Expert says producers should make decisions on pasture readiness in the spring based on plants’ growth stage rather than height
The grazing strategies ranchers use in the first five to seven weeks of the growing season will determine pasture condition for the rest of the season, says grazing guru Jim Gerrish.
The Idaho grazing consultant said putting cattle out to pasture before the forage is ready to sustain grazing can have long-term effects. However, providing stored feed to cattle is two to three times as expensive as feeding via grazing, so there is great incentive to get cattle onto grass as soon as possible each spring.
Gerrish warned against gauging pasture readiness by the height of grass. The most important thing is growth stage of the plants and their physiological age. Ideally, grazing begins when plants are in phase two of their three-phase growth stage, that being the three- to five-leaf stage.
With managed grazing, the idea is to keep as many acres in phase two for as many days of the year as possible.
“The growing season and the grazing season are two completely different things,” Gerrish told a recent webinar sponsored in part by the Foothills Forage and Grazing Association.
“How much grazing impact can we put on plants in the spring and still expect them to be productive? Six weeks at nominal stocking rate on many cool season and native warm season species in many different environments, that will result in 30 to 50 percent loss of production for the remainder of the year. That’s a pretty significant consideration.”
There is a big difference between overgrazing and overstocking, said Gerrish. Overgrazing results when cattle are allowed to bite plants that are in a negative carbohydrate status. This can occur when cattle stay on one pasture for too long or are returned to a pasture too soon after leaving it.
“It isn’t a matter of the number of animals out there near as much as it is the period of time that they’re allowed to be out there,” he said.
“Overstocking is a chronic ranch-wide problem where we simply have more animals than the resource will bear. That is a correction that has to be done by reducing animal numbers.”
Thus overgrazing can occur even if a pasture is under-stocked.
As pasture managers seek to extend the grazing season, Gerrish advised them to keep areas of high-fibre dormant feed for use in spring in combination with new grass.
New green growth in spring is high in protein and low in fibre, so animals can become energy deficient if eating it exclusively. Giving access to dormant older growth as well as new grass allows cattle to balance their diets.
“That is an important strategy in the spring of the year to get your pastures into good growing condition and maintain healthy rumen function in your livestock.”
As well, early season grazing in cool-season grasses should aim to eliminate seed head production in the first growth cycle. That will improve forage quality later in the season.
Gerrish said grasses tend to have their peak yield in spring so they will dominate the sward if left unchecked. Minimizing early seed head growth improves the opportunity for forbs, legumes and secondary grasses to develop, improving the pasture diversity and feed availability.
Arid and semi-arid areas, like the Prairies, are easily subject to range degradation if management is poor. He noted areas of Idaho, excessively grazed by sheep 70 to 100 years ago, have still not recovered.
“Until we have that full understanding that overgrazing and land degradation is a time function, and it’s because the animals are in the same place for too many days at a time, we will never correct these kind of problems,” said Gerrish.
“You can reduce, reduce, reduce the stocking rate, and the preferred grazing sites will always be hit harder as we extend the time that we allow animals to be in the pasture.”
He recommended taking regular pasture inventory to determine what is available that day, what can be expected in the future, whether inventory is increasing or decreasing and to assess how management is affecting supply.