©2013 Poultry Science Association, Inc.
Effects of guanidinoacetic acid supplementation
to broiler diets with varying energy contents
S. N. Mousavi,*1 A. Afsar,† and H. Lotfollahian‡
*Department of Animal Science, Varamin-Pishva Branch, Islamic Azad University,
Varamin, Iran; †Evonik Degussa Iran AG, 1918973578 Tehran, Iran; and ‡Department
of Animal and Poultry Nutrition, Animal Science Research Institute,
Karaj, Alborz, 31466-18361 Iran
Primary Audience: Broiler Producers, Nutritionists, Researchers
SUMMARY
The purpose of this experiment was to determine the effect of guanidinoacetic acid (GAA)
addition to diets containing different levels of ME on the growth performance, energy efficiency, and carcass yield of broiler chickens. A total of 1,536 straight-run Cobb 500 broilers
were allocated to 24 floor pens (64 birds/pen). The dietary treatments consisted of a 3 × 2 factorial arrangement with different levels of ME [100% (2,988 kcal/kg of starter from 0 to 10 d,
3,083 kcal/kg of grower from 11 to 22 d, and 3,176 kcal/kg of finisher from 23 to 40 d), 95%,
and 90% of the Cobb recommendation], with or without GAA (0.06%). Guanidinoacetic acid
supplementation improved FCR from 23 to 40 d and 0 to 40 d of age (P ≤ 0.05) and reduced
feed intake from 23 to 40 d of age (P ≤ 0.09), with no significant effects on BW gain. Body
weight gain was significantly reduced when dietary energy was reduced by 10% from 11 to 22
d, 23 to 40 d, and 0 to 40 d of age (P ≤ 0.05). The energy reduction affected feed intake from 0
to 10 d and 11 to 22 d of age, with no effect during other periods. An interaction was found between energy level and GAA for FCR during the 0 to 40 d of the experiment. Addition of GAA
improved the FCR of treatments with higher energy concentrations (100 and 95% of the management guide recommendation). The main effects of GAA supplementation and energy levels
on carcass traits were not significant, except that addition of GAA reduced the percentage of
liver significantly (P ≤ 0.05). The weight of the small intestine was reduced in the low-energy
(90%) diets supplemented with GAA. Supplementation with GAA decreased caloric intake per
kilogram of BW gain and per kilogram of carcass weight. It was concluded from the current
experiment that GAA has the potential to improve FCR and energy efficiency.
Key words: broiler, carcass, energy, performance, guanidinoacetic acid
2013 J. Appl. Poult. Res. 22:47–54
http://dx.doi.org/10.3382/japr.2012-00575
DESCRIPTION OF PROBLEM
All the processes of cells involved in growth
and metabolism require energy. In body cells,
adenosine triphosphate (ATP), which is the
1
Corresponding author: snmousavi@hotmail.com
main source of energy, is used for maintenance
and growth. Creatine phosphate is a rapidly mobilizable reserve of high-energy phosphate for
ATP formation. It is likely that the requirement
for creatine is proportionally greater in growing
JAPR: Research Report
48
animals than in adults, because, in addition to
replacing creatine losses in the form of creatinine, there may be a need to provide creatine to
the growing tissues [1]. Brosnan et al. [1] concluded that one-fourth of creatine accretion in
neonatal piglets may be provided by sow’s milk
and three-fourths by de novo synthesis by the
piglet. Therefore, the capacity for de novo synthesis may be limiting in high-yielding farm animals, especially in those fed all-vegetable diets
[2]. In contrast to animal sources, purely vegetable-based diets are free of creatine, and creatine should be synthesized de novo only from
guanidinoacetic acid (GAA). Guanidinoacetic
acid, a creatine precursor, is synthesized from
l-Arg and Gly by the enzyme l-arginine:glycine
amidinotransferase. Guanidinoacetic acid is
then methylated by S-adenosyl-methionine to
form creatine through the enzyme S-adenosyll-methionine:N-guanidinoacetate methyltransferase.
Guanidinoacetic acid supplementation of up
to 0.12% GAA to all-vegetable diets has been
shown to improve performance in male and female broilers [3, 4]. In further studies, supplementation of GAA to turkey diets also improved
turkey performance [5]. The increase in creatine
concentration and the creatine phosphate:ATP
ratio in muscle tissue after dietary supplementation of GAA play central roles in energy metabolism [4, 5]. Recently, Michiels et al. [6] suggested that supplementing GAA in all-vegetable
diets improves performance and carcass characteristics in terms of the G:F ratio and breast meat
yield.
Diets with higher energy levels may allow
for more rapid gains or for a greater quantity
of meat to be produced in a given time [7]. The
higher muscle creatine demand in high-energy
diets may contribute to a more efficient utilization of dietary nutrients and energy, resulting
in improved growth and particularly improved
FCR. The objective of the current study was to
evaluate the response of broiler chicks to dietary
supplementation of GAA at different dietary energy concentrations.
MATERIALS AND METHODS
The bird care and use procedures were approved by the Karaj Animal Science Research
Institute. Straight-run Cobb 500 day-old broiler
chickens [8] were purchased from a commercial
hatchery, weighed, and randomly distributed to
24 floor pens (64 chicks per pen). Each pen was
equipped with a pan feeder, a bell drinker, and
fresh pine shavings. Birds were vaccinated for
Newcastle disease virus on d 8 and 18, for infectious bronchitis on d 1 and 14, and for Gumboro
disease on d 15 and 24. The overall experimental period was divided into 3 phases: starter (1
to 10 d), grower (11 to 22 d), and finisher (23
to 40 d).
Birds were randomly assigned to 6 dietary
treatments in a 3 × 2 factorial arrangement of
treatments. The dietary treatments were formulated to have different levels of ME [100%
(2,988 kcal/kg of starter, 0 to 10 d; 3,083 kcal/
kg of grower, 11 to 22 d; and 3,176 kcal/kg of
finisher, 23 to 40 d), 95%, and 90% of the Cobb
recommendation] [9], each containing 0 and
0.06% CreAMINO [10] as the GAA source. The
corn and soybean meal used for formulating the
experimental diets were analyzed for DM, CP,
and amino acid contents by near-infrared spectroscopy [11]. Metabolizable energy contents of
corn and soybean meal were estimated by using the regression models presented by the NRC
[12]. All dietary nutrients met or exceeded Cobb
recommendations except for ME (Table 1). Energy content of diets was adjusted by various inclusion levels of soybean oil, corn, and soybean
meal, with sand as a diluent. Feed intake and
BW gain were determined, and mortality-corrected FCR was calculated by pen at 10, 22, and
40 d of age. All birds had free access to feed and
water throughout the 40-d experiment. Mash as
the physical feed form was used during the experiment. A 23L:1D photo schedule was applied
throughout the experiment.
At 40 d of age, 2 birds (1 male and 1 female)
close to the mean BW were selected from each
replicate for processing. Birds were fasted for
12 h before processing. Carcass, breast, thigh,
abdominal fat, liver, and small intestine weights
were recorded. Weights for each variable measured were expressed as relative to live weight
at processing.
The treatment design consisted of a 3 (ME
levels) × 2 (GAA) factorial arrangement. Each
treatment was randomly allotted to 4 replicates.
Data were subjected to the GLM procedure [13]
59.0
32.2
3.0
0.03
1.19
2.13
0.36
0.10
0.20
0.19
0
0.50
0.05
1.0
2,839
21
1.20
0.53
0.89
0.79
0.24
1.31
0.88
0.99
1.00
0.50
0.20
2,988
21
1.20
0.52
0.89
0.79
0.23
1.27
0.87
0.99
1.00
0.50
0.20
95%
ME
59.0
29.7
5.0
1.6
1.20
2.13
0.36
0.10
0.19
0.25
0.01
0.50
0.05
0
100%
ME
2,689
21
1.20
0.53
0.89
0.80
0.25
1.36
0.89
0.99
1.00
0.50
0.20
54.7
35.6
1.0
0
1.16
2.13
0.36
0.10
0.22
0.12
0
0.50
0.05
4.0
90%
ME
3,083
19
1.10
0.51
0.84
0.74
0.21
1.17
0.79
0.90
0.90
0.48
0.17
62.3
27.4
3.0
2.8
0.99
2.05
0.29
0.10
0.20
0.22
0.02
0.50
0.05
0
100%
ME
2,929
19
1.10
0.51
0.84
0.74
0.22
1.20
0.79
0.90
0.90
0.48
0.17
64.7
29.5
1.0
0.42
0.98
2.04
0.29
0.10
0.22
0.17
0.02
0.50
0.05
0
95%
ME
11 to 22 d
2,775
19
1.10
0.51
0.84
0.74
0.23
1.23
0.80
0.90
0.9
0.48
0.17
61.1
31.3
0
0
0.98
2.05
0.29
0.10
0.23
0.13
0.15
0.50
0.05
3.1
90%
ME
3,176
18
1.05
0.51
0.82
0.72
0.21
1.16
0.75
0.85
0.9
0.45
0.16
61.6
29.1
0
5.0
1.07
1.90
0.26
0.10
0.24
0.14
0.03
0.50
0.05
0
100%
ME
3,017
18
1.05
0.51
0.82
0.72
0.21
1.15
0.75
0.85
0.9
0.45
0.16
65.4
28.4
0
1.89
1.08
1.89
0.26
0.10
0.23
0.15
0.04
0.50
0.05
0
95%
ME
23 to 40 d
2,858
18
1.05
0.51
0.82
0.72
0.21
1.15
0.75
0.85
0.9
0.45
0.16
65.5
28.4
0
0
1.10
1.89
0.26
0.10
0.23
0.15
0.03
0.50
0.05
1.66
90%
ME
The dietary treatments were formulated to have different levels of ME [100% (2,988 kcal/kg of starter from 0 to 10 d; 3,083 kcal/kg of grower from 11 to 22 d; and 3,176 kcal/kg of finisher
from 23 to 40 d), 95%, and 90% of the Cobb recommendation] [9], each containing 0 and 0.06% CreAMINO [10] as the guanidinoacetic acid source.
2
Provided the following per kilogram of diet: vitamin A, 14,000 IU; vitamin D3, 5,000 IU; vitamin E, 80 mg; vitamin K3, 4 mg; vitamin B2, 9 mg; vitamin B6, 4 mg; vitamin B12, 0.020 mg;
nicotinic acid, 28 mg; folic acid, 0.5 mg; pantothenic acid, 60 mg; choline chloride, 400 mg; Mn, 100 mg; Zn, 100 mg; Cu, 15 mg; Se, 0.3 mg; and I, 1 mg.
1
Ingredient, %
Corn
Soybean meal
Corn gluten meal
Soybean oil
Limestone
CaHPO4
NaCl
NaHCO3
dl-Met
l-Lys
l-Thr
Vitamin and mineral premix2
Coccidiostat (salinomycin)
Sand
Nutrient composition, %
ME, kcal/kg
CP
Lys
Met
Met + Cys
Thr
Trp
Arg
Ile
Val
Ca
Available P
Na
Item
1 to 10 d
Table 1. Ingredients and calculated nutrient composition of the experimental diets1
Mousavi et al.: GUANIDINOACETIC ACID AND BROILERS
49
JAPR: Research Report
50
for ANOVA in a randomized complete block design. Differences among means were separated
with the LSMEANS option of SAS [13]. Statistical significance was considered at P ≤ 0.05.
RESULTS AND DISCUSSION
The effect of GAA supplementation on BW
gain was not significant throughout the experiment (Table 2). This observation was in
agreement with the result of Lemme et al. [4],
who reported that 41-d BW differences among
graded levels of GAA supplementation and the
nonsupplemented control group were not significant. Lemme et al. [3] also reported that dietary supplementation of 0.06% GAA increased
the BW gain of female broilers raised to 42 d of
age; however, the effects were not significant in
male broilers.
Body weight gain was less in response to reducing the dietary ME level from 11 to 22 d and
0 to 40 d of age. A significant energy effect was
observed from 23 to 40 d as well. The interac-
tions between ME levels and GAA supplementation for BW gain were not significant. Controversy exists regarding the influence of dietary
energy levels on the BW gain of broilers. Leeson
et al. [14] and Dozier et al. [15] concluded that
varying energy levels during the finishing period
had no significant effect on final BW of broilers. Hidalgo et al. [16] showed no differences
in growth rate, feed consumption, and feed conversion as AMEn increased from 3,020 to 3,196
kcal/kg from 0 to 17 d of age, but growth rate
was reduced as AMEn was decreased to 2,976
kcal/kg. Saleh et al. [7] found differences in BW
from 0 to 21 d attributable to AME. These discrepancies may be partly due to varying ME-toamino acid ratios in the ME treatments. In the
current study, ME-to-amino acid levels were not
constant with varying levels of ME. Reece and
McNaughton [17] also reported that increasing
dietary AME improved 49-d BW and 23- to 49-d
feed conversion of broilers at 18.3°C but that
BW was not affected by dietary AME at 26.7°C.
Feed form may affect the response of broilers to
Table 2. Body weight gain of broiler chickens fed diets containing varying levels of AMEn and supplemental
guanidinoacetic acid (GAA)1
BW gain, g/bird
Item
GAA, %
0
0.06
SEM
ME, %
100
95
90
SEM
ME, % + GAA, %
100 + 0
100 + 0.06
95 + 0
95 + 0.06
90 + 0
90 + 0.06
SEM
0 to 10 d
11 to 22 d
23 to 40 d
0 to 40 d
230.8
230.7
2.41
521.6
520.8
5.53
1,429.0
1,421.6
14.21
2,174.1
2,180.5
19.21
232.6a
221.5b
238.1a
2.95
545.6a
506.6b
511.1b
6.78
1,467.4a
1,416.7ab
1,391.8b
17.41
2,245.6a
2,144.9b
2,141.2b
23.53
233.9
231.3
220.9
222.1
237.6
238.6
4.18
539.3
551.8
507.7
505.6
517.6
505.1
9.59
1,445.4
1,489.5
1,421.7
1,411.8
1,397.8
1,385.7
24.62
2,218.7
2,272.6
2,150.4
2,139.5
2,153.1
2,129.3
33.27
P-value
GAA
ME
GAA × ME
a,b
0.965
0.004
0.877
0.926
0.002
0.444
0.720
0.023
0.452
Means within a column not sharing a common superscript are significantly different (P ≤ 0.05).
CreAMINO [10].
1
0.816
0.010
0.475
Mousavi et al.: GUANIDINOACETIC ACID AND BROILERS
energy density. Linares and Huang [18] reported
that with decreasing ME from 100 to 95%, the
BW of birds on pellets was maintained, whereas
it was decreased in those fed all-mash treatments. It must be noted that in contrast to most
of the other experiments, a mash form of diet
was used in the current experiment.
Although feed intake was not significantly
affected (P ≤ 0.05) by dietary GAA supplementation (Table 3), an almost significant reduction in feed intake was observed with addition
of GAA during the finishing period (P ≤ 0.09).
This reduction was most pronounced at the 100
and 95% ME concentrations. In agreement with
current results, Lemme et al. [5] found that total feed intake of BUT turkeys over the entire
21-wk experimental period was reduced with
increasing GAA inclusion levels, with the highest inclusion level resulting in a 2.4% lower feed
intake (P ≤ 0.05) compared with the control diet.
The feed intakes from 0 to 10 d and 11 to 22
d of age were significantly affected by energy
levels. Feed intake increased as dietary ME level
51
decreased by 10% from 11 to 22 d. A 10% reduction in dietary AME increased feed consumption
only from 11 to 22 d of age, and then a trend for
a parallel reduction in feed intake was observed
with a reduction in dietary ME. Results are inconsistent in the literature regarding whether the
modern broiler chicken has the ability to adjust
caloric intake when fed diets varying in energy
content [14, 15, 19] or whether broilers eat to
a certain capacity regardless of dietary AME
[7, 16]. Nielsen [20] concluded that birds may
have difficulty maintaining energy intake with
high levels of dilution, with adverse effects on
growth rate. When low-energy diets are used in
modern broiler nutrition, feed form must be considered [18].
As shown in Table 4, dietary supplementation
of GAA improved FCR from 23 to 40 d and 0 to
40 d of age. In agreement with the present study,
Michiels et al. [6] recently reported that GAA
supplementation was most beneficial in the finisher period, when growth rates are the highest.
Reducing dietary energy impaired FCR from 11
Table 3. Feed intake of broiler chickens fed diets containing varying levels of AMEn and supplemental guanidinoacetic
acid (GAA)1
Feed intake, g/bird
Item
GAA, %
0
0.06
SEM
ME, %
100
95
90
SEM
ME, % + GAA, %
100 + 0
100 + 0.06
95 + 0
95 + 0.06
90 + 0
90 + 0.06
SEM
0 to 10 d
11 to 22 d
23 to 40 d
0 to 40 d
263.9
265.4
2.01
860.8
851.9
11.46
2,679.1
2,588.8
34.96
3,803.8
3,706.1
42.67
267.0a
258.3b
268.8a
2.47
848.2b
825.0b
895.7a
14.03
2,666.51
2,635.01
2,600.30
42.82
3,781.7
3,683.6
3,799.4
52.27
266.3
267.7
257.8
258.8
267.8
269.7
3.49
846.1
850.4
839.1
811.0
897.1
894.3
19.84
2,717.2
2,615.8
2,683.3
2,517.3
2,636.7
2,633.4
60.56
3,829.6
3,733.9
3,780.2
3,587.0
3,801.5
3,797.4
73.92
P-value
GAA
ME
GAA × ME
a,b
0.618
0.020
0.989
0.593
0.009
0.697
0.088
0.562
0.422
Means within a column not sharing a common superscript are significantly different (P ≤ 0.05).
CreAMINO [10].
1
0.126
0.271
0.460
JAPR: Research Report
52
to 22 d of age. Birds fed diets with 10% lower
energy had a significantly higher FCR. A significant interaction (P ≤ 0.05) was observed for
the FCR between dietary GAA supplementation
and energy concentration from 0 to 40 d of age
(P ≤ 0.05). It should be mentioned that most of
this effect was due to the differences from 23 to
40 d. Supplementation of GAA resulted in lower
FCR at higher energy levels (95 and 100%). An
trend toward increasing FCR was observed with
ME reduction except in the starter period. The
response of feed conversion to dietary AME was
more pronounced. Differences in feed energy
are expected to affect FCR more markedly than
BW gain [7, 19, 21, 22]. In the current study,
soybean oil was used to achieve high-energy diets. Dietary fat supplementation has been shown
to improve feed conversion [7, 19, 21]. The addition of dietary fat has been shown to improve
the feed conversion of broilers exposed to high
temperatures [23]. In the current study, dietary
supplementation of GAA was effective only
during the late phase of production. It seems
reasonable to assume that higher muscle growth
and yield during the late period of broiler life
require more ATP.
No differences related to dietary GAA supplementation and energy level were observed
for carcass yield and yields of commercial parts
(Table 5). The liver percentage of birds supplemented with GAA was significantly lower than
that for nonsupplemented birds (P ≤ 0.05). The
small intestine weight was reduced by low-energy (90%) diets supplemented with GAA. Guanidinoacetic acid supplementation decreased
ME intake per kilogram of BW gain in the diets
containing 100 and 95% ME.
As shown in Table 6, GAA supplementation
resulted in lower caloric intake per kilogram of
BW gain and carcass weight (P ≤ 0.01), which
was the result of improved FCR. Caloric intake,
caloric intake per kilogram of BW gain, and carcass weight were decreased as dietary ME was
reduced by 5 and 10% (P ≤ 0.01). In the current
study, CP and the ME-to-amino acid ratio were
increased as the ME content of diets was re-
Table 4. Feed conversion ratio of broiler chickens fed diets containing varying levels of AMEn and supplemental
guanidinoacetic acid (GAA)1
FCR
Item
GAA, %
0
0.06
SEM
ME, %
100
95
90
SEM
ME, % + GAA, %
100 + 0
100 + 0.06
95 + 0
95 + 0.06
90 + 0
90 + 0.06
SEM
0 to 10 d
11 to 22 d
23 to 40 d
0 to 40 d
1.146
1.152
0.009
1.65
1.64
0.012
1.89a
1.81b
0.019
1.75a
1.70b
0.012
1.15ab
1.17a
1.13b
0.011
1.55c
1.63b
1.75a
0.014
1.82
1.83
1.89
0.023
1.68b
1.72b
1.77a
0.015
1.14
1.16
1.17
1.17
1.13
1.13
0.016
1.57
1.54
1.65
1.60
1.73
1.77
0.020
1.88
1.75
1.89
1.78
1.89
1.90
0.033
1.73ab
1.64c
1.76a
1.68bc
1.77a
1.78a
0.021
0.666
0.102
0.826
0.460
<0.001
0.524
0.017
0.086
0.090
0.013
0.002
0.045
P-value
GAA
ME
GAA × ME
a–c
Means within a column not sharing a common superscript are significantly different (P ≤ 0.05).
CreAMINO [10].
1
Mousavi et al.: GUANIDINOACETIC ACID AND BROILERS
53
Table 5. Carcass traits (% of BW) of broiler chickens fed diets containing varying levels of AMEn and supplemental
guanidinoacetic acid (GAA)1
Item
GAA, %
0
0.06
SEM
ME, %
100
95
90
SEM
ME, % + GAA, %
100 + 0
100 + 0.06
95 + 0
95 + 0.06
90 + 0
90 + 0.06
SEM
Carcass
Thigh
Breast
Drum
Liver
Fat pad
Gizzard
Small
intestine
66.00
66.60
0.359
19.50
19.11
0.227
24.59
24.53
0.311
20.67
20.49
0.303
2.42a
2.23b
0.073
2.12
2.02
0.113
3.51
3.43
0.125
3.29
3.16
0.083
66.23
66.24
66.40
0.440
19.21
19.36
19.36
0.278
24.65
24.75
24.29
0.381
21.05
20.54
20.16
0.371
2.35
2.31
2.31
0.088
2.28
1.96
1.98
0.138
3.35
3.38
3.67
0.153
3.26
3.26
3.17
0.100
65.44
67.02
66.44
66.04
66.15
66.65
0.622
18.98
19.43
19.08
19.63
19.28
19.44
0.394
24.43
24.87
25.39
24.11
23.96
24.61
0.539
20.80
21.31
21.09
19.99
20.14
20.18
0.131
2.37
2.34
2.35
2.27
2.53
2.05
0.13
2.35
2.20
1.84
2.08
2.16
1.78
0.174
3.31
3.40
3.32
3.44
3.90
3.45
0.216
3.23ab
3.29ab
3.13ab
3.37ab
3.49a
2.85b
0.145
0.276
0.953
0.291
0.234
0.904
0.878
0.879
0.668
0.159
0.675
0.245
0.302
0.559
0.200
0.283
0.666
0.269
0.334
0.337
0.773
0.008
P-value
GAA
ME
GAA × ME
0.047
0.751
0.098
a,b
Means within a column not sharing a common superscript are significantly different (P ≤ 0.05).
CreAMINO [10].
1
Table 6. Metabolizable energy efficiency of broiler chickens fed diets containing varying levels of AMEn and
supplemental guanidinoacetic acid (GAA)1
Item
GAA, %
0
0.06
SEM
ME, %
100
95
90
SEM
ME, % + GAA, %
100 + 0
100 + 0.06
95 + 0
95 + 0.06
90 + 0
90 + 0.06
SEM
ME intake
ME intake/kg of BW gain
ME intake/kg of carcass
11,358.0
11,059.0
127.10
11,881.7a
11,003.7b
10,740.0b
155.67
5,222.6a
5,069.9b
35.79
5,292.6a
5,129.1b
5,017.0b
43.82
7,757.7a
7,467.6b
58.98
7,842.9a
7,587.9b
7,404.3b
72.23
12,034.0
11,729.5
11,294.0
10,713.5
10,746.0
10,734.0
220.15
5,424.3a
5,161.0ab
5,252.5ab
5,005.7b
4,991.0b
5,043.0b
61.97
8,130.75a
7,555.0b
7,745.7ab
7,430.0b
7,396.7b
7,414.7b
102.16
P-value
GAA
ME
GAA × ME
a,b
0.120
<0.001
0.450
0.009
0.002
0.038
Means within a column not sharing a common superscript are significantly different (P ≤ 0.05).
CreAMINO [10].
1
0.003
0.003
0.033
JAPR: Research Report
54
duced. Dozier et al. [24] reported that caloric efficiency was improved per unit of BW gain and
breast meat weight in birds fed diets containing
a high amino acid density.
Supplementation with GAA was effective in
reducing the caloric consumption per kilogram
of BW gain and per kilogram of carcass weight
only at 100 and 95% of energy recommendations. Overall, dietary supplementation of GAA
improved FCR and energy efficiency.
CONCLUSIONS AND APPLICATIONS
1. Dietary supplementation of GAA has the
potential to improve the FCR of broilers
in the finisher period.
2. Addition of GAA may increase energy
efficiency in broilers at higher energy
levels.
3. Birds could not maintain their energy
intake with high levels of dilution when
diets were fed in mash form.
REFERENCES AND NOTES
1. Brosnan, J. T., E. P. Wijekoon, L. Warford-Woolgar,
N. L. Trottier, M. E. Brosnan, J. A. Brunton, and R. F. P. Bertolo. 2009. Creatine synthesis is a major metabolic process
in neonatal piglets and has important implications for amino
acid metabolism and methyl balance. J. Nutr. 139:1292–
1297.
2. Wallimann, T., M. Tokarska-Schlattner, D. Neumann,
R. M. Epand, R. F. Epand, R. H. Andres, H. R. Widmer,
T. Hornemann, V. A. Saks, I. Agarkova, and U. Schlattner.
2007. The phosphocreatine circuit: Molecular and cellular
physiology of creatine kinases, sensitivity to free radicals,
and enhancement by creatine supplementation. Pages 195–
264 in Molecular System Bioenergetics: Energy for Life. V.
Saks, ed. Wiley-VCH, Weinheim, Germany.
3. Lemme, A., J. Ringel, H. S. Rostagno, and M. S. Redshaw. 2007. Supplemental guanidino acetic acid improved
feed conversion, weight gain, and breast meat yield in male
and female broilers. Pages 335–338 in Proc. 16th Eur. Symp.
Poult. Nutr., Strasbourg, France. World’s Poult. Sci. Assoc.,
Beekbergen, the Netherlands.
4. Lemme, A., J. Ringel, A. Sterk, and J. F. Young. 2007.
Supplemental guanidino acetic acid affects energy metabolism of broilers. Pages 339–342 in Proc. 16th Eur. Symp.
Poult. Nutr., Strasbourg, France. World’s Poult. Sci. Assoc.,
Beekbergen, the Netherlands.
5. Lemme, A., R. Gobbi, A. Helmbrecht, J. D. Van Der
Klis, J. Firman, J. Jankowski, and K. Kozlowsk. 2010. Use
of guanidino acetic acid in all-vegetable diets for turkeys.
Pages 57–61 in Proc. 4th Turkey Sci. Prod. Conf., Macclesfield, UK. Turkeytimes, Tarporley, Cheshire, UK.
6. Michiels, J., L. Maertens, J. Buyse, A. Lemme, M.
Rademacher, N. A. Dierick, and S. De Smet. 2012. Supplementation of guanidinoacetic acid to broiler diets: Effects
on performance, carcass characteristics, meat quality, and
energy metabolism. Poult. Sci. 91:402–412.
7. Saleh, E. A., S. E. Watkins, A. L. Waldroup, and P.
W. Waldroup. 2004. Effects of dietary nutrient density on
performance and carcass quality of male broilers grown for
further processing. Int. J. Poult. Sci. 3:1–10.
8. Cobb 500, Cobb-Vantress Inc., Siloam Springs, AR.
9. Cobb-Vantress. 2008. Cobb Broiler Performance &
Nutrition Supplement. Europe, Middle East, Africa version.
Cobb-Vantress Inc., Siloam Springs, AR.
10. Evonik Degussa GmbH, Hanau-Wolfgang, Germany.
11. Paya Amin Mehr, Tehran, Iran.
12. NRC. 1994. Nutrient Requirements of Poultry. 9th
rev. ed. Natl. Acad. Press, Washington, DC.
13. SAS Institute. 2004. Version 9.1. SAS Inst. Inc., Cary,
NC.
14. Leeson, S., L. Caston, and J. D. Summers. 1996.
Broiler response to energy or energy and protein dilution in
the finisher diet. Poult. Sci. 75:522–528.
15. Dozier, W. A., III, C. J. Price, M. T. Kidd, A. Corzo,
J. Anderson, and S. L. Branton. 2006. Growth performance,
meat yield, and economic responses of Ross × Ross 308
broilers provided diets varying in metabolizable energy from
30 to 59 days of age during low and moderate temperatures.
J. Appl. Poult. Res. 15:367–382.
16. Hidalgo, M. A., W. A. Dozier III, A. J. Davis, and
R. W. Gordon. 2004. Live performance and meat yield responses to progressive concentrations of dietary energy at
a constant metabolizable energy-to-crude protein ratio. J.
Appl. Poult. Res. 13:319–327.
17. Reece, F. N., and J. L. McNaughton. 1982. Effects of
dietary nutrient density on broiler performance at low and
moderate environmental temperatures. Poult. Sci. 61:2208–
2211.
18. Linares, L., and K. H. Huang. 2010. Influence of energy levels and different feed processing methods on performance of broilers. In Proc. XIIIth Eur. Poult. Conf., Tours,
France.
19. Leeson, S., L. Caston, and J. D. Summers. 1996.
Broiler responses to diet energy. Poult. Sci. 75:529–535.
20. Nielsen, B. L. 2004. Behavioural aspects of feeding
constraints: Do broilers follow their gut feelings? Appl.
Anim. Behav. Sci. 86:251–260.
21. Cheng, T. K., M. L. Hamre, and C. N. Coon. 1997.
Effect of environmental temperature, dietary protein, and
energy levels on broiler performance. J. Appl. Poult. Res.
6:1–17.
22. Proudfoot, F. G., and H. W. Hulan. 1987. Interrelationships among lighting, ambient temperature, and dietary energy and broiler chicken performance. Poult. Sci.
66:1744–1749.
23. Dale, N. M., and H. L. Fuller. 1980. Effect of diet
composi-tion on feed intake and growth of chicks under
heat stress. II. Constant vs. cycling temperatures. Poult. Sci.
59:1434–1441.
24. Dozier, W. A., III, A. Corzo, M. T. Kidd, and S. L.
Branton. 2007. Dietary apparent metabolizable energy and
amino acid density effects on growth and carcass traits of
heavy broilers. J. Appl. Poult. Res. 16:192–205.