Here is a start for you - I have hi-lighted the crude protein content comments that you might find interesting. You might also note the compaction issues mentioned at the end:
How much straw can I put in my cow winter ration?
It is important to know that straw is a low energy, and low protein feed. It is not as digestible as hay or greenfeed. Generally, a cow can consume 1.25% of her body weight in straw dry matter (DM). Therefore, a 1400 lb cow could consume 17.5 lbs on a DM basis, or 19.9 lbs on an 'as-fed' basis if the straw was 90% DM (17.5/0.9 = 19.9 lbs, this calculation is to adjust for the moisture content of the straw).
Near the end of gestation, the capacity of the rumen is reduced by about 12 to 13% because the growing calf takes up internal space. Straw-based rations should not be fed at this time and they should not be fed once the cow has started to lactate, save your best quality feed for this time.
What is the best type of straw to feed cattle?
In order of preference, cattle will eat oat straw before barley straw, followed by legume straws, and wheat straw. The quality of legume straw can be extremely variable. The more leaves that are on the stems the better, but it can be very coarse and of poor quality. Coarse stems are also harder to dry down so mould growth may be present.
Cattle also prefer straw that has aged a year or more, it is slightly more palatable and digestible.
Type of Straw Crude protein (CP, %) Total Digestible Nutrients (TDN, %) Calcuim (Ca, %) Phosphorous (P,%) Potassium (K, %)
Oat 4.4 45 0.23 0.06 2.53
Barley 4.4 40 0.30 0.07 2.37
Wheat 3.5 41 0.17 0.05 1.41
Pea 6.4 46.0 0.60 0.19 2.04
Canola 3.9 41.5 0.29 0.18 0.80
Lentil 6.4 46 0.65 0.20 ---
*Adapted from Nutrient Requirements of Beef Cattle NRC 1996 and Saskatchewan Agriculture
Can processing improve the quality of the straw?
Processing does not improve quality but can increase the daily straw intake. However, to prevent malnutrition, impaction, poor conception rates and lower milk production you need to supply adequate amounts of energy, protein, minerals and vitamins.
Treating straw with anhydrous ammonia is one way to improve its crude protein content and digestibility. In a study conducted by Manitoba Agriculture and Food, the crude protein content of barley straw went from 5.1 to 9.4% crude protein when anhydrous ammonia was applied at 3% of the forage dry matter.
Since protein and energy are not adequate what can I add to the ration to meet the cow's requirements?
There are a number of protein and energy supplements that can be used. Provide a good energy source such as cereal grains or good quality pellets or cubes. Protein can be supplemented by feeding canola meal, soybean meal, or beef protein supplements. If you decide to use pellets, request the nutrient analysis including both the protein and energy values of the product.
What are the problems associated with feeding straw-based rations?
Impaction can occur when the weather turns cold as cattle will try to keep warm by increasing their feed intake. Since straw is not easily digested it does not pass quickly enough through the animal, they become impacted and this may result in the death of the animal.
Straw and grain are high in potassium (K), a ration high in K can cause a magnesium deficiency which results in winter tetany, which is similar to grass tetany or milk fever. Limestone or magnesium oxide should be added to the ration to prevent this deficiency.
Enjoy,
Bez>
