115
7.2.4 Nutrient Digestibility of Rice Straw
The leaf and stem ratio is essential when it comes to the digestibility of cereal straw.
Relatively, rice straw has a higher proportion of leaves at 60% compared with other
cereal straw, such as barley (35%) and oats (43%) (Sarnklong et al. 2010; Theander
and Aman 1984). Having this high proportion of leaves to stems promotes lower
in vitro dry matter digestibility (IVDMD) of the leaves at 50–51% compared to the
stems at 61% (Vadiveloo 2000). These data were supported by Phang and Vadiveloo
(1992) who observed that, in goats, IVDMD for rice leaves is 56.2% while for stems
is at 68.5%. To increase the degradability of rice straw leaves, pretreating them with
4% urea solution for 21 days shows significant increase in the IVDMD of the leaves
compared with the stems (Vadiveloo 2000). This improvement of the feeding value
of rice straw should be taken into consideration to optimize digestibility.
Rice straw, when offered to ruminants, gave DM digestibility ranging from 45 to
50%. Various enzymes secreted in the reiculo-rumen, such as glucanase, cellulase,
and hemi-cellulase—not including ligninase—have the potential capacity to degrade
the cell wall components of rice straw, (Schiere and Ibrahim 1989). These enzymes
are not produced by the animals themselves but are secreted by the rumen microorganisms. The degree of lignification or with higher the lignin content, this has a
direct effect on the reduction of the rice straw’s nutrient digestibility. In addition,
Agbagla-Dohnani et al. (2003) pointed out that silica has a direct effect on cell wall
digestibility of rice straw since silica forms a physical barrier that lowers microbial
degradation resulting to poor enzymatic hydrolysis of the straw.
7.3 Pretreatment of Rice Straw as Ruminant Fodder
Developed technologies have been published and are available for farmers to help
them enhance the utilization and improvement of the nutritive value of rice straw for
animal feeding. These techniques include different physical, chemical, and biological processing methods and combinations of these (Ibrahim 1983). However, adoption of these technologies takes time since they require additional inputs and farmers
need to see improvement to believe it.
7.3.1 Physical Processes
The physical process is a practical and inexpensive method to enhance utilization
and recycling of nutrients from rice straw when used as fodder for ruminants.
Physical treatment of rice straw aims to improve the palatability and increase intake
as well as improve the potential digestibility of ruminants. These physical processes
include soaking, grinding or chopping, pelleting, steaming pressure, and gamma
7 Rice Straw-Based Fodder for Ruminants
7.2.4 Nutrient Digestibility of Rice Straw
The leaf and stem ratio is essential when it comes to the digestibility of cereal straw.
Relatively, rice straw has a higher proportion of leaves at 60% compared with other
cereal straw, such as barley (35%) and oats (43%) (Sarnklong et al. 2010; Theander
and Aman 1984). Having this high proportion of leaves to stems promotes lower
in vitro dry matter digestibility (IVDMD) of the leaves at 50–51% compared to the
stems at 61% (Vadiveloo 2000). These data were supported by Phang and Vadiveloo
(1992) who observed that, in goats, IVDMD for rice leaves is 56.2% while for stems
is at 68.5%. To increase the degradability of rice straw leaves, pretreating them with
4% urea solution for 21 days shows significant increase in the IVDMD of the leaves
compared with the stems (Vadiveloo 2000). This improvement of the feeding value
of rice straw should be taken into consideration to optimize digestibility.
Rice straw, when offered to ruminants, gave DM digestibility ranging from 45 to
50%. Various enzymes secreted in the reiculo-rumen, such as glucanase, cellulase,
and hemi-cellulase—not including ligninase—have the potential capacity to degrade
the cell wall components of rice straw, (Schiere and Ibrahim 1989). These enzymes
are not produced by the animals themselves but are secreted by the rumen microorganisms. The degree of lignification or with higher the lignin content, this has a
direct effect on the reduction of the rice straw’s nutrient digestibility. In addition,
Agbagla-Dohnani et al. (2003) pointed out that silica has a direct effect on cell wall
digestibility of rice straw since silica forms a physical barrier that lowers microbial
degradation resulting to poor enzymatic hydrolysis of the straw.
7.3 Pretreatment of Rice Straw as Ruminant Fodder
Developed technologies have been published and are available for farmers to help
them enhance the utilization and improvement of the nutritive value of rice straw for
animal feeding. These techniques include different physical, chemical, and biological processing methods and combinations of these (Ibrahim 1983). However, adoption of these technologies takes time since they require additional inputs and farmers
need to see improvement to believe it.
7.3.1 Physical Processes
The physical process is a practical and inexpensive method to enhance utilization
and recycling of nutrients from rice straw when used as fodder for ruminants.
Physical treatment of rice straw aims to improve the palatability and increase intake
as well as improve the potential digestibility of ruminants. These physical processes
include soaking, grinding or chopping, pelleting, steaming pressure, and gamma
7 Rice Straw-Based Fodder for Ruminants