ANN 111: Principles of Animal Nutrition and Feed Technology (2+1)

CHEMICAL TREATMENT

Acid treatment:

• Straw is soaked in dilute acids for a specified period of time, washed with water drained and fed to the animals.
• Not popular due to the corrosive action of acids.
• Causes rupture of ligno celluosic bonds and makes cellulose available for microbial action.

Alkali treatment:

• Straw is treated with NaOH, NH₄OH, CaOH, KOH, Urea.
• When straw is exposed to the alkali the ester linkages between lignin and cellulose / hemicellulose are hydrolysed causing the cellulose / hemicellulose to be available for digestion by microbes.

NaOH treatment:

• Beckman process:
  • Straw is soaked for 1-2 days in dilute solution of NaOH (15-30 g / litre), washed to remove excess alkali and fed to the animals.
• Dry method:
  •  Straw is chopped and sprayed with NaOH 300g/ litre (170 litre / tonne of straw)

Ammonia treatment:

• Anhydrous form or concentrated solution is used – 30 to 35 kg/ tonne of straw.
• Straw is stacked, ammonia solution is sprayed over the straw, kept covered for 20 days and then fed to the animals.
• This method not only increases the digestability of the straw it also increases the nitrogen content of it.
• Disadvantage – On opening the stack most of the ammonia is lost by volatilization.
• Sometimes there is formation of toxic imidazoles from reactions between ammonia and sugars leads to dementia (Bovine bonkers)

Procedure for preparing Urea Enriched Paddy Straw:

Required Materials:

• Paddy straw - 100 kg.
• Urea - 4 kg.
• Water (Clean) - 65 litres
• Spinkler

Procedure:

To enrich 100 kg of paddy straw

• Dissolve 4 kg urea in 65 litres of water
• Spread a polythene sheet/Gunny bag on the floor. Initially spread 5 kg of paddy straw in layers.
• Using the sprinkler, sprinkle the prepared urea solution over the paddy straw ensuing that all the paddy straw is wet by it.
• Similarly spread another layer of paddy straw over the first layer and repeat the sprinkling of urea solution.
• Repeat the spreading and sprinkling for the entire 100 kg of paddy straw and heap it and cover the straw with polythene sheets to prevent the escape of ammonia liberated from urea. This step facilitates the breakage of lignocellulose bond by ammonia thereby releasing cellulose from lingin bondage for digestion and utilisation.
• After 21 days the urea treated paddy straw is ready for feeding.

Click to view animation 

Advantages:

• TDN increased from 45 to 60%.
• CP increased from 2% to 10%.
• Palatability increased, therefore feed intake increases.

Feeding Urea treated Paddy Straw:

• It is advisable to feed the urea treated Paddy Straw for calves above 6 months of age
• Adaptation period is required. The same precautions adopted when feeding NPN substances are to be followed.
• The urea enriched paddy straw, may be left in the open for 5 minutes prior to feeding in order to remove the pungent odour of urea.