With few producers reporting an abundance of hay this year many will be stretching these supplies out with straw in their daily rations. Straw can make up a large portion of the ration when hay is in shortage as long as it is accompanied with a concentrate such as oats, barley or grain screenings pellets. It is important to plan an adequate ration as straw does have its limitations when used to feed beef cattle.
Straw does not contain adequate levels of energy, protein, minerals or vitamins to winter a cow. Cows cannot eat and digest enough straw to meet their nutritional requirements. Since straw is digested at a slower rate than hay, cows consume less straw than hay on a daily basis. Grinding or processing straw will increase intakes, but without proper and balanced supplementation of energy and protein, problems such as malnutrition, impaction, reduced milk output and lowered conception rates can result.
In most instances, straw has a lower energy content than grass hay and is very low in digestible protein. Adequate protein levels in a straw diet are necessary to avoid impaction. Rumen microbes require a certain level of crude protein just to maintain their important function of fiber digestion. Diets low in protein lead to lower dry matter intakes and lower fiber digestibility.
Due to straw's higher fiber content, it takes longer for a cow to digest straw than it does to digest hay or grain. This poses the problem of limited intakes. For example: a 1,200 lb. cow may be capable of eating 25 or 30 lb. of straw in a 24 hour period. The microbes in a cow's rumen are only capable of digesting 15 to 18 lb. of straw in that same time period. Impaction can and does occur.
Feeding limited amounts of hay, even poor to medium quality hay, will improve any straw ration. The cheapest source of protein will likely be from alfalfa or alfalfa-grass hay. It is advisable to feed cows hay instead of straw starting at least six weeks prior to calving and throughout the lactation period (until the cows are turned out to spring pasture).
A mature cow can safely consume about eight to nine lb. of concentrate such as grain or pelleted screenings at one feeding. If the level of concentrate being fed each day exceeds that amount, consider dividing the concentrate and feed equal portions twice per day. Ionophores may be added or mixed with the concentrate to reduce the incidence of bloat.
Ensure that adequate and balanced levels of minerals (calcium, phosphorus, magnesium, potassium and sulfur), trace minerals (copper, zinc, manganese, iodine, cobalt, selenium) and vitamins A, D and E are incorporated into the ration. These requirements change throughout the various stages of pregnancy and lactation.
Developing a balanced ration is the key to success when feeding straw. It is important to understand straws limitations in a daily ration. A little planning can go a long way in making straw stretch out other higher quality feed sources.