Post on 01-Dec-2015
Urea treatment of wheat Straw
Wheat Straw as animal feed
poor quality dry roughagegiven to the cattle (ruminants) as fillers
because straw hardly has any feeding value
highly deficient in minerals, vitamins, proteins
DCP=0.0; TDN=48.3
Digestive utilisation of straw Straw has Parietal carbohydrates in
their cell wall The microbes in the rumen colonise
the ingested feed particles The cellulolytic strains partially
degrade (or hydrolyse) the cellulose and the hemicelluloses through using the enzyme, cellulase
The degradation of the cell walls requires the microbes to attach themselves to the feed particles so that the enzymes can penetrate inside the fibrous structures, hence the need for the microflora which secretes these enzymes.
But wheat straw shows a high proportion of lignified walls, incrusted with lignin in a very complex manner
the lignified walls resist for a long time the microbial degradation and the peristatic mastication (of rumination) and they are thus only digested slowly.
Conditions for good digestive utilisation In order for the cellulolytic fermentation
process to be correctly carried out, the microorganisms in the rumen must be able to find• the nutritive elements which they need for
self development and to enable them to degrade (through cellulolysis) the polysaccharides of the cell walls of the wheat straw
the physical and chemical conditions for maintenance of good cellulolysis.
Importance of wheat straw
fibrous in nature Generally low in digestibility produce laxative effect after absorbing
more water from intestine. cheap and readily available source of
energy to the animal body
Need for urea treatment of straw
To increase nutritive value (protein source as in rumen microorganism convert nitrogen into protein) of wheat straw
To increase digestibility of
wheat straw
Urea treatment: principle CO (NH2)2 + H2O -------> 2 NH3 +
CO2 urease
urea +water ammonia+carbonic gas Once hydrolysis is completed one molecule of urea(i.e. 60 g) generates two
molecules of ammonia (i.e. 34 g). 5 kg of urea thus allows production of 2.83 kg
of ammonia.
Urea treatment : process Three ways of urea treatment
– Treating small quantities within walled enclosures
– Treatment of large amounts of forage in stacks or heaps
– the use of urine
Convential method of urea treatment Weigh the urea about 4% of straw. Prepare the urea solution (30-50%) Sprinkle the urea solution on wheat
straw Press the straw and seal in the plastic
bag or silo or pit or trench
Procedure(new method)
Weigh the required amount of urea (4% of straw)
Mix it with double the amount of farm manure (as urease source)
30% moisture by adding water Putting this mixture in a bag, piling the
straw on the bag, again moistening the straw with water (50% of straw)
Incubating this material for a month under the cover of plastic sheet or mud plaster.
Difference from conventional method
Three steps are eliminated preparation of urea solution sprinkling of solution on straw pressing the straw during treatment
process
Result in labour saving upto 55%
However, efficiency is 30% less than the conventional urea treatment method
Preparation of urea treated straw
Urea treatment : Advantages It acts in just the same way on the
vegetal matter as if anhydrous ammonia is used:– dissolving the parietal carbohydrates
(mainly the hemicelluloses)
– swelling the vegetal matter in an aqueous environment, so easing access by the rumen's cellulolytic microorganisms
– reducing the physical strength of the cells, so easing mastication by the animal and digestion by the microbes,
– enriching the forage in nitrogen, as is also the case if anhydrous ammonia is used.
Key success factors for urea treatment Practical conditions affecting successful
treatment include the:– presence of urease– application rate of urea– moisture content– ambient temperature – the length of the treatment period– the degree of hermetic sealing achieved
during the treatment– the quality of the wheat straw to be treated
THANKS