Travis Peardon, the regional livestock specialist in Outlook, Sask., says few producers were reporting an abundance of hay this year, so he presumes many will be stretching what they do have with straw to get their cows through the winter. That being the case, Peardon recently prepared a short primer on straw-bolstered rations for producers in his area.
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 a winter feeding ration, since straw does have its limitations when used in beef cattle diets.
One of those limitations is that it does not contain enough energy, protein, minerals or vitamins to be the sole source of winter feed. 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 increases intake, but without proper balanced supplementation of energy and protein, problems can appear. Malnutrition, impaction, reduced milk output and lowered conception rates are just the big ones that can hit your herd if you put too much emphasis on straw to carry the cows through.
In most cases, Peardon says, straw has lower energy content than grass hay and quite a bit less digestible protein. Adequate protein levels are necessary to avoid impaction on a straw-rich diet. Rumen microbes need a certain level of crude protein just to maintain their ability to digest fibre. Diets low in protein lead to lower dry matter intakes and lower fibre digestibility.
Due to its higher fibre content, straw takes longer for a cow to digest than it does to digest hay or grain, which results in limited intakes. For example, a 1,200-pound cow may be capable of eating 25 or 30 pounds of straw in a 24-hour period but the microbes in her rumen are only capable of digesting 15 to 18 pounds 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 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 pounds 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 feeding equal portions twice a day. Ionophores can be added or mixed with the concentrate to reduce the incidence of bloat.
Ensure that adequate and balanced levels of the main minerals, calcium, phosphorus, magnesium, potassium and sulphur plus trace minerals copper, zinc, manganese, iodine, cobalt, selenium and vitamins A, D and E are incorporated into the ration. The requirements for minerals change throughout the various stages of pregnancy and lactation.
Developing a balanced ration is the key to successfully feeding straw, Peardon adds.