High feed and fuel costs have many ranchers eager to put cows out on grass as soon as possible this spring. But range specialists caution that early spring grazing can have negative effects on season-long forage yields of native rangelands.
North Dakota research suggests that grazing native range before the third-leaf stage can reduce carrying capacity by up to 50% in some situations, says Eric Mousel, South Dakota State University extension range livestock production specialist. “The effects of early grazing on improved pastures are likely not as pronounced due to differences in management, climate and level of agronomic inputs. But a reduction of 10-30% in carrying capacity is not out of the question.”
Optimal turnout time depends on the type of vegetation available on native range and pastures, Mousel says. Crested wheatgrass, for example, typically greens up a week to two earlier than most other cool-season forage species. “To avoid season-long reductions in forage yield, grazing managers should wait until crested wheatgrass reaches a height of 4-6” before turning cattle out.”
Turnout on taller species such as smooth bromegrass and intermediate wheatgrass should be delayed until plants reach about 8”. Mousel notes that key forage species on native range, such as western wheatgrass, green needlegrass, etc., typically take longer to develop to the third-leaf stage than do improved species. In most years, turnout on native range should be delayed until key forage species are at least 4-6” tall, which is typically near the end of May or first part of June in South Dakota.
Conversely, warm-season tallgrasses can benefit from light, early season grazing. Research in east-central Nebraska revealed that grazing big bluestem at a light stocking rate in mid-May can improve utilization later in the grazing season without reducing season-long yield. However, those species still shouldn’t be grazed until they reach the third-leaf stage, or about 10” in height, says Mousel.