16 A
. Tolera, F. Sundstøl Livestock Production Science 68 2001 13 –23
2.2. Estimated DM degradability of the diets experiments. The in sacco DM disappearance after 4
and 8 h of incubation was significantly higher P ,
The estimated in sacco DM degradability of the 0.05 in maize stover harvested at stage I than at
maize-stover-based diets with graded levels of de- stage III. The desmodium hay had significantly
smodium hay supplements were determined assum- higher P
,0.05 DM disappearance than the maize ing additive effects of the maize stovers and de-
stovers after 4, 8, 16, 24 and 48 h of incubation. The smodium hay as follows.
washing loss A value was highest in desmodium hay and lowest in maize stover harvested at stage III.
MSDMI 3 MSISDMD 1 DiDMI 3 DiISDMD
In general, the washing loss showed a significant
]]]]]]]]]] EISDMD
5 3 100
TDMI
decrease P ,0.05 with increasing stage of maturity
where EISDMD
5estimated in sacco DM de- of the stover. The insoluble but potentially degrad-
gradability of the diet ; MSDMI 5maize stover
able fraction B value was significantly lower DM intake; MSISDMD
5in sacco DM degradability whereas the degradation rate was significantly higher
of maize stover; DiDMI 5Desmodium intortum hay
P ,0.05 in the desmodium hay than in the maize
DM intake; DiISDMD 5in sacco DM degradability
stovers. The maize stover harvested at stage III of Desmodium intortum hay; TDMI
5total DM showed an unexpectedly higher P
,0.05 degra- intake.
The EISDMD of the diets was used for prediction
Table 3
of DMI, DMD, DDMI and growth rate of sheep
In sacco DM degradability and degradability characteristics
feeding on these diets based on the intake, diges-
of maize stover and Desmodium intortum hay used in the growth
tibility and body-weight change data obtained from
and digestibility experiments
the growth and digestibility experiment reported by
Parameters Maize stover Desmodium
Tolera and Sundstøl 2000.
intortum hay Stage I
Stage II Stage III
6S.E.
b bc
c a
DMD 19.9
18.5 17.1
29.1 0.5
2.3. Statistical analysis
4h b
bc c
a
DMD 20.4
19.5 17.7
32.6 0.6
8h b
b b
a
DMD 27.1
26.7 28.1
44.4 1.4
16h
Analysis of variance was carried out on the in
b b
b a
DMD 37.3
36.1 35.7
54.4 1.4
24h b
b b
a
sacco DM degradation of the individual feeds using
DMD 51.1
49.3 51.7
65.1 1.4
48h a
a a
a
a completely randomized design and on the esti-
DMD 60.6
62.8 59.9
65.8 1.8
72h a
a a
a
DMD 67.5
65.4 63.8
67.2 1.4
mated DM degradability of the diets using factorial
96h b
c d
a
A 14.6
12.9 11.9
23.6 0.0
arrangement of treatments. Significant differences
a a
a b
B 63.8
67.0 59.9
44.4 2.2
between means were tested using Duncan’s New
ab a
bc c
A 1 B
78.4 79.9
71.8 68.0
2.2
c c
b a
Multiple Range test SAS, 1985; Montgomery,
c 0.018
0.017 0.022
0.05 0.001
ab b
ab a
1991. Correlation as well as simple and multiple
L 1.1
0.7 1.8
2.2 0.4
b b
b a
ED 38.0
37.3 37.7
45.8 0.9
linear regression analyses were performed on the
R.S.D. 2.4
2.5 2.6
2.3
data to examine the relationships of DMI, DMD,
a,b,c
DDMI and growth rate of the sheep with estimated
Means with one or more similar superscripts within a row are not significantly different P
.0.05.
in sacco DM degradability of the diets SAS, 1985.
DMD 5DM disappearance after 4 h of incubation ;
4h
DMD 5DM disappearance after 8 h of incubation ;
8h
DMD 5DM disappearance after 16 h of incubation ;
16h
3. Results
DMD 5DM disappearance after 24 h of incubation ;
24h
DMD 5DM disappearance after 48 h of incubation ;
48h
DMD 5DM disappearance after 72 h of incubation ;
72h
3.1. DM degradability of the individual feeds
DMD 5DM disappearance after 96 h of incubation ; A5
96h
washing loss ; B 5insoluble but slowly degradable ; A 1
Table 3 shows the in sacco DM disappearance and
B 5potential degradability ; c5degradation rate h; L5lag
degradability characteristics of the maize stovers and
time h; ED 5effective degradability ; R.S.D.5residual stan-
dard deviation.
desmodium hay used in the growth and digestibility
A . Tolera, F. Sundstøl Livestock Production Science 68 2001 13 –23
17
dation rate than the stover harvested at stages I and P
,0.001 with DMI, DMD, DDMI and growth II. The potential degradability A
1 B was signifi- rate. The degradation rate was positively correlated
cantly lower P ,0.05 in the desmodium hay than in
whereas the insoluble, but potentially degradable, the maize stovers harvested at stages I and II. The
fraction was negatively correlated with DMI P ,
lag time was significantly higher P ,0.05 in de-
0.01 and with DMD, DDMI and growth rate P ,
smodium hay than in maize stover harvested at stage 0.001. DMD and growth rate were negatively
II and it also tended to be higher P .0.05 in maize
correlated P ,0.05 with the potential degradability
stover harvested at stage III than in the stover and positively correlated P
,0.05 with the lag harvested at stages I and II. The effective de-
phase. gradability ED was significantly higher P
,0.05 Table 6 shows equations predicting DMI of sheep
in the desmodium hay than in the maize stovers. from DM disappearance and DM degradability
characteristics of the diets. Using simple linear 3.2. Estimated DM degradability of the diets
regression, the A value was the best predictor of DM intake followed by DMD
, ED and DMD . The
24h 48h
Table 4 shows the estimated DM degradability of lag phase and the potential degradability were very
a basal diet of maize stover harvested at three stages poor predictors of feed intake. The DM disappear-
of maturity and supplemented with graded levels of ance after 72 h of incubation DMD
and the DM
72h
desmodium hay. When maize stover harvested at disappearance after 96 h of incubation DMD
96h
stage II was used as a basal diet, its estimated DM also had very low precision in predicting DMI. The
disappearance after 48 h of incubation DMD use of A and B or A and c in multiple regressions
48h
was significantly lower than that of diets based on improved the coefficient of determination by one
maize stover harvested at stages I and III. The percentage unit over the use of the A value alone.
washing loss of the diets showed a significant When A, B and c were used together in a multiple
decrease P ,0.05 with increasing stage of maturity
regression, they accounted for 91 of the variation of the stover. The potential degradability was sig-
in feed intake. However, addition of the lag phase nificantly lower whereas the degradation rate and the
could not improve the precision of prediction any lag time were significantly higher P
,0.05 in the further.
diets based on stage III maize stover than those Equations predicting DDMI of the sheep from DM
based on stovers harvested at stages I and II. disappearance and DM degradability characteristics
The DMD , washing loss, degradation rate and
of the diets are shown in Table 7. The soluble
48h
effective degradability showed a significant increase fraction A was the best single predictor, accounting
whereas the insoluble, but slowly degradable, frac- for 95 of the variation in DDMI. The DMD
,
24h
tion showed a significant decrease P ,0.05 with
ED, DMD , c and B accounted for 93, 90, 88, 79
48h
increasing level of supplementation. The lag time and 72 of the variation in DDMI, respectively. The
was lowest at 0 and highest P ,0.05 at 450 g of
lag phase, potential degradability and DMD were
96h
supplementation and generally showed an increasing poor predictors of DDMI P
.0.05. The use of A trend with increasing level of supplementation.
and B or A and c in multiple regressions improved the coefficient of determination by one percentage
3.3. Prediction of feed intake, digestibility and unit over the use of the A value alone. However, the
body-weight change of sheep use of A, B and c values together in a multiple
regression could not improve the prediction ability Table 5 shows the correlation of feed intake,
any further. On the other hand, the addition of the digestibility and body-weight change of sheep with
lag phase to A, B and c values in a multiple estimated in sacco DM degradability of the diet. The
regression decreased the precision of prediction to DM
disappearance after
24 h
of incubation
91. DMD
, DMD , washing loss and effective
Table 8 shows equations predicting DMD from
24h 48h
degradability showed strong positive correlations DM disappearance and DM degradability charac-
18 A
. Tolera, F. Sundstøl Livestock Production Science 68 2001 13 –23 Table 4
Estimated DM degradability of total diet based on maize stover harvested at three stages of maturity and supplemented with graded levels of Desmodium intortum hay
Parameters Supplement
Stage of maturity of stover level g head day
Stage I Stage II
Stage III Mean
6S.E.
d
DMD 51.1
49.3 51.7
50.7 0.7
48 h c
150 54.9
53.8 55.5
54.7 0.5
b
300 57.4
56.9 58
57.4 0.3
a
450 60.6
59.5 60.2
60.1 0.3
a b
a
Mean 56.0
54.9 56.3
6S.E. 2.0
2.2 1.8
d
A washing loss, 14.6
12.9 11.9
13.1 0.8
c
150 17.0
16.0 15.2
16.1 0.5
b
300 18.7
18.1 17.4
18.0 0.4
a
450 20.7
19.8 19.3
19.9 0.4
a b
c
Mean 17.7
16.7 16.0
6S.E. 1.3
1.5 1.6
a
B insoluble 63.8
67.0 59.9
63.6 2.1
b
but potentially 150
58.6 60.5
55.5 58.2
1.4
c
degradable, 300
55.1 56.1
52.6 54.6
1.0
d
450 50.7
52.4 50.1
51.0 0.7
b a
c
Mean 57.0
59.0 54.5
6S.E. 2.8
3.1 4.2
a
A 1B potential
78.4 79.9
71.8 76.7
2.5
ab
degradability, 150
75.6 76.5
70.7 74.3
1.9
bc
300 73.7
74.2 70.0
72.6 1.3
c
450 71.4
72.2 69.4
71.0 0.8
a a
b
Mean 74.8
75.7 70.5
6S.E. 1.5
1.7 1.0
d
c degradation 0.018
0.017 0.023
0.019 0.002
c
rate, h 150
0.026 0.027
0.031 0.028
0.001
b
300 0.032
0.033 0.035
0.034 0.001
a
450 0.04
0.038 0.04
0.039 0.001
b b
a
Mean 0.029
0.029 0.032
6S.E. 0.005
0.005 0.004
c
L lag time, h 1.1
0.7 1.8
1.2 0.2
bc
150 1.4
1.1 1.9
1.5 0.2
ab
300 1.6
1.4 2.0
1.7 0.2
a
450 1.9
1.7 2.1
1.9 0.1
b b
a
Mean 1.5
1.2 1.9
6S.E. 0.2
0.2 0.1
d
ED effective 38.1
37.3 37.7
37.7 0.2
c
degradability, 150
40.2 39.7
40.0 40.0
0.1
b
300 41.6
41.4 41.5
41.5 0.04
a
450 43.3
42.8 42.8
43.0 0.2
a a
a
Mean 40.8
40.3 40.5
6S.E. 1.1
1.2 1.1
a,b,c,d
Means with one or more similar superscripts within a row or within a column are not significantly different P .0.05.
teristics of the diets. Using simple linear regression, was also a poor predictor of DMD. The use of A and
DMD and ED were the best predictors of DMD,
B in multiple regressions improved the coefficient of
24h
followed by A, DMD , c and B values. The
determination by two percentage units over the use
48h
DMD , lag phase and potential degradability had
of the A value alone, to 95, whereas the use of A
96h
very low precision of predicting DMD. The DMD and c further increased the coefficient of determi-
72h
A . Tolera, F. Sundstøl Livestock Production Science 68 2001 13 –23
19 Table 5
multiple regressions further increased the coefficient
Pearson correlation coefficients of the relationship between esti-
of determination to 95, and the addition of L in the
mated in sacco DM degradability characteristics of the diet and
multiple regression further increased the coefficient
feed intake, digestibility and body-weight change in sheep
of determination to 96.
Dry matter Dry matter
Digestible Growth
intake digestibility
DM intake rate
DMD 0.89
0.97 0.97
0.98
24 h
4. Discussion
