Supplemental dairy forage options

Q. What are some options for supplemental forage production for dairy cattle?

A. Short-season forages provide dairy producers an excellent opportunity to supplement forage supplies when needed during specific seasons, while adding flexibility to forage production systems. Warm-season or cool-season annual species can fit into a double-cropping or triple cropping system, or integrated into cropping rotations, depending on length of the growing season. The options of species to use depends on the time of seeding, length of growing season, and forage production goals.

Q. What options are there when planting late spring to early summer?

A. Short-season annual forages can be planted following a spring harvest of a perennial forage stand that is being discontinued due to thinning plant stand or winter injury. Annual forages can also be double-cropped after a winter cereal species harvested as forage in the spring, such as winter rye. Another option in late spring is to interseed annual forages into a winter cereal toward the end of its cycle but before it will be harvested for grain in mid-summer. Forage options for this time of year include corn silage, summer annual grasses, soybean, and brassicas.

Q. Would these other varieties be better than a late planting of corn?

A. Corn for silage can be planted later than optimal for grain production in most regions; however, later planted silage corn has increased risk should dry weather develop. Despite the risk associated with late planting, corn silage should be a top choice because with adequate rainfall, it can produce more forage with greater feeding value than most other summer annual grasses. Even without grain formation, the feeding value of corn is at least equal to that of the other summer annual grasses, and forage yields are likely to be higher.

Q. Tell us more about the other choices for spring planting?

A. Sudangrass, sorghum x sudangrass hybrids (Figure 1), pearl millet, and forage sorghum grow rapidly in summer and are excellent choices for planting in early summer. They are more drought tolerant than corn. When managed properly, these grasses can provide forage with good nutritive value, especially if selecting sorghum varieties with the brown-midrib trait. Most of these grasses can be harvested multiple times and will produce a total of 3.5 to 6 tons of dry matter per acre across all harvests depending on location and growing conditions; forage sorghum is harvested once and can produce as much as 8 to 12 tons DM per acre depending on location and growing conditions. Pearl millet is essentially free of prussic acid poisoning potential, but the sorghum species have the potential for prussic acid poisoning, which varies by species. Nitrate toxicity is possible with all summer annual grasses (including corn silage) and management steps should be taken to reduce that risk.

Teff is a warm-season grass that can be used for hay, silage, or pasture (Figure 1). Multiple harvests can be taken in many regions, with yields ranging from 3 to 4 tons of DM per acre in short growing seasons and up to 8 tons of DM per acre in regions with long growing seasons. Teff can tolerate both drought-stressed and waterlogged soils.

Figure 1. Teff and sorghum x sudangrass grown in research plots.

Several brassica species (e.g., turnips, rape) can be planted in late spring to early summer for late summer grazing or autumn grazing 50 to 100 days later, depending on variety and growing conditions. These species contain high moisture content, so they should be used for grazing only. Brassicas have very low fiber with high energy content and should be treated more like a concentrate than as forage in ruminant diets.

Q. What about mixes including legumes, are they worthwhile?

A. Mixtures of summer-annual grasses and legumes, such as field peas and soybeans, are marketed by some seed dealers. The legumes generally improve protein content but only in the first harvest because they don't regrow after cutting. Legumes usually increase the seed cost, so consider the cost-to-benefit ratio of purchasing mixtures with legumes vs. supplementing livestock with other protein sources.

Soybean can be grown for forage, but it is difficult to dry sufficiently to make hay. Ensiling soybean also has challenges. The high concentration of fat (about 10%) in soybean inhibits bacteria in the silage, causing slow fermentation that is often incomplete. The best approach to using soybean forage is to mix 1 part soybean with 1 part or more of whole plant corn during silo filling.

For silo bags, mixing is difficult so the ratio of corn to soybeans should be increased and the amount of soybeans put in the silo at one time should be small.

Q. Please sum up the reasons why producers might consider these crops?

A. Short-season annual forages offer many opportunities to produce supplemental forage within cropping systems. They can be used together in sequence, such as planting a winter cereal species for spring forage followed by a summer annual grass during the summer. They also can be incorporated between cash crops, increasing the efficiency of land use while protecting the soil that often sits idle without cover for an extended period of time between the cash crops.

For more options including suggestions for mid-summer and autumn planting, click here.

Author: Mark Sulc

Ohio State University