Evaluation of cool-season perennial forage varieties as monocultures and legume–grass binary mixtures under intensive grazing

Abstract

In Canada, new forage varieties need not undergo grazing trials before registration and sale. To evaluate the effect of grazing, six cool-season species including meadow bromegrass (Bromus riparius Rehmann), orchardgrass (Dactylis glomerata L.), sainfoin (Onobrychis viciifoila Scop.), and three alfalfa varieties (Medicago sativa L.) were established in monocultures and grass–legume binary mixtures in Saskatchewan, Canada. Forage treatments were randomly established within each of three 3.5 ha paddock replicates. In Year 1, 69 Bos taurus crossbred steers, and in Year 2, 149 steers were homogenously allocated to the three paddocks for the grazing trials. Alfalfa monocultures had the greatest (p < 0.05) pre-graze forage yields and crude protein content. Leaf area index was greater in alfalfa monocultures than in all other treatments (p < 0.01). Etiolated growth differed (p < 0.05) among binary mixtures but not monocultures. Alfalfa monoculture stands were preferred over grass monocultures and most grass–legume mixtures, and sainfoin was avoided relative to alfalfa. Killarney orchardgrass was the least productive and least preferred among forages evaluated. In summary, alfalfa monocultures had greater (p < 0.05) forage yields and quality than sainfoin monocultures, grass–legume binary mixtures, or grass monocultures.