By Mark Sulc, Extension Forage Specialist, Department of Horticulture and Crop Science and Bill Weiss, Extension Dairy Specialist, Department of Animal Sciences, The Ohio State University
Many dairy producers are facing a critical forage shortage to feed their herds. Forage stands were damaged across Ohio this past winter, and the wet spring has further deteriorated the few stands that initially appeared they might recover from winter damage. It is now too risky to try to establish new perennial forage stands, with the warmer summer weather coming on. We should wait until August to establish perennial stands. Meanwhile, what options can we consider for growing forage this year?
We are well past the time when cool-season species like oats, triticale, Italian ryegrass, and spring barley can be planted. Sudangrass, sorghum x sudangrass hybrids, pearl millet, and forage sorghum grow rapidly in summer and yield a total of 3.5 to 5 tons of DM with acceptable nutritive value. Forage sorghum can produce up to 8 tons/acre of DM in a single cut in Ohio. For dairy cows, varieties with the brown-midrib (BMR) trait should be planted, as BMR produces forage almost as good as regular corn silage (although lower in starch) with very good fiber digestibility. Variety performance data are available at:
• Kentucky: http://forages.ca.uky.edu/variety_trials (see Annual Grass Report)
Soil temperatures should be at least 60 to 65 degrees F before planting the sorghum species. They can be planted up to late June in northern Ohio and mid-July in central and southern Ohio. For those needing additional forage as soon as possible, sudangrass and sorghum x sudangrass, including the BMR varieties, can be ready for harvest in as little as 40 days at which time up to 2 tons/acre of DM is possible. Additional cuttings are possible thereafter.
In the fall, the sorghum species will have the danger of prussic acid poisoning potential after frost events. Pearl millet is essentially free of prussic acid poisoning potential. Nitrate toxicity is possible with all summer annual grasses and management steps should be taken to reduce that risk under high nitrogen conditions and if the summer becomes very dry. Ensiling reduces risk of both prussic acid and nitrate poisoning.
Teff is a warm-season grass that can be used for hay, silage, or pasture. Soils should be at least 60 to 65 degrees F before planting Teff. The first crop should be ready in 40 to 50 days. It produces 3 to 4 tons/acre of DM over several cuttings and can tolerate both drought-stressed and waterlogged soils. More details on managing this forage can be found in a factsheet from Cornell University (http://nmsp.cals.cornell.edu/publications/factsheets/factsheet24.pdf).
Brassica species can be planted for fall grazing by cattle or sheep. These species contain high moisture content, so they should be used for grazing only. Brassicas have very low fiber and high energy and should be treated more like a concentrate than as forage in diets. For more information on brassicas for forage, see the Penn State factsheet at: http://www.forages.psu.edu/topics/species_variety_trials/species/brassica/index.html.
Seeding Rates and Mixtures
Plant high quality seed of a known variety, which will ensure high germination rate and avoid unpleasant surprises regarding varietal identity and crop characteristics. Table 1 outlines recommended seeding rates and dates for the different annual grasses. Mixtures of summer-annual grasses and legumes, such as field peas and soybeans, are marketed by some seed dealers. The legumes can increase protein content but only in the first harvest because they don’t regrow after cutting. Legumes increase the seed cost, so consider the benefit of including legumes versus supplementing with other protein sources.
Chopping and ensiling or wet wrapping are the best mechanical harvest alternatives for most of the summer annual grasses. Wilting is often recommended; storage and harvest costs are greater; and fermentation quality can be poor with crops less than about 30% DM. Ideally, silage should be left undisturbed for at least two weeks to allow the forage to reach stable fermentation. If forage is needed sooner, consider daily green chopping of forage or wet wrapping individual bales for feeding until the silage is ready. Except for Teff, dry baling the summer annual grasses is a challenge. Grazing is really the only option for the brassicas because of the high moisture content.
Table 1. Guidelines for seeding various annual forages. Ranges for yield and nutritive values are for forages stored as silage, which vary greatly with maturity stage at harvest. Generally for hay, expect lower crude protein (CP) and higher neutral detergent fiber (NDF) concentrations.