Ammoniated straw can be a handy alternative to expensive forages in drought years.
Should I feed ammoniated straw?
By far the biggest expense for cattlemen in many areas of the country is the cost of supplemental winter feeds. The nutrient needs of a cow in the last trimester of pregnancy can be met with ammoniated wheat straw and proper supplementation.
Straw alone is low in protein, low in digestibility, low in phosphorus and low in Vitamin A. Ammoniating the straw increases the protein content, improves dry-matter digestion and makes the straw more palatable. Supplementing with a vitamin-mineral product will balance the diet.
How do I ammoniate straw?
The ammoniation is done by adding anhydrous ammonia at a rate of 3% total weight or 60 lbs./ton of straw (dry matter basis). Straw that has been round baled can be stacked in a pyramid. The stack must be covered with 6- or 8-mil. black plastic, which comes in 40- by 60-foot rolls.
A pyramid 12 bales long, three bales wide and three bales high works for this size plastic. The plastic must be sealed with soil or sand around the bottom at least 1-ft. wide and 6-in. deep. A trench about 6-in. deep around the stack can be used to tuck the plastic into and then put the soil onto the plastic.
All punctures in the plastic should be repaired with tape. A 1 11/42-in. PVC pipe should run inside the stack for the length of the stack with 11/44- to 11/42-in. holes drilled every 3 or 4 feet and a plug in the end. The other end needs the proper fitting to connect to the anhydrous tank. The tank hose should be calibrated to apply the proper amount of anhydrous to the tonnage of straw in the stack. Two people can cover a stack in a little more than an hour.
What is the resulting quality?
Typically, ammoniation will double the protein content of the straw. Wheat straw generally will be 3-4% protein, and ammoniated straw will be 8-9% protein. This additional protein is non-protein nitrogen (NPN), so care should be taken to ensure that cows do not get urea toxicity. The digestibility of the straw will improve 8-15%. The ammoniated straw is low in calcium and phosphorus and devoid of Vitamin A.
Supplementation of ammoniated straw diets with a 6% calcium, 12% phosphorus mineral supplement with Vitamin A added will balance the diet. The addition of 2 lbs./day of a 14% all-natural protein will further enhance the diet and ensure that protein and energy needs are being met. The addition of protein feeds that contain urea would increase the risk of urea toxicity and therefore should not be used.
How do I feed the treated straw?
Treated straw can be fed in a variety of ways. Cows will usually consume 15-20 lbs./day of the straw when fed alone. Alternate-day feeding of the treated straw and alfalfa or grass hay has been used. Putting the treated straw in self feeders also has been used successfully.
If the cows still have forage available for grazing, self feeders filled with treated straw work well to extend the grazing. Calves may consume 2-3 lbs. of the treated straw/day when offered in self feeders while also being fed 5 lbs. corn and 12 lbs. alfalfa.
As a precaution, cows will not be able to gain condition when on an ammoniated straw diet; therefore, they should be in moderate to good condition going into the winter months if they are going to be fed a strictly straw-based diet.
Are there other precautions?
Urea toxicity is probably the most important thing to watch for when feeding ammoniated straw. Prior to feeding the straw, the stacks should be uncovered to air out for a couple of days to remove any free ammonia. Usually the cows will not eat the straw until the ammonia has evaporated.
Compaction of a cow's rumen could occur from eating a highly indigestible diet. Feeding straw in self feeders or on an every-other-day basis ensures that this is less likely to happen, as cows eat smaller portions of the straw but eat more often. Also, when fed with hay or on alternate days, urea levels should not reach toxic levels even for cows that tend to over consume.
Do not ammoniate higher-quality feeds such as grass hay, as feeds with soluble carbohydrates can become toxic if ammoniated. When handling ammonia, every precaution should be taken to ensure that people treating the straw have been informed of safety measures; anhydrous ammonia is a very hazardous material. Work upwind and wear the proper safety equipment.
What is the total cost?
Ammoniating straw is relatively inexpensive. Black plastic will cost $130-$150/roll and will cover about 35 tons of straw. Anhydrous ammonia will cost $9-$12/ton of treated straw. The treated straw will cost about $50-$60/ton. At a cost of $50/ton for the straw and $147 for a protein supplement, cows can be wintered for less than 70›/day.
Compared to feeding a cow $80/ton hay fed at a rate of 20 lbs., this is a 10›/day savings for every cow. If you own 400 cows, during a three-month period you would save $3,600. If you own your own straw, the savings could be much greater.