©2014 Poultry Science Association, Inc.
Copper and lysine amino acid density responses
in commercial broilers
H. Wang,* C. Zhang,* Y. Mi,*1 and M. T. Kidd†
*Department of Veterinary Medicine, College of Animal Science, Zhejiang University,
Hangzhou 310058, China; and †Center of Excellence for Poultry Science,
Division of Agriculture, University of Arkansas, Fayetteville 72701
Primary Audience: Nutritionists, Feed Mill Managers
SUMMARY
Nutritional modulation of live performance and meat yield must be continuously tested as
broiler strains become more efficient every year. This study evaluates both copper- and lysinederived amino acid balance. In experiment 1, amino acid balance (high, moderate, and low) and
copper (5 and 200 ppm) were investigated in a factorial array of treatments (6 treatments with
8 replications; 1,536 Cobb 500 male broilers across 48 floor pens from 1–40 d of age; 32 birds
per pen). In experiment 2, amino acid density (high and low) was assessed in 2 broiler strains (a
multipurpose and a high-yield strain) obtained from the field in a factorial array of treatments
(4 treatments with 21 replications; 1,344 multipurpose and 1,344 high-yield broilers across 84
floor pens from 1–42 d of age; 32 birds per pen). Amino acid density treatments were created
by altering digestible lysine and other essentials amino acids at a fixed ratio. Copper and amino
acid density did not interact, but supplementing broilers with 200 ppm of copper in the form
of tribasic copper chloride improved growth rate. Lysine-derived amino acid density improved
performance and yields, but should be assessed as strains are improved for efficiency to ensure
digestible lysine adequacy in the nutrient formulation matrix. Although both copper and lysine
influence growth rate, interactive effects were not assessed in this study.
Key words: tri-basic copper chloride, lysine, processing attribute
2014 J. Appl. Poult. Res. 23:470–477
http://dx.doi.org/10.3382/japr.2014-00959
DESCRIPTION OF PROBLEM
The essentiality of copper for poultry has
been well documented [1]. Moreover, copper
is typically an essential supplement in poultry
diets for growth promotion and antimicrobial effects. Dietary concentrations to support the former are higher than that established by the NRC
[2]. Feeding either 125 or 250 mg/kg of copper
improved growth and feed conversion rate in
broilers, but supplementation of 375 mg/kg of
1
Corresponding author: [email protected]
copper was of no further benefit [3]. The inorganic copper sources used in poultry diets are
typically copper sulfate pentahydrate (CuSO4 ×
5H2O) or tribasic copper chloride [TBCC; Cu2
(OH)3 Cl]. Because of the lower hygroscopicity
and solubility in water, TBCC is considered to
be a less reactive and destructive form of copper
compared with CuSO4. Also, TBCC is a more
concentrated form of copper relative to CuSO4
(58 vs. 25%). Spears et al. [4] reported that the
copper in TBCC is more bioavailable compared
Wang et al.: COPPER AND AMINO ACID DENSITY
with CuSO4. Studies with chicks have shown
that the copper from TBCC has the same availability and safety as that in feed-grade CuSO4
[4]. Miles et al. [5] demonstrated that the oxidation in TBCC diets is lower than oxidation in
diets supplemented with CuSO4. Furthermore,
research has established that dietary supplementation of copper has a positive effect on intestinal microbiota profiles and decreases the growth
of pathogenic bacteria in birds [6].
Because copper has growth-promoting and
intestinal health effects, it was hypothesized that
copper might alter the efficacy of amino acid
balance. Lysine is the second-limiting amino
acid for broilers fed diets based on corn and soybean meal [2] and is the reference amino acid in
the ideal protein concept [7]. Moreover, lysine is
known to exhibit strain-specific improvements
in breast muscle yield [8–10]. Corzo et al. [11]
conducted amino acid density research in highyield and multipurpose strains and observed
live performance, processing, and economic improvements with increasing amino acid density.
Dietary limitation of lysine, especially early in
the birds’ life, decreases skeletal muscle synthesis from a reduction in protein synthesis and
RNA content [12]. Because dietary Cu modifies
intestinal bacteria and amino acid density dictates bird performance and meat yields, the current study was conducted to investigate possible
synergies between copper and amino acid density on broiler performance and carcass characteristics, and to further assess amino acid density
effects on modern commercial broiler strains.
MATERIALS AND METHODS
Bird Husbandry
In experiment 1, Cobb 500 male chicks (byproduct off-sex males) were sourced from a
commercial hatchery, transferred to the university hatchery, and provided a triple dose of coccidiosis vaccination [13] at d 1 by spray cabinet to create early a mild enteric stress. Chicks
were vaccinated for Marek’s disease, Newcastle disease, and infectious bronchitis in the
commercial hatchery. Chicks were weighed in
groups of 32 and allocated to each of 48 floor
pens measuring 5 × 5 ft (0.78 ft2/bird or 0.07 m2/
bird). The facility was a solid side-walled house
with radiant tube heating and negative pressure
471
ventilation for air exchange and cooling. Each
pen was equipped with 1 supplemental heater
for brooding, 1 tube feeder (32-lb capacity), 1
nipple drinker line, and used built-up shavings.
The light procedure followed the primary breeder recommendation for Cobb 500 broilers [14].
Feed and water were provided ad libitum. Mortality was obtained daily and the weights were
recorded to calculate adjusted feed conversion.
One bird per pen was evaluated for lesion scores
at d 7 but lesions were not detectable, verifying
that any enteric stress was mild.
In experiment 2, eggs from a multipurpose
broiler strain (strain A; 1,800 eggs; rapidly
growing broiler strain with good performance
and meat yield) and a high-yield strain (strain
B; 1,800 eggs; slow-growing broiler strain with
good performance and high meat yield) were
obtained from commercial broiler breeder farms
and set in hatchers at the university hatchery.
Chicks from both strains hatched simultaneously and were sexed. All chicks were vaccinated
for coccidiosis via coarse spray at d 1 at a rate
of 3 times the commercial recommended dose,
as in experiment 1 [13], and were vaccinated
against Marek’s disease, Newcastle disease, and
infectious bronchitis at the university hatchery.
A total of 1,344 broilers from each strain were
placed into 84 floor pens (16 male and 16 female
broilers per pen). Housing conditions were identical to experiment 1, except birds were reared
in pens that measured 2.5 × 10 ft (0.78 ft2/bird
or 0.07 m2/bird). Also, litter was built-up from
previous research and downtime between flocks
was 1 d. In both experiments, all bird procedures
were approved by the University of Arkansas Institutional Animal Care and Use Committee.
Experimental Design, Methods,
and Statistical Analysis
In experiment 1, the corn-soybean meal diet
(Table 1) was formulated to have 3 levels of digestible lysine (1.0, 1.1, and 1.2% in the 1- to
18-d starter period; 0.8, 0.9, and 1.0% in the 18to 40-d finisher period) and 2 levels of copper (5
and 200 ppm) from TBCC (6 treatments with 8
replications per treatment randomized across 48
pens). The experimental period was from d 1 to
40. In experiment 2, the test diets were formulated to contain low- or high-amino acid density.
JAPR: Research Report
472
Table 1. Test diets and calculated and analyzed contents fed from 1 to 40 d of age (experiment 1)1
Starter diet (1–18 d)
Item
Finisher diet (18–40 d)
5 ppm of 200 ppm of 5 ppm of 200 ppm of
Cu,
Cu,
Cu,
Cu,
low Lys
low Lys
high Lys high Lys
Ingredient, %
Corn
67.05
Soybean meal
23.91
Proplus 542
5.00
Poultry fat
0.50
Dicalcium P
1.39
Limestone
1.08
Salt
0.40
0.23
dl-Met
l-Lys HCl
0.22
l-Thr
0.09
Mineral3
0.08
Vitamin4
0.03
TBCC5
0.00
Phytase6
0.02
Content
ME, kcal/kg
3,031
CP, %
18.59
Digestible Lys, %
1.00
Digestible TSAA, %
0.74
Digestible Thr, %
0.69
Digestible Ile, %
0.67
Digestible Val, %
0.77
Cu, ppm
5
Analyzed Lys,7 %
1.20
Analyzed Cu,8 ppm
13
5 ppm of 200 ppm of 5 ppm of
Cu,
Cu,
Cu,
low Lys
low Lys
high Lys
67.01
23.92
5.00
0.50
1.39
1.08
0.40
0.23
0.22
0.09
0.08
0.03
0.03
0.02
57.68
32.12
5.00
1.64
1.31
1.06
0.40
0.31
0.23
0.12
0.08
0.03
0.00
0.02
57.41
32.13
5.00
1.66
1.31
1.06
0.40
0.31
0.23
0.12
0.08
0.03
0.03
0.02
75.46
17.05
4.00
0.59
1.04
0.99
0.36
0.16
0.19
0.05
0.06
0.03
0.00
0.02
75.40
17.06
4.00
0.61
1.04
0.99
0.36
0.16
0.19
0.05
0.06
0.03
0.03
0.02
3,040
18.59
1.00
0.74
0.69
0.67
0.77
200
1.19
160
3,031
21.71
1.20
0.89
0.83
0.80
0.90
5
1.39
13
3,031
21.71
1.20
0.89
0.83
0.80
0.90
200
1.42
150
3,131
15.46
0.80
0.60
0.54
0.54
0.64
5
0.99
NA9
3,131
15.46
0.80
0.60
0.54
0.54
0.64
200
0.88
NA
65.74
25.41
4.00
1.95
0.96
0.97
0.35
0.24
0.19
0.08
0.06
0.03
0.00
0.02
200 ppm of
Cu,
high Lys
65.69
25.41
4.00
1.97
0.96
0.97
0.35
0.24
0.19
0.08
0.06
0.03
0.03
0.02
3,131
3,131
18.61
18.61
1.00
1.00
0.75
0.75
0.68
0.68
0.68
0.68
0.77
0.77
5
200
1.18
1.13
NA
NA
1
Test diets consisted of low-amino acid density ratios to Lys and high-amino acid density ratios to Lys. The medium amino acid
density was achieved by blending the 2 diets. The 15-ppm Cu diets represent no TBCC and 15 ppm of Cu from copper sulfate
contained in the mineral premix. The 215-ppm Cu diets were achieved by restricting the minimum and maximum inclusion of
TBCC resulting in a 200 ppm of Cu addition.
2
Proplus 54, H. J. Baker, Little Rock, AR.
3
Mineral premix contained per kilogram of diet: Mn, 150 mg; Zn, 150 mg; Fe, 75 mg; Cu, 15 mg; I, 1.5 mg; and Se, 0.1 mg.
The finisher mineral levels were reduced accordingly.
4
Vitamin premix contained per kilogram of diet: vitamin A, 9,259.4 IU; vitamin D3, 6,613.9 IU; vitamin E, 19.84 IU; vitamin
B12, 0.016 mg; menadione, 1.80 mg; riboflavin, 7.94 mg; d-pantothenic acid, 11.90 mg; niacin, 46.3 mg; folic acid, 1.06 mg;
pyridoxine, 3.31 mg; thiamine, 1.85 mg; and biotin, 0.08 mg.
5
TBCC = tribasic copper chloride [Cu2 (OH)3 Cl].
6
Phytase used was Phyzyme 2500 (Danisco Animal Nutrition, St. Louis, MO), providing 500 FTU/kg.
7
Analyzed total Lys for the medium (blended) starter diets in the 15- and 215-ppm Cu diets were 1.29 and 1.29%, respectively.
Analyzed total Lys for the medium (blended) finisher diets in the 15- and 215-ppm Cu diets were 1.00 and 1.04%, respectively.
8
Analyzed Cu for the 15- and 215-ppm treatments in the medium (blended) Lys starter diets was 12 and 180 ppm, respectively.
9
NA = not analyzed.
As in experiment 1, diets were formulated to
digestible lysine (1 to 14 d, 1.0 vs. 1.2%; 14 to
28 d, 0.9 vs. 1.1%; and 28 to 42 d 0.8 vs. 1.0%)
to derive 2 amino acid density treatments by 2
commercial strains (4 treatments with 21 replications per treatment; Table 2).
All feed was pelleted and the starter feeds
(1 to 18 d in experiment 1 and 1 to 14 d in ex-
periment 2) were crumbled. The mash low- and
high-lysine diets were blended to derive the
moderate-lysine diet in both the starter and finisher feeds in experiment 1 before pelleting. Essential amino acids were maintained at a ratio
to lysine mimicking industry standards (Tables
1 and 2); therefore, as lysine was changed diet
amino acid density was proportionately altered.
Wang et al.: COPPER AND AMINO ACID DENSITY
473
Table 2. Test diets and calculated and analyzed contents fed from 1 to 42 d of age (experiment 2)1
Starter (1 to 14 d diets)
Item
Ingredient, %
Corn
Soybean meal
Proplus 542
Poultry fat
Dicalcium P
Limestone
Salt
dl-Met
l-Lys HCl
Choline Cl 60
l-Thr
Mineral3
Vitamin4
Phytase5
Content
ME, kcal/kg
CP, %
Digestible Lys, %
Digestible TSAA, %
Digestible Thr, %
Digestible Ile, %
Digestible Val, %
Analyzed CP, %
High
Low
Grower (14 to 28 d diets)
High
Low
Finisher (28 to 42 d diets)
High
Low
53.96
35.40
5.00
2.17
1.36
1.02
0.40
0.28
0.13
0.09
0.06
0.08
0.03
0.02
65.71
25.22
5.00
0.50
1.46
1.03
0.40
0.22
0.18
0.09
0.06
0.08
0.03
0.02
60.25
29.96
4.50
2.05
1.16
0.99
0.38
0.27
0.18
0.08
0.08
0.06
0.02
0.02
70.93
20.77
4.50
0.55
1.25
1.00
0.38
0.19
0.19
0.08
0.06
0.06
0.02
0.02
64.88
26.02
4.00
2.19
0.96
0.95
0.35
0.24
0.18
0.07
0.07
0.05
0.02
0.02
74.74
17.55
4.00
0.82
1.04
0.96
0.36
0.16
0.17
0.07
0.04
0.05
0.02
0.02
3,031
22.80
1.20
0.89
0.82
0.86
0.96
25.24
3,031
19.04
1.00
0.74
0.68
0.69
0.79
20.93
3,086
20.56
1.10
0.83
0.75
0.76
0.86
21.66
3,086
17.13
0.90
0.68
0.61
0.61
0.71
18.13
3,142
18.82
1.00
0.76
0.68
0.69
0.78
20.83
3,142
15.63
0.80
0.61
0.54
0.55
0.65
17.60
1
Test diets consisted of low-amino acid density ratios to Lys and high-amino acid density ratios to Lys.
Proplus 54, H. J. Baker, Little Rock, AR.
3
Mineral premix contained per kilogram of diet: Mn, 150 mg; Zn, 150 mg; Fe, 75 mg; Cu, 15 mg; I, 1.5 mg; and Se, 0.1 mg.
The grower and finisher mineral levels were reduced accordingly.
4
Vitamin premix contained per kilogram of diet: vitamin A, 9,259.4 IU; vitamin D3, 6,613.9 IU; vitamin E, 19.84 IU; vitamin
B12, 0.016 mg; menadione, 1.80 mg; riboflavin, 7.94 mg; d-pantothenic acid, 11.90 mg; niacin, 46.3 mg; folic acid, 1.06 mg;
pyridoxine, 3.31 mg; thiamine, 1.85 mg; and biotin, 0.08 mg. Subsequent diets (grower and finisher) were reduced accordingly.
5
Phytase used was Phyzyme 2500 (Danisco Animal Nutrition, St. Louis, MO), providing 500 FTU/kg.
2
Hence, the lysine amino acid treatment represents dietary amino acid density in both experiments. Complete diets were collected after
mixing for analyses. For mixing verification,
starter feed from experiment 1 was analyzed for
copper, starter and finisher feed in experiment 1
were analyzed for CP, and all feed in experiment
2 was analyzed for lysine [15].
In experiment 1, pen weights of birds and
feed disappearance were obtained at d 1 and 40.
At d 40, after pen weights for live performance
and 6 h after feed withdrawal time, 6 broilers
per pen were randomly selected for processing and weighed. In experiment 2, pen weights
and feed disappearance were measured on d 1
and 42. Two male and 2 female broilers per pen
were randomly selected for processing at d 42
after pen weights were obtained, marked for
processing with paint, weighed, and processed
after a 6-h feed withdrawal period. In both experiments, processing was conducted in a pilot
processing plant. After birds exited the feather
picker, all subsequent processing (e. g., hock
removal, evisceration, and lung removal) was
done manually. After a 3-h chill, carcasses were
placed on cones for manual cutting. In both experiments, the factorial arrangement of treatments [16] was analyzed by the General Linear
Models procedure of SAS [17].
RESULTS AND DISCUSSION
Experiment 1
The dietary addition of TBCC was calculated
to be an increase of 195 ppm of elemental cop-
JAPR: Research Report
474
per. The starter diets were verified for treatment
additions and averaged 142 ppm higher than the
control diets (Table 1). Copper additions were
not analyzed in the finisher diets because the additions were large enough to verify at the feed
mill. However, we expect the lower estimated
level of copper verified in the starter diets was
due to sampling too tight a range of feed from
the pellet mill. All diets were analyzed for total
lysine. Calculated digestive lysine versus total
analyzed lysine, respectively, for all diets presented from starter to finisher in Table 1 was
1.00 versus 1.20%; 1.00 versus 1.19%; 1.20
versus 1.39%; 1.20 versus 1.42%; 0.80 versus
0.99%; 0.80 versus 0.88%; 1.00 versus 1.18%;
and 1.00 versus 1.13%. The digestible coefficient used for lysine was 90%. On average, our
total lysine was analyzed 3.4% higher than calculated lysine, which we attribute to the source
of the soybean meal. However, all analyses validated proper diet-mixing procedures.
Copper has not only been shown to have antimicrobial activity [6], but to improve growth
and FE in broilers when it is added above that
considered adequate [2] (i.e., 125–250 ppm [3]).
Pesti and Bakalli [3] conducted 4 studies evaluating copper responses and 2 of the experiments
were dose responses. Broiler BW gain was improved in 1 experiment by increasing copper
from 125 to 250 ppm and in another experiment
by increasing copper from 65 to 125 ppm [3]. In
our work, increasing copper from 5 to 200 ppm
improved BW gain, but our primary objective
was to assess interactions with amino acid density, which approached significance (P = 0.08) for
BW gain (Table 3). Improvements to broiler live
weight occurred with copper, but our work demonstrated its efficacy was independent of amino
acid density. Future work should be conducted
to assess potential copper × amino acid density
responses in diets differing in stress models than
those used in the current study (coccidiosis vaccination and built-up litter).
Increasing amino density from low to moderate in broilers improved (P < 0.05) overall BW
gain and feed conversion, as well as 40-d carcass yield (Table 3). Further improvements (P <
0.05) from increasing amino acid density from
moderate to high occurred with breast meat
yield (21.83 vs. 22.58%; boneless and skinless
pectoralis major and minor). Both abdominal
fat and thigh (bone-in and skin-on) yields were
decreased (P < 0.05) as amino acid density was
increased from moderate to high. Because our
Table 3. Cobb male broiler performance and carcass traits (1–40 d) when fed diets varying in dietary Lys density1
and Cu level2
Live performance3
Dietary variable
Cu
5
200
SEM
P-value
Cu
Lys
Cu × Lys
a–c
Lys
L
M
H
SEM
Processing attribute4
BW gain,
kg/bird
FCR,
kg/kg
Livability,
%
Carcass,
%
Fat,
%
Breast, Wing, Thigh, Drumstick,
%
%
%
%
2.58
2.64
0.016
2.52b
2.64a
2.66a
0.043
1.726
1.717
0.0122
1.794a
1.705b
1.665b
0.0149
98.18
98.05
0.419
98.83
97.46
98.05
0.513
71.47
71.76
0.157
70.97b
71.80a
72.07a
0.192
1.06
0.98
0.033
1.23a
1.02b
0.81c
0.040
21.61
21.86
0.139
20.79c
21.83b
22.58a
0.170
0.010
0.001
0.081
0.633
0.001
0.151
0.827
0.180
0.138
0.194
0.001
0.841
0.084
0.001
0.100
7.76
7.74
0.029
7.71
7.72
7.82
0.035
12.97
12.96
0.060
13.07a
13.04a
12.79b
0.073
9.75
9.69
0.060
9.78
9.69
9.69
0.073
0.233 0.633
0.001 0.052
0.286 0.066
0.913
0.016
0.856
0.432
0.609
0.900
Means within a column for Cu or Lys with uncommon superscripts differ (P ≤ 0.05).
Dietary Lys density represents low (L), medium (M), and high (H) levels for dietary Lys of 1.0, 1.1, and 1.2% digestible Lys,
respectively, fed from 1 to 18 d of age and 0.8, 0.9, and 1.0% digestible Lys, respectively, fed from 19 to 40 d. Essential amino
acid ratios were maintained for adequacy in all diets.
2
Dietary Cu represents diets containing 5 or 200 ppm of Cu provided from tri-basic CuCl.
3
n = 32 birds per pen averaged in each experimental unit; FCR represents feed conversion corrected for the weight of mortality.
4
Processing attributes are expressed relative to live weight of birds selected for processing; n = 6 birds per pen averaged in
each experimental unit.
1
Wang et al.: COPPER AND AMINO ACID DENSITY
amino acid density treatments fed from 1 to 40
d were continuous, amino acid density needs by
phase cannot be referenced. Amino acid density
research in the early 2000s was initiated to evaluate industry feeding practices for performance
and carcass yields. Our work agrees with an initial report in that moderate amino acid density
diets can support good feed conversion, but not
optimal breast meat yield [18].
Experiment 2
Dietary high- and low-amino acid density
treatments were validated by CP analyses. In
all 3 phases, CP was decreased on average by
17%. Analysis of CP verified a 16% decrease in
amino acid density when comparing CP reductions between high and low. Hence, although analyzed CP was 5 to 10% higher than calculated
levels, treatment differences represented a valid
comparison.
Dietary lysine density and strain effects are
presented in Table 4. However, interactions (P
< 0.05) between strain and amino acid density
occurred for BW gain and livability (Table 5).
For BW gain, decreasing amino acid density in
the high-yield, but not the multipurpose strain,
reduced BW gain indicating the sensitivity of
the high-yield strain to amino acids. Livability
was reduced in the multipurpose, but not the
475
high-yield strain, in the low-amino acid density
treatment. It is important to point out that birds
received coccidiosis vaccination at a 3-fold
higher need than normal and were raised on
built-up litter with less than 1 wk of down time.
Our work points to strain-dependent amino acid
needs for health. Indeed, specific amino acids
(e.g., methionine and arginine [19]) have profound effects on bird immunity, but immune response and disease-resistant work with broilers
fed diets differing in amino acid density has not
been carried out. No interaction between broiler
strain and amino acid density was noted for feed
conversion. Hence, both strains lost between 8
and 9 points of feed conversion by decreasing
lysine by 15 to 20% from d 1 to 42.
The high-yield strain weighed less (P < 0.05)
but had similar (P = 0.55) feed conversion as
the multipurpose strain. However, the high-yield
strain had less (P < 0.05) percentage fat and
higher (P < 0.05) carcass and total breast yields
than the multipurpose strain. Further, feeding
broilers high-amino acid density diets from 1 to
42 d improved (P < 0.05) all live performance
and carcass traits. Again, it is interesting to note
the improvement in livability (92.0 to 94.3%; P
= 0.01) from feeding birds higher amino acid
density diets. Corzo et al. [11] fed varying amino acid density diets to 2 multipurpose broiler
strains and 1 high-yield broiler strain from 1
Table 4. Multipurpose (A) and high-yield (B) broiler strain performance and carcass traits (1 to 40 d) when fed diets
varying in dietary Lys density1
Dietary variable
Lys
H
L
SEM
P-value
Strain
Lys
Strain × Lys
1
Strain
A
B
SEM
Live performance2
Processing attribute3
BW gain,
kg/bird
FCR,
kg/kg
Livability
Carcass,
%
Fat,
%
Major, Minor, Breast, Wing,
%
%
%
%
2.368
2.318
0.0143
2.393
2.293
0.0142
1.788
1.784
0.0047
1.742
1.829
0.0047
92.13
94.10
0.609
94.25
91.98
0.614
73.13
73.63
0.144
73.91
72.85
0.144
1.59
1.43
0.027
1.23
1.79
0.027
18.57
19.38
0.127
19.79
18.16
0.127
0.015
0.001
0.009
0.549
0.001
0.200
0.025
0.010
0.028
0.015
0.001
0.146
0.001
0.001
0.674
Leg,
%
4.20
4.24
0.032
4.40
4.04
0.032
22.77
23.62
0.135
24.20
22.19
0.139
7.86
7.85
0.035
7.91
7.79
0.035
21.91
22.11
0.081
21.83
22.18
0.0841
0.001 0.443
0.001 0.001
0.082 0.238
0.001
0.001
0.061
0.875
0.014
0.077
0.100
0.003
0.743
Dietary Lys density represents low (L) and high (H) levels for dietary Lys of 1.0 and 1.2% digestible from d 0 to 14, 0.90 and
1.10% digestible from 14 to 28 d, and 0.80 and 1.0% digestible from 28 to 42 d, respectively. Essential amino acid ratios were
maintained for adequacy in all diets.
2
n = 32 birds per pen averaged in each experimental unit; FCR represents feed conversion corrected for the weight of mortality.
3
Processing attributes are expressed relative to live BW of birds selected for processing; n = 4 birds per pen averaged in each
experimental unit.
JAPR: Research Report
476
Table 5. Multipurpose (A) and high-yield (B) broiler strain interactions for BW gain and livability (1–40 d) when fed
diets varying in dietary Lys density1
Dietary Lys density
Strain,2 %
BW gain, kg/bird
A
B
Livability, %
A
B
H
2.391a
2.395a
94.23a
94.27a
L
2.345a
2.241b
90.02b
93.93a
SEM
P-value
0.0200
0.009
0.861
0.028
a,b
Body weight gain and liveability means with uncommon superscripts differ (P ≤ 0.05).
Dietary Lys density represents low (L) and high (H) levels for dietary Lys of 1.0 and 1.2% digestible from d 0 to 14, 0.90 and
1.10% digestible from d 14 to 28, and 0.80 and 1.0% digestible from d 28 to 42, respectively. Essential amino acid ratios were
maintained for adequacy in all diets; n = 32 birds per pen averaged in each experimental unit.
2
Significant dietary lysine density by strain interaction.
1
to 56 d. At 42 d, amino acid density by strain
interactions occurred for breast meat yield, indicating the sensitivity of skeletal muscle accretion in the high-yield strain compared with the
multipurpose strain; other diet by strain interactions at d 42 did not occur, however [11]. Also,
no amino acid density effects were noted for
mortality [11]. The differences in our strain by
amino acid density results compared with previous work [11] may be attributable to the wide
degree of dietary amino acid density, the strains
used, and the coccidiosis vaccination procedure
used on all birds at d 1.
CONCLUSIONS AND APPLICATIONS
1. Increasing copper from 5 to 200 ppm in
the form of TBCC improved growth promotion, but did not interact with amino
acid density.
2. The high-yield strain, but not the multipurpose strain, had depressed BW gain
when fed low-amino acid density.
REFERENCES AND NOTES
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16.In experiment 1, the 6 treatments of the factorial arrangement of 2 copper by 3 amino acid density treatments
were analyzed by the following model: Yijk = µ + Cui + AAj
+ CuAAij + eijk, where µ is the common mean; Cui is the
effect of the ith copper; where AAj is the effect of the jth
amino acid density; CuAAij is the effect of the interaction
of the ith copper with the jth amino acid density; and eijk
is random error. Experiment 2 was analyzed in an identical
matter to assess main effects and interactions of the factorial
arrangement of 2 strains by 2 amino acid density diets. Pen
was the experimental unit for all analyses. Both experiments
were blocked from tunnel inlet to exhaust fan outlet. When
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477
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Acknowledgments
The authors gratefully acknowledge James Usry of Micronutrients (Indianapolis, IN) for supporting this research,
diet formulation, and experimental design input.