Effects of a polycrop or oat monocrop on forage yield, nutritive value, utilization, and weaned steer performance for winter swath grazing

This 3-year study assessed winter beef cattle performance swath-grazing either (i) polycrop system (PC) comprising CDC-SO1 oat ( Avena sativa L.), Golden Globe turnip ( Brassica rapa L.), Hunter turnip ( Brassica rapa L.), Goliath forage rape ( Brassica napus L.), and 4010 forage pea ( Pisum sativum L.) or (ii) a monocrop system (oats monocrop system, OMC; CDC-SO1 oats). Other evaluations included dry matter (DM) yield at oat’s soft dough (SD) and hard dough (HD) stages, nutrient composition, estimated DM intake and economics. A 12 ha field was subdivided into six, 2 ha paddocks. Each paddock was assigned to PC or OMC treatment. Crossbred beef steers’ initial body weight (BW) averaged 267 ± 14.1 kg at allocation to each forage system. The OMC had a greater ( P < 0.01) DM yield than PC. Compared to the SD stage, neutral detergent fibre (NDF) at HD decreased ( P = 0.03) by 5.9%, starch increased ( P < 0.01) by 36.8%, and total digestible nutrients increased ( P = 0.01) by 2.5%. The average daily gains of steers grazing the OMC or PC were similar ( P = 0.47). Swath cost per kg steer gain was lower ( P = 0.04) for OMC ($0.62 kg −1 ) than PC ($0.91 kg −1 ). The PC retained higher post-graze swath crude protein and lower NDF than OMC.