Straw contains oxalate, silica as anti-nutritional factors. Straw also contains lignin, a complex carbohydrate that is beyond the digestion capacity of animals. Oxalate interferes with calcium absorption from intestine, with magnesium it can form stone in kidney. Excessive silica causes destruction of intestinal tissues and sever bleeding. In order to eliminate these factors, and to increase nutritive value, straw should be treated by following methods;
1. Physical Method: This is a method in which straw is cut into small pieces in order to make easy to feed animals.
Types:
A. Grinding
B. Chopping
2. Chemical Method: This is a method in which straw is mixed with chemicals.
Alkali treatment of straw/ NaOH Treatment: Straw is exposed to alkali, the ester linkage between lignin and cell wall polysaccharides, callulose and hemi-cellulose are hydrolyzed thereby causing the carbohydrates to become more available to micro-organisms in rumen. 1.5% of NaOH soln @ 40-50 ml is sprayed over 1kg of chaffed straw and fed after 2-3 days. Uniform spraying should be taken care. Though mixing can be done if straw is left to soak in water containing same concentration of NaOH for 12-23 hours but straw has to be washed after soaking. NaOH binds the oxalate and silica and converts to non-absrobable form, thus checking their harmful effect. 20-30% moisture in NaOH treated straw imparts greater palatability that helps to increase voluntary intake by animals. It has been reported that alkali treated straw has 40-50% of grater digestibility than untreated straw.
Urea Treatment: In ruminants, dietary nitrogen are converted to VFA (Volatile Fatty Acids) through microbial fermentation and VFA then used for synthesis of essential nutrients required for growth and production. That is for ruminants, feeding non-protein nitrogen (Urea) and high quality protein make no difference. Urea treated straw destroys the strong carbohydrate bonds of lignin and helps its digestion, thereby increasing the nutritive value of straw. 1 kg straw and 1 liter of 1.5-2% urea solution is mixed uniformly and mixed mass is ensiled in a pit or container. The mixed mass can be put inside a plastic sheet as well by air tighten. The treated straw becomes ready for feeding after 14 days. Feeding urea or non-protein nitrogen treated straw to calves is restricted due to lack of proper development of rumen, and same for the non-ruminants as well.
Guidelines for feeding urea treated straw
Digestibility of treated straw increases if given in combination with molasses. There should be casual increase in the amount of treated straw for feeding so that animals become habituated to feed it. Concentration of urea solution can be increased up to 2.5% of more if the animals are well accustomed to digest treated straw.
0 comments:
Post a Comment