Agriculture Reference
In-Depth Information
Table 15.2.
Content of basal diet (g) contributing to the total amount fed (TFI) (g) per treatment for
the amino acids tested.
Treatment
Trial
1
2
3
4
5
6
7
a
TFI
Met+Cys
BovW
h
0
20
30
35
37.5
40
20
b
40
Cobb
10
22.5
35
47.5
50
60
22.5
c
60
Thr
BovW
0
20
30
35
37.5
40
20
d
40
Cobb
0
10
20
30
45
50
10
e
50
Lys
BovW
0
10
20
30
40
10
f
-
40
Val
Cobb
0
8
16
24
32
40
8
g
40
a
Additional level to verify the limiting amino acid in each trial.
b
Treatment
2
+ 8.5 mg dl-methionine.
c
Treatment
2
+ 13.1 mg dl-methionine.
d
Treatment
2
+ 28.9 mg l-threonine.
e
Treatment
2
+ 28.9 mg l-threonine.
f
Treatment
2
+
28
mg l-Lysine.
g
Treatment
2
+
96
mg l-valine.
h
Bovans White strain.
which was determined using the Kjeldahl
method as described by the AOAC (1990).
that a bird requires
8
g of protein per unit
of maintenance (Emmans and Fisher, 1986).
Daily intake of each amino acid required per
maintenance unit was divided by
8
g.
Statistical analysis
Results
Nitrogen balance (
NB
) was calculated as the
difference between nitrogen intake and ni-
trogen excretion. Linear regressions between
NB
and amino acid intake, and the require-
ments were expressed using four different
scales (mg/bird day, mg/
BW
kg
day, mg/
BW
k
0.75
day, or mg/
BP
0.73
.
u
day, where
BW
is empty
body weight,
BP
m
is mature body protein
content and
u
is the degree of maturity or
BP
/
BP
m
). The body protein content of birds
was calculated as
184
g/kg and
199
g/kg for
Bovans White and Cobb, respectively (Bonato
et al
., 2011). Because the roosters used in
the trial were mature (
u
= 1), mg/
BP
0.73
.
u
day is
equal to mg/
BP
0.73
day. Based on these equa-
tions, digestible amino acid requirement for
maintenance was determined as the intake
(expressed using the scales described above)
that corresponds to zero
NB
.
Statistical analysis was performed us-
ing the GLM procedure of the software pro-
gram SAS 9.2 (2002) at 0.05 significance
level. The concentration of each amino acid
required to make up the 'ideal' protein for
maintenance was calculated based on the
results obtained for each amino acid, assuming
In order to estimate amino acid require-
ments for maintenance, nitrogen intake and
nitrogen excretion need to be measured,
and the difference between intake and excre-
tion is the nitrogen balance (
NB
). The main-
tenance requirement is defined at the point
where the line estimated by the regression
of amino acid intake (
AAI
) on nitrogen bal-
ance intersects the
x
-axis, when
NB
= 0. The
results of each trial (Met+Cys, Thr, Lys and Val)
are presented in
Table 15.3
.
The results of the Met+Cys and Thr
trials (with both strains) were compared us-
ing the parallelism test, and one equation
was sufficient to explain Met+Cys and Thr
maintenance requirements of both strains
(Bonato
et al
., 2011). Therefore, only one
equation was considered for these amino
acids.
Table 15.4
shows the regression equa-
tions for Met+Cys, Thr, Lys and Val accord-
ing to the scales (mg/bird day, mg/
BW
kg
day,
mg/
BW
k
0.75
day, mg/
BP
0.73
day), and the main-
tenance requirement estimated using each
of these equations.
