Grazing sudangrass, pearl millet and sorghum hydrids update
August 1, 2011
Summer annual grasses planted this spring soon could be ready to graze. In a moment I’ll quickly review some grazing guidelines to help you avoid any potential hazards or problems.
Most of the sudangrass and sorghum-sudan hybrids planted this spring will be ready to graze soon, but they contain a compound called prussic acid that is potentially poisonous. Prussic acid is nothing to fear, though, as long as you use a few precautions to avoid problems.
Most importantly, do not turn hungry animals into sudangrass or sorghum-sudan pastures. They may eat so rapidly that they could get a quick overdose of prussic acid.
Secondly, since the highest concentration of prussic acid is in new shoots, let the grass get a little growth on it before grazing to help dilute out the prussic acid. Begin grazing sudangrass at about 18 inches in height. Since sorghum-sudan hybrids usually contain a little more prussic acid, wait until they are 20 to 24 inches tall before grazing. If you planted pearl millet these grazing precautions aren’t needed because it does not contain prussic acid. So you can let your animals graze pearl millet when it reaches 12 to 15 inches tall.
Summer annual grasses respond best to a simple, rotational grazing system. Divide fields into three or more smaller paddocks of a size that permits your animals to graze a paddock down to about eight or so inches of leafy stubble within 7 to 10 days. Repeat this procedure with all paddocks. If some grass gets too tall, either cut it for hay or rotate animals more quickly so grass doesn’t head out.
A well-planned start, a good rotation, and a little rain will give you good pasture from these grasses all the rest of the summer.