By Daren Redfearn, Mary Drewnoski
Forage production systems include spring and fall grazing of perennial cool-season grasses, summer grazing of warm-season perennial grasses, and winter grazing of corn residues, with annual forages filling forage needs during various grazing periods. Annual forages are used to increase the forage production potential per acre, and reduce the need to rent or purchase pasture, and to modify or expand livestock production systems. Planting date is the most important management factor that affects forage production. Late summer planting reduces fall forage growth potential and these effects carry over into the spring with reduced spring forage production, especially for winter small grains. From a plant perspective it is common to see variable growth or forage production due to planting date and moisture availability.
Nearly all successful integrated crop-livestock systems rely on using perennial grass pastures. Smooth bromegrass, intermediate wheatgrass, and crested wheatgrass are used for spring and fall grazing. In a two-year, on-farm grazing trial in the Nebraska Sandhills, mean average daily gain (ADG) ranged from 1.8 to 2.1 lb/head/day and produced 290 to 409 lb beef/acre. In eastern Nebraska, ‘Lincoln’ smooth bromegrass is the dominant perennial cool-season grass.
Grasses are the biomass producers. In diverse cover crop mixtures, one or two species dominate and three or four will contribute to biomass.
A three-year cattle grazing study showed 14% greater ADG and 13% greater beef gain/acre for cattle grazing ‘Newell’ smooth bromegrass compared with cattle grazing ‘Lincoln’ smooth bromegrass. Likewise, steers grazing intermediate wheatgrass had ADG up to 2.7 lb/head/day and produced up to 656 lb beef/acre with 42 grazing days in eastern Nebraska. Improved native, perennial, warm-season grasses, such as big bluestem, have been developed to supplant smooth bromegrass for summer grazing. A three-year big bluestem grazing study was conducted in eastern Nebraska from 2000 through 2002 with 2.9 lb/head/day ADG for the three years. Beef production averaged 999 lb beef/acre on pastures grazed for 62, 43, and 38 days in 2000, 2001, and 2002, respectively.
Many annual forage options are available, but the planting window and/or the window of forage use narrows these options. Grazing use and desired re-growth versus use for hay, silage, or stockpiled grazing can also impact species selection. Annual forages can be divided into three types:
- cool-season, winter hardy (winter types),
- cool-season, winter sensitive (spring types), and
- warm-season, summer annuals.
The type of annual forage selected should be based on planting date and forage need. Cool-season, winter hardy forages can be planted in fall and used in the early spring. Cool-season, winter-sensitive forages can be planted in spring and used in late spring/early summer or can be planted in late-summer for fall or winter forage.
Warm-season, summer annual forages are planted in late spring/early summer for late summer, fall, or winter forage. Within a type there are differences among species and even within species (varieties) there are differences in growth and productivity. Grasses produce the greatest biomass and are usually the most cost effective annual forage source. However, strategic use of brassicas in a fall-planted mix with cool-season, spring small grains, such as oats, can be cost effective.
Annual forages can be cost effective and fit into some cropping systems. One of the most important drivers of productivity and cost effectiveness of annual forages is planting date. Planting dates outside the recommended planting window are unlikely to result in desired growth. For instance, planting cool-season winter-sensitive annuals like oats in mid-September is likely to result in reduced growth with little return on investment. Using annual forages as a double-crop is not foolproof and can have major challenges. Having realistic expectations of planting date is one of the keys to proper species selection.