mass
Diet (kcal/kg ME)
High
High
High
High
Intermediate
Intermediate
Intermediate
Intermediate
Low
Low
Low
Low
SEM
Main effects
ME
High
Intermediate
Low
SEM
Cage space/hen
690
516
413
342
SEM
Statistical probabilities
ME
Cage space
ME × cage space
Cage
space
(cm2/hen)
Feed
intake
(g/hen/d)
ME
intake
(kcal/hen/d)
Egg
production
(%)
Egg
weight
(g)
Hen
weight1
(kg)
BW
change
(g/hen/d)
Bone
ash (%)
690
516
413
342
690
516
413
342
690
516
413
342
90.54
88.72
83.87
84.99
91.84
90.33
84.03
86.20
92.25
89.49
87.60
84.56
2.095
279.16
274.95
260.46
264.11
271.71
267.56
260.02
254.36
277.26
267.89
260.58
249.47
7.906
81.89
81.18
76.04
75.92
86.91
84.49
76.58
75.44
89.78
79.85
73.48
76.66
1.999
52.16
51.88
52.25
51.15
51.90
49.94
50.94
51.07
51.54
51.93
51.25
50.84
0.605
1.418
1.398
1.386
1.382
1.431
1.370
1.362
1.380
1.403
1.437
1.378
1.396
0.214
1.671dc
1.602dc
1.223c
2.174d
1.853fg
1.888fg
2.332f
1.275g
1.728hi
2.300h
1.196i
1.868h
0.333
59.41
60.41
59.85
60.84
60.01
60.78
60.70
60.31
60.80
60.59
59.77
59.98
0.527
87.04
88.10
88.50
1.119
269.67
263.09
263.41
5.517
78.76
80.85
79.94
1.176
51.85
50.97
51.39
0.303
1.396
1.386
1.403
0.110
1.668
1.773
1.836
0.196
60.13
60.17
60.45
0.374
91.55a
89.52a
85.19b
82.25b
1.259
276.04a
270.13ab
260.35b
255.98b
5.530
86.19a
81.84b
75.37c
76.00c
1.293
51.86
51.25
51.48
51.02
0.350
1.418
1.402
1.375
1.386
0.0125
1.751
1.930
1.583
1.772
0.215
59.92
60.59
60.11
60.38
0.394
NS
NS
NS
NS
NS
NS
NS
NS
0.02
NS
NS
NS
NS
0.0002
NS
NS
0.0002
NS
NS
0.0001
NS
Means with no common superscript differ significantly (P < 0.05).
High ME means with no common superscript differ significantly (P < 0.05).
f,g
Intermediate ME means with no common superscript differ significantly (P < 0.05).
h,i
Low ME means with no common superscript differ significantly (P < 0.05).
1
The average weight of hens at the start of the trial was 1.223 kg/hen and the standard deviation was 0.0474.
a–c
d,e
significantly greater digestible AMEn than those fed intermediate and low ME, with differences of 107 and 118 kcal
of ME/kg, respectively.
DISCUSSION
In the present study, an increase in FI was observed
when cage space available for hens was increased. Feed
intake increased by 6.30 g/hen per d as cage space was
increased from 342 to 690 cm2/hen. The effect of increasing cage space on FI is consistent with results reported
by Sohail et al. (2001) and Adams and Craig (1985). Our
findings disagree with those reported by Anderson and
Adams (1992) and Brake and Peebles (1992), who found
no effects of cage space on FI. Although our results indicate no significant effect of dietary ME level on FI, previous researchers (Carew et al., 1980; Jackson and Waldrup,
1988) reported a decrease in FI as ME level was elevated.
It appears that there was too much variation in FI to
detect differences because one may have expected more
of a response to a difference of 100 kcal/kg in dietary
ME based on previous assumptions. Carew et al. (1976,
1980) used diets with a difference of >150 kcal of ME/kg
to elicit a response in FI and detected much less variation
compared with our results.
The reduction in EP due to decreased cage space is
well cited (Cunningham, 1982; Adams and Craig, 1985;
Hester and Wilson, 1986; Craig and Milliken, 1989; Sohail
et al., 2001). Our results are in congruence with previous
research as EP declined as much as 10.1% (86.19 vs. 76%)
as the number of hens per cage was increased from 3 to
6. In our study, increasing dietary energy level did not
improve EP as cage space was reduced. Jackson and
Waldrup (1988) reported that increasing dietary energy
partially alleviated the reduction in EP resulting from
decreased cage space. Egg mass exhibited a similar trend
to EP with a decline as cage space decreased. Earlier
research has shown decreased EM as the number of hens
was increased per cage (Cunningham, 1982; Craig and
Milliken, 1989).
Body weight change was the only parameter exhibiting
a significant diet × cage space interaction. There was no
consistent change in gain between cage spaces at each
ME level, as one would anticipate an increase in gain
with increased cage space and ME level. At high ME
levels, hens housed at 342 cm2/hen attained the greatest
BW change gain at that level, whereas at intermediate
and low ME, hens housed at 413 and 516 cm2/hen, respectively, exhibited the greatest BW gain. Carew et al. (1980)
310
JALAL ET AL.
Table 3. Metabolizable energy data
Diet (kcal of ME/kg)
High
High
High
High
Intermediate
Intermediate
Intermediate
Intermediate
Low
Low
Low
Low
SEM
Main effects
ME
High
Intermediate
Low
SEM
Cage space/hen1
690 (107)
516 (80)
413 (64)
342 (53)
SEM
Statistical probabilities
ME
Cage space
ME × cage space
Cage space
(cm2/hen)
ME intake
(kcal/hen per d)
ME efficiency
of egg production
(kcal/kcal)
Digestible AMEn
(kcal/kg)
690
516
413
342
690
516
413
342
690
516
413
342
98.56
98.68
95.98
96.54
88.05
94.97
94.57
93.68
90.66
89.87
101.16
86.46
5.174
0.263
0.263
0.264
0.255
0.287
0.269
0.261
0.262
0.288
0.269
0.253
0.273
0.00822
3,081.38
3,096.99
3,104.02
3,107.25
2,956.17
2,962.04
3,092.10
2,951.00
3,006.17
2,995.80
2,967.16
2,949.70
43.712
97.44
92.75
92.03
3.020
0.261
0.270
0.271
0.00497
3,097.41a
2,990.33b
2,979.71b
28.364
92.43
94.41
97.24
92.23
3.329
0.280a
0.267b
0.259b
0.263b
0.00542
3,014.57
3,018.28
3,054.43
3,002.65
30.455
NS
NS
NS
NS
0.013
NS
0.0001
NS
NS
Means with no common superscript differ significantly (P < 0.05).
Values in parentheses for cage space/hen are in square inches/hen.
ab
1
reported that BW gains improved as ME level increased,
thus reversing loss in BW due to reduction in cage space.
Maintenance requirement did not decrease as cage
space was increased and was not significantly affected
by ME level. Reducing the hen’s space in cage has been
shown not to alter time allocated to activities such as
eating, standing, resting, and preening (Sefton, 1976; Ouart and Adams, 1982). Madrid et al. (1981) reported that
maintenance energy requirements increased as the number of hens per cage was increased from 3 to 7, which
was in disagreement with our findings. Madrid et al.
(1981) reported that crowding of birds was responsible
for increasing voluntary activity.
Laying hens became energetically more efficient as cage
space increased. Hens reared at 690 cm2/hen were energetically more efficient than those housed at other space
allowances. Our findings show that as cage space increased, energy intake was increased. This is consistent
with the fact that maintenance requirements did not significantly change as the number of birds changed. It is,
therefore, possible to assume that hens that consumed
more feed were energetically more efficient.
Digestible AMEn values were significant for hens fed
the high ME diet compared with those fed the intermediate and low ME diets. Cage space did not influence ME
digestibility for laying hens and the digestible ME values
were very close.
In summary, reducing the number of hens per cage
improved feed intake, ME intake, egg production, egg
mass, digestible AMEn, and dietary ME efficiency for laying hens. There were no significant effects of dietary ME
levels on these response variables. Increasing ME level
in the diet did not reverse the negative effects of crowding
and decreasing cage space on egg production.
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