Spring Grazing Management: When Should I Turn Out the Cows?
By Tom Gervais, USDA-NRCS Grazing Specialist
Even during a relatively mild winter like the one we’ve been having it can be really tempting to turn your livestock onto pasture as soon as the snow melts and you start to see a little green. Most beef cattle (or other livestock) have been on stored forages since sometime last fall, and operators of early spring calving herds usually want to get the calves off the calving area and onto a nice clean pasture as soon as possible.
Luckily, in many parts of Minnesota our cattle are grazing cool season perennial forages, which given somewhat normal temperatures, grow pretty darn quickly once they break dormancy in spring. Due to this early growth activity you’ll see a fair amount of green grass somewhere around the beginning to mid-May.
But while turning out livestock as early as possible might be a good thing in terms of getting animals on clean pasture and saving dwindling hay supplies, is early to mid-May a good time to start grazing from the perspective of forage health and productivity? There’s a fair bit of evidence that shows that it may not be.
When grass begins to grow in early spring, the energy for growth generally comes from stored carbohydrates in the roots and crowns (bases) of the plant. Once the plant grows for a little while and grows some significant green leaf area, then energy for growth comes from the process of photosynthesis. If a plant is grazed or harvested without having enough leaf material available to utilize photosynthesis for regrowth, then that plant has to rely again on energy reserves to regrow. After a couple of cycles of utilizing energy reserves for growth, the plant cannot grow efficiently and may become unproductive or stunted for the rest of the growing season. Delaying turnout can help avoid this repeated grazing of short plants which are putting a bunch of stored energy into growth.
If you can allow forages to grow until they develop 3 or 4 leaves (4-8 inches for most cool season grass
plants) prior to grazing, it’s likely that they will have a good jump start on a productive growing season. This extra top growth will also result in extra root growth that can reach additional nutrients and water deeper in the soil profile: a big help later in the summer when the first couple inches of topsoil start to dry out.
2015 was a pretty good year for growing stored feed. So if you have a little hay left over this spring, consider delaying turnout until the forages are up and running, even if it’s two or three weeks later than your typical turnout time. Hopefully you’ll reap some benefits by producing more forage during the summer.