Agriculture Reference
In-Depth Information
total dietary fibre contents (
TDF
). Feed in-
take reduction (
rFI
) of birds fed diets with
TDF
increasing levels was expressed as a
percentage relative to a control diet (con-
ventional diet containing corn and soybean
meal). Data on
rFI
were regressed against
TDF
content
(
Fig. 14.3
).
The equation estimates feed intake reduc-
tion as a function of
TDF
percentage in the diet:
Cobb female:
mFI
= -0.001146346
x
2
+ 0.8735
x
+ 7.7553 (g/day)
Ross male:
mFI
= -0.000482069
x
2
+ 0.66129
x
+ 8.708551 (g/day)
Ross female:
mFI
= -0.0007711
x
2
+ 0.74407
x
+ 9.24998 (g/day)
Hy-Line white:
mFI
= -0.0002677
x
2
+ 0.34919
x
+ 6.2229 (g/day)
rFI
= [
100
+ (17.6 + 0.52 × (
36
-
TDF
))]/
100
(%)
Hy-Line brown:
mFI
= -0.000666269
x
2
+ 0.44387
x
+ 5.6498 (g/day)
Hise
x
white:
mFI
= -0.0005078
x
2
+ 0.40907
x
+ 5.07180 (g/day)
Total dietary fibre content (
TDF
) of the feed-
stuffs in the model may be obtained using
the equation of Bellaver
et al
. (2004):
Hise
x
brown:
mFI
= -0.0003668
x
2
+ 0.38615
x
+ 4.89426 (g/day)
TDF
= 2212.56 - 0.0492 ×
EM
- 1.103 ×
ADF
- 7.053 ×
EE
- 9.196 ×
MM
(%)
One aspect that must be considered in the
model is the hypothesis confirmed by Gous
et al
. (2012) that chickens of any age attempt
to maintain the body lipid to protein ratio
determined by their genetic potential by
long-term regulation mechanisms. Therefore,
feed intake will always depend on the bird's
current state. According to this theory, which
was first proposed by Emmans (1981), when
an animal has more body lipid than its genet-
ically determined lipid:protein ratio, the
extra amount of lipid will be used as an en-
ergy source whenever possible. In a recent
study, Gous
et al
. (2012) observed that for a
given feed, body lipid reserves in broilers in-
creased at first due to the need to consume
Where
ADF
is acid-detergent fibre,
EE
is
ether extract and
MM
is ashes.
In order to correct feed intake according
to physical capacity, based on the effect of
dietary fibre, the following equation is applied:
cFI
=
rFI
×
mFI
(g/day)
Where
cFI
is feed intake corrected for phys-
ical capacity and
mFI
is maximum feed in-
take. In order to calculate
mFI
, daily feed
intake was related to protein weight (
x
).
The equation for each genetic strain is pre-
sented below:
Cobb male:
mFI
= -0.0006279
x
2
+ 0.71542
x
+ 1.7489 (g/day)
0
10
20
30
40
50
5
0
−
5
−
10
−
15
−
20
-
25
Total dietetic fibre (%)
Fig. 14.3.
Effect of total dietary fibre on broiler feed intake.
