Agriculture Reference
In-Depth Information
Table 19.3.
Mean (± standard error) feed intake (g/day), amino acid intake (mg/bird/day), rate of lay (%),
egg weight (g) and egg output (g/bird/day) from
35
to
48
weeks in response to lysine, methionine + cysteine
and threonine.
Amino acid intake
Feed intake
Rate of lay
Egg weight
Egg
output
Lysine
952
105
± 2.45
96.2 ± 1.78
64.5 ± 1.67
62.0 ± 1.21
847
103
± 2.29
95.1± 2.71
64.4 ± 0.80
61.2 ± 1.62
659
104
± 3.42
94.8 ± 2.21
62.9 ± 1.53
59.6 ± 2.42
579
106
± 3.41
92.1 ± 2.74
61.3 ± 2.14
56.4 ± 3.07
439
96.6 ± 7.08
75.5 ± 4.55
59.3 ± 0.99
44.7 ± 3.08
289
79.6 ± 9.73
51.5 ± 3.67
55.4 ± 1.99
28.5 ± 1.36
190
69.6 ± 5.67
28.0 ± 1.32
52.1 ± 2.44
14.6 ± 0.91
254
a
70.3 ± 3.96
31.3 ± 1.78
53.2 ± 0.78
16.6 ± 0.86
Methionine + cysteine
899
100
± 2.36
96.5 ± 2.88
66.3 ± 1.58
63.4 ± 1.81
791
99.8 ± 3.54
95.1 ± 3.14
66.9 ± 1.41
63.1 ± 2.80
690
100
± 4.73
95.2 ± 3.20
64.9 ± 1.25
61.1 ± 2.47
580
105
± 3.74
93.9 ± 5.02
62.7 ± 1.30
58.2 ± 2.93
302
72.8 ± 6.22
50.0 ± 6.80
57.7 ± 1.34
30.2 ± 3.62
168
61.0 ± 2.05
20.5 ± 1.84
54.0 ± 1.69
11.2 ± 1.22
51.9
37.9 ± 5.52
3.27 ± 0.90
47.5 ± 1.63
2.86 ± 0.55
114
a
41.5 ± 3.35
6.27 ± 2.22
49.0 ± 2.33
3.42 ± 1.37
Threonine
737
98.6 ± 3.36
96.0 ± 2.30
66.7 ± 0.97
62.6 ± 1.89
672
99.9 ± 3.09
95.9 ± 2.48
66.3 ± 1.13
62.2 ± 2.05
578
100
± 3.52
93.7 ± 3.00
66.3 ± 1.15
61.0 ± 2.58
480
104
± 2.99
93.4 ± 2.95
63.6 ± 1.86
56.9 ± 2.62
247
71.4 ± 4.67
47.6 ± 5.54
58.4 ± 1.52
29.2 ± 3.11
132
57.2 ± 4.46
20.5 ± 1.99
52.8 ± 3.66
11.9 ± 1.30
35.1
30.5 ± 6.39
5.22 ± 0.85
46.7 ± 2.54
3.60 ± 0.57
104
a
45.1 ± 8.87
6.40 ± 1.68
50.6 ± 2.40
3.80 ± 0.86
a
Control treatment.
output (
Table 19.3
;
Fig. 19.1
)
with the low-
est levels of Met+Cys and Thr resulting in
egg outputs close to zero. The four highest
levels used in the three assays produced
outputs that probably represent the poten-
tial for the strain used.
Estimates of the coefficients
a
and
b
of
the Reading model are given in
Table 19.4.
The current marginal costs of the three
amino acids in this study were R$10/kg for
Lys, R$12/kg for Met+Cys and R$15/kg for
Thr. Current prices for the four egg grades
used in Brazil were R$ 0.22, 0.23, 0.24 and
0.25 per gramme for small (
45
g), medium
(
50
g), large (
55
g) and extra-large (
60
g) eggs,
respectively. From these values
k
(g/mg)
was calculated to be 0.0023, 0.0025 and
0.0034 for the three amino acids, and the
worth feeding above the mean was therefore
221
mg,
206
mg and
169
mg, respectively.
The optimum economic amino acid intake
of the three test amino acids was calculated
to be 746 mg/bird/day, 717 mg/bird/day and
593 mg/bird/day, respectively.
A range of cost ratios (
k
) representing
0.15, 0.30 and 0.45 above and below the
current value for each amino acid was used
to calculate the optimum economic intakes
of the three amino acids under test for three
maximum egg outputs (
45
g/bird/day,
50
g/
bird/day and
55
g/bird/day) and three mean
body weights (1.45 kg, 1.55 kg and 1.75 kg)
and the results are given in
Table 19.5
. The
optimum intakes decreased in all cases as
the cost ratio increased, but in all cases the
optimum intake increased with potential
egg output and mean body weight.
