Review: The composition and availability of straw and chaff from small grain cereals for beef cattle in western Canada

Small cereal grain residues are heterogeneous feeds consisting of several botanical fractions: chaff, grain, leaf blade, leaf sheath, internode and node. These parts vary in composition, digestibility, resistance to comminution, intake potential and energy availability. Large differences in the nutritional quality of straw and chaff may occur from year to year and between locations due to effects of environmental conditions on botanical composition and cell anatomy. Stage of maturity, harvest method and weathering will influence composition and quality of the most nutritious parts of cereal residues, the leaf and chaff. In addition, cultivars and species differ in the proportion, anatomy and digestibility of botanical fractions. As a result, the quality of crop residues is highly variable with an economic value that is difficult to accurately assess. Cereal straw and chaff are of low economic value as they are low in nutritive value, where nutritive value is the product of nutrient intake, digestibility, and efficiency of use. However, due to availability, cereal crop residues have the potential to be a substantial feed resource for beef cows. Previous reviews have not focused on straw and chaff nutrition research relevant to use by beef cattle in western Canada. This review includes discussions on yield and nutritive value with a focus on identifying information deficiencies, including the lack of detailed production statistics for determining residue yields on a regional bases and the need for more detailed nutrient composition to update regional feed data bases for western Canada.