YULISTIANI et al.: Intake and digestibility of untreated and urea treated rice straw base diet fed to sheep

Intake and Digestibility of Untreated and Urea Treated Rice Straw Base Diet
Fed to Sheep
D. YULISTIANI1, J.R. GALLAGHER2 and R.J. VAN BARNEVELD3
1

Research Institute for Animal Production, PO BOX 221, Bogor 16002
2
Department of Animal Science, The University of Adelaide
3
Pig and Poultry Production Institute, South Australia
(Diterima dewan redaksi 29 Januari 2003)

ABSTRAK
YULISTIANI D, J.R. GALLAGHER and R.J. VAN BARNEVELD. 2003. Konsumsi dan kecernaan jerami padi tanpa perlakuan dan
diberi perlakuan urea untuk pakan basal domba. JITV 8(1): 8-16.
Jerami padi merupakan salah satu limbah pertanian yang mempunyai kualitas rendah yang disebabkan karena rendahnya
kandungan nutrisi esensial seperti protein, energi, mineral dan vitamin dan juga rendahnya kecernaan dan palatabilitasnya. Oleh
karena itu kualitas jerami padi perlu ditingkatkan sehingga pemanfaatannya dalam saluran pencernaan ternak ruminansia bisa
ditingkatkan. Tujuan dari penelitian ini adalah untuk membandingkan pakan basal jerami padi dan jerami padi yang diberi
perlakuan dengan urea untuk pakan domba. Dua belas domba Merino jantan dewasa (rataan bobot hidup 53,62 + 3,44 kg)
dikelompokkan menjadi 4 kelompok berdasarkan bobot hidup, dan dari setiap kelompok diacak untuk mendapatkan salah satu
dari tiga pakan perlakuan. Pakan perlakuan terdiri dari 3 macam yaitu: Pakan 1, terdiri dari jerami padi tanpa perlakuan; Pakan 2,
jerami padi dengan perlakuan urea; dan Pakan 3, jerami padi disemprot dengan larutan urea sesaat sebelum diberikan pada
domba. Rancangan percobaan yang dipakai adalah rancangan acak kelompok. Jerami padi yang diberi perlakuan urea
dipersiapkan dengan menyiram jerami padi yang sudah dipotong-potong disemprot dengan larutan urea sehingga didapatkan
kandungan urea 4% dan kadar air 40%. Selanjutnya campuran ini dimasukkan dalam plastik diikat dan disimpan selama 6
minggu. Jerami padi yang diberi perlakuan maupun yang tidak diberi perlakuan dicampur dengan bahan pakan lain untuk
mendapatkan ransum isoenergi dan isoprotein. Ransum disusun berdasarkan kebutuhan untuk mencukupi kebutuhan pokok
hidup dengan acuan dari NRC. Domba diadaptasikan dengan pakan perlakuan selama 15 hari, pengamatan kecernaan dilakukan
pada akhir periode adaptasi. Hasil penelitian menunjukkan konsumsi bahan kering permetabolis berat badan (DMI/W0,75),
konsumsi energi tercerna (DE) dan kecernaan dinding sel tidak berbeda nyata antara perlakuan 1 dan 2. Sedangkan kecernaan
bahan kering, bahan organik, serat deterjen asam (ADF), serta retensi nitrogen tidak berbeda nyata antar perlakuan. Hanya pakan
perlakuan 2 yang menghasilkan retensi nitrogen positif, sedangkan perlakuan lain negatif. Dari hasil penelitian ini dapat
disimpulkan bahwa pakan jerami padi yang disuplementasi dengan hijauan legum dapat dipergunakan sebagai alternatif pakan
jerami padi yang diberi perlakuan urea.
Kata kunci: Jerami padi, perlakuan urea, kecernaan, dan domba
ABSTRACT
YULISTIANI D, J.R. GALLAGHER and R.J. VAN BARNEVELD. 2003. Intake and digestibility of untreated and urea treated rice straw
base diet fed to sheep. JITV 8(1): 8-16.
Rice straw as one of agricultural by-products has low quality due to low content of essensial nutrients like protein, energy,
minerals and vitamin as well as poor palatability and digestibility. Therefore, the quality of rice straw needs to be improved in
order to increase its utilization by gastrointestinal tract of ruminants. The purpose of this study is to compare untreated and urea
treated rice straw as basal diets for sheep. Twelve mature Merino wethers (average body weight 53.62 + 3.44 kg) were separated
into 4 groups based on their live weight with each groups assigned three diets, that are: diet 1 untreated rice straw with high
forage legume content, diet 2 urea ensiled rice straw and diet 3 rice straw sprayed with urea solution at feeding time. Diets were
allocated based on a randomized complete block design. Urea ensiled rice straw was prepared by spraying chopped straw with
urea solution to yield straw containing 4% urea and 40% moisture, then kept in air tight polythylene bags for 6 weeks. The
untreated, ensiled and urea supplemented rice straw were mixed with other feed ingredients to provide isoenergetic and
isonitrogenous diets. Diets were formulated to meet maintenance requirement according to NRC. Sheep were adapted to
experimental diets for 15 days, and after adaptation period, a metabolism trial was conducted. Results reveal that dry matter
intake permetabolic body weight (DMI/W0.75), DE (digestible energi) intake and apparent digestibility of NDF (neutral detergent
fibre) were not significantly different between diet 1 and diet 2. Apparent digestibility of DM (dry matter), OM (organic matter),
and ADF (acid detergent fibre), as well as N retention were not significantly different between three diets. Positive result in N
retention was only observed in diet 2, while others were negative. It may be concluded from this study that untreated rice straw
basal diet supplemented with forage legume offer an alternative method other than urea ensiled for improving the nutritional
value of rice straw as a ruminant feed on small farmer.
Key words: Rice straw, urea treated, digestibility, and sheep

8

JITV Vol. 8. No. 1. Th. 2003

INTRODUCTION
Rice straw is commonly used as a ruminants feed in
tropical countries. This residues is available on most
rice base farms in Indonesia and is an important source
of fodder especially in the dry season. Rice straw is
characterised by low protein content, mineral, and
energy levels. The lower energy content of rice straw
has been reported by RISTIANTO et al. (1998), they
observed the average total digestible nutrient of rice
straw were 39.13%, consequently rice straw have a poor
nutritive value for ruminants (DOYLE et al., 1986). This
low nutritive value can be improved by pre-treatment or
supplementation with high quality feed.
Urea treatment is one of the various chemical
treatment which has been found beneficial as it
increased the nutritive value of rice straw by increasing
the protein content and nutrient digestibility and
palatability of rice straw, this in turn, may increase dry
matter intake (WONGSRIKEAO and WANAPAT, 1985).
However, the application of urea treatment by farmers
in the village level may be limited due to the fact that it
is labour intensive and time consuming and causes
management problems (CHEVA and JAERACHI, 1987).
WALLI et al. (1995) reported the feed back collected
from farmers after field demonstartion and on-farm
trials have been conducted with treatment technology
the response has been positive, however the results not
always sufficent for most farmer, despite the beneficial
effect they observed, they also observed the constrains
and the most cases the returns from this technology are
marginal.
Rice straw sprayed with urea at feeding time might
be an alternative means of treatment as it eliminates the
long process associated with ensiling (CHEVA and
JEERACHAI, 1987). In practice, supplementation with
NPN (non protein nitrogen) can stimulate animal
performance. However, care must be taken to avoid
excessive intake of urea, as urea can be toxic when
small amounts are consumed rapidly. At present, non
protein supplements are not widely used by farmers in
Asia because of the uncertainty surrounding the
provision of urea (DOYLE et al., 1986). Since urea need
to be fed slowly, several ways was explored to ensure
an even intake of urea, one technical solution is the
addition of urea in urea mollases mineral block
(SHARMA et al., 1995). Supplementation of urea
mollasses block in the rice straw basal diet increased
feed intake (PURNOMOADI and RIANTO, 2002). ASTUTIK
et al. (2002) reported that urea mollases mineral block
together with rice bran and cassava supplemented to
rice straw basal diet resulted in incrased body weight
gain of ongole crossbred cattle at 740 g head-1 day-1.
Feeding only rice straw generally does not provide
suficient nutrient to maintain body weight of ruminant
animals. Supplementation to rice straw basal diet can be

done with either concentrates, roughage or both. Forage
legumes supplementation have been found to be
effective in improving the utilization of crop residues
(RICHARD et al., 1994). Forage legume supplementation
is more applicable, and legumes already are commonly
fed to animals on small farms. This is because legumes
are available near farms, are relatively cheap compared
to concentrates, and, are easier to use compared to urea
treatment. Forage legumes may provide useful
supplements to cover the nutrient deficiencies of rice
straws (VAN SOEST, 1988). NDEMANISHO et al. (1998)
reported that dry Leucana leucocephala leaves can
substitute up to two third of cotton seed cake as a
protein source in to maize straw basal diet for weaner
goat, this susbtittution did not reduce goat performance,
this indicated that dry Leucana leucocephala leaves
might reduce usage of expensive oil cakes as protein
source.While sesbania supplementation to wheat straw
diet for sheep at the level 20% resulted in better
utilization of the diet by increasing nutriens digestibility
(KHANDAKER et al., 1998).
An increase in protein content of the diet without
balancing with energy could result in inefficient protein
utilisation by animals (CLOETE et al., 1983). Therefore,
in the current experiment isoenergetic and
isonitrogenous diets were formulated using untreated
rice straw with high legume content, urea ensiled rice
straw, and urea supplemented rice straw. Using these
diets the objectives of this experiment were to compare
these three diets in term of energy intake and apparent
digestibility of nutrients, and nitrogen utilisation.
MATERIALS AND METHODS
Feeds preparations and treatments
Rice straw was chopped into 5 cm lengths prior to
being subjected to various treatments. These included
Diet 1, untreated rice straw
Diet 2, urea ensiled rice straw
Diet 3, untreated rice straw supplemented with urea
Urea ensiled rice straw was prepared by spraying
chopped straw with urea solution to yield treated straw
containing 600g DM per kg straw and 40g urea/kg
straw DM (WILLIAM et al., 1984). The treated straw
was then kept in air tight polyethylene bags for 6 weeks
at ambient temperature (6-20°C). After 6 weeks the bags
were opened and the treated straw was aerated on the
floor for 24 hours prior to feeding (to reduce the smell
of ammonia). The urea supplemented treatment was
prepared by spraying 1 kg untreated rice straw with 200
ml urea solution 20% at feeding time.
The untreated, ensiled, and urea supplemented
straws were mixed with other feed ingredients to
provide isoenergetic and isonitrogenous diets. The
rations were formulated using a ''Take Away" computer

9

YULISTIANI et al.: Intake and digestibility of untreated and urea treated rice straw base diet fed to sheep

program (BARBER, 1992). The diets were formulated to
provide a maintenance ration for mature South
Australian Merino wethers of 50 kg body weight. The
metabolisable energy (ME) of untreated and ensiled rice
straw was estimated using the following equation from
MAFF (1984):
ME = 0.81 (GE x OMD)
where:
GE = gross energy (MJ/kgDM), and
OMD = in vitro organic matter digestibility
ME for other feed ingredients used in the diets was
obtained from the "Take-Away" data base. The feed
composition and the chemical composition of the diets
is given in Table 1.
The untreated basal diet contained the highest
proportion of legume compared to other diets in order
to adjust the nitrogen and energy content and make it
similar to the other diets. Urea was added in the urea
supplemented diet to adjust nitrogen levels.
The nutrient composition, especially ME and N

content of the experimental diets, (presented in table 1)
were relatively similar.
Animals and management
Twelve mature Merino wethers (53.62 + 3.44 kg)
were separated into 4 groups based on their live weight
with each group assigned to three diets (untreated; urea
ensiled or urea supplemented diets). Diets were
allocated based on a randomised complete block design.
Before the experimental period, the wethers were
drenched with a Valbezen-broad spectrum. During an
adaptation period of 15 days, the sheep were placed in
individual pens and gradually introduced to their
experimental diets. Sheep were offered 1023 g DM
daily of their allocated diets at 08.30 and 17.00 each
day. At the conclusion of the adaptation period, the
sheep were transferred to metabolism crates, designed
to separately collect urine and faeces. Total faecal and
urine output were collected for a seven day period.
Water was available at all times.

Table 1. Ingredient and chemical composition of the experimental diets (% dry matter basis)
Fractions

Diets
1

2

3

Ingredients:
Untreated rice straw

48.96

-

48.48

Ensiled rice straw

-

54.61

-

Lucerne hay

31.61

10.63

18.04

Oaten hay

-

25.31

20.04

Wheat bran

15.10

5.08

10.13

Molasses

2.39

2.41

2.40

Urea

-

-

0.48

Rockphos

1.79

1.81

0.30

Salt

0.15

0.17

0.15

OM

85.01

86.41

86.59

N

1.52

1.51

1.48

NDF

61.88

65.86

63.71

ADF

43.13

45.51

43.38

HC

18.75

20.35

20.33

Cellulose

30.94

33.20

31.32

ME (MJ/kg)

7.04

7.00

7.05

Chemical composition:

The composition was not 100% is due to the addition of rockphos to adjust the balance of the ratio of calcium to phospor
OM: organic matter; N: nitrogen; NDF: neutral detergent fibre; ADF: acid detergent fibre; HC: hemicellulose
ME: metabolisable energy

10

JITV Vol. 8. No. 1. Th. 2003

Chemical analysis and measurements

Sample collection
Feed
Feed ingredients were collected and analysed
separately. Urea ensiled rice straw was sampled every
day, after the ensiled straw has been aerated for 24
hours. Sub-samples were analysed for NDF, ADF,
lignin and N. For the first three analyses, the subsamples were dried in an forced-air oven at 600C for 48
hours before grinding to pass through a 1 mm sieve.
Sub-samples were freeze-dried before grinding and
sieving, prior to N analyses.
Refusals
Feed refusal samples for analysis were collected
daily during the collection period, prior to the morning
feed. The residues were sub-sampled and dried in an
air-forced oven at 600C for 48 hours before being
ground through a 1mm sieve. The samples were then
kept in air tight plastic containers until required for
chemical analysis.
Faeces
Ten percent of the total faeces from each animal
were sampled daily and retained. At the end of the
collection period, faecal samples from each animal were
bulked and composited. Samples were then dried in an
air-forced oven at 600C for 48 hours, before grinding to
pass through a 1mm sieve. These samples were stored
in plastic containers for NDF, ADF, and lignin analysis.
Fresh faeces were dried in a freeze drier, then ground
through a 1mm sieve and stored in air tight containers
prior to nitrogen analysis.
Urine
Urine was collected in plastic containers containing
50 ml of glacial acetic acid (MC MENIMAN et al., 1988)
to prevent nitrogen loss during collection and storage.
Ten percent of the total urine collection was subsampled daily, pooled on an animal basis, and stored at
-200 C until required for analysis.

Dry matter (DM), organic matter (OM) and nitrogen
(N) analysis was determined by the method of AOAC
(1991). Neutral detergent fibre (NDF), acid detergent
fibre (ADF), permanganate lignin and silica (insoluble
ash) were determined using the methods of GOERING
and VAN SOEST (1970). Hemicellulose (HC) was
calculated by the difference between NDF and ADF.
Cellulose was obtained from the weight loss of ADF
residue, after being treated with permanganate solution
and ashed at 5000 C (GOERING and VAN SOEST, 1970).
Gross energy (GE) was measured using adiabatic bomb
calorimeter.
Measurement of apparent digestibility of nutrients
and nitrogen balance was facilitated by total urine and
faeces collection. The apparent digestibility coefficients
of the nutrients were calculated using the equation.
% NAD =

NI – NF
NI

x 100%

where:
NAD = nutrient apparent digestibility
NI = nutrient intake, and
NF = nutrient in faeces
The nitrogen balance was calculated by measuring
the difference between total N intake and N excretion in
faeces and urine.
Statistical analysis
Digestible energy intake, apparent nutrient
digestibility coefficients, and nitrogen balance values
were analysed using analysis of variance of a
randomised complete block design (GENSTAT 5; LAWES
AGRICULTURAL TRUST, 1994). Significant differences
between treatments were determined using the least
significant difference tests.
RESULTS
The chemical composition of untreated and urea
treated straw in Table 2 shows that urea treatment
increased the nitrogen content, but there were small
differences in cell wall components between untreated
and urea treated straw.

Table 2. Chemical analysis of untreated and urea ensiled rice straw (% dry matter basis)
Rice straw

N

NDF

ADF

cellulose

OM

HC

Ensiled

1.43

78.93

60.04

41.08

81.31

18.89

Untreated

0.53

77.71

59.48

39.40

80.98

18.23

N: nitrogen; NDF: neutral detergent fibre; ADF: acid detergent fibre; OM: organic matter; HC: hemicellulose

11

YULISTIANI et al.: Intake and digestibility of untreated and urea treated rice straw base diet fed to sheep

(P<0.05) to Diet 3 (Table 3). There were no significant
difference in DM, OM and ADF digestibility between
diets (Table 3).

Dry matter intake, digestible energy intake and
apparent digestibility of the diets
The voluntary dry matter intake per metabolic
weight (DMI/W0.75) of Diet 2 was significantly higher
(P<0.05) than Diet 3 (Table 3). However, there was no
significant difference in DMI/W0.75 between Diet 2 and
Diet 1. DE intake of Diet 2 was significantly higher
compared to Diet 3, but not significantly different from
Diet 2 (Table 3).
The crude protein digestibility of Diet 2 was
significantly (P<0.05) lower compared to other diets
(Table 3). The HC digestibility of Diet 2 (75.6%) was
significantly higher (P<0.01) than the other diets (Table
3). The cellulose digestibility of Diet 2 (66.1%) was
significantly higher (P<0.05) than the other diets. The
NDF digestibility of Diet 2 was not significantly
different to Diet 1, but was significantly different

Nitrogen balance of the diets
The N intake was not significantly different between
Diet 1 and Diet 2 (Table 4). However, the N intake of
both these diets was significantly greater (P<0.01) than
Diet 3 (Table 4). The faecal nitrogen of Diet 2 was
significantly (P<0.05) higher compared to the other
diets. However, N excretion from urine in animals fed
on Diet 2 was significantly (P<0.05) lower compared to
other diets (Table 4). There was no significant
difference between Diet 1 and Diet 3 in N excretion
from urine. There was no significant difference in the
nitrogen retention between diets (Table 4).

Table 3. Voluntary intake, DE intake and apparent digestibility of nutrients from untreated rice straw, urea ensiled rice straw and
urea supplemented rice straw
Diets

Measurements

Significance

s.e.d.

772b
40.1b

*

32.8

*

2.53

7.28a

6.32b

*

0.441

50.4
58.1
62.9a

52.0
59.6
50.2b

50.1
56.9
64.7a

N.S.
N.S.
**

2.94
2.65
2.86

54.1a
44.1
75.6a

44.3b
38.3
56.0b

*

3.87

ADF
HC

47.5b
40.9
62.4b

N.S.
**

3.91
3.23

Cellulose

59.8b

66.1a

56.7b

*

2.26

1

2

3

/day

892a
45.9ab

930a
47.3a

DE intake (MJ/day)

7.76a

Intake :
DMI (g/day)
0.75

g DMI/BW

Apparent digestibility (% DM):
DM
OM
CP
NDF

s.e.d.: standard error of difference
N.S.: non significant; * P<0.05; ** P<0.01; Different letters in the same row indicate significant difference (LSD 5%)
DMI: dry matter intake; DE: digestible energy; DM: dry matter; OM: organic matter;
CP: crude protein; NDF: neutral detergent fibre; ADF: acid detergent fibre; HC: hemicellulose

Table 4. Nitrogen balanced of untreated rice straw, urea ensiled rice straw and urea supplemented rice straw diets (g/day)
Description
N intake
N faeces
N urine
N retention

Diets
1

2

3

14.25a
5.32b
9.80a
-0.87

14.42a
7.16a
5.73b
1.52

12.13b
4.29c
9.23a
-1.38

Significance

s.e.d.

**
**
*
N.S.

0.325
0.349
1.267
1.145

N
= nitrogen
s.e.d. = standard error different
N.S. = non significant; * P<0.05; ** P<0.01 different letters in the same row indicate significant difference (LSD 5%)

12

JITV Vol. 8. No. 1. Th. 2003

DISCUSSION
Urea treatment of rice straw (Table 2) resulted in
increase nitrogen content by 2.7 times, this result
slightly higher compared to previous experiment
reported by PRASAD et al. (1998) which is 2.34 for urea
treatment kept in bale and 2.43 kept in stack. However
the increase of nitrogen content in the expriment
currently reported was slightly lower compared to the
result reported by AHMED et al. (2002). This differences
could be due to method of the ensiling or the variety of
rice straw as well as the nitrogen content of rice straw.
YULISTIANI et al. (2000) reported that rice straw with
low nitrogen content could benefit more from urea
treatment to improve nutritive value especially nitrogen
content. Urea treatment decreased slightly cell wall
component previous study reported by YULISTIANI et
al. (2000) showed that effect of urea treatment on cell
wall component was not consistent.
Dry matter intake, digestible energy intake and
apparent digestibility of the diets
The urea ensiled straw diet (Diet 2) and the
untreated rice straw diet (Diet 1) had similar effects on
DMI/metabolic weight. The apparent digestibility of
cell wall components, particularly cellulose and
hemicellulose, was improved in the urea ensiled straw
diet. The DMI of Diet 3 was lower compared to Diet 2
in this experiment (40.1 vs 47.3 g/W0.75). The greater
DMI in Diet 2 may have been associated with improved
palatability of urea ensiled straw (LAWLOR and O'SHEA,
1979). A similar result was obtained with wheat straw
by CLOETE et al. (1983) and PRASAD et al. (1998).
Legume supplementation may have promoted an
increase in the DMI of Diet 1. In the current study, total
DMI and DE intake of Diet 1 (892 g/day and 7.76
MJ/day respectively) was significantly higher (P<0.05)
than Diet 3 (772 g/day and 6.32 MJ/day respectively).
This is due to the legume supplementation providing to
the rumen fermentable energy (in addition to protein) in
the form of available cellulose and hemicellulose, both
of which are known to stimulate fibre digestion (SILVA
and ORSKOV, 1988). Furthermore SILVA and ORSKOV
(1988) reported that the rate of fibre digestion was
significantly faster in sheep fed on supplemented
legume straw. This straw could have stimulated DMI
(MCMENIMAN et al., 1988). MCMENIMAN et al. (1988)
also observed that supplementation with NPN did not
stimulate the rate of rumen degradability of rice straw
to the extent achieved with legume straw
supplementation, even though the rumen ammonia
concentration may be similar in sheep fed on rice straw
supplemented with urea, compared to those fed with
rice straw supplemented with legumes.

In the current study the DM digestibility of Diet 2
(52.0 vs 50.1%) was not significantly different to Diet
1. Despite this, urea ensiled rice straw may have the
advantage of greater fibre digestibility. The NDF, ADF,
cellulose and hemicellulose content of the three diets
were relatively similar (Table 1), however the
digestibility of NDF, cellulose and hemicellulose in
Diet 2 was higher than the other diets (Table 3). This is
because the ammonium hydroxide which is released
following ensiling with urea causes a cleavage of the
alkali-labile linkages between lignin and the structural
carbohydrates (HARTLEY and JONES, 1978), and such a
cleavage increases the fibre degradability. Data from
the current study suggest that the digestibility of cell
wall constituents of urea ensiled rice straw increased.
This result is comparable to the result obtained by
DIAS-DA-SILVA and SUNDSTOL (1986) who obtained a
hemicellulose digestibility in urea ensiled wheat straw
of 726 g/kg. In the current experiment a hemicellulose
digestibility of 756 g/kg was obtained. The increased
fibre digestibility could have increased the dry matter
intake of Diet 2 which was 18% higher than that of Diet
3. Urea treatment may cause the structural carbohydrate
of the cell wall to become more accessible to rumen
micro organisms. Hence urea treatment may increase
the digestibility of organic matter and cell wall
components. Comparable results with ammoniated
wheat straw have also been reported by CLOETE et al.
(1983).
The crude protein digestibility of Diet 2 was
significantly (P<0.05) lower compared to Diet 1 and
Diet 3 (50.2 vs 62.9 and 64.7%, respectively). This
indicates that ammonia treatment reduced CP
digestibility. CLOETE and KRITZINGER (1984) suggested
that supplemental urea is more easily degraded by
rumen microbes, and hence is associated with a high
digestibility of protein compared with urea ammoniated
straw. DIAS-DA-SILVA and SUNDSTOL (1986) and RATH
et al. (2001) also observed the lower nitrogen
digestibility of ammoniated straw compared to straw
supplemented with urea at feeding time. As ammonia is
more readily absorbed in the hindgut, this could partly
account for the high level of faecal nitrogen observed
on the ammoniated diet and the enhancement of protein
synthesis by microflora in the rumen, caecum and
colon. Moreover, CANN et al. (1991) found
significantly higher total rectal bacterial counts in sheep
fed on ammoniated rice straw diet compared to
untreated rice straw (which could contribute to the
higher faecal nitrogen). This finding was supported by
HASSEN and CHENOST (1992), who observed faecal
nitrogen to be composed mostly of bacterial nitrogen
and nitrogen bound to undegraded cell walls. More
nitrogen was bound to cell walls in ammoniated straw
compared to untreated straw (HASSEN and CHENOST,
1992). The cell walls that are not degraded in the rumen

13

YULISTIANI et al.: Intake and digestibility of untreated and urea treated rice straw base diet fed to sheep

are fermented in the large intestine. This condition may
be responsible, in the current study, for the higher
faecal nitrogen excretion from sheep fed on Diet 2
rather than on Diet 1. HASSEN and CHENOST (1992)
suggested that the higher excretion of faecal nitrogen in
sheep fed on an ammoniated straw diet, might be due to
phenolic nitrogenous compounds generated from the
ammonia treatment which could be incorporated into
the microbes in the rumen, but which are lost in the
faeces in a soluble form. A reduction in CP digestibility
on urea ensiled straw diets compared to untreated straw
was also reported by CLOETE et al. (1983) and
compared to urea supplemented straw by CHEVA and
JEERACHAI (1987), CLOETE and KRITZINGER (1984) and
SAHOO et al. (2000). CLOETE and KRITZINGER (1984)
obtained a 22.1% decrease in crude protein digestibility
when urea ensiled wheat straw was compared with urea
supplemented wheat straw. In the current study, the
reduction was 22.4%.
Nitrogen balance of the diets
In the current study the nitrogen retention was not
significant different between treatments. Lack of
significance in nitrogen retention could have been due
to the high individual variations recorded in the feeding
trial, as indicated by the high standard error (Table 4). If
the replication was increased and the variation reduced,
the nitrogen retention of the urea ensiled diet could be
improved. The evidence for this is provided by the fact
that N retention of Diet 2 was improved from -1.38 to
+1.52 g/day. Higher N retention resulting from a urea
ensilage diet might be attributed to the urea treatment
increasing the protein, as well as the energy supply, in
the diet, as structural carbohydrates of the cell wall
become more accessible to micro organisms in the
rumen. This was indicated by the significantly higher
DE intake in sheep fed Diet 2 than those fed Diet 3
(7.28 vs 6.31 MJ/day). In the urea ensiled diet (when
the ration was balanced for energy and protein content)
the utilisation of nitrogen by rumen microbes was more
efficient because of a more synchronous availability of
energy and nitrogen (ZORRILA-RIOS et al., 1989).
Results in the current study are also supported by
CLOETE et al. (1983), who showed that when diets
contained equal protein, the nitrogen retention of
ammoniated wheat straw was lower than that of
untreated straw. This was due to a lower energy content
of the diets resulting in the utilisation of muscle protein
to fulfil energy requirements. Similar results have been
reported by CANN et al. (1991).
CONCLUSIONS
Formulating isoenergetic and isonitrogenous rations
using urea ensiled and untreated rice straws

14

supplemented with legumes had similar effects on DMI,
DE intake and digestible cell wall components. This
suggests that untreated rice straw basal diets
supplemented with legume straws or forage legumes
offer an alternative method of improving the nutritional
value of rice straw as a ruminant feed on small farms.
Urea ensiled rice straw resulted in higher DMI, DE
intake, and digestible cell wall components compared to
rice straw which was supplemented with urea at feeding
time. This suggests that the urea ensiled rice straw is a
superior choice for use in ruminant diets. Although
ensiled rice straw had a longer preparation time (42
days in temperate weather) compared to urea
supplemented rice straw, the former had a 15% higher
DE intake and resulted in a positive N balance.
ACKNOWLEDGEMENT
The work described in this paper was performed
with the financial of Australian Agency for
International Development Scholarship. The author is
grateful to thank DR. LAURIE LEWIN from Yanco
Agricultural Institute Leeton, N.S.W, for providing the
rice straw used for this experiment.
REFERENCES
AHMED.S., M.J. KHAN, M. SHAHJALAL, and K.M.S. ISLAM.
2002. Effect of feeding urea and soybean meal-treated
rice straw on digestibility of feed nutrients and growth
performance of bull calves. Asian-Aust. J. Anim. Sci. 15:
522 – 527.
AOAC. 1991. Official Methods of Analysis. Association of
Official Analytical Chemists. Arlington, Virginia,
U.S.A.
ASTUTIK, S.I.B.I.S., MUKH ARIFIN and W.S. DILAGA. 2002.
Respon produksi sapi peranakan Ongole berbasis pakan
jerami padi terhadap berbagai formula urea molases
block. Prosiding Seminar Nasional Teknologi
Peternakan dan Veteriner. Ciawi-Bogor, 30 September1 Oktober 2002. Pusat Penelitian dan Pengembangan
Peternakan. Pp 82-86.
BARBER, A. 1992. Take Away: A least cost ration calculator
for sheep and cattle. A decision support software
package. South Australian Department of Agriculture.
CANN, I.K.O., Y. KOBAYASHI, M. WAKITA, and S. HOSHINO.
1991. Digestion properties of ammoniated rice straw in
the rumen and lower tract of sheep. Anim. Feed Sci.
Technol. 35, 55-68.
CHEVA
ISARAKUL
BOONSERM
and
JAERACHAI
KANJANAPHRUTHIPONG. 1987. A comparison of urea
treated rice straw with urea molasses sprayed rice straw
as basal diet for growing cattle. In: Ruminant Feeding
System Utilising Fibrous Agricultural Residues-1986.
R.M. DIXON (Ed.). Pp. 191-198. IDP. Canberra.

JITV Vol. 8. No. 1. Th. 2003

CLOETE, S.W.P., T.T. DE VILLIERS and N.M. KRITZINGER
1983. The effect of ammoniation by urea on the
nutritive value of wheat straw for sheep. South African
J. Anim. Sci. 3 : 143 – 146.
CLOETE, S.W.P. and N.M. KRITZINGER. 1984. Urea
ammoniation compared to urea supplementation as a
method of improving the nutritive value of wheat straw
for sheep. South African J. Anim. Sci. 14 : 59 – 63.
DIAS-DA-SILVA, A.A. and F. SUNDSTOL. 1986. Urea as a
source of ammonia for improving the nutritive value of
wheat straw. Anim. Feed Sci. Technol. 14 : 67 – 79.
DOYLE. P.T., C. DEVENDRA, and G.R. PEARCE. 1986. Rice
Straw As Feed For Ruminants. IDP. Canberra.
GOERING, H.K. and P.J. VAN SOEST. 1970. Forage Fiber
Analysis. U.S. Dept. Agric. Hand book No. 379,
Washington, D.C.
HARTLEY, R.D.

and E.C. JONES. 1978. Effect of aqueous
ammonia and other alkalis on the in vitro digestibility of
barley straw. J. Sci. Food Agric. 29 : 92 – 98.

HASEN, L. and M. CHENOST. 1992. Tentative explanation of
the abnormally high faecal nitrogen-excretion with
poor-quality roughages treated with amonia. Anim. Feed
Sci. Technol. 38 : 25-34.

1 Oktober 2002. Pusat Penelitian dan Pengembangan
Peternakan. pp. 79-81.
RATH. S., A.K. VERMA, P. SINGH, R.S. DASS, and U.R.
MEHRA. 2001. Performance of growing lambs fed urea
ammoniated and urea supplemented wheat straw based
diets. Asian-Aust. J. Anim. Sci. 14 : 1078 – 1084.
RICHARD, D.E., W.F. BROWN, G. RUEGSEGGER, and D.B.
BATES. 1994. Replacement value of tree legumes for
concentrates in forage based diets 1: Replacement value
gliricidia sepium for growing goats. Anim. Feed Sci.
Technol 46 : 37 – 51.
RISTIANTO UTOMO, S. REKSODIPRODJO, B.P. WIDYOBROTO, Z.
BACHRUDIN and B. SUHARTANTO. 1998. Determination
of nutrients digestibility, rumen fermentation
parameters, and microbial protein concentration on
Ongole Crossbred cattle fed rice straw. Bull. of Anim.
Sci. Supplement edition. Faculty of Animal Science,
Gadjah Mada University. pp. 82 – 88.
SAHOO.B., M.L. SARASWAT, N. HAQUE, and M.Y. KHAN. 2000.
Energy balance and methane production in sheep fed
chemically treated wheat straw. Small Rumin. Res. 35 :
13 –19.

KHANDAKER, Z.H., H. STEINGASS, and W. DROCHNER. 1998.
Supplementation of wheat straw with sesbania on
voluntary intake, digestibility and ruminal fermentation
in sheep. Small Rumin. Res. 28 : 23-29.

SHARMA, D.D., T.K. WALLI and R.C. SAHA. 1995. Feeding of
non-protein nitrogen and crop residues. In: “Handbook
for Straw Feeding System” Principles and application
with emphasis on Indian Livestock production. KIRAN
SINGH and J.B. SCHIERE (Eds.). Indo-Dutch Project on
Bioconversion of Crop Residues. pp. 215-224.

LAWES AGRICULTURAL TRUST. 1994. Genstat 5 Release 3.1.
Rothamstead Experimental Station. Clarendon Press,
Oxford.

SILVA, T. A. and E.R. ORSKOV. 1988. Fibre degradation in the
rumen of animals receiving hay, untreated or ammoniatreated straw. Anim. Feed Sci. Technol. 19 : 277 – 287.

LAWLOR, M.J. and J. O’SHEA. 1979. The Effect of
ammoniation on the intake and nutritive value of straw.
Anim. Feed Sci. Technol. 4 : 169 – 175.

VAN SOEST, P.J. 1988. Effect of environment and quality of
fibre on the nutritive value of crop residues. In: “Plant
Breeding and The Nutritive Value of Crop Residues”
REED J.D., CAPPER B.S., and NEATE, P.J.H. (Eds.). pp.
71-96. ILCA, Adis Ababa, Ethiopia.

MAFF. 1984. Energy Allowances and Feeding System For
Ruminants. Ministry of Agriculture, Fisheries and Food.
HMSO, London.
MCMENIMEN, N.P., R. ELLIOT, and A.J. ASH. 1988.
Supplementation of rice straw with crop by-products. I.
Legume straw supplementation. Anim. Feed Sci.
Technol. 19 : 43-53.
NDEMANISHO, E.E., L.A. MTENGA, E.F.C. KIMBI, A.E.
KIMAMBO, and E.J. MTENGETI. 1998. Substitution of dry
Leucaena leucocephala (DLL) leaves for cotton seed
cake (CSC) as a protein supplement to urea treated
maize stover fed to dairy weaner goats. Anim. Feed Sci.
Technol. 73 : 365 – 374.
PRASAD, R.D.D., M.R. REDDY, and G.V.N. REDDY. 1998.
Effect of feeding baled and stacked urea treated rice
straw on the performance of crossbred cows. Anim.
Feed Sci Technol. 73 : 347 – 352.
PURNOMOADI, A. and EDY RIANTO. 2002. Feeding behaviour
of Buffalo Heifers fed rice straw supplemented with
urea-mollases. Prosiding Seminar Nasional Teknologi
Peternakan dan Veteriner. Ciawi-Bogor, 30 September-

WALLI, T.K., A. SUBBA RAO, MAHENDRA SINGH, D.V.
RANGNEKAR, P.K. PRADHAN, R.B. SINGH, S.N. RAI and
M.N.M. IBRAHIM. 1995. Urea treatment of straw. In:
“Handbook for Straw Feeding System” Principles and
application with emphasis on Indian Livestock
production. KIRAN SINGH and J.B. SCHIERE (Eds.). IndoDutch Project on Bioconversion of Crop Residues. pp.
271-290.
WILLIAMS, P.E.V., G.M. INNES, and A. BREWER. 1984a.
Ammonia treatment of straw via the hydrolisis of urea.
1. Effect of dry matter and urea concentration on the
hydrolisis of urea. Anim. Feed Sci. Technol. 11 : 103 –
114.
WONGSRIKEAO, M and M. WANAPAT. 1985. The effects of
urea treatment of rice straw on feed intake and live
weight gain of buffaloes. In: The Utilization of Fibrous
Agricultural Residues as Animal Feeds. Doyle. P.T.
(Ed.) pp 81-84 IDP Canberra.

15

YULISTIANI et al.: Intake and digestibility of untreated and urea treated rice straw base diet fed to sheep

YULISTIANI, D. J.R. GALLAGHER and R. VAN BARNEVELD.
2000. Nutritive value improvement of rice straw
varieties for ruminants as determined by chemical
composition and in vitro organic matter digestibility.
JITV 5 : 23 – 31.

16

ZORRILA-RIOS, J., HORN,G.W. and MC NEW, R.W. 1989.
Effect of ammoniation and energy supplementation on
the utilisation of wheat straw by sheep. Anim. Feed Sci.
Technol. 22, 1305.