Agriculture Reference
In-Depth Information
3000
2500
2000
1500
1000
14-
28 days (I)
56-
70 days (II)
500
98-
112 days (III)
0
0
150
300
450
600
750
0.6
7
Threonine intake (mg/BW
kg
/day)
Fig. 20.5.
Nitrogen deposition in pullets during periods I (
14
to 28 days), II (
56
to 70 days) and III (
96
to 112
days) in response to threonine.
Table 20.5.
Calculated amino acid requirements and optimal dietary contents of Lys, Met and Thr for pullets
during growth period I (
14
to 28 days, mean BW =
222
g) depending on protein deposition (PD) and
observed amino acid efficiency.
Lys
Met
Thr
Efficiency of AA (
bc
-1
)
a
50
170
100
PD (g/day)
b
2.9
3.7
4.4
2.9
3.7
4.4
2.9
3.7
4.4
AA requirement
c
mg/BW
k
0.67
/day
651
884
1168
190
257
340
304
413
546
mg/day (at mean BW)
238
322
426
69
94
124
111
151
199
Optimal dietary content (g/kg)
d
9.50
12.9
17.1
2.77
3.75
4.96
4.44
6.03
7.96
a
Eficiency of amino acid utilization (
bc
-1
) considering that
b
= [ln
NR
max
T
- ln (
NR
max
T
-
NR
)]/
NI
and
c
= protein content of
the feed.
b
Protein deposition values at 40%, 50% and 60% of the theoretical maximum for the daily nitrogen deposition (
ND
max
T
).
c
Amino acid requirements were calculated using the equation
LAAI
= [ln
NR
max
T
- ln (
NR
max
T
-
NR
)]/16
bc
-
1
.
d
For a daily feed intake of
25
g according to the pullet management guide.
potential for daily protein deposition.
Therefore, a description of the potential ni-
trogen deposition of various strains is indis-
pensable. As in other approaches for growth
studies, the increased deposition of nitro-
gen or protein with age was considered
here. Unlike other approaches, the descrip-
tion of nitrogen retention was separated
into two parts, the first being the
NMR
,
which is independent of nitrogen intake
and appears to be specific for each genotype,
and the second part is the physiological
response boundary for given nitrogen de-
position rates.
The average value for
NMR
, based on
the three growth phases studied, was 307
mg/BW
k
0.67
/day, with
NMR
being extrapo-
lated from
NI
= 0. The equivalent value for
