Agriculture Reference
In-Depth Information
Table 6.1.
Analysed nutrient content of lysine limiting soybean meal-wheat gluten diets (g/kg dry matter
based). (From Samadi and Liebert, 2008.)
N1
N2
N3
N4
N5
N6
Crude protein
63.0
122
177
246
307
347
Ether extract
25.1
45.0
59.1
51.4
81.0
81.2
Crude fibre
16.0
15.4
17.3
14.4
19.2
21.0
Crude ash
55.4
60.3
63.1
66.0
71.4
73.9
N-free extract
841
757
683
622
521
477
Starch
784
698
615
542
436
348
Sugar
34.9
31.4
91.2
97.3
116
109
ME (MJ/kg)
a
13.6
13.6
13.7
13.2
13.5
13.3
a
Calculated, based on WPSA (1984).
Table 6.2.
Analysed nutrient content of threonine limiting soybean meal diets (g/kg dry matter based).
(From Samadi and Liebert, 2008.)
N7
N8
N9
N10
N11
N12
Crude protein
59.1
128
192
252
314
362
Ether extract
22.2
45.1
67.0
88.3
116
139
Crude fibre
18.0
16.2
15.4
19.0
30.1
27.4
Crude ash
52.1
63.0
69.4
81.4
83.9
90.8
N-free extract
849
748
656
559
456
381
Starch
785
668
556
428
283
144
Sugar
15.2
15.4
24.0
41.3
61.0
57.1
ME (MJ/kg)
a
13.3
13.2
13.1
13.1
13.0
13.0
a
Calculated, based on WPSA (1984).
The model parameter for the theoretical
genetic potential can be seen to be under the
influence of the genetic progress in poultry
breeding, as indicated by an elevated potential
is compared to an older one
(Fig. 6.2)
.
However, prior to estimation of the
threshold value
ND
max
T
it is recommended
that the daily N maintenance requirement
(
NMR
) is estimated, making use of the rela-
tionship between N intake (
NI
) and total N
excretion (
NEX
). Within our model appli-
cations the resultant
NMR
is not utilized
as a real maintenance requirement but is
understood to be a part of the total N retention
(
NR
=
ND
+
NMR
) indicating that
ND
> 0
requires the replacement of endogenous
losses via faeces and urine, respectively. Ac-
cordingly, the influence of dietary factors
on estimated
NMR
cannot be excluded com-
pletely. Both the N digestibility of the basal
diet and the protein quality resulting from
the dietary AA balance may influence the
estimate of
NEX
as derived by breakpoint
modelling procedure,
NMR
data are not util-
ized to derive maintenance requirements, but
by providing a fixed point on the
NR
-curve
(breakpoint with
y
-axis,
NMR
) the iterative
process when using the Levenberg-Marquardt
algorithm is facilitated.
Similar applications to yield model
parameters for further requirement studies
have been conducted in growing pigs as a
function of age. An example of these experi-
Current Applications
Amino acid requirements based on dietary
amino acid efficiency
As indicated from selected experiments
(
Tables 6.1
-
6.4
), in addition to both the
