T . Yan et al. Livestock Production Science 64 2000 253 –263
257
Research Council 1990. The statistical programme ing from 0.639 to 0.847 had no significant relation-
used was
GENSTAT
5 Genstat 5 Committee, 1993. ship with either CH -E GEI or CH -E DEI when
4 4
using Eq. IIa. However, when using Eqs. IIb–c feeding level and dietary factors were each sig-
3. Results nificantly P ,0.001 related to CH -E GEI or CH -
4 4
E DEI Table 3. The relationship between CH -E
4
3.1. Difference between dairy and beef cattle GEI or CH -E DEI and feeding level was negative,
4
while the relationship between CH -E GEI or CH -
4 4
The data on diet type and CH -E for dairy and E DEI and each of the dietary factors was positive.
4
beef are presented separately in Table 2. There were An increase in feed intake of one level above
no significant differences between dairy and beef maintenance would result in a reduction of pro-
cattle in terms of S T
0.548 vs. 0.532, S.E. portionately 0.0078 or 0.0123 in CH -E GEI or
DMI DMI
4
0.0210, T T
0.248 vs. 0.249, S.E. 0.0055 CH -E DEI. However, increasing 0.10 of S
ADFI DMI
4 DMI
and S T
0.784 vs. 0.778, S.E. 0.0130. T
, T T
or S T
would result in an
ADFI ADFI
DMI ADFI
DMI ADFI
ADFI
Animal type dairy vs. beef also had no significant increase of proportionately 0.0025, 0.0069 or 0.0048
effect on CH -E GEI 0.068 vs. 0.069, S.E. 0.0020 in CH -E GEI; or 0.0035, 0.0107 or 0.0067 in CH -
4 4
4
or CH -E DEI 0.089 vs. 0.090, S.E. 0.0017. These E DEI.
4
two sets of data were then pooled together for all subsequent analysis. Four beef cattle had a relatively
3.3. Methane energy output as a proportion of low CH -E DEI 0.040–0.045, which were offered
energy intake with feeding level and dietary
4
diets with low silage proportions 0.169–0.222 and factors
had relatively high feeding levels 1.75–2.37. Simi- larly, the minimum range in CH -E DEI for dairy
The regression equations for these relationships
4
cows was derived from those animals which were are presented in Table 3. When using Eq. I, the
given low silage 0.405–0.440 diets and had rela- relationship between CH -E and GEI or DEI was
4 2
tively high feeding levels 3.25–3.46. significant P ,0.001 and the R value was high
0.846 or 0.841. The coefficient was 0.0547 or 3.2. Effect of digestibility, feeding level and
0.0714 and the constant 3.23 or 3.32. The relation- dietary factors
ship between CH -E and GEI or DEI was improved
4
when feeding level above maintenance FL-1 was
2
In the present study apparent energy digestibility added using Eq. IIIa. The R
values for the measured with cattle offered diets ad libitum rang-
relationships of CH -E with energy intake GEI and
4
Table 2 Variation between lactating dairy cows and beef steers
Cattle Mean
S.D. Minimum
Maximum Methane energy GE intake
Dairy 0.068
0.0112 0.037
0.101 Beef
0.069 0.0176
0.029 0.101
Methane energy DE intake Dairy
0.089 0.0148
0.051 0.130
Beef 0.090
0.0244 0.040
0.139 Silage DM total DM intake
Dairy 0.548
0.2120 0.181
1.000 Beef
0.532 0.2940
0.169 1.000
Total ADF total DM intake Dairy
0.248 0.0536
0.131 0.372
Beef 0.249
0.0829 0.144
0.375 Silage ADF Total ADF
Dairy 0.784
0.1420 0.412
1.000 Beef
0.778 0.1886
0.409 1.000
258 T
. Yan et al. Livestock Production Science 64 2000 253 –263 Table 3
Relationships between methane energy output and energy intake, feeding level or dietary factors all relationships are significant P ,0.001
a
and the data in brackets in each equation are S.E. values
2
Equations RSD
R No.
CH -E5 0.0547 0.0018 GEI13.2340 0.5230
3.016 0.846
1
4
0.0714 0.0024 DEI13.3180 0.5240 3.032
0.841 2
CH -E GEI5 20.0078 0.0005 [FL-1]10.0877 0.0016
0.008 0.608
3
4
0.0252 0.0028 S T
10.0553 0.0017 0.012
0.431 4
DMI DMI
0.0694 0.0112 T T
10.0522 0.0029 0.012
0.463 5
ADFI DMI
0.0476 0.0039 S T
10.0315 0.0031 0.011
0.463 6
ADFI ADFI
CH -E DEI5 20.0123 0.0006 [FL-1]10.1203 0.0021
0.011 0.640
7
4
0.0346 0.0038 S T
10.0719 0.0023 0.016
0.402 8
DMI DMI
0.1074 0.0149 T T
10.0646 0.0038 0.016
0.448 9
ADFI DMI
0.0665 0.0053 S T
10.0382 0.0042 0.015
0.445 10
ADFI ADFI
a
RSD, residual standard deviation; CH -E, methane energy output MJ day; GEI, gross energy intake MJ day; DEI, digestible energy
4
intake MJ day; FL, feeding levels Agricultural and Food Research Council, 1990; S , silage dry matter intake kg day; T
, total
DMI DMI
dry matter intake kg day; S , silage acid detergent fibre intake kg day; T
, total acid detergent fibre intake kg day.
ADFI ADFI
DEI and feeding level FL-1 were, respectively
CH -E 5
4
0.874 and 0.881. Feeding level had a significant
DEI [0.096 0.005 1 0.035 0.005 S T
] 2 2.298 0.161 FL-1 0.89 2.18
DMI DMI
effect P ,0.001 on CH -E in each of these two
4
12 equations. A similar procedure was also applied to
dietary factors S T
, T T
and S where RSD is the residual standard deviation, the
DMI DMI
ADFI DMI
ADFI
T for the relationship of CH -E with GEI or
unit for CH -E and DEI is MJ day and the data in
ADFI 4
4
DEI using Eq. IIIb. This approach also improved brackets are S.E. values. Eqs. 11 and 12 each had
the relationship between CH -E and GEI or DEI. a small constant 20.49 S.E. 0.81 and 20.63 S.E.
4 2
The R values for these relationships ranged from
0.85 MJ day, respectively. Because the constants 0.851 to 0.864. These three dietary factors each had
had no significant effects on the predicted CH -E
4
a significant effect on CH -E P ,0.001. MJ day, they were adjusted to be zero. The S.E.
4
The relationship of CH -E was finally examined value for the coefficient of each component in both
4
using various combinations of energy intake GE or equations was relatively small, indicating that each
DE, feeding level above maintenance FL-1 and component had a significant effect on CH -E P ,
4
dietary factor S T
, T T
or S
DMI DMI
ADFI DMI
ADFI
0.001. These two equations indicate that methane T
. A total of six combinations were examined
ADFI
production of cattle is proportional to DE intake and using Eq. IV. The relationship between CH -E and
4
is increased with increasing silage proportion in the GEI or DEI was further improved by addition of
diet, while CH -E DEI would reduce with increas-
4 2
both [FL-1] and a dietary factor. The R values were ing feeding level. If the ADF concentrations in
all increased 0.879–0.888. The [FL-1] and dietary silages and concentrates are available, Eq. 11
factors each had a significant effect P ,0.001 on should be used as this equation gave a more accurate
2
CH -E in each of these 6 equations. Based on the R
4
prediction than Eq. 12 when testing these equations value of the relationship and the accuracy of predic-
using published data obtained with grass silage-based tion when testing all equations using published data
diets discussed later. discussed later, the following two equations are
recommended 3.4. Effect of live weight
CH -E 5
4 2
R RSD
The effects of live weights of animals were also
DEI [0.094 0.005 1 0.028 0.005 S T
] 2 2.453 0.159 FL-1 0.89 2.13
ADFI ADFI
examined. CH -E MJ day and daily intakes of GE
4
11 and DE MJ day were scaled to a metabolic live
T . Yan et al. Livestock Production Science 64 2000 253 –263
259
0.75
weight basis kg . All the above mentioned
also been some studies which showed no reduction methods, where appropriate, were examined. There
in methane production with increment of dietary were no improvements in the levels of significance
forage levels, e.g. Beever et al. 1988 in beef cattle
2
or the R values of the equations. Therefore the
offered grass silage diets. effects of live weight of the cattle were not presented
In the present study, CH -E GEI and CH -E DEI
4 4
in the current paper. Holter and Young 1992 also were both related to S
T , T
T or
DMI DMI
ADFI DMI
reported no significant effect of live weight of S
T . These relationships were all highly
ADFI ADFI
2
lactating or dry dairy cows on CH -E in any of their significant with the R values ranging from 0.402 to
4
six experiments. 0.463. This analysis indicated that an increase of
0.10 in S T
, T T
or S T
DMI DMI
ADFI DMI
ADFI ADFI
would increase
CH -E GEI by
proportionately
4
0.0025, 0.0069 or 0.0048; or CH -E DEI by 0.0035,
4
4. Discussion
