Agriculture Reference
In-Depth Information
Table 6.6.
Derived lysine requirement data for modern genotype growing barrows depending on BW,
aimed percentage of
ND
max
T
and graded dietary lysine efficiency. (From Wecke and Liebert, 2009.)
65
55
Dietary Lys efficiency (EL)
a
75
Percentage of
ND
max
T
b
BW (kg)
EL1
EL2
EL3
EL1
EL2
EL3
EL1
EL2
EL3
30
PD, g/day
128
128
128
151
151
151
174
174
174
bc
-
1
·
10
6
48.6
43.8
38.9
48.6
43.8
38.9
48.6
43.8
38.9
Lys, g/day
11.4
12.7
14.3
14.6
16.2
18.2
18.8
20.8
23.4
50
PD, g/day
142
142
142
168
168
168
194
194
194
bc
-
1
·
10
6
60.5
54.4
48.4
60.5
54.4
48.4
60.5
54.4
48.4
Lys, g/day
13.2
14.6
16.5
16.8
18.6
21.0
21.6
24.1
27.1
70
PD, g/day
147
147
147
174
174
174
200
200
200
bc
-
1
·
10
6
72.0
64.8
57.6
72.0
64.8
57.6
72.0
64.8
57.6
Lys, g/day
14.1
15.6
17.6
17.9
19.9
22.4
22.8
25.3
28.5
90
PD, g/day
147
147
147
174
174
174
200
200
200
bc
-
1
·
10
6
84.0
75.6
67.2
84.0
75.6
67.2
23.3
35.8
29.1
Lys, g/day
14.4
16.0
18.1
18.3
20.3
22.9
23.3
25.8
29.1
110
PD, g/day
144
144
144
170
170
170
196
196
196
bc
-
1
·
10
6
96.8
87.2
77.5
96.8
87.2
77.5
96.8
87.2
77.5
Lys, g/day
14.5
16.1
18.1
18.2
20.2
22.8
23.2
25.8
29.0
a
EL1, dietary Lys efficiency as observed; EL2, dietary Lys efficiency 10% below EL1; EL3, dietary Lys efficiency 20% below EL1.
b
Theoretical maximum for daily ND.
relative needs, it is not difficult to ensure the
individual limiting position in an experimental
diet. If the limiting position is not completely
certain, a single supplementation step of the
AA under study can confirm that the AA is
limiting. In the case of AAs where the re-
quirements are still not well defined, this
method of validating the limiting position is
generally recommended.
Based on this exponential model only
one increment of
LAA
in the diet is sufficient
to derive AA requirements by modelling,
taking into account varying levels of animal
performance (
ND
resp.
NR
) by modifying the
term (
NR
max
T
-
NR
) in Eqn 6.7. Obviously this
procedure works quite differently from dose-
response studies that make use of the supple-
mentation technique. To create a dose-response
curve that can be statistically analysed to
derive requirements, several graded incre-
ments within the limiting area of the AA under
study are needed. In this way disadvantages
may arise (Yen
et al
., 2004) such as the grad-
ual modification of the dietary AA balance
and the mixing of both protein-bound and
supplemented AA in varying ratios. Both fac-
tors may be of importance for ensuring the
reliability of derived AA requirements. Non-
linear models are also applied for evaluating
such supplementation studies (Gahl
et al
.,
1991, 1995) but nevertheless the noted dis-
advantages remain.
From model applications in fish nutri-
requirement curves can be calculated for in-
dividual AAs. As mentioned above, making
use of the observed AA efficiency or graded
levels of this parameter may yield such re-
quirement curves, which provide at least the
physiological background for deriving indi-
vidual AA requirements depending both on
the intended performance and the assumed
or observed AA efficiency in the diet. It has
to be pointed out that the efficiency of protein
bound AAs is the focus of our procedure.
However, diverse applications including
the evaluation of supplemental AAs are
possible but are more interesting when the
efficiency of utilization of supplemented
AAs is under scientific discussion, as is the
case with aqua feeds.
Finally, a very important area of model
application is the evaluation of individual AA
efficiency from the viewpoint of feed science.
