114
presence of adulterants when not properly collected and stored. Nevertheless, rice
straw still remains to be a practical fodder particularly in times of El Nino or in
times of critical periods when sources of fresh fodders are insufficient. In addition,
according to a dairy cow nutrient expert from Israel (Hanan Saggi, Feeding &
Nutrition Director, TH True Milk Group), rice straw is a good feed component if
pretreated properly, particularly when the milk cows are not producing fully.
Rice straw contains higher quantities of potassium (1.58% of DM), calcium
(0.53%), and magnesium (0.24%). But it is low in phosphorus (0.12%), sodium
(0.13%), iron (0.07%), and manganese (0.07%), (Shen et al. 1998). The bioavailability of these minerals is still to be investigated since most of these minerals
are cross-linked to other substances in rice straw in the form of acid-insoluble ash.
The phosphorus (0.02–0.16%) content of rice straw is not sufficient to meet the
required 0.3% for growth and normal fertility of animals (Jackson 1977). However,
its calcium content of 0.4% is considered adequate to meet the daily requirement for
livestock but this does not always hold true. The bioavailability of calcium from rice
straw is important to consider since the report of Nath et al. (1969) showed that
cattle fed with rice straw has a negative calcium balance even though the calcium
content of the straw used in the feeding experiment was apparently adequate. In
similar experiments by Joshi and Talapatra (1968), they have higher positive calcium balances with animals fed with wheat straw and sorghum stover diets than on
rice straw diets, even though the calcium intake on rice straw diets was higher.
According to the authors, when feeding rice straw, it is safe to provide calcium
supplementation to the animals.
7.2.3 Rice Straw Intake by Ruminants
Generally, the quantity of rice straw that the animal can eat each day is limited to
less than 2% of its body weight. According to the report of Devendra (1997), the
amount of rice straw that ruminants can consume can be as high as 1.2 kg DM
100 kg
−1
of live weight day
−1
. The rice straw intake, however, varies among animals
and this is also influenced by the proportion or parts of the rice straw used in the
ration. The intake of rice straw also varies according to the manner in which it is
prepared, processed, and fed to the animals. Physical processing, such as chopping
or the use of chemical or microbiological treatments, considerably improves an animal’s rice straw intake. When offered as is, rice straw intake is lower because it is
bulky or occupies more space in the rumen. The digestibility of the straw is also
affected due to the slow passage rate of ingested straw and its fermentation by
microorganisms in the rumen. Chopping the straw provides more space in the rumen
and allows more entries of microorganisms to ferment the straw’s degradable
components.
D. Aquino et al.
presence of adulterants when not properly collected and stored. Nevertheless, rice
straw still remains to be a practical fodder particularly in times of El Nino or in
times of critical periods when sources of fresh fodders are insufficient. In addition,
according to a dairy cow nutrient expert from Israel (Hanan Saggi, Feeding &
Nutrition Director, TH True Milk Group), rice straw is a good feed component if
pretreated properly, particularly when the milk cows are not producing fully.
Rice straw contains higher quantities of potassium (1.58% of DM), calcium
(0.53%), and magnesium (0.24%). But it is low in phosphorus (0.12%), sodium
(0.13%), iron (0.07%), and manganese (0.07%), (Shen et al. 1998). The bioavailability of these minerals is still to be investigated since most of these minerals
are cross-linked to other substances in rice straw in the form of acid-insoluble ash.
The phosphorus (0.02–0.16%) content of rice straw is not sufficient to meet the
required 0.3% for growth and normal fertility of animals (Jackson 1977). However,
its calcium content of 0.4% is considered adequate to meet the daily requirement for
livestock but this does not always hold true. The bioavailability of calcium from rice
straw is important to consider since the report of Nath et al. (1969) showed that
cattle fed with rice straw has a negative calcium balance even though the calcium
content of the straw used in the feeding experiment was apparently adequate. In
similar experiments by Joshi and Talapatra (1968), they have higher positive calcium balances with animals fed with wheat straw and sorghum stover diets than on
rice straw diets, even though the calcium intake on rice straw diets was higher.
According to the authors, when feeding rice straw, it is safe to provide calcium
supplementation to the animals.
7.2.3 Rice Straw Intake by Ruminants
Generally, the quantity of rice straw that the animal can eat each day is limited to
less than 2% of its body weight. According to the report of Devendra (1997), the
amount of rice straw that ruminants can consume can be as high as 1.2 kg DM
100 kg
−1
of live weight day
−1
. The rice straw intake, however, varies among animals
and this is also influenced by the proportion or parts of the rice straw used in the
ration. The intake of rice straw also varies according to the manner in which it is
prepared, processed, and fed to the animals. Physical processing, such as chopping
or the use of chemical or microbiological treatments, considerably improves an animal’s rice straw intake. When offered as is, rice straw intake is lower because it is
bulky or occupies more space in the rumen. The digestibility of the straw is also
affected due to the slow passage rate of ingested straw and its fermentation by
microorganisms in the rumen. Chopping the straw provides more space in the rumen
and allows more entries of microorganisms to ferment the straw’s degradable
components.
D. Aquino et al.