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fungi act on its substrates is dependent on the fungal species. There are species that
prefer to access first on readily degradable carbohydrates, such as simple sugars,
cellulose, and hemicellulose and eventually degrade lignin, thus resulting in a lower
energy supply for ruminants (Karunanadaa and Varga 1996a, b; Jalc 2002). The
length of incubation in treatment of straw is dependent on the white-rot fungi species. During the early stage of incubation, some losses in energy are expected due
to mycelial growth but after a certain time, some white-rot species preferably attack
lignin without degrading cellulose and hemicellulose, thus supplying more degradable energy for the ruminants.
Nowadays, it is important to do research on mycology by selecting fungi species
that prefer to attack lignin rather than the structural carbohydrates or cell walls of
rice straw. Once these species are identified, mycologists can breed even better
strains (Rodrigues et al. 2008). Growing edible mushrooms is a dual purpose of
treating rice straw. As described elsewhere in this book, rice straw serves as a substrate to produce food (mushrooms) and feed from the mushroom-spent bedding.
Some of the edible fungal species include Pleurotis ostreatus and Volvarella sp.
These can be grown easily and the left-over mycelia from the mushroom bedding
can increase the protein as well as the degradable carbohydrates of the rice straw.
Continuous research on white-rot species has to be done and identification of new
edible fungi species is necessary to explore the potential and characteristics to produce more fruiting bodies for farmers’ harvest as well as achieving optimum feeding quality of the unutilized mushroom bedding.
7.3.3.2 Treatment with Enzymes
The catabolic breakdown of any complex substance into its simplest component is
brought about by chemical reactions and/or by enzymatic processes. Enzymes
involved in the degradation of rice straw are mostly of microbial origin and their
action is very specific to the substrates to be degraded. There are commerciallyavailable fiber-degrading enzymes, such as cellulases, hemicellosi, glucanase, and
xylanases and many others. However, their stability and potency are always affected
by many factors, such as temperature and duration as well as how the enzyme products were processed and packaged. Commercial enzymes used in the livestock feed
industry are generally of fungal (Trichoderma longibrachiatum, Aspergillus niger,
and A. oryzae) or bacterial (Lactobacillus and Staphylococcus species) origins
(Colombatto et al. 2003).
The degradability of cereal straw can be increased through enzyme treatment or
any combination of other treatments (Liu and Ørskov 2000; Wang et al. 2004; Zhu
et al. 2005; Eun et al. 2006; Fazaeli et al. 2006; Rodrigues et al. 2008). Additionally,
using fibrolytic enzymes show improvements in the average daily gain of steers
(Beauchemin et al. 1995), fleece weight and wool production of lambs (Jafari et al.
2005), and milk production of dairy cows (Yang et al. 2000). Enzyme treatment of
rice straw is not yet very popular in raising ruminants under small-scale production
7 Rice Straw-Based Fodder for Ruminants
fungi act on its substrates is dependent on the fungal species. There are species that
prefer to access first on readily degradable carbohydrates, such as simple sugars,
cellulose, and hemicellulose and eventually degrade lignin, thus resulting in a lower
energy supply for ruminants (Karunanadaa and Varga 1996a, b; Jalc 2002). The
length of incubation in treatment of straw is dependent on the white-rot fungi species. During the early stage of incubation, some losses in energy are expected due
to mycelial growth but after a certain time, some white-rot species preferably attack
lignin without degrading cellulose and hemicellulose, thus supplying more degradable energy for the ruminants.
Nowadays, it is important to do research on mycology by selecting fungi species
that prefer to attack lignin rather than the structural carbohydrates or cell walls of
rice straw. Once these species are identified, mycologists can breed even better
strains (Rodrigues et al. 2008). Growing edible mushrooms is a dual purpose of
treating rice straw. As described elsewhere in this book, rice straw serves as a substrate to produce food (mushrooms) and feed from the mushroom-spent bedding.
Some of the edible fungal species include Pleurotis ostreatus and Volvarella sp.
These can be grown easily and the left-over mycelia from the mushroom bedding
can increase the protein as well as the degradable carbohydrates of the rice straw.
Continuous research on white-rot species has to be done and identification of new
edible fungi species is necessary to explore the potential and characteristics to produce more fruiting bodies for farmers’ harvest as well as achieving optimum feeding quality of the unutilized mushroom bedding.
7.3.3.2 Treatment with Enzymes
The catabolic breakdown of any complex substance into its simplest component is
brought about by chemical reactions and/or by enzymatic processes. Enzymes
involved in the degradation of rice straw are mostly of microbial origin and their
action is very specific to the substrates to be degraded. There are commerciallyavailable fiber-degrading enzymes, such as cellulases, hemicellosi, glucanase, and
xylanases and many others. However, their stability and potency are always affected
by many factors, such as temperature and duration as well as how the enzyme products were processed and packaged. Commercial enzymes used in the livestock feed
industry are generally of fungal (Trichoderma longibrachiatum, Aspergillus niger,
and A. oryzae) or bacterial (Lactobacillus and Staphylococcus species) origins
(Colombatto et al. 2003).
The degradability of cereal straw can be increased through enzyme treatment or
any combination of other treatments (Liu and Ørskov 2000; Wang et al. 2004; Zhu
et al. 2005; Eun et al. 2006; Fazaeli et al. 2006; Rodrigues et al. 2008). Additionally,
using fibrolytic enzymes show improvements in the average daily gain of steers
(Beauchemin et al. 1995), fleece weight and wool production of lambs (Jafari et al.
2005), and milk production of dairy cows (Yang et al. 2000). Enzyme treatment of
rice straw is not yet very popular in raising ruminants under small-scale production
7 Rice Straw-Based Fodder for Ruminants