Agriculture Reference
In-Depth Information
Table 16.1.
Mean weights of feather-free body protein (
BP
), feather protein (
FP
and
FPc
), ovary, oviduct and
liver, and parameters of the Gompertz equation for Dekalb White hens.
Age (weeks)
BP
(g)
FP
(g)
FPc
(g)
Ovary (g)
Oviduct (g)
Liver (g)
0
5
2
2
2
14
7
8
4
31
17
17
6
55
28
29
8
66
25
26
10
103
58
61
12
137
68
71
14
136
85
88
15
0
0
4.1
16
162
102
106
0.2
0.2
4.4
17
2
3
4.6
18
5
7
4.8
19
7
9
5.1
20
9
10
5.3
21
10
10.4
5.5
22
10.3
10.4
5.7
Gompertz equation parameter values
Pm
(g)
220
127
133
10.6
10.4
8.2
B (per day)d
0.024
0.023
0.023
0.111
0.176
0.013
t*
(day)
55.0
63.0
63.5
124
120
77
Pm
, weight at maturity;
B
, rate of maturing;
t*
, age at maximum growth rate;
FP
, without correction for feather loss;
FPc
, with
correction for feather loss.
Based on the parameter
t*
in the Gompertz
equation (
Table 16.1)
the maximum growth
of the different components occurred at: fea-
thers, 63 days; feather-free body, 55 days;
ovary, 124 days; and oviduct, 120 days.
PD-
max
was 1.08 g/day, 1.94 g/day, 0.43 g/day,
0.68 g/day and 0.04 g/day for the five com-
ponents, respectively, these being achieved
at the following approximate degrees of
maturity (
u
): 0.43, 0.37, 0.82, 0.81 and 0.55,
respectively.
The rate of maturing,
B
(
Table 16.1
), de-
termined for feathers, feather-free body and
ovary, oviduct and liver showed that feathers
grew at a rate similar to that of the feather-free
body, while the ovary and oviduct matured
4.6 to 7.3 times faster than the feather-free
body. The rate of maturing of the liver corres-
ponds to half that of the feather-free body.
Using the parameters
Pm
and
B
shown
in
Table 16.1
,
PD
was calculated for each
component and summed to obtain the total
PD
for each component. The proportion of
PD
for each component over the growing
period in relation to the total amount depos-
ited is shown in
Fig. 16.1
.
The total
PD
to
15
weeks corresponded
to the sum of the
PD
of feather-free body
and feather protein. At the end of the first
week the proportion of feather-free body
protein and feather protein corresponded to
0.74 and 0.25, respectively, of the bird's
total
PD
. The proportion of feather protein
(
pFP
) in the total
PD
increased linearly (
pFP
=
0.01064 ×
Age
(
week
)
+ 0.255) to
15
weeks at
a rate close to 0.0011 per week; reciprocally,
the proportion of feather-free body protein
(
pBP
) decreased.
Between
15
and
17
weeks,
pBP
and
pFP
decreased linearly by approximately 12%
and 75% per week; however, during the
same period, the proportion of protein in
the oviduct (
pPOvi
) and ovary (
pPOva
) in-
creased by 12.8% and 70%, respectively.
Between
17
and
18
weeks of age 55% of the
total
PD
was due to the growth of the ovi-
duct (25% the
pPOvi
) and ovary (20% the
pPOva
).
