Summer annual grass grazing is a great tool for livestock operations. While it adds flexibility, management decisions are needed to make it worth the time and cost.
Sorghum-sudangrass (sudex), sudangrass, pearl millet, foxtail millet, and teff are the most commonly used grazing summer annuals.
Brad Schick, University of Nebraska-Lincoln extension educator, offered some advice for utilizing summer annuals in a recent UNL BeefWatch newsletter.
If earlier grazing is desired, sorghums and sudangrasses can be used but only if planted when the soil temperature is above 60°F, which is typically reached in late May to early June.
For millets and teff, a soil temperature of 65 to 70°F is needed. A lower soil temperature causes stunted growth and reduced forage yields. Schick explains that planting in mid-June to late July will have good results, if water is adequate.
Also keep in mind forage availability.
“A good rule to follow is that forage will be ready to graze six to eight weeks after planting,” explains Schick. “To reduce the chance of forage getting ahead of the cattle, stagger plantings of a forage type by two weeks. By staggering, rotational grazing can be implemented and the forage will be grazed more efficiently.”
Although managing the harvest efficiency while grazing is a key factor, mismanagement of grazing timing can cause issues.
Using a short, rotational grazing system is a simple solution. Schick recommends having a minimum of three paddocks per field as it allows time for regrowth. Graze paddocks for seven to 10 days and then allow two to three weeks for regrowth.
Waiting till sorghum-sudangrass reaches 18 to 24 inches tall will avoid prussic acid (cyanide) poisoning, and sudangrass, foxtail, and pearl millet can be grazed at 15 to 20 inches. Leave 6 to 8 inches of stubble following the seven to 10 day rotation for regrowth.
“If choosing between leaving cattle on a paddock for a longer or shorter time, just remember that retaining some leaf area will cause more photosynthesis, and ultimately a faster regrowth,” Schick adds.
A major concern for summer grazing is the possibility of cyanide and nitrate poisoning. Waiting until grasses reach the desirable height and grazing each paddock for the appropriate amount of time will help alleviate the problem.
“Nitrates generally aren’t a concern if forages aren’t grazed too low because the lower one-third of the plant will contain the highest nitrate concentration,” Schick explains.
Under dry conditions, or where soil nitrate levels are thought to be high, it’s always a good practice to test for nitrates before grazing.
Schick recommends planting a few extra acres of summer annuals as part of a drought plan for both grazing and haying. It can also be a back up if growth and regrowth isn’t as productive as planned.
Summer annuals can be used as an option before reseeding an aging alfalfa stand, providing quality forage for haying or grazing.
Kassidy Buse is serving as the 2018 Hay & Forage Grower summer editorial intern. She is from Bridgewater, S.D., and recently graduated from Iowa State University with a degree in animal science. Buse will be attending the University of Nebraska-Lincoln to pursue a master’s degree in ruminant nutrition this fall.
