Cool-season annual grass species include small cereal grains such as rye, oats, wheat, triticale or barley. While some of these are typically thought of being planted in the fall, they can also be planted in early spring, allowing for late spring to early summer grazing.
Once the cool-season annual has been grazed or removed as silage or hay, warm-season annuals can be planted in the late spring or early summer. Most common warm-season species for grazing include sudangrass, pearl millet and sorghum-sudangrass.
Warm-season annuals provide a mid- to late-summer grazing opportunity, which coincides with mid-summer slumps in our standard cool-season pastures. If planted early enough in the year, there is an opportunity for regrowth. Likewise, warm-season annuals planted in the summer are a great opportunity for stockpiling and grazing in the fall, allowing pastures to recover before turnout on crop residue.
Of course, moisture levels and temperature impact success, but typically, 30 to 45 days post-planting, annuals will be ready to graze. Especially with tall warm-season annuals, forage waste due to trampling can be high, so implementing strip grazing management can help minimize waste.
However, the last paddocks cows gain access to may become mature, and forage quality starts to diminish when strip grazing. Therefore, staggering plant dates can help keep forage vegetative and allow for more efficient forage utilization.
High nitrates or prussic acid may be a concern when grazing annual forages, so timing of grazing is important. It’s recommended sudangrass be at least 15 inches tall prior to grazing and sorghum-sudangrass be at least 18 inches tall. The risk of prussic acid poisoning in pearl millet is low. 
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Erika Lundy
- Extension Beef Program Specialist
- Iowa Beef Center - Iowa State University
- Email Erika Lundy
