119
treatments as reflected by the increase in IVDMD from 45% to 55–62%. Numerous
evaluations were done in the laboratory (Reddy 1996; Shen et al. 1998; Vadiveloo
2003) or in field trials (Prasad et al. 1998; Vu et al. 1999; Akter et al. 2004) in treatment of rice straw using pure urea or in combination with other chemicals or feed
supplements and the results had clear improvement on the nutritive as well as feeding value of treated straw.
7.3.2.4 Lime Treatment
Treatment of straw with lime solution [CaO/Ca(OH) 2 ] is expected to have the same
effect on improving fiber degradability as NAOH. Lime is also a source of calcium
for ruminants in low-calcium rations but it has longer solubility in water compared
to NAOH or urea. Treatment of straw with lime can be done in two ways: by soaking
and ensiling. Lime treatment provides complementary effects in combination with
urea. The combination of lime and urea has been shown an advantage in increasing
degradability and incrementing both the calcium and nitrogen contents of the treated
straw (Nguyen 2000).
In a separate study of Pradhan et al. (1997), using 4% or 6% Ca(OH) 2 to treat rice
straw, showed, after ensiling, a higher IVDMD. However; it is further suggested
that a combination of lime and urea would give better results than either urea or lime
alone. Sirohi and Rai (1995) used 3% urea plus 4% lime at 50% moisture for
3 weeks of incubation. They found this to be the most effective treatment process
for rice straw. This was due improving the digestibility and degradable nutrients of
the treated straw. Saadulah et al. (1981) and Hadjipanayiotou (1984) found that the
use of lime and other alkali agents had additive effects on rice straw treatment and
utilization in addition to being safer and more cost-effective to use than NaOH.
As cited by Trach et al. (2001), there are reports that treated rice straw with pure
lime posed contradicting results in its effect on delignification or degradation of rice
straw. There was a report that the dry matter intake of animals was reduced due a
palatability problem of the treated straw. Lime treatment did not affect N content,
but it appeared to be more powerful in delignification or reducing neutral detergent
fiber (NDF) and hemicellulose contents of the treated straw. Increasing levels of
lime and/or urea during rice straw treatment resulted in some negative interactions
between the two chemicals. However, a level of 2% urea alone seemed to be too low
for effective treatment and a level of 6% lime seemed to be too high for rumen
cellulolysis.
7.3.3 Biological Treatment
Biological treatment of rice straw involves the use of enzymes and different microorganisms, such as bacteria and fungi. Different fungi strains have the capacity to
act on the cell wall contents of the straw thereby improving the degradation rates
7 Rice Straw-Based Fodder for Ruminants
treatments as reflected by the increase in IVDMD from 45% to 55–62%. Numerous
evaluations were done in the laboratory (Reddy 1996; Shen et al. 1998; Vadiveloo
2003) or in field trials (Prasad et al. 1998; Vu et al. 1999; Akter et al. 2004) in treatment of rice straw using pure urea or in combination with other chemicals or feed
supplements and the results had clear improvement on the nutritive as well as feeding value of treated straw.
7.3.2.4 Lime Treatment
Treatment of straw with lime solution [CaO/Ca(OH) 2 ] is expected to have the same
effect on improving fiber degradability as NAOH. Lime is also a source of calcium
for ruminants in low-calcium rations but it has longer solubility in water compared
to NAOH or urea. Treatment of straw with lime can be done in two ways: by soaking
and ensiling. Lime treatment provides complementary effects in combination with
urea. The combination of lime and urea has been shown an advantage in increasing
degradability and incrementing both the calcium and nitrogen contents of the treated
straw (Nguyen 2000).
In a separate study of Pradhan et al. (1997), using 4% or 6% Ca(OH) 2 to treat rice
straw, showed, after ensiling, a higher IVDMD. However; it is further suggested
that a combination of lime and urea would give better results than either urea or lime
alone. Sirohi and Rai (1995) used 3% urea plus 4% lime at 50% moisture for
3 weeks of incubation. They found this to be the most effective treatment process
for rice straw. This was due improving the digestibility and degradable nutrients of
the treated straw. Saadulah et al. (1981) and Hadjipanayiotou (1984) found that the
use of lime and other alkali agents had additive effects on rice straw treatment and
utilization in addition to being safer and more cost-effective to use than NaOH.
As cited by Trach et al. (2001), there are reports that treated rice straw with pure
lime posed contradicting results in its effect on delignification or degradation of rice
straw. There was a report that the dry matter intake of animals was reduced due a
palatability problem of the treated straw. Lime treatment did not affect N content,
but it appeared to be more powerful in delignification or reducing neutral detergent
fiber (NDF) and hemicellulose contents of the treated straw. Increasing levels of
lime and/or urea during rice straw treatment resulted in some negative interactions
between the two chemicals. However, a level of 2% urea alone seemed to be too low
for effective treatment and a level of 6% lime seemed to be too high for rumen
cellulolysis.
7.3.3 Biological Treatment
Biological treatment of rice straw involves the use of enzymes and different microorganisms, such as bacteria and fungi. Different fungi strains have the capacity to
act on the cell wall contents of the straw thereby improving the degradation rates
7 Rice Straw-Based Fodder for Ruminants