Effect of two different inoculants and roughage sources on ruminal volatile fatty acids and in vitro gas production
M Wanapat, O
Poungchompu, S Wora-anu and C
Wachirapakorn
Department of Animal Science,
Faculty of Agriculture,
Khon Kaen University, Khon Kaen,
40002,Thailand,
metha@kku.ac.th
Abstract
Four fistulated beef cattle were fed rice straw (RS) or urea-treated rice straw (UTRS) as sources of inoculum for the in vitro gas production technique. Four substrates were compared: cassava hay (CH) or lucern hay (LH), rice straw (RS) or urea-treated rice straw (UTRS). In addition supplementation of the media with 2-bromoethane sulfonate (BES) was also studied. The incubations were carried out according to a 2x4x2 factorial arrangement of the treatments.
Gas production was higher when the rumen fluid was from animals fed urea-treated rice straw compared with untreated straw, was lowest when the substrate was untreated rice straw and highest when it was lucern hay or cassava hay. Addition of the compound - 2-bromoethane sulfonate (BES) - reduced gas production and methane concentration but increased the total VFA.
Key words: Gas production, in vitro, VFA,
methane, 2-bromoethane sulfonate
Introduction
The rate and extent of DM fermentation in the rumen are very
important determinants for the
It was the objective of this study to use the gas production technique to evaluate inoculants (rumen fluid) from cattle fed untreated or urea-treated rice straw, different roughage substrates and the effect of the compound 2-bromoethane sulfonate (BES).
Materials and Methods
The method used was the in vitro fermentation technique described by Menke et al (1979). Rate and extent of gas production was determined for each substrate by measuring gas volumes at 0, 4, 8, 12, 24 and 48 hr and fitting the data to the equation Y = b(1-e-ct) (Ørskov and McDonald 1979). Volatile fatty acids (VFA) were determined using High Performance Liquid Chromatography (HPLC; Model Water 600; UV detector, Millipore Crop.) according to the method of Samuel et al (1997). Methane (CH4) was analysed by Gas Chromatography (GC). Data were subjected to analysis of variance using Proc. GLM (SAS 1999). Differences among means were compared as well as interactions, using single and multiple degree of freedom contrasts.
Results and Discussion
There were no important interactions and results are therefore presented for the main effects (Table 1). Gas production was lowest when the substrate was untreated rice straw and highest for lucern hay and cassava hay which did not differ from each other (Figure 1). As was to be expected, gas production was higher when the rumen fluid was from animals fed urea-treated rice straw compared with untreated straw. Addition of the compound - 2-bromoethane sulfonate (BES) - reduced gas production (Figure 1) and methane concentration but increased the total VFA.
|
Table 1. Effects of source of substrate (roughage), of rumen fluid (diet of donor animal), and of addition of 2 –bromo-ethane-sulfonate, on gas production (ml/g DM), concentration of total VFA (mM), C2, C3, C4 (mol/100mol) and CH4 (mM) |
||||||
|
|
Gas prod. |
TVFA |
C2 |
C3 |
C4 |
CH4 |
|
2 –bromo-ethane-sulfonate |
||||||
|
WO |
82.7a |
114a |
88 |
24.0a |
7.2 |
6.1a |
|
W |
46.6b |
131b |
86.6 |
18.7b |
11.8 |
2.6b |
|
Diet of donor animal |
||||||
|
RS |
33.8a |
4.6 |
88.9 |
22.4a |
6.4 |
4.8 |
|
UTS |
95.5b |
111a |
85.7 |
20.2b |
12.6 |
3.8 |
|
SEM |
5.32 |
133b |
2.59 |
0.52 |
2.29 |
0.53 |
|
Substrate |
||||||
|
LH |
84.8a |
112a |
85.2 |
22.2a |
8.5 |
4.3 |
|
CH |
73.4a |
140b |
87.3 |
21.1a |
12 |
5.5 |
|
UTS |
57.2ab |
126ab |
86 |
25.0b |
9.3 |
3.7 |
|
RS |
43.2b |
111a |
90.8 |
17.2c |
8.1 |
3.8 |
|
SEM |
7.52 |
6.5 |
3.69 |
0.74 |
3.25 |
0.74 |
|
LH =
lucerne hay; CH=cassava hay; UTS=urea-treated rice straw; RS=rice straw; |
||||||
Figure 1:
Effects of source
of substrate (LH
= lucerne hay; CH=cassava hay;
UTS=urea-treated rice straw; RS=rice straw),
of rumen fluid (diet of donor animal),
and of addition of 2 –bromo-ethane-sulfonate (BES), on gas production
References
Menke H H and Steingass H 1988
Estimation of the energetic
feed value obtained from chemical analysis and in vitro gas
production using rumen fluid. Anim. Res. Dev., 28,
7-55.