Summer Annuals

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cows grazing in field

As we head into August, the summer heat continues to beat down, causing a loss of productivity in our pastures. Often called the “summer slump”, this period can prove problematic for livestock operations that rely on pasture forages. Many pastures in this region are based on a cool-season forage, like fescue or orchardgrass. These grasses have a peak of productivity in the cooler months of April through May and again around October. This leaves a gap in forage growth and production during the hotter months of June, July, and August. In order to graze during this time, alternative forage options should be considered. Summer annuals, such as sorghum-sudangrass or pearl millet, are popular alternatives for this region because they handle the heat well and are drought tolerant.

Pearl millet is a popular choice for livestock producers. It has a higher leaf to stem ratio, making it more palatable for animals. However, it is typically lower yielding than sorghum-sudan hybrids. It does well in both a grazing and hay setting. Dwarf varieties, which grow less than four feet, tend to be a better fit for grazing and hay since it has smaller stalks while still having the same number of leaves as the larger varieties. It should be allowed to grow to 14-24 inches before being grazed and animals should be removed when the stubble height is 6-8 inches in order to maximize tillering and regrowth. Additionally, pearl millet does not produce prussic acid, which is poisonous to livestock, making it a safer alternative.

Sorghum-sudan hybrids are typically higher yielding than pearl millet and are very fast growing. The Brown Mid Rib, or BMR, varieties are more palatable to animals. As the name suggests, these varieties have a brown colored rib down the center of the leaf and are more digestible due to the lower amounts of lignin in the plant. These can be grazed once it reaches 18-30 inches and should be grazed down to 8 inches within 10 days. This ensures the best regrowth. The field can be clipped to this height after grazing to reach a more uniform height throughout the field. Prussic acid poisoning can be a concern with this forage, therefore care should be taken to not graze animals on a field that has been drought stressed or over-fertilized with nitrogen.

Many factors should be taken into consideration when deciding if summer annuals should be incorporated into your grazing schedule. N.C. Cooperative Extension, in conjunction with Union County Soil and Water Conservation District, is holding a forage field day on Aug 22, 2019, from 6–8 p.m. The program will cover summer annuals and will highlight the summer annual variety demonstration plot here in Union County. For more information and to register, please call our office at 704-283-3742. Dinner is provided so please RSVP by August 21.