Agriculture Reference
In-Depth Information
(a)
1. 2
(b)
1. 3
1. 2
1. 1
1. 1
1
1
0.9
0.9
0.8
0.8
0.7
0.7
Ved
=
f
(
ME
)
Ed
=
f
(
ME
)
Ved
=
f
(ME:CP)
Ed
=
f
(ME :CP)
0.6
-1200
0.6
-
120
-800
0
ME content difference (kcal/kg, Sim-Ref)
-400
400
800
1200
-
80
0
ME:CP ratio difference (kcal/%CP, Sim-Ref)
-
40
40
80
120
(c)
1. 6
1. 4
1. 2
1
0.8
0.6
Prehensibility =
f(Fine particles)
PAL
=
f(Fine particles)
Ved
=
f
f(1st limiting EAA)
Ed
=
f(1st limiting EAA)
0.4
0
60
Fine particles content (%), Level of 1st limiting EAA (%)
20
40
80
100
Fig. 9.4.
Responses of
Ed
(ME deposition efficiency),
Ved
(energy value of the body weight gain), prehensi-
bility (ease of feed intake),
PAL
(physical activity level) to interacting parameters: (a) changes in
Ed
and
Ved
according to ME dietary content; (b) changes in
Ed
and
Ved
according to ME:CP ratio; (c)
Ed
and
Ved
changes according to the first limiting essential amino acid (EAA), prehensibility and
PAL
according to fine
particle levels in the diet.
it is expressed as a percentage (e.g. a value
of 80% corresponding to a level equivalent
to 80% of requirements).
A deficiency in an EAA has consequences at
different levels. First of all,
Ed
is reduced be-
cause the protein syntheses are limited by the
first limiting EAA. This decrease in protein
syntheses is associated with an ME excess,
which is converted into lipids (Quentin
et al
.,
2005), thereby inducing an increase in
Ved
.
Sibbald and Wolynetz (1986) measured
the response of young broilers (
10
to 18 days
of age) to the content of lysine in the regime.
NED
and
Ved
were recalculated from body
composition data. By indexing
Ved
and the
level of lysine as
100
for the optimal regime,
the linear increase of
Ved
up to 120% of the
initial
Ved
value was observed for between
100% and 70% of the optimum lysine level.
It was extrapolated to reach 140% of the
Ved
value for the reference for 40% of the
lysine requirement
(Fig. 9.4c
).
The effect of the EAA level on
Ed
val-
ues is more difficult to quantify due to the
complexity of experimental measurement.
Nevertheless, the
Ed
value is essential in the
adaptation of feed intake due to its effect on
the energy balance and the thermostat.
Ed
was therefore estimated by adjusting simu-
lated feed conversion to the measurements
of Mack
et al
. (1999) for different levels of
first limiting EAA. Two situations may be
distinguished in the evolution of
Ed
with the
changing levels of first limiting EAA: first,
there is a slight improvement of
Ed
between
100% and 80% of requirements; second,
there is a decrease in
Ed
at between 80% and
50% of requirements (
Fig. 9.4c
). The im-
provement in
Ed
observed in sub-deficiency
conditions can be explained by the adapta-
tion of the animal. A slight overconsumption
of feed is generally observed in these condi-
tions. In the model, the same phenomenon
can be observed because production of heat
