Timing is everything when it comes to getting the most out of pastures. According to Dr. John Jennings, University of Arkansas Extension forage specialist, after grasses emerge from dormancy they pass through three growth phases: early greenup in the spring or the summer, depending on the type of forage it is; the early, leafy vegetative growth phase; and maturity, as the grass moves into the reproductive phase where stems and seed heads are produced.
That’s also when there’s less nutritive value to the pound, but whether producers should limit the cattle during different phases, Jennings told Ozarks Farm & Neighbor, depends on what they’re trying to do with the field. “For instance,” he said, “during early greenup in early April when the fescue is starting to grow fairly fast, if you need to have good vegetative growth 30 days later you may want to put cattle on that pasture, graze it down fairly short by mid-April, and then pull off of that pasture. That regrowth will come back 30 days later, and be much more vegetative with fewer seed heads, than if you had left that pasture alone.”
On the other hand, if the producer plans to harvest a hay crop, cattle should be left off the pasture so the grass can accumulate. Yet another management option arises on a field where ryegrass has been interseeded with bermudagrass. “As long as that ryegrass is rapidly growing through April,” Jennings said, “we want to rotationally graze that and not graze it all the way to the ground – leave a good stubble of 3-4 inches each time we pull the cattle out to go to the next paddock, so it will grow back faster.” When the ryegrass stops growing in mid-to-late May, send the cattle back in to graze it down and take the canopy off the bermudagrass, which will grow out as the weather warms up.
Dr. Rob Kallenbach, University of Missouri Extension forage specialist, said the nutritional quality of tall fescue can be measured by the number of leaves on the tillers. “You’ll find that very rarely are there more than three live leaves on a single tiller,” Kallenbach told OFN. “If we graze the field when all of the plants just have one leaf on a tiller, it’s too early, and if they all have more than three leaves we’ve missed it. So we like to graze when there are between two and three live leaves on a tiller.” For most of the year, cool-season grasses will be about 8 inches tall when they reach this stage; he recommended removing the stock when they’ve grazed the grass down to about 3 inches of stubble, leaving enough leaf material so the plants can regrow rapidly.
At the three leaf stage, cool-season grasses have the maximum carbohydrates for nutritional value. Kallenbach said the only reasons for letting a field get beyond that point would be to allow a really thin stand to go to seed, or with the intention of harvesting a field to sell as seed.
It was a poor spring this year for early season grass; Kallenbach said production was down from normal by about 50 percent. “Reproductive growth is governed more by day length than it is temperature; that is, stems are produced on plants based on how long the days are, so that occurs whether it’s cool or dry or wet or hot – they come out the same time each year,” he explained. “When we get a spring like this, we get a lot less leaf growth while stems are being produced, so the hay that’s being produced this year is a shorter crop, and the crop has more stem in it than normal.”
