N .T. Mui et al. Livestock Production Science 66 2000 25 –34
29
covariance using initial weight as independent vari- where Y is the jth observation of the ith treatment, a
able adjusting feed intake, live weight gain and feed the intercept, b the slope of Y against the corre-
i
conversion ratio FCR calculated as total DM intake sponding value of X , X
the effect of the ith
i i
divided by total liveweight gain of the animals for treatment, and e the random error effect.
ij
the overall experimental period. The model used was:
3. Results
Y 5 m 1 T 1 bX 2 X 1 e
ij i
ij ij
3.1. Voluntary feed intake of different parts of where Y is the jth observation of the ith treatment,
ij
whole sugar cane m is the general mean, T is the effect of the ith
i
treatment, b is the regression of Y on X , X is the
ij ij
ij
The results from the intake studies are shown in record of the covariate in the individual indicated by
Table 3. Voluntary intake of fresh green leaves varied the subscripts, X, is the overall mean of the
according to chopping length and was in the range of covariate, and e is the random error effect.
ij
687–812 g head per day or 203–231 g DM head In the digestibility experiment, DDM, DCP and
per day. Feed intake was highest when the leaves DCF of the total diet were calculated by difference,
were chopped into 25-cm lengths, but there were no with the assumption that there were no interactions
significant differences in intake between the different with the basal diet. Regression analysis was used to
chopping lengths in the experiment. determine the relationship between level of CWSC
The intake of fresh sugar cane tops was sig- included in the diet and the DDM of the diet and the
nificantly higher for animals fed the tops chopped relationship between fibre content and DCF of the
into slices of 1–3 cm 1002 g head per day diet. The model used was:
compared with chopped at 15 or 20-cm lengths 876 and 899 g head per day, respectively. When com-
Y 5 a 1 bX 1 e
ij i
ij
Table 3 Intake experiment: DM intake by goats of sugar cane leaves, tops and stalks chopped in different ways
Treatments Liveweight kg
Feed intake g day DM kg
BW Initial
Final Fresh
DM Leaves
: 5 cm
10.4 10.3
767 206
20.0 10 cm
11.9 11.6
687 203
17.3 15 cm
10.6 10.5
755 218
20.6 20 cm
11.0 11.0
772 220
20.0 25 cm
10.5 11.1
812 231
20.0 Whole
10.6 10.3
737 214
20.5 P value
– –
0.40 0.06
0.76 Tops
:
a
1–3 cm 10.3
11.7 1002
167 15.2
b
15 cm 10.5
11.8 871
146 13.2
b
20 cm 10.3
11.4 899
150 13.8
P value –
0.06 0.07
0.09 0.11
Stalks :
a a
a
1–3 cm 10.9
12.4 924
345 30.0
b b
20 cm, no rind 11.0
11.0 792
215 18.7
c c
c
15 cm, rind 10.9
11.5 627
175 15.6
P value –
0.1 0.001
0.001 0.004
LS-means within columns and plant parts with different superscripts differ significantly P ,0.05.
30 N
.T. Mui et al. Livestock Production Science 66 2000 25 –34
pared on a DM basis or as g kg BW the smallest the leaves had the highest level of CP, 7.6. Since
the stalk constitutes the major part of the DM of the chopping size still resulted in the highest intake, but
whole sugar cane the average value is low. Jack fruit the differences were not significant.
leaves had a high CP value 14.5 and a CF value Chopping of sugar cane stalks into 1–3-cm slices
comparable to that of CWSC. The ash content was significantly increased feed intake of fresh and dry
high in jack fruit and GG but low in the whole sugar material as well as DM intake expressed in g per kg
cane. BW. Removing the rind also improved intake com-
Analysis of variance of levels of inclusion of pared to when the rind was included. All goats
CWSC on voluntary feed intake Table 4 showed maintained body weight with green sugar cane leaves
that total DM intake was significantly different and increased live weight in the trials with sugar
between the treatments 437–495 g day. The in- cane tops or stalks after 19 days on the diet.
tended levels of inclusion of CWSC in DM were not achieved but the actual intake was lower than
3.2. Chemical composition of the feeds, voluntary planned at all levels. The average DM intake in
feed intake , feed conversion ratio and live weight
percent of BW was, however, similar for all treat- gain of goats in relation to level of inclusion of
ments, between 3.3 and 3.6. The intake of DM CWSC in the diets
.
0.75
related to the metabolic body weight W did not
0.75
Chemical compositions of the feeds in both the differ between treatments 65–71 g kg W
. The
0.75
growth and digestibility studies are presented in intake of CP, both total and per kg W
decreased Table 1. CWSC and GG had a similar DM content.
significantly with increasing level of CWSC. CWSC had a low value for CP, only 2 of DM. The
The DDM, DCP and DCF of the six diets are lowest content of CP was in the stalks, 1.7, while
presented in Table 5. The actual intake was follow-
Table 4 Growth experiment: total intake of DM and CP at different levels of inclusion of CWSC in the diet
CWSC GG S.E.
Prob. 0 100
20 80 40 60
60 40 80 20
100 0 CWSC of total DM
offered: 15
30 45
60 75
DM intake
a b
c d
e
CWSC g day 81.6
116.4 137.5
188.7 268.1
3.3 0.001
a b
c d
e
Guinea grass g day 218.6
225.3 175.5
122.0 71.0
0.0 6.2
0.001
a b
b b
b b
Jack fruit g day 159.4
89.6 87.4
83.8 84.1
88.8 29.8
0.053
a a
a a
b b
Concentrate g day 77.6
79.1 a 80.1
78.6 85.5
87.3 16.8
0.001
b a,b
b,c b
a a b
MUB g day 17.4
18.0 16.5
17.3 18.4
5.3 0.001
17.7 ,
a b
a c
c a
Total g day 471.7
494.7 474.8
437.2 443.7
461.1 5.51
0.057 Total kg 100 kg BW per day
3.4 3.66
3.4 3.4
3.3 3.5
0.23 0.88
0.75
Total g kg W per day
68.4 65.1
65.6 67.7
71.2 67.0
3.3 0.81
a b
c d
e
CWSC of total DM –
12.5 23.0
26.2 36.8
50.6 0.087
0.001 consumed
CP intake
a b
c d
e
CWSC g day 3.3
4.7 5.5
7.6 10.7
0.13 0.001
a b
c d
e
Guinea grass g day 29.0
23.5 18.6
12.3 6.8
0.5 0.001
a b
b b
b b
Jack fruit g day 19.2
17.6 14.4
15.8 13.8
14.3 4.08
0.050
a a
a a
b b
Concentrate g day 14.4
14.7 14.9
14.6 15.9
16.2 3.1
0.001 MUB g day
3.2 3.4
3.1 3.3
3.2 3.4
0.09 0.10
a b
c d
e f
Total g day 66.0
62.0 56.0
51.0 47.0
44.0 0.48
0.001
0.75 a
a b
b c
b
Total g kg W per day
9.3 8.9
8.0 7.6
6.8 6.5
0.29 0.001
LS-means within rows with different superscripts differ significantly P ,0.05.
N .T. Mui et al. Livestock Production Science 66 2000 25 –34
31 Table 5
Digestibility experiment: Total intake of DM and apparent digestibility coefficients at different levels of inclusion of CWSC in the diet CWSC GG
S.E. Prob.
0 100 20 80
40 60 60 40
80 20 100 0
CWSC of total DM offered:
15 30
45 60
75 DM intake
a b
c d
e
CWSC g day 63
149 156
174 243
11 0.001
a b
c d
e
Guinea grass g day 389
244 229
120 72
18 0.001
Jack fruit g day 123
123 120
120 125
123 3.78
0.17
a a
a b
a a
Concentrate g day 88.5
90 90
69 89
90 2.7
0.001
a a
a b
a a
MUB g day 19.5
18.7 19.5
15.9 19.3
19.3 0.87
0.03 Total intake
a b
a c
c c
DM g day 603
540 608
481 478
475 22
0.002
a b
c d
e g
CF g day 156
123 134
101 91
80 6.9
0.001
a b
b c
c c
CP g day 78
64 64
48 50
45 1.8
0.001
a b
c d
e
CWSC of total DM 11.9
24.3 32.4
36.2 49.8
0.089 0.05
consumed Apparent digestibility
DDM 66.7
66.5 65.9
62.1 65.8
66.7 0.16
0.31
a b
b c
d c
DCF 66.0
62.0 60.2
52.3 54.7
49.8 0.25
0.001
a b
c d
d d
DCP 63.4
56.3 50.35
43.5 44.7
43.0 0.19
0.001 LS-means within rows with different superscripts differ significantly P ,0.05.
ing the same trend as in the growth trial though the tive relationship between the DCF and the proportion
values were somewhat different. The DDM of the of actual intake of CWSC in the diets, represented by
2
diets was between 62.2 and 66.7 and did not differ the equation: Y 50.597–0.0017X, r 50.016 where
significantly between treatments. The DCP was Y 5DCF and X 5 CWSC in the diet.
significantly higher in the diets containing up to The effect of including CWSC in the diets on the
24.3 CWSC as a roughage compared to the diets live weight gain is shown in Table 6. When the diet
with 32.4 or more CWSC, which had a similar consisted to 36.8 and 50.6 of DM of CWSC there
DCP. The DCF was highest for the treatment con- was a significantly lower daily gain as compared to
taining 100 GG and decreased gradually when the 12.5, 23 and 26.2 DM of CWSC. The diet in which
level of CWSC increased. There was a weak nega- 23 of the DM consisted of CWSC gave the
Table 6 Live weight gain LWG, feed conversion ratio FCR and feed costs at different levels of inclusion of CWSC in the diet to goats
CWSC GG Prob.
0 100 20 80
40 60 60 40
80 20 100 0
CWSC of total DM offered:
15 30
45 60
75 Initial weight kg
11.6 10.2
10.8 10.9
10.6 10.9
0.54
a a
b c
a a
Final weight kg 16.0
16.2 18.1
16.9 15.5
15.7 0.054
a b
c b
d d
LWG g day 46.0
51.4 64.8
53.6 37.3
39.0 0.023
a b
c d
b e
FCR of DM kg kg LWG 11.8
10.4 7.5
8.5 10.7
13.1 0.05
a b
c c
b b
FCR of CP kg kg LWG 1.54
1.30 0.84
0.98 1.34
1.23 0.052
Feed costs 100
83 61
68 89
77 LS-means within rows with different superscripts differ significantly P ,0.05.
32 N
.T. Mui et al. Livestock Production Science 66 2000 25 –34
significantly highest live weight gain P ,0.05, the The lower feed intake noted when the goats were
best FCR and lowest feed cost. There was an fed chopped cane stalk with the rind remaining
indication that when using 50.6 of the DM as indicates that the highly lignified outer rind has a
CWSC in the diet, i.e., replacing all GG with sugar negative effect on intake. Preston 1977 suggested
cane, the feed costs were reduced by 23 compared that the long fibres present in the rind act as a
to feeding only GG, but the lowest costs were limiting factor on intake. When the cane was chop-
obtained with 23 CWSC, which reduced the feed ped into 1–3-cm lengths these fibres were shortened,
costs by 40. which resulted in a higher intake. Slicing sugar cane
can also give the goats the possibility to select the more digestible components in the core of the stalk.
4. Discussion The animals on all the treatments consumed more
