NEWS for North Dakotans
Agriculture Communication, North Dakota State University
7 Morrill Hall, Fargo, ND 58105-5665

June 29, 2000

Grazing at Some Growth Stages Damaging to Grass

Allowing livestock to graze at growth stages when grass plants are vulnerable can reduce forage production and in turn reduce livestock production and increase costs, according to a North Dakota State University range scientist.

Lee Manske, range scientist at NDSU=s Dickinson Research Extension Center, says the growth stages where grazing can have detrimental effects on grass occur in early spring before plants have reached the third-leaf stage, and after secondary tillers have started to grow, before they reach the third-leaf stage. Selective heavy fall and winter grazing of late secondary tillers and fall lead tillers of cool-season grasses also can reduce grass growth and herbage production, he says.

Manske says the grazing management strategy that best matches grazing periods with the growth stages of grass is a twice-over rotation system with three to six native range pastures and with spring and fall grazing on cool-season tame grass pastures. This system synchronizes grazing periods with growth stages of grasses to minimize negative effects on grass and provide the most beneficial grazing to livestock.

Research shows that starting seasonlong grazing on native range in mid May results in 45 to 60 percent of potential herbage being lost and never available to grazing livestock, says Manske. Delaying until early to mid July makes nearly all of potential grass production available to grazing livestock, but nutritional quality will be at or below the crude protein levels required by a cow nursing a calf. Delaying past mid July reduces the total grass available because the grass plants are maturing and transferring cell material to the root system.

A starting date between early June and early July has the least negative effect on grass production and the nutritional quality of the available grass will be highest, Manske says. Seasonlong grazing should be delayed until mid June, but rotation systems could start on native range in early June.

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Source: Lee Manske, (701) 483-2076
Editor: Gary Moran, (701) 231-7865