Paddy Straw as Cattle Feed

Q Why is it in News ?

A Punjab has now proposed to use the paddy crop residue as fodder for animals, especially cattle.

Q Why such a move?

A 

• In Punjab, the total availability of paddy straw is about 20 million tones per annum.
• The total value of this straw is Rs 400 crore approx., calculated on an average rate of Rs 200/quintal. Almost all of it is burnt in fields.
• This accounts for economic loss apart from the loss of 77,000 tonnes of nitrogen and 5.6 million tonnes of Total Digestible Nutrients (TDN) which could be used for ruminant production.
• Also nearly 30.4 per cent of rice straw is used for animal feed in Southeast Asia, Mongolia and China.

Q What are contents of paddy straw ?

A 

• High silica and lignin content reduces its digestive properties.
• Higher selenium content in paddy straw also limits its use as fodder in animals as compared to wheat straw.
• However, if given in moderate quantities (up to 5 kg per animal per day), selenium poses no health hazard to the animal.
• Paddy straw also contains oxalates (2-2.5%) which leads to calcium deficiency so mineral mixture should always be fed along with the straw.

Q How can paddy straw be made suitable for animal feed ?

A Treatments for feeding paddy straw to animals

• Paddy Straw cannot be directly fed to animals. It has to undergo some treatments.
• Two of them are: Urea-only treatment and urea plus molasses treatment.

[A] Urea treatment of paddy straw

• 14 kg of urea is dissolved in 200 litres water and spray on chopped paddy straw.
• The fermented straws have soft texture with 6.0-8.0 per cent crude protein, 3.0-4.0 percent DCP and 55-60 per cent TDN.
• This involves a combination of physical, chemical and biological treatments.
• The paddy straw is chaffed and moistened (physical) with urea solution (chemical).
• The breakdown of urea release ammonia gas, a part of which is utilised by microbes (biological) for their proliferation (enriching the straw with microbial protein).
• This in turn results in breakage of lingo-cellulosic bonds making cellulose and hemi-cellulose assessable for utilization by microbes in the rumen.
• The digestibility of cellulose increases from 40-45% in untreated paddy straw to 70-75 per cent in fermented wheat straw.

[B] Urea plus molasses treatment

• Also called “Urea-Molasses impregnated straw”, this method involves treating paddy straw with urea and molasses.
• Urea 1 kg and molasses 3 kg was mixed thoroughly and mixed with water 10 kg. This is mixed with chaffed paddy straw and fed to animals on same day.
• The experts however clarify that for maintenance of body weight in animals, paddy straw alone is not sufficient.
• Minerals and green fodder supplementation is required.

Q How does the nutritional value of paddy straw increase after urea treatment?

A 

• The TDN values in urea treated paddy straw increased manifold as compared to untreated straw.
• Crude protein (CP) increased from 4.5% to 8%, digestible crude protein (DCP) from 1.5% to 4% and total digestible nutrients (TDN) from 40% to 55%.
• The feeding of urea treated straw (6 kg/day) to lactating buffaloes giving about 10 kg milk/day can result in saving about 60 per cent of oilseed cake in the ration.
• Feeding of paddy straw should be mixed with berseem, cowpea or Lucerne as it forms a maintenance ration.
• The straw should be fed with concentrate mixture and additional DCP or limestone should be given to the animals to reduce the effect of oxalates.
• Oxalates also interfere in carbohydrate metabolism perhaps due to non-availability of calcium as cofactor.

Q What are the potentially harmful effects?

• The intake of siliceous forages has been associated with urinary siliceous calculi in drier regions where water may be limited.
• There have been no definitive studies in India, but urinary calculi are associated with rice straw consumption.
• It has high selenium (0.5 to 4.5 % ) content which can cause serious health problems in dairy animals.