81999 Applied Paultry Science, Inc
LYSINE
LEVEL
INCREASES
LIVE
PERFORMANCE
AND BREAST
YIELDIN
MALE BROILERS
B. J. K E R d
Nuti-Quest, Inc., 1400 Elbridge Payne Road, Suite 110, Cheste$eld, MO 63017-8520
Phone: (636) 537-4057
F M : (636) 532-1710
E-mail: [email protected]
M. T.KIDD
Mississippi State University,Mississippi State, MS 39762-9665
K. M. HALPIN
International Ingredient Coporation, 4240 Utah Street, St. Louis, MO 63116
G. W. McWARD
Global Poultry Consulting, Inc., 2602 Linhey Grace Lane, Buford, G A 30519
C . L. QUARLES
Colorado Quality Research, 400 East County Road 72, Wellington, CO 80549
X i m a r y Audience: Nutritionists, Researchers, Poultry Producers
1 To whom correspondence should be addressed
LYSINE RESPONSES IN BROILERS
382
carcass characteristics of broilers fed graded
DESCRIPTION
OF PROBLEM
levels of crystalline Lys in the starter, grower,
Controversy continues to exist regarding
the level of dietary lysine (Lys) for optimal
body weight gain, feed conversion, and breast
meat development. Because breeding companies have selected the broiler for increased
meat yield, breast meat represents a large
portion of the total carcass meat, and breast
muscle contains a high concentration of Lys, it
is reasonable to assume that dietary Lys concentrations can have a large influence on
breast meat development. The NRC [l] recommends that broilers receive 1.10,1.00, and
0.85% Lys of diet at 0 to 3,3 to 6, and 6 to 8 wk
of age, respectively. Utilizing multiple dietary
CP levels, it has been demonstrated that starting broilers require 1.29% Lys for growth and
1.31% Lys for feed efficiency in a 23% CP diet
[2,3]. Studiesbysurisdiarto andFarrell [4] and
Kiddet al. [5] suggest that the Lys requirement
for starting broilers is higher than the level
recommended by the NRC [l].In addition to
data suggesting that the Lys requirement for
feed efficiency is higher than that for body
weight (BW) gain, there is abundant evidence
suggesting the Lys requirement for meat yield
is higher than the level considered adequate
for feed efficiency [6,7,8,9, 10, 11,12,13].
The following experiments were conducted to evaluate live performance and
oline chloride 70%
and finisher periods above levels recommended by the NRC [11.
MATERIALS
AND METHODS
EXPERIMENT 1
A total of 3250 day-old male Peterson X
Arbor Acres broilers were allocated to five
treatment groups across 50 pens, in a closedsided, positive-pressure ventilated house.
There were 10 replications per treatment with
65 birds/pen (650 birdsheatment). Concrete
floor pens measured 5.6 m2 and contained
one automatic bell-type drinker and two tube
feeders. Litter consisted of 2 cm of fresh
wood shavings layered over used shavings
(12 cm) from a previous broiler experiment.
All birds received Marek’s vaccination at
1day of age in the hatchery and Newcastle and
Bronchitis vaccinations at 5 days of age. All
birds began treatments at 1day of age. They
had ad libitum access to feed and water and
were provided with 23 hr of incandescent light
and 1hr dark/day.
Birds received a mash starter ration from
1to 21 days, a pelleted grower ration from 21
to 42 days, and a pelleted frnisher ration from
42 to 48 days (Table 1). Basal rations were formulated to be deficient in Lys (85% relative to
Research Report
383
KERR et af.
TABLE 1. (Continued)
’%race mineral mix provides in mgkg of diet: manganese, 160;zinc, 130; iron, 45; copper, 4; iodine, 1.5.
v i t a m i n premix provides er kgof diet: vitamin A (source unspecified), 3629 IU; cholecalciferol, 1134IU;vitamin E
unspecified), 6.8 Id;niacin, 17 m ,etho qum, 32 mg; pantothenic acid, 4.5 mg; riboflavin, 3.2 mg; pyridoxine,
5 mg; menadione, 0.7 mg; thiamine, 0.76mg f z c acid, 0 5 mg; biotin, 34pg; cobalamin, 5pg.
‘Monensin sodium; Elanco Animal Health, a division of Eli Lilly and Co.,Indianapolis, IN.
D3-nitro4-hydroxyphenylarsonicacid; Salsbury Laboratories, Inc., Charles City, IA.
%mbermycins; Hoechst-Roussel Agri-Vet. Co.,Somerville, NJ.
FL3acitracin methylene disalicylate; ALP-,
Fort Lee, NJ.
the 1984 NRC) and were supplemented with
L-Lys*HCl to obtain rations calculated to
contain 85,95,105, 115, or 125% the level of
Lys recommended by the NRC [14]. Basal
diets were formulated to be adequate in all
other amino acids [14] except TSAA; these
were formulated to be approximately 120% of
the NRC [l] recommendation, since previous
research has suggested that Lys and TSAA
may interact to affect breast meat production
[“I.Basal diets were analyzed for all amino
acids and CP (Table 1)and Lys concentrations
using composite samples of all experimental
diets (Table 2). Crude protein was calculated
as nitrogen (N) x 6.25. Amino acid concentrations were determined following acid
JAPR
LYSINE RESPONSES IN BROILERS
384
I
TABLE 2. Calculated (CAL) and analyzed (ANL) lysine composition of experimental diets
EXPERIMENT 1
109L
9 n
CALIANL
121L
133L
cAL(ANL C A L I A N L
0.99
1.00
1.08
1.13
1.23
1.25
- ~ E ~ c A L I A N L
145L
157L
CALIANL
c+NL
1.38
1.58
1.51
1 GROWTH
PERIOD
2 1 4 2 Days
0.88
1.36
1.63
42-46 Days
0.76
0.83
0.87
0.93
0.98
1.00
1.08
1.11
1.19
1.17
1.30
1.36
46-52 Days
0.73
0.79
0.84
0.92
0.94
1.08
1.05
1.08
1.15
1.22
1.25
1.29
*Percentage relative to NRC [14 based u n analysis of basal diet and amount of crystalline L-lysine*HCI
suuulemented to the basal diet. wit2 the N R g r c e n t a e e followed bv an L.
~~~~~
~
~
hydrolysis; Trp concentrations following
alkaline hydrolysis;and Met and C y s following
performic acid oxidation [15] using a highperformance cation exchange resin column
(Beckman Systems, Inc., Fullerton, CA).
Broiler weight gain, feed consumption,
and feed conversion (adjusted for mortality)
were measured on a pen basis for the 1- to
48-day period. Mortality was recorded
throughout the experiment. Prior to selection
of birds for processing, feed and water were
removed for 10 and 4 hr, respectively. At
49 days of age, six birds/pen were selected
(&5% of the pen mean BW with no visible
abnormalities) for processing (60birddtreatment). Birds were subsequently cooped in
the dark, transported to the pilot processing
facility (30 min), and individually weighed.
After weighing, birds were stunned with an
electric knife, bled for 1.5 min by severing the
jugular vein, scalded in water for 1.5 min, and
defeathered in a rotary picker for 1 min.
Eviscera were removed and discarded while
abdominal fat weights were obtained. Carcasses were chilled in an aerated ice bath for
35 min. Carcass data included cold carcass
weight and breast meat weight (skinless and
boneless Pectoralis major and Pectoralis minor
combined).
Amino acid analysis of breast meat (skinless and boneless Pectoralis major and
Pectoralis minor) was performed on five
birddtreatment from samples obtained during
processing at 49 days of age. Samples were
placed in plastic bags and frozen (-80OC) for
shipment to a commercial laboratory. Samples were then thawed (OOC), minced, refrozen
(-80°C), placed in liquid nitrogen, freezedried by lyophilization, ground, and analyzed.
Amino acid concentrations were determined
followingacid hydrolysis;Met and Cys analysis
followed performic acid oxidation [SI.
EXPERIMENT 2
A total of 4,680 day-old male Avian 24 x
Avian broilers were allocated to six treatment
groups across 72 pens in a closed-sided,
positive-pressure ventilated house. There
were 12 replications per treatment with 65
birddpen (780 birddtreatment). Housing and
husbandry were identical to that described in
Experiment 1. All birds received a common
crumble starter diet from 1to 21 days of age
containing 23% CP, 3200 ME kcavkg, and
1.31% Lys. The pelleted grower, finisher, and
withdrawal basal diets were fed from 21 to 42,
42 to 46, and 46 to 52 days, respectively
(Table 1). Basal rations were formulated to be
deficient in Lys (88% relative to the 1984
NRC) and were supplemented with LLyseHCl to obtain levels calculated to be 88,
100, 113, 125, 138, or 150% of the NRC [14]
Research Report
385
KERR et al.
Data for each experiment were analyzed
Lys recommendation. Basal diets were formulated to be adequate in all other amino acids
[141except Thr and TSAA, which were formulated to be approximately 110% and lU)%,
respectively, of the NRC [l] recommendation.
Basal diets were analyzed for all amino adds
and CP (Table 1) and Lys concentrations on
composite samples of all experimental diets
(Table 2) by the methodology described in
Experiment 1.
Birds were weighed on a pen basis and
began receiving treatments at 21 days of age.
On Day 46,birds in four pendtreatment were
weighed prior to processing. On Day 52, buds
from the remaining eight penshreatment were
weighed prior to processing. Broiler weight
gain, feed consumption, and feed conversion
(adjusted for mortality) were measured on a
pen basis for the 21- to &day period (four
replicationdtreatment) and for the 21- to 52day period (eight replications/treatment).
Fifteen birds/pen were selected for processing
from the four replicationshreatment weighed
on Day 46; eight birds/pen were selected for
processing from the remaining eight replications/treatment weighed on Day 52. Birds
were processed as described in Experiment 1.
using the General Linear Models procedure
of SAS [16], using the pen as the experimental unit for all analysis. Analysis for linear,
quadratic, and cubic responses were calculated using orthogonal polynomials [lq. All
percentage data were subjected to arc sin
square root transformations prior to analysis.
This transformation did not alter statistical
interpretation; therefore data are presented as
actual percentages. Statements of statistical
sigrufcance are based on P I .05.
RESULTS
AND DISCUSSION
EXPERIMENT 1
Diets in Experiment 1 had consistently
higher analyzed Lys levels than calculated
(Table 2). Due to this elevated analysis, the
level of Lys in the basal diet is 93% relative
to the NRC [14]. As a result, treatments in
Experiment 1 will be defined as 93L, 103L,
113L, 123L, and l33L, respectively. Day 48
BW was increased (cubic, P < .Ol) in broilers
fed graded levels of Lys, with no increase in
BW noted above the 1l3L level (Table 3).
Likewise, feed conversion improved (cubic,
P e .Ol) with increasing levels of Lys with
P VALUEB
mLAm LYSINEA
93L
Bodyweight,g
247d
103L
2596'
113L
l23L
2636'
2663'
FeedGain
l.Xa
1.8?
1.8F
Mortality, %
5.0'
4.4'
7.1k
DData are means of 10 replicate pens of 6 Peterson
X
133L
26Ba
SEM
LIN
QUAD
CUB
6.3
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.24
0.21
1.89
1.86'
0.004
10.3ab
12.1a
1.15
Arbor Acres male broilers each.
a%gnificant differences among treatments within a row (P < .OS).
LYSINE RESPONSES IN BROILERS
386
little improvement noted above the 103L
level. Mortality increased (linear, P < .Ol) in
response to graded levels of dietary Lys.
Chilled carcass yield increased (linear,
P < .Ol) in response to increasing dietary
Lys, but the response appeared to plateau at
the 103L level. Percentage abdominal fat
decreased linearly (P < .02) with increasing
dietary Lys, being minimized at the 103Llevel.
Breast meat weight and proportional yield increased in a cubic manner (P< .01 and P < .03,
respectively) in response to increasing levels
of dietary Lys, with most of the improvement
noted in buds fed the 113L diet. Amino acid,
moisture, and CP concentrations of the
Pectoralis major and Pectoralis minor muscles
were unaffected by dietary treatment
(Table 4).
EXPERIMENT 2
As in Experiment 1,diets in Experiment 2
analyzed consistently higher in Lys than calculated values (Table 2). Due to this elevated
analysis, the concentration of Lys in the basal
diet calculates to be 97% relative to the NRC
[14], so the treatments in this experiment will
be defined as 97L, lWL, 121L, 133L, 145L,
Arginine
5.71
5.69
5.61
and 157L, respectively. Body weights on
Days 46 and 52 increased (quadratic, P < .Ol)
with increasing levels of dietary Lys, with the
greatest response achieved by feeding the
109L level (Tables 5 and 6, respectively). Feed
conversion improved (quadratic, P < .Ol),
reaching an apparent optimum with the 121L
diet. Mortality was high in this experiment,
averaging 16%, but was unaffected by dietary
treatments.
Cold carcass yield was improved (quadratic, P < .01) by feeding elevated Lys levels
in buds processed on Day 47, but not in birds
processed on Day 54. Neither abdominal fat
weight nor percentage abdominal fat was significantly affected by dietarytreatment. Breast
meat weight and proportional yield increased
(quadratic, P < .01) in birds processed on
Days 47 and 54, appearing to be maximized in
birds fed the 121L diets. Drumstick weights
were affected linearly by increasing levels of
dietary Lys for buds processed on Day 47
(P<.O2) and in a cubic manner for birds
processed on Day 54 (P < .Ol). Percentage
drumstick was unaffected by dietary Lys for
birds processed on Day 47, but was reduced
as dietary Lys increased in birds processed
5.62
5.63
0.047
0.11
0.44
0.68
Crude protein
92.46
91.80
90.82
91.32
9157
0.670
0.30
0.21
0.97
Moisture
72.23
72.94
73.22
73.47
7253
0.305
0.37
0.26
0.08
BProbabilityvalues associated with linear, quadratic, and cubic sources of variation.
‘Data are means of five birddtreatment from separate pens in Experiment 1. Protein and amino acid values are
emressed on a DM basis.
Research Report
KERR ef d.
387
RELATIVE LYSINE LEVEL^
97L
I
109L
I
I
121L
I
133L
145L
P VALUEB
I
157L
I
I
LIN IOUAD CUB
SEM
IPERFORMANCE DATA. 21-46 Daw'
I
2574b
2603'
2487b
254T
Carcass yield, %
68.80'
69.02bc
6952'
Abdominal fat, g
66.1
63.3
62.8
% of carcass
Breast meat, g
% of carcass
Drumstick,g
% of carcass
Thigh, g
% of carcass
3.86
375d
21.90'
253ab
14.81
287'
16.75'
mbc
16.39b
22.9Tb
)249Sb
12476b
69.MbcII
69.39abI
68.75'
64.2
58.3
59.4
3.37
23.1Sa
I
295'
252b
287'
294ab
16.63ab
1459
16.75a
1656'b
114.4
I
I
0.01
0.20
0.01
058
0.49
0.73
0.57
I I
0.01
I I
0.01
I
22.37k
251b
I
14.7
279d
16.39b
0.08
0.156 II 0.78
1.81
381d
22.31bc
I
14.62
0.01
0.07
2.08
350
386d
25Tb
260'
14.64
13.5
40Tb
10.1
1.84ab 0.010
15.4
3.65
408'
22.32bC
14.79
I
I
353
3.61
392bc
260a
12544'
2556a
246Sd
1.82b
13.8
135
Live body
weight, g
2516'
1.79'
1.81k
I
0.01
0.91
I
1
0.66
I
I
0.87
0.113
0.02
0.31
0.66
5.1
0.80
0.01
0.26
0.236
0.21
0.01
0.63
2.3
I
I
0.08
0.08
0.02
0.09
0.120
1 0.39 I
0.19
I 0.43
2.2
[
0.03
0.01
0.45
0.087
[
0.14
0.36
0.01
o the basal diet relative to a percentage of the NRC [14], with the NRC
1
I
BProbabilityvaluesassociated with linear, quadratic, and cubic sources of variation.
'Data are means of four replicate pens of 65 Avian 24
X
Avian male broilers each.
DData are means of four replicate pens of 15 Avian 24
X
Avian male broilers each.
a4Significant differences among treatments within a row (P e .05).
on Day 54 (quadratic, P < .Ol). Thigh weights
increased (quadratic, P < .01) in birds processed at either time period, with the heaviest
weight being achieved with the 121L diet.
Thigh yield was affected in a cubic manner by
dietary Lys in buds processed on Day 47
(P < .Ol), but was unaffected by dietary Lys in
birds processed on Day 54.
A great deal of controversy exists over the
level of dietary Lys required to maximize
broiler performance and breast meat yield.
For example, recent data [5, 13, 181 demonstrate that feeding a dietary Lys level 25% of
the NRC [l] results in suboptimal gain and
feed conversion in broilers from 1to 18 days
of age compared to feeding a Lys level approximately 10to 20% above recommended levels.
Because breast meat yield is a primary concern
for the poultry industry in order to meet consumer demand for white meat, primary poultry
breeder companies have selected the modern
broiler for increased breast meat yield. The
concentration of dietary Lys can significantly
influencebreast meat yield for several reasons:
Breast meat represents a large portion of
carcass meat [19]; it contains a high concentration of Lys (Table 4); and breast muscle
development is affectedby sex, age, breed, and
genetics [8, 9,10,12,20,21]. Our studies were
been designed to evaluate semi-deficient to
excess dietary Lys concentrations on broiler
performance and breast meat yield.
Previous data suggested the Lys requirement for maximum meat yield was higher than
the level considered adequate for feed efficiency [6]. Improvement in feed efficiency
and breast meat yield were clearly noted by
increasing dietary Lys levels as reported by
Moran and Bilgili [8], but because levels of
dietary Lys ranged from slightly deficient to
adequate, only a linear effect of dietary Lys on
feed efficiency and breast meat yield was
noted. Renden et al. [ l l ] utilized a dietary Lys
level approximately 15% above the NRC [14]
JAPR
LYSINE RESPONSES IN BROILERS
388
TABLE 6. Performance and carcass characteristics of broilers fed graded levels of dietary lysine from 21 to
97L
Bodyweight,g
FeedGain
Mortality, 70
3025'
1.96a
16.2
109L
I
RELATIVE LYSINEP
133L
145L
121L
30nab
1.92b
18.3
1
30ak
3059abc
1.9lbC
1.90'
15.0
15.8
1.92b
16.2
P VALUEB
157L
SEM
I LIN / Q U A D CUB
]
0.01
0.01
058
1.96'
0.006 0.36
0.01
0.87
165
1.96
0.82
0.74
0.61
2932'
15.0
BProbabilityvalues associated with linear, quadratic, and cubic sources of variation.
'Data are means of eight replicate pens of 65 Avian 24
X
DData are means of eight replicate pens of eight Avian 24
Avian male broilers each.
X
Avian male broilers each.
a%gnificant differences among treatmentswithin a row (P < .OS).
recommendation and reported not only improved broiler performance, but also reduced
abdominal fat and increased breast meat yield.
In addition, Bilgili et al. [lo] reported that
feeding an elevated dietary Lys level for the
last 11 days of the finishing period improved
breast meat weight and proportional yield with
no effect on broiler performance. In contrast,
Gorman and Balnave [12] reported improved
performance and breast meat yields in one
experiment due to elevating dietary Lys concentration; in a second experiment, however,
this response did not occur.
Evaluation of these previous experiments in addition to experiments by Han and
Baker [21] and Kidd et al. [131 shows a peculiar
aberration of the data suggesting that breast
meat yield may be increased at a dietary Lys
concentration approximately 20% above
recommended levels. These earlier studies,
however, were not designed to focus on dietary
Lys levels well above NRC [l]recommendations. In contrast, the two experiments re-
ported herein were specifically designed to
evaluate Lys levels ranging from adequate to
in excess of NRC [ l ] recommendations. In
Experiment 1, BW was maximized in birds fed
the 113L diet, with no additionalimprovement
noted by feeding higher levels of dietary Lys.
This was confirmed in Experiment 2 in both
time periods where most of the BW improvement was noted with feeding the 109L diet
and only a numerical improvement in BW
occurred when the Lys concentration was increased to 12lL. In contrast to Experiment 1,
higher levels of dietary Lys in Experiment 2,
above 121L, caused a depression in BW. This
depression in BW was unexpected, since research indicates that supplementing an additional 0.5% Lys to starting broilers fed a
corn-soybeanmeal-based diet has no effect on
BW [22]. It has been reported, however, that
modest excesses of Lys tend to depress feed
intake, which could cause a depression in BW
gain [u),231.
Research Report
KERR et ai.
Past research suggests that amino acid
requirements for feed efficiency are higher
than those for growth [21, 23, 24, 251. In
Experiment 1, feed conversion appeared to
plateau at 103L, which was slightly below the
level at which BW appeared to be optimized.
This was unexpected but has been reported by
others [XI. In Experiment 2, feed conversions
were optimized at either weigh-day in broilers
fed the 121L diet compared to the apparent
optimization of BW at 109L. The reason for
these conflicting results are unclear, but both
experiments clearly indicate that feed conversions are optimized at levels of dietary Lys that
exceed the level currently recommended [11.
The effect of dietary Lys concentration on
mortality is highly variable. Most studies have
reported no effect of dietary Lys concentration on mortality [lo, 12,21,271,but Kidd et al.
[13] reported an increase in mortality due to
increasing dietary Lys. In Experiment 1there
was a linear increase in total mortality due to
increasing dietary Lys, which may be attributable to increased growth from Lys as noted
by Kidd et ai. [13]. This was not repeated in
Experiment 2, however, even though higher
levels of dietary Lys were evaluated.
Although there was a trend for a reduction in fat pad weight due to increasing dietary
Lys within each experiment, the effect was not
significant. As a percentage of carcass, however, fat deposition decreased significantly
with increased Lys in Experiment 1, but not
in Experiment 2. The lack of a reduction in
percentage abdominal fat due to increasing
dietary Lys is in contrast to data reported by
HanandBaker [21],but is supportedbyothers
[lo, 181. These data support the concept that
percentage abdominal fat is variable, being
affected not only by dietary Lys, but possibly
by genetic strain [9] and processing age [ll].
Breast meat weight and proportional yield
clearly increased in Experiment 1, with the
greatest response achieved by feeding the
113L diet. This was also the level of Lys that
appeared to optimize BW gain, although it
was slightly higher than the level necessary to
optimize feed efficiency. The fact that more
breast meat is deposited at higher levels of
dietary Lys is not surprising since others [lo,
111 have shown that an additional 10 to 15%
389
Lys increases breast meat accretion. Increasing dietary Lys from 113L to 133Lsignificantly
increased breast meat weight (353 vs. 366 g)
and numerically increased breast meat yield
(19.93 vs. 20.36%). This apparent increase in
breast meat production is interesting since
both Acar et ai. [9] and Han and Baker [21]
reported a similar result in breast meat production in Ross x Ross male broilers fed
elevated levels of dietary Lys. More recently,
Kidd et ai. [13] showed an increase in breast
meat production in Avian 34 x Avian male
broilers by increasing dietary Lys approximately25% above NRC [l] recommendations.
It was expected that breast muscle production
would be increased due to higher levels of
dietary Lys since male broilers show a greater
response to higher levels of dietary Lys than
female broilers [23]. The response in breast
muscle production due to feeding higher levels
of dietary Lys was surprising, however, since
Experiment 1used Peterson x Arbor Acres,
which have been shown to be less responsive
to elevated levels of dietary Lys [9].
For each processing period in Experiment 2, increasing dietary Lys up to 121L increased breast meat weight and proportional
yield with no improvement noted thereafter.
Moreover, higher levels of dietary Lys depressed breast meat production much as they
depressed BW. The peak in breast muscle
production at 121L occurs above the Lys level
required to optimize BW but at a level similar
to that of optimum feed conversion, as suggested by others [21,25]. Examining the results
of the current experiments in conjunction with
other research [6, 9, 10, 11, 13, 211 indicates
that the level of dietary Lys required for optimal breast meat production is clearly higher
than current recommendations [l].
The reduction in percentage of drumsticks and thighs noted in Experiment 2 represents a change in their weight relative to
total carcass meat deposition. Since breast
meat weight increasedwith increasinglevels of
dietary Lys while weights of drumsticks and
thighs changed little, percentage of drumsticks
and thighs could only decrease. This is supported by changes in broiler development as
described by others [19,28].
JAPR
LYSINE?RESPONSES IN BROILERS
390
CONCLUSIONS
AND APPLICATIONS
1. Feeding broilers concentrations of dietary Lys above M C recommendations improves
body welght gain and feed conversion, but may have a detrimental effect on mortality.
2. Feeding broilers concentrations of dietary Lys above levels determined to be adequate for
body weight gain improves breast meat deposition on an actual weight basis as weli as on
a percentage of carcass basis.
REFERENCES
AND NOTES
1. National Research Council, 1994. Nutrient Re9th Rev. Edition. Natl. Acad.
uirements of Poult
%ress,Washington, D?.
14. National Research Council, 1984. Nutrient Reuirements of Poult . 8th Rev. Edition. Natl. Acad.
jress, Washington, Dz.
2. Morris, T.R, K. AI Azzawi, RM. Cons, and G.L
Simpson, 1987. Effects of protein concentration on
responses to dietary lysine by chicks. Br. Poultry Sci.
28:185-195.
15.Associationof Official Analytical Chemists, 1984.
Official Methods of Analysis. 14th Edition. Assn. Offic.
Anal. Chem., Washington, DC.
.
3. Abebe, S. andT.R Morris, 1990. Note on the effects
of protein concentration on res onses to dietarylysine by
chicks. Br. Poultry Sci. 31:255-h0.
4. Surisdiarto, and DJ. Farrell, 1991. The relationship between dietary crude protein and dietary lysine
requirement by broiler chicks on diets with and without
the "ideal" amino acid balance. Poultry Sci. 7083CM36.
5. Kid4 M.T., W.Kerr, and N.B. Anthony, 1997.
Dietaly interactions between lysine and threonine in
broilers. Poultry Sci. 76608-614.
6. Jackson, M.E, S. Li, E J . Day, and S. Omar, 1989.
The effects of different lysine levels fed in constant
pro rtions to different crude protein levels on the live
pegrmance and carcass characteristics of broiler chickens. Poultry Sci. 68(Suppl):186 (Abs).
7. Hickling, D.R, W. Guenkr, and M.E Jackson,
1990. The effects of dietary methionine and lysine on
broiler chicken perfonname and breast meat yield. Can.
J. Anim. Sci. 70:673478.
8. Moran, ET., Jr. and S.F. Bilgili, 1990. Processing
losses, carcass quality, and meat yield of broiler chickens
as influenced by dietaly lysine. Poultry Sci. 69:702-709.
9. Acar, N., ET. Moran, Jr.,and S.F. Bugill 1991. Live
perfomance and carcass yield of male broilers from two
commercial strain crosses receiving rations containing
lysine below and above the established requirement
between six and eight weeks of age. Poultry Sci. 7023152321.
10. Bilgili, SF., ET. Moran, Jr., and N. Acar, 1992.
Strain-cross response of heavy male broilers to dietary
lysine in the finisher feed: Live erformance and furtherprocessing yields. Poultly Sci. 7b5-8.
11. Renden, J.k, ET. Moran, Jr., and S.A K i n 4 4
1994. Lack of interactions between dietary lysine or strain
cross and photoschedule for male broiler performance
and carcass yield. Poultry Sci. 73:1651-1662.
12. Gorman, I. and D. Balnave, 1995. The effect of
dietary lysine and methionine concentrations on the
growth characteristicsand breast meat yields of Australian broiler chickens. Australian J. Agric. Res. 4615691577.
13. Kidd, M.T., B.J. Kerr, K.M. Halpin, G.W.
McWard, and C.L Quarles, 1998. Lysine levels in starter
and grower-finisher diets affect broiler performance and
carcass traits. J. Appl. Poultry Res. 7:351-358.
16. SAS Institute, 1988. SAWSTAT User's Guide.
Release 6.03 Edition. SAS Institute, Inc., Cary, NC.
17. S k i , RG.D. and J.H. Tome, 1980. Anal is of
Variance. 111: Factorial experiments. Pages 336-$6 in:
Principles and Procedures of Statistics: A Biometrical
Approach. McGraw-HillBook Company, New York, NY.
18. Holsheimer, J.P. and EW. Ruesink, 1993. Effect
on performance, carcass composition, yield, and financial
return of dietary energy and lysine levels in starter and
finisher diets fed to broilers. Poultry Sci. 72:806-815.
19. Halvorson, D.B. and M. Jacobsen, 1970. Variations in development of muscles in chickens. Poultry Sci.
49132-136.
20. Han, Y. and D.H. Baker, 1991. Lysine requirements of fast- and slow-growing broiler chicks. Poultry
Sci. 70:210%2114.
21. Han, Y. and D.H. Baker, 1994. Digestible lysine
requirement of male and female broiler chicks during the
eriod three to six weeks posthatching. Poultry Sci.
3: 1739-1745.
22. Han, Y. and D.H. Baker, 1993a. Effects of excess
methionine or lysine for broilers fed a corn-soybean meal
diet. Poultry Si.72:107G1074.
23. Han, Y. and D.H. Baker, 1993b. Effects of sex,
heat stress, body weight, and genetic strain on the lysine
requirement of broiler chicks. Poultly Sei. 72:701-708.
24. Thomas, O.P., P.V. Twining, Jr., and E.H.
BossPrd, 1977. The available P n e requirement of 7-9
week old sexed broiler chicks. oultly SEI. 5657-60.
25. Skinner, J.T., A.L. Waldroup, and P.W.
Waldroup, 1992. Effects of dietaly amino acid level and
duration of finisher nod on performance and carcass
content of broilers t%ty-nine days of age. Poultry Sci.
71:1207-1214.
26. Kharlakian, H.G., T . k Shellem, O.P. Thomas,
and C.K. Baer, 1996. Lysine, methionine, and threonine
requirements in broilers during the withdrawal period.
Pages5343 in: Proc. Maryland Nutr. Conf., College Park,
MD.
27. Lot!, B.D., S . L Branton, and J.D. May, 1997.
Dietary lysine and asates incidence. J. Appl. Poultry Res.
6~331-334.
28. Slilborn, H.L, ET. Moran, Jr., R M Gous, and
M.D. Harrison, 1994. Experimental data for evaluating
broiler models. J. Appl. Poultry Res. 3:379-390.
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