Grazing Warm Season Annuals
In a perfect world of grazing, your warm season annual, or blend of annuals, would be grazed when the grasses are in boot stage. This is when the quality is highest for most warm season species. However, as you rotationally graze, the paddocks at the end will be far past the boot stage and much poorer quality. There are a few ways to overcome this. One way would be to stagger planting of the warm seasons to allow different paddocks to be at the boot stage when you need them to be. That may help in planning for next year, but what about for what is already growing this year?
Our recommendation would be to start grazing warm season annuals once it reaches at least 24 inches. This allows you to rotationally graze through your stand and hopefully never have livestock reach a past-prime paddock. Another benefit to this method is easing livestock into the high-quality forage that warm seasons provide at boot stage. As they move through paddocks that are increasingly closer to boot stage, it allows the rumen to adjust to this new forage. Switching to warm seasons directly from hay or pasture can be a shock to their system in some cases.
Stubble Height -
Rotational grazing warm season annuals will result in increased utilization of the forage, but leaving an adequate stubble height is key. Sorghum sudangrass and sudangrass can be grazed down to 4-6 inches and still have adequate regrowth for multiple grazing passes. When grazing millet or blends of millet, warm season legumes, and brassicas, maintain a higher stubble height of 8-10 inches in order to have productive regrowth. We know that every grazing move will not be perfect, but it will be beneficial to try to stick to these guidelines for stubble height.
Grazing Schedule -
As you are moving livestock through your warm seasons, be sure to move in a timely manner as they graze. This will help achieve the stubble height goals mentioned above, but also helps avoid concern of nitrates. As plants take up nitrates from the soil, they store some within their tissues. The concentrations of nitrates are high in new growth, drought-stressed plants, as well as the lower portion of the plant’s stem. Keeping livestock moved quickly enough to avoid grazing of the paddock’s regrowth will keep nitrate concerns very low.
Let us know what other questions you have about grazing your summer annuals!