Potential of High-Sugar Corn as a Fall and Winter Forage Resource for Grazing Beef Cattle

Abstract Three grazing experiments were conducted to determine the potential of dryland, high sugar (Cargill HS 60A; Cargill, Minneapolis, MN) corn forage for fall and winter grazing. For Trials 1 and 2, two ruminally cannulated steers continuously grazing a 1-ha high-sugar corn pasture during fall and winter were used to collect masticate samples. Masticate N declined (P=0.03) from mid September to mid October, but was not affected (P=0.19) by sampling date in the winter. Masticate fiber steadily increased (P=0.04) from mid November to mid December. Rate of in vitro OM digestion (IVOMD) was least (P=0.04) by the study’s end in both trials; however, extent of IVOMD did not change (P=0.26) in the fall. For Trial 3, 34 pregnant beef cows were allowed to graze either windrowed or standing corn forage during the fall. Leaves and upper and lower stalks were separated from whole corn plant collected from each forage type for chemical and nutrient determination before and during the grazing period. Lower and upper stalks had less (P=0.009) fiber content and greater (P=0.002) in vitro DM digestibility than leaves. Although harvesting method did not affect (P=0.10 to 0.88) nutrient variables, cows grazing standing corn forage had greater (P=0.03) ADG than cows grazing windrowed corn forage. Despite a decline in nutritional quality of high-sugar corn forage as the grazing season progressed, high-sugar corn forage provided a sufficient nutritional base to support BW gain of pregnant beef cows. Grazing windrowed high-sugar corn forage would not be recommended because an undetermined quantity of forage was lost to a windstorm, which might have contributed to a lower ADG for cows grazing the windrowed corn forage.