Rumen environment and feed degradability in swamp buffaloes fed different supplements
Nguyen Van Thu and T R Preston*
College of Agriculture, Cantho University, Vietnam
nvthu@ctu.edu.vn
* University of Tropical Agriculture Foundation, Phnom Penh, Cambodia
trpreston@email.com
Abstract
Two
experiments of Latin square design were carried out to investigate the effect of different
supplements on the rumen environment and rumen degradability of local feeds in swamp
buffaloes fitted with rumen fistulas. In Experiment 1 the four diets were: untreated rice straw ad libitum
(R); 3.5 kg/day urea-treated rice straw plus untreated rice straw ad libitum (RUTS); untreated rice straw ad libitum and 450 g/day of a urea-molasses
cake (RUMC); untreated rice straw ad libitum and 2 kg/day of fresh leaves
of Sesbania grandiflora (RSES). In
Experiment 2, the diets were: rice straw ad
libitum supplemented with natural grass (0.25%
animal live weight, DM basis) (RG); rice straw
ad libitum supplemented with grass (0.25% animal live weight based on DM basis)
and 700 g/day urea-molasses cake (RGUMC); natural grass ad libitum (G); and natural grass ad libitum and 700 g/day urea-molasses cake
(GUMC). The adaptation period of the animals for each diet was ten days, then the
measurements were taken in the four consecutive days.
In experiment 1, rumen N-NH3 concentration, bacteria and protozoa
populations, and feed dry matter intake, were significantly higher on the combination of Sesbania
grandiflora leaves and untreated rice straw than for all other treatments.
In experiment 2, supplementation of a combination of rice straw and grass with the
urea-molasses cake led to increases in rumen ammonia, in protozoal and bacterial
populations and in feed intake. The buffaloes lost weight on the basal diet
and gained weight with the UMC supplementation (P=0.07). These effects were less
pronounced when the basal diet was only grass. There were no apparent effects on the rate
of rumen degradation of rice straw and water hyacinth when rice straw was
supplemented with grass or a urea-molasses cake.
Key words: Swamp buffaloes, urea-molasses cake, rice straw, grasses,
Sesbania grandiflora, rumen environment, rumen degradation.
Introduction
Swamp buffaloes have played a very important role in providing draught power and beef
for people in the Mekong delta of Vietnam. Farmers have benefited much from swamp buffalo
production, but there are few studies on how to improve their performance and the profit
for the farmers due to the lack of research resources. Traditional feeding systems, based
on extensive grazing and use of fibrous crop residues without supplementation, have
dominated management systems and been the cause of slow growth rates, poor working
performance and ill-health in the dry and working season.
Supplementing the buffaloes with a urea-molasses cake (UMC), which includes urea,
molasses, rice bran, coconut meal, salt and minerals, improved working capacity, growth
rate and milk yield (Nguyen Van Thu et al 1996). The soft cake was easy to make and to
transport. Foliage from forage trees, especially leguminous species, was proposed by
Preston and Murgueitio (1992) as an inexpensive way of providing supplementary protein to
complement the nutrients provided by the urea-molasses cake or even as a complete
replacement in situations where both molasses and urea were not easily obtained. Many tree
species grow in the Mekong delta and while these have been studied as supplements, and
even as complete feeds, for goats (Nguyen Thi Hong Nhan 1998) there has been no comparable
work with buffaloes.
The aim of this study was to obtain some preliminary regarding the possible role
of tree foliages as supplements for swamp buffaloes fed basal diets of rice straw.
Materials and methods
Two experiments with Latin square arrangement of four treatments and periods of 14 days
were carried with four swamp buffaloes fitted with rumen fistulas. These were 14 to 16
months of age with average liveweight of 184 ± 7.4 and 200 ± 17 kg, in Experiments 1 and
2, respectively. The diets were: (In Experiment 1) rice straw ad libitum (R);
rice straw ad libitum and 3.5 kg/day of urea-treated
rice straw (RUTS); rice straw ad libitum and 450g/day of a
urea-molasses cake (RUMC); rice straw ad libitum and 2 kg/day of fresh
leaves of Sesbania grandiflora (RSES); and in Experiment 2, rice straw ad
libitum and natural grass (0.25% animal liveweight based on DM basis) (RG);
rice straw ad libitum, natural grass (0.25% animal live weight based on DM basis)
and 700g/day urea-molasses cake (RGUMC); natural grass ad libitum (G) and
natural grass ad libitum and 700g/day of a urea-molasses cake (GUMC). The
UMC contained (%): "B" molasses 37.9, urea 7.6, coconut oil meal 7.5, rice bran
39.4, bone meal 3.8, salt 3.8, and trace minerals 0.15. Its chemical composition (%) based
on DM basis was DM 78.0, N*6.25 33.5, crude fibre 7.60, ether extract 9.0 and ash 11.5.
The experiments were carried out at the experimental farm of Cantho University of Vietnam
in 1997. The adaptation period of each animal for each diet was ten days. Measurements
were taken in the four consecutive days.
The effects of the diets on the rumen environment were studied by incubating standard
feed samples in the rumen of each animal according to the procedure of Ørskov
et al (1980). The standard feeds were: rice straw and leaves of water hyacinth (Eichornia
crassipes) collected in the acid-sulfate soil area of Hoa An village,
Cantho province. In both experiments, the rice straw fed to the buffaloes was
bought from villages around Cantho city where the soil is rich and not acid (pH >6.0).
By contrast, the feed samples for rumen incubation were collected from the Acid-Sulphate
Soil Research Station in Hoa An village (pH from 2.0 to 4.0), some 40 km from Cantho
city.
The standard feeds were dried and cut into 2-3mm length before placing them in nylon
bags (pore size 50 µ) which were then inserted in the rumen. The incubation times
were: 6, 12, 24, 48, 72 and 96 hours with triplicate samples for each time. Observed
values for losses of substrate were fitted to the model DMD= a + b (1- e-ct
) following Ørskov and Mc Donald (1979), where DMD is the
degradability after time "t", " a" is the intercept of the degradation
curve at time zero, " b" is the fraction which degrades with time at a rate
constant " c" and " a+b" represents potential degradability or the
fraction that will be degraded in the rumen given sufficient time. Samples of rumen
contents were collected at 6.00 am before the animal had access to the feeds. pH was
measured by a pH meter. N-NH3 was analyzed by the Micro-Kjeldahl method. The preparation
of rumen samples for counting of protozoa and bacteria was according to the procedure
outlined by . Protozoa were counted in a 0.2mm deep chamber under [x100]
magnification (Navas et al 1992). Bacteria were counted in a Neubauer chamber under
[x1200] magnification (Warner 1962a). Feeds and refusals were collected daily and
pooled weekly for analysis of DM. Feed samples for placing in the rumen were
analyzed for dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent
fibre (NDF), acid detergent fibre (ADF), acid detergent lignin (ADL) and ash following
procedures of AOAC (1990) and Goering and Van Soest (1970). The animals were weighed on
two consecutive days at the end of each period. to prepare for a rumen incubation.
The data were subjected to an analysis of variances (ANOVA) by using the general linear
model (GLM) of Minitab Reference Software (Release 11, 1996). When the "F" test
was significant, the least significant difference test was used to test differences
between means following the procedure of Mead et al (1996).
Results and discussion
The rice straw produced from the acid soil area had a higher lignin content but less
ash than that produced from the normal soil (Table 1). Reduced availability of calcium and
phosphorus in acid soils have been reported by Ellis and Mellor (1995) which could
explain the low ash content of the rice straw (8.1%) grown on the acid-sulphate
soil. The cell wall fractions differed markedly between the Sesbania leaves compared
with the straw and natural grass. Concentrations of NDF, ADF, cellulose and hemi-cellulose
in Sesbania leaves were less than half those in the straw and the grass. By contrast
the lignin in Sesbania leaves was high (7.3%) and in the same range as for the straw and
the grass. A similar value for lignin (8.1%) in Sesbania leaves was reported by Norton
(1994) who also observed low values for NDF (24.4 to 37.1%). The composition of the
water hyacinth was similar to that of the grass.
| Table 1. Chemical composition (%) of feeds given to
the buffaloes and incubated in the rumen (dry matter basis). |
![]() |
|
OM |
CP |
NDF |
ADF |
Lignin |
Cellulose |
Hemi-
cellulose |
Ash |
![]() |
| Feeds offered |
|
|
|
|
|
|
|
|
| Rice straw |
85.4 |
3.94 |
79.0 |
46.9 |
6.55 |
40.4 |
32.1 |
14.6 |
| Urea-treated straw |
88.1 |
12.2 |
79.0 |
48.9 |
7.52 |
39.5 |
30.1 |
11.9 |
| Natural grass |
89.8 |
9.7 |
69.9 |
38.0 |
5.54 |
32.5 |
31.9 |
10.2 |
| Sesbania |
92.1 |
33.8 |
35.4 |
18.7 |
7.31 |
11.0 |
16.7 |
7.93 |
| Feeds incubated |
|
|
|
|
|
|
|
|
| Eichornia crassipes |
85.7 |
11.4 |
67.3 |
34.1 |
4.79 |
29.3 |
33.2 |
14.2 |
| Rice straw |
91.9 |
6.14 |
77.5 |
47.3 |
7.21 |
40.1 |
30.2 |
8.10 |
![]() |
In experiment 1, rumen N-NH3 concentration, bacteria and protozoa populations, and feed
dry matter intake were significantly higher on the combination of Sesbania grandiflora
leaves and untreated rice straw than for all other treatments (Table 2). Sesbania
grandiflora foliage was shown to have a high nutritive value when given as the
sole feed to growing goats (Nguyen Thi Hong Nhan 1998). Bonsi et al (1995) also
reported that it supported higher feed intake of a tef straw diet than did Leucaena
leucocephala.
| Table 2. Rumen pH, ammonia-N and protozoal and bacterial
populations in the rumen fluid of swamp buffaloes fed rice straw alone (R), "R"
plus urea-treated rice straw (RUTS), "R" supplemented with a urea-molasses cake
(RUMC) or "R" supplemented with leaves of Sesbania grandiflora (RSES)
(Experiment 1) |
![]() |
|
R |
RUTS |
RUMC |
RSES |
± SE / P |
![]() |
| pH |
7.32a |
7.13b |
7.01c |
7.17b |
± 0.06/0.004 |
| N- NH3 (mg/100ml) |
5.83a |
8.16b |
8.29c |
9.72d |
± 0.61/0.001 |
| Bacteria (108/ml) |
10.5a |
12.3a |
14.1c |
15.2d |
± 0.46/0.001 |
| Protozoa (105/ml) |
3.13a |
3.36b |
3.51c |
3.70d |
± 0.09/0.001 |
Feed intake
(g DM/kg W0.75/day) |
68.5a |
71.9b |
76.6c |
80.1d |
± 1.77/0.001 |
![]() |
| Means with different letters within the same rows are significantly
different at 5% level |
In experiment 2 (Table 3), supplementation of a combination of rice straw and
grass with the urea-molasses cake led to increases in rumen ammonia, in protozoal and
bacterial populations and in feed intake. The buffaloes lost weight on the basal
diet and gained weight with the UMC supplementation (P=0.07). These effects
were less pronounced when the basal diet was only grass. The improvement in rumen
parameters (Tables 2 and 3) and in liveweight change (Table 4) from supplementing
the rice straw with a urea-molasses cake are in line with reports from many workers
concerning the efficacy of this technology (see review by Chenost and Kayouli
1997).
| Table 3. Mean values for pH,
N-NH3, protozoal and bacterial populations in rumen fluid from swamp buffaloes fed rice
straw and grass (RG), rice straw, grass and urea-molasses cake (RGUMC), grass (G)
and grass and urea-molasses cake (GUMC) (Experiment 2) |
![]() |
|
RG |
RGUMC |
G |
GUMC |
± SE / P |
![]() |
| pH |
7.16a |
7.04b |
7.06b |
7.19a |
± 0.033/0.009 |
| N- NH3 (mg/100ml) |
6.35 a |
9.59b |
12.9c |
18.0d |
± 0.72/0.001 |
| Bacteria (108/ml) |
11.8a |
14.4b |
17.7c |
18.6c |
± 0.40/0.001 |
| Protozoa (x105/ml) |
3.56a |
4.02b |
4.09b |
4.45c |
± 0.03/0.003 |
Feed intake
(gDM/kgW0.75/day) |
66.1a |
78.2cd |
74.0bc |
72.5bc |
± 2.01/0.002 |
| Live weight change (kg) |
-8.37 |
8.75 |
3.75 |
7.31 |
± 5.25/0.073 |
![]() |
| Means with different letters within the same rows are significantly
different at 5% level |
There were no apparent effects on the rate of rumen degradation of rice straw and
water hyacinth when rice straw was supplemented with grass or a urea-molasses cake (Tables
4 and 5). This is contrary to many reports in the literature of positive effects on rumen
degradability of fibrous substrates from addition of these supplements to fibrous crop
residues (eg: addition of African Star grass to a sisal pulp diet fed to sheep [Gutierrez
and Elliott 1984], and of
molasses-urea blocks as supplement to rice straw [Wanapat et al 1991; Bui Xuan An et al
1992a,b]).
| Table 5. Relative DM degradability (%) of Eichornia
crassipes in rumen of swamp buffaloes fed with different diets in experiment 2.
(RG: rice straw and grass; RGUMC: rice straw, grass and urea-molasses cake; G:
Grass; GUMC: grass and urea-molasses cake) |
![]() |
|
RG |
RGUMC |
G |
GUMC |
± SE / P |
![]() |
Dry matter loss, % |
0 h (washing loss) |
18.1±0.26 |
|
| 6 h |
23.7 |
23.9 |
24.9 |
25.8 |
± 1.29/0.443 |
| 12 h |
26.5 |
28.6 |
32.3 |
32.1 |
± 1.07/0.004 |
| 24 h |
33.0 |
34.8 |
38.6 |
37.8 |
±3.08/0.323 |
| 48 h |
47.9 |
49.2 |
54.3 |
54.8 |
±3.86/0.275 |
| 72 h |
54.6 |
54.7 |
58.7 |
62.5 |
±3.43/0.166 |
| 96 h |
60.6 |
62.8 |
65.9 |
66.5 |
±2.24/0.120 |
| Constants from the model: DMD= a + b (1- e-ct ) |
| a+b |
76.4 |
75.7 |
71.6 |
75.3 |
|
| "c" |
0.014 |
0.015 |
0.021 |
0.020 |
|
| R2 |
0.99 |
0.99 |
0.99 |
0.99 |
|
![]() |
Conclusions
Supplements of urea-molasses cake and leaves of Sesbania grandiflora to
a basal diet of rice straw brought about improvements in the rumen environment and
the feed intake of swamp buffaloes. However, under the conditions of this study there
appeared to be no improvement in feed dry matter degradability by supplementation of the
rice straw with either grass or the urea-molasses cake.
Acknowledgements
This work was partly supported by a grant (No: B/2296-1) to the senior
author from the International Foundation for Science. The authors are indebted
to the Department of Animal Husbandry and Veterinary Medicine of the Faculty
of Agriculture, Cantho University for access to the facilities for carrying out the
experiments.
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