Agriculture Reference
In-Depth Information
Table 15.4.
Maintenance requirements for methionine + cystine (Met+Cys), threonine (Thr), lysine (Lys) and
valine (Val) based on four scales that describe the intake of these amino acids.
Amino acid
Scale
Regression equation
R
2
Requirement estimate
Met+Cys
a
mg/bird day
-
174
(±43.8) + 2.92 (±0.18)
X
0.72
59.5
mg/
BW
kg
day
-59.8 (±10.5) + 3.16 (±0.20)
X
0.83
18.9
mg/
BW
k
0.75
day
-81.4 (±14.0) + 3.20 (±0.20)
X
0.82
25.5
mg/
BP
0.73
day
-
279
(±48.0) + 3.20 (±0.20)
X
0.82
87.2
Thr
a
mg/bird day
-82.2 (±15.3) + 1.83 (±0.16)
X
0.45
44.9
mg/
BW
kg
day
-45.8 (±12.6) + 2.69 (±0.20)
X
0.71
17.1
mg/
BW
k
0.75
day
-54.7 (±9.70) + 2.50 (±0.20)
X
0.60
22.0
mg/
BP
0.73
day
-
191
(±59.7) + 2.53 (±0.20)
X
0.60
44.7
Lys
mg/bird day
-
155
(±19.9) + 3.59 (±0.21)
X
0.94
43.0
mg/
BW
kg
day
-71.6 (±9.08) + 3.54 (±0.20)
X
0.94
20.2
mg/
BW
k
0.75
day
-86.9 (±11.0) + 3.56 (±0.20)
X
0.94
24.4
mg/
BP
0.73
day
-
304
(±38.5) + 3.56 (±0.20)
X
0.94
85.4
Val
mg/bird day
-456 (±55.7) + 2.33 (±0.20)
X
0.84
195
mg/
BW
kg
day
-
105
(±11.2) + 2.27 (±0.16)
X
0.89
46.1
mg/
BW
k
0.75
day
-
150
(±16.0) + 2.29 (±0.16)
X
0.89
65.4
mg/
BP
0.73
day
-501 (±53.4) + 2.29 (±0.16)
X
0.89
219
a
Bonato
et al.
(2011).
2200
NB
= -
279
(±48) + 3.20 (±0.2) Met+Cys
(
r
2
= 0.82)
1800
1400
1000
600
200
0
100
200
300
400
500
600
700
−
200
−
600
0.73
Methionine + cystine intake (mg/BP
m
day)
Fig. 15.1.
Graphic representation of methionine + cystine intake (mg/
BP
0.73
day) as a function of nitrogen
balance in two chicken genotypes (Bovans White
▲
and Cobb
■
).
The dilution technique (Fisher and
Morris, 1970) was used to achieve the amino
acid intake interval in each trial in order to
maintain a constant ideal amino acid ratio.
In order to obtain both negative and positive
NB
values in trials, requirements recom-
mended in the literature were used. Each
amino acid was tested at different intake
levels. The results shown in
Table 15.3
are
consistent with the assumption that when
amino acid intake is equal to zero, nitrogen
true; that is, high amino acid intake results
in positive
NB
.
The scales applied in the experiments
here (
Table 15.4)
are commonly used when
expressing maintenance requirements, and
are independent of bird size. The scale mg/
bird does not take into account bird weight;
mg/
BW
kg
considers body weight, but not body
composition; mg/
BW
k
0.75
also enables a com-
parison to be made of the requirements of
birds of different sizes (mass/surface ratio) but
