118
Fadel-Elseed et al. 2003). The treatment of rice straw with ammonia (NH 3 ) is similar to treating with NaOH. NH 3 has been observed to be advantageous over the use
of NAOH because it is readily available because it can be derived from the hydrolysis of urea. NH 3 treatment does not only increase degradability of rice straw but it
also supplies nitrogen (Abou-EL-Enin et al. 1999), thereby increasing the protein
content of the straw. It can also be used as a preservative agent since it inhibits the
growth of molds in the treated straw (Calzado and Rolz 1990). Other benefits that
can be derived from NH 3 treatment include reducing costs of buying protein-rich
supplements and enhancing acceptability and voluntary intake of the treated straw
by ruminants.
Liu et al. (2002) observed that the use of NAOH treatment is more efficient than
NH 3 treatment in terms of improving the energy values of the straw. However; using
NH 3 is usually more profitable for farmers than NAOH because it provides an additional source of nitrogen in the straw. Selim et al. (2004) studied sheep fed with
NH 3 -treated rice straw packed in polyethylene bags for 4 weeks with gaseous
ammonia (3 g NH 3 100 g dry matter
−1
). NH 3 increased the N content of the treated
rice straw from 8.16 to 18.4 g kg
−1
or with an equivalent increase of CP from 51 to
115 g kg
−1
. A slight decrease in the NDF of treated straw (from 571 to 551 g kg
−1
)
was observed but with an increase in acid detergent fiber (ADF) from 303 to
327 g kg
−1
. This further indicated positive changes on the cell wall content of the
treated straw.
7.3.2.3 Urea Treatment
Urea treatment is the most practical and widely used chemical method in treating
rice straw. It is adoptable by both small-scale and commercial livestock farms. The
main function of urea is to increase the protein content of the treated straw during
the fermentation process. Urea or NH 3 is best used in combination with molasses
(urea-molasses solution) at 30% moisture content of the treated straw. First, urea is
hydrolyzed or undergoes ureolysis to produce ammonia-nitrogen (Sahnounea et al.
1991). The role of the molasses is to supply energy so that cellulosic fermentation
of the treated straw is hastened. Urea or its combination with molasses can make
rice straw a complete and safe basal ration for ruminants (Langar et al. 1985).
Rice straw can be effectively treated with urea using different concentrations i. e.
from 1% to 5% w/w. Urea should be dissolved first in water at the desired proportion and it can be sprayed into the rice straw. The treated straw can be packed in the
silo, empty drum or plastic bag. This treatment process is practical and can be easily
adopted by farmers. Urea is a chemical which is a source of nitrogen to crops and a
source of non-protein nitrogen to ruminants. It is a crystalline substance and it is
easy to handle and locally available in the market, (Sundstøl and Coxworth 1984).
Urea increases the nitrogen (crude protein or CP) content of the treated rice straw,
(Schiere and Ibrahim 1989). It is cheaper than NaOH or pure NH 3 . Vadiveloo (2003)
reported that treating different rice varieties with low degradable carbohydrates
responded positively compared to high-quality rice straw varieties after urea
D. Aquino et al.
Fadel-Elseed et al. 2003). The treatment of rice straw with ammonia (NH 3 ) is similar to treating with NaOH. NH 3 has been observed to be advantageous over the use
of NAOH because it is readily available because it can be derived from the hydrolysis of urea. NH 3 treatment does not only increase degradability of rice straw but it
also supplies nitrogen (Abou-EL-Enin et al. 1999), thereby increasing the protein
content of the straw. It can also be used as a preservative agent since it inhibits the
growth of molds in the treated straw (Calzado and Rolz 1990). Other benefits that
can be derived from NH 3 treatment include reducing costs of buying protein-rich
supplements and enhancing acceptability and voluntary intake of the treated straw
by ruminants.
Liu et al. (2002) observed that the use of NAOH treatment is more efficient than
NH 3 treatment in terms of improving the energy values of the straw. However; using
NH 3 is usually more profitable for farmers than NAOH because it provides an additional source of nitrogen in the straw. Selim et al. (2004) studied sheep fed with
NH 3 -treated rice straw packed in polyethylene bags for 4 weeks with gaseous
ammonia (3 g NH 3 100 g dry matter
−1
). NH 3 increased the N content of the treated
rice straw from 8.16 to 18.4 g kg
−1
or with an equivalent increase of CP from 51 to
115 g kg
−1
. A slight decrease in the NDF of treated straw (from 571 to 551 g kg
−1
)
was observed but with an increase in acid detergent fiber (ADF) from 303 to
327 g kg
−1
. This further indicated positive changes on the cell wall content of the
treated straw.
7.3.2.3 Urea Treatment
Urea treatment is the most practical and widely used chemical method in treating
rice straw. It is adoptable by both small-scale and commercial livestock farms. The
main function of urea is to increase the protein content of the treated straw during
the fermentation process. Urea or NH 3 is best used in combination with molasses
(urea-molasses solution) at 30% moisture content of the treated straw. First, urea is
hydrolyzed or undergoes ureolysis to produce ammonia-nitrogen (Sahnounea et al.
1991). The role of the molasses is to supply energy so that cellulosic fermentation
of the treated straw is hastened. Urea or its combination with molasses can make
rice straw a complete and safe basal ration for ruminants (Langar et al. 1985).
Rice straw can be effectively treated with urea using different concentrations i. e.
from 1% to 5% w/w. Urea should be dissolved first in water at the desired proportion and it can be sprayed into the rice straw. The treated straw can be packed in the
silo, empty drum or plastic bag. This treatment process is practical and can be easily
adopted by farmers. Urea is a chemical which is a source of nitrogen to crops and a
source of non-protein nitrogen to ruminants. It is a crystalline substance and it is
easy to handle and locally available in the market, (Sundstøl and Coxworth 1984).
Urea increases the nitrogen (crude protein or CP) content of the treated rice straw,
(Schiere and Ibrahim 1989). It is cheaper than NaOH or pure NH 3 . Vadiveloo (2003)
reported that treating different rice varieties with low degradable carbohydrates
responded positively compared to high-quality rice straw varieties after urea
D. Aquino et al.