How Urea Treatment Fodder Works:
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Urea treatment is one of the simplest, lowest-cost ways to turn poor-quality roughage into feed that can actually sustain your livestock through winter. Straw and mature grass hay on their own often fall short of even maintenance requirements — but treating them with urea can dramatically boost their crude protein content, no extra capital investment required.
Where This Technology Comes From:
Researchers in Northern Europe did the original work on treating crop residues. The preservation of straw (with ammonia), which was damp at the time, was the main reason for the investigation and the improvement of quality was incidental. The possibilities of this became apparent as the technology developed. Farmers widely use ammonia treatment of low-quality fodder across the large grain-producing areas of America and Canada. Uptake of this technology has been slower than expected in Africa. It has fared slightly better in China and India. The main reasons cited for the slow uptake in third world countries was:
- Cost and availability of urea
- Cost and availability of sealing materials
- Labour constraints for gathering straw (by hand) compared to grazing
- Seasonal variation in feed supply
- Benefits are not always obvious to poor farmers
- Transport costs of residues
- Lack of knowledge and training
- Rigid procedures for applying treatment (especially with ammonia gas )
None of these constraints should apply to farmers. With our level of mechanization in the agricultural industry, farmers could easily adopt this ‘new’ technology. Farmers can choose from three sources of ammonia to treat fodder. We decided to use urea treatment because it’s safe, easy to handle, readily available, and free of the other ammonia sources’ drawbacks.
Getting Started With Urea Treatment:
At best rank grass-hay can barely sustain maintenance requirements for dry stock and at worst cereal straw is only good enough for “bedding” material. You can treat these low-quality fodders on-farm, however, with no extra capital expense and very little added cost.
After urea treatment, straw becomes feed that can sustain body weight through winter. Low quality grass will provide the nutritional requirements of lactating sheep and beef cattle after treatment.
Limit how much you include in rations for high-producing dairy cattle, though.
You mix urea with water and spray it onto hay just before wrapping, or inject it into bales after wrapping and reseal them.
What can be achieved?
Urea-treatment (ammoniation) can increase crude protein (CP) content of wheat straw from (4% – 6%) to (12% – 14%) and mature grass hay from (8% – 12%) to (18% – 20%).
Urea treatment can improve digestibility of straws by 5% to 10%, and mature grass hay and maize stover by 10% to 20%. It can also substantially increase voluntary intake of low-quality forage, and combined with higher digestibility, this significantly increases the total energy intake per animal. An added advantage of urea-treatment is the effective preservation of hay and silage with up to 30% moisture.
How does it work?
Combining ammonia (NH3) with carbon dioxide (CO2) makes urea (NO2)2CO.
Mixing urea with water releases the ammonia again. Temperature determines the rate of release. Treatment duration varies from 3 weeks in summer to 7 weeks in winter. Urea solution releases ammonia inside the wrapped bale or tube. In this airtight environment, the ammonia attaches itself to the hay fibers. You can complete urea treatment in 24 hours. Pack hay bales treated with urea-solution into a large airtight container and heat it to 90°C.
Increasing Crude Protein content:
Nitrogen makes up 78 percent of air but is unavailable to most living organisms. In nature, two processes make nitrogen available to plants: lightning, and bacterial action on the roots of legumes and in the rumens of ruminants.
The bacteria in the rumen build the nitrogen into their own bodies to form microbial protein. The bacteria move with the broken-down feed through the four stomachs. In the last stomach, gastric juices (hydrochloric acid) kill them. The animal then digests and absorbs microbial protein the same way as any other protein in the animal’s diet.
Increasing the nitrogen available to rumen bacteria lets them produce more microbial protein for the animal.
In monogastric grazing animals, like horses, bacteria live in the blind gut or ceacum. Microbial protein isn’t available to the animal. The caecum sits too far down the digestive tract for the animal to digest and absorb protein there. You should therefore not feed urea-treated hay to horses.
Preservative:
The ammonia not clinging to the hay acts as a preservative. It excludes oxygen from aerobic decomposing microorganisms like moulds and fungi. Forage can remain covered with ammonia for long periods without problems. Some people recommend leaving the forage uncovered for 3 to 5 days before feeding, to let free ammonia escape. This generally isn’t necessary, but animal acceptance may be poor initially if you don’t air ammoniated bales out before feeding.
Increased digestibility:
Grazing animals derive the vast majority of their energy from plants in the form of carbohydrates. Carbohydrates consist of sugars, starches and fibrous components called cellulose, hemicellulose and lignins.
Animals store excess energy in the form of fat and plants store it as starch, usually in seeds or roots. Dissolved sugars provide the fuel for immediate energy needs of the plant. These two are easily digestible and commonly used by all plant eating animals.
The vast majority of the potential energy in plants, used for grazing, is in the form of cellulose and hemicellulose. Lignin is totally indigestible for animals and provides the structural strength for plants as it grows taller.
Long chains of sugars make up cellulose and hemicellulose, just like starch, but much stronger chemical bonds hold them together.
Ammonia treatment disrupts these chemical linkages in cellulose and hemicellulose and makes it more digestible. Cellulose digestibility also increases as lignified hemicellulose often encases cellulose. Ammonia treatment also changes the physical characteristics of forage making it more pliable and increases its uptake of water (hydration). Hydration rate plays an important role in digestion rate. The faster a forage particle hydrates, the faster the animal can digest it.
Increased intake:
We don’t know whether treatment increases the fodder’s palatability. Faster digestion reduces the time feed takes to process and excrete, leaving room for more intake. Straw and stover are inherently deficient in many vitamins, minerals and trace elements. These deficiencies, especially vitamin A and sulphur, have to be supplemented to optimise animal production, if these feed sources make up a large part of the animal’s rations.
Materials and methods:
Bale tubes or wraps are a huge improvement on the old covered stacks or earth-bunkers used elsewhere in the world — they eliminate ammonia losses from leaks into air or ground. You use large round or square bales in the treatment, placing them in the bale tube or wrapping them as usual. Place the tube out in the sun, since extra heat speeds up the process substantially — black or green plastic will also increase heat inside the tube. Standard bale tubes or bags work best because they’re not as snug-fitting, so ammonia can spread throughout the tube and penetrate bales more easily.
Make urea solution by mixing 10kg of urea (normal fertiliser grade) with 90 litres of cold water until it fully dissolves — a 10% solution by weight. Mixing urea with cold water limits the amount of ammonia gas released during mixing and application.
Remember, ammonia is a toxic gas, so follow proper safety precautions: work in a well-ventilated area, upwind from the application area, and wear goggles and gloves for protection. Keep ample clean water on hand to promptly rinse ammonia off eyes and skin.
Apply the solution to hay at a rate of 40 litres per 100kg of dry matter (DM). In small-scale operations, you can apply it just before wrapping by pouring it into the flat side of a round bale. You can also inject it under pressure through a bale probe (see illustration) into the middle of a bale after wrapping it.
You can make a bale probe by attaching a 1.5-metre length of 15mm-diameter steel pipe to the end of a high-pressure hose. Close off the end of the pipe, sharpen it to a tip, and perforate it with small holes (2–4mm) around that tip. Slide a second, heavier 20–32mm pipe over the first and use it like a waratah rammer to drive the probe into a bale.
In larger operations, you can use the bulk tank of a tractor-mounted weed sprayer to provide injection pressure, then reseal the puncture hole afterward. The advantage of this method is that you can do it later, without slowing the hay contractors down.
Economic Comparison:
To see if the urea treatment of low quality fodder is economically viable, the total costs have to be calculated and compared with the cost of buying in a similar quality (CP content and digestibility) feed. The total cost of treated fodder must include the price of urea (landed on the farm) plus the cost of the plastic tube and wrapping it. If the plastic tube can be used more than once, the cost will be reduced considerably. The cost of urea-treatment must then be added to the value of the untreated forage.
Low quality fodder produced on your farm will save on transport costs and therefore favour treatment. Urea-treatment of low quality forage can easily be done on an average farm without a large investment in additional equipment.
Each farmer or contractor’s situation will vary as to the availability of resources and equipment. Urea-treatment requires no specialized skills or equipment. All equipment that is needed can be found on an average farm or can be hired, for a day, in most rural towns.
Reference site: FAO.org