Context: Recently, Punjab government has proposed to use the paddy crop residue as fodder for animals, especially cattle.

• Punjab is producing over 20 million tonnes of paddy straw every year, most of which is burnt in fields by farmers, leading to widespread air pollution that even spreads to neighbouring states.

Facts on the paddy straw in Punjab

• Nearly 30.4 per cent of rice straw is used for animal feed in Southeast Asia, Mongolia and China.
• 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.
• If all of it is burnt in fields, it 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.
• Nutritional value: 10 lakh tonnes of crude protein (CP), 3 lakh tonnes of digestible crude protein (DCP), 80 lakh tonnes of total digestible nutrients (TDN) and phosphorous.

Can animals be fed paddy straw directly?

• 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.

Two methods of treatments recommended before feeding paddy straw to animals:
1. Urea-only treatment:

• 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), resulting in rise of stack temperature, which facilitates the penetration of ammonia in the cell wall, resulting 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.

2. Urea plus molasses treatment

• Also called “Urea-Molasses impregnated straw”.
• It involves treating paddy straw with urea and molasses. Urea and molasses mixed with water. Then it is mixed with chaffed paddy straw and fed to animals on same day.
• This treated straw along with mineral mixture and salt makes up a maintenance ration for non-producing animals.
• However, maintenance of body weight in animals, paddy straw alone is not sufficient. Minerals and green fodder supplementation are required.

Potential harmful effects of silica, oxalates and selenium
Silica: Intake of siliceous forages has been associated with urinary siliceous calculi in drier regions where water may be limited.

• It commonly formed in sheep and cattle.
• Oxalates are broken down in the rumen to carbonates and bicarbonates, absorbed, and then excreted in the urine. The pH of water extracts of rice straw is about 8 and that of urine from stock-fed rice straw as high as 9.
• The high oxalate content has been implicated in the greater need for calcium supplementation.
• High selenium (0.5 to 4.5 %) content which can cause a serious health problem in dairy animals.