Plan now for summer forages and grazing

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You probably don't want to think about summer forages and grazing with all of the talk about dangerous wind chills, the polar vortex, and lots of snow. However, you should be because spring and summer are just around the corner.

This is a good time to study new developments in forage varieties and pasture grass species.

The 2014 seed and forage guides are out, and varietal test results have been published. If seed is not yet ordered for frost seeding, planned renovation, new pasture development, or for summer annuals, it should be done before supplies are reduced. Key points in pasture and forage development include choice of adapted varieties and species that will persist for several years and adding legumes to provide nitrogen. Some research has recommended diversifying pasture and forage systems to include warm season species in the summer and annual cool season species in the fall. Why should summer annuals be considered by all dairy producers? They are very drought tolerant and can fill a gap in feed when other species experience the "summer slump". They are great emergency forages during dry weather and are multipurpose, so you can be use them for grazing, silage, or for baling.

During the summer of 2013, we planted two summer annuals for grazing for the first time at the University of Minnesota West-Central Research and Outreach Center dairy in Morris. BMR sorghum-sudangrass and teff grass were planted to create a more uniform and extended forage supply. These grasses were seeded with a drill on May 28, 2013, but because of the late spring, this was about 2 weeks later than what we had planned.

BMR sorghum-sudangrass has increased in popularity due to the BMR gene and increased NDF digestibility (5 to 10% higher than regular sorghum-sudangrass). The plants have thick stems and are very leafy. Sorghum-sudangrass has moderate regrowth potential, but you should not graze or cut for forage until the plants are at least 18 inches tall to reduce prussic acid concentration. The ideal height for forage is 18 to 36 inches tall. When grazing sorghum-sudangrass, animals should be moved so they leave 6 to 8 inches of stubble, but they might waste 20 to 30% of the forage through grazing. Lastly, sorghums and sudangrasses are luxury consumers of potassium, so they should not be used for dry cow forages. For seeding rate, we seeded our fields and pastures at 20 pounds per acre.

Teff grass is native to Northern Africa. Teff is drought tolerant and can be seeded into many different soil types. With this grass, you will have high yield with competitive forage quality, and will have rapid growth for 9 to 12 weeks. The seed is very, very small, and we seeded our pastures at 8 pounds per acre.

Both of these annuals should be planted at 60 to 65 degree soil temperature and planted 1 to 1.5 inches deep. Perhaps manure should be added as a fertilizer before planting because they have nitrogen requirements that are similar to corn.

The table shows averages for forage quality of BMR sorghum-sudangrass, teff grass, and cool-season grasses during 2013. The cool-season species consist of mixtures of smooth bromegrass, orchardgrass, red and white clover, and alfalfa. The dry matter of the sorghum-sudangrass was low because the cattle grazed the fresh forage in the early vegetative state. The summer annuals were not as high in crude protein as the cool-season grasses. However, with lower crude proteins, we probably improved nitrogen utilization of the milking herd. The ADF values of the grasses were very similar and are within the range of low 30s to mid-50s. All of these grass species were high in digestibility. The NDF levels were higher for the summer annual grasses compared to cool-season species. However, the total tract NDF digestibility (TTNDFD) was lowest for the teff grass. The TTNDFD is a measure of how much of the fiber is digestible, how fast the fiber digests, and how long a cow holds the fiber in the digestive system. The summer annuals were similar to the cool-season grasses for sugar and non-fiber carbohydrates, and they provided similar net energy for lactation and milk per ton as the cool season grasses.

Remember, sorghum-sudangrass and teff grass are not replacements for cool-season forages, but should be added to a forage program to complement the cool-season grasses. If there is a drought or dry weather, these two forages may prevent you from having to buy expensive hay during a drought. If you need any assistance with these unique forages or would like more information please contact me at 320-589-1711 or hein0106@umn.edu.

Results for forage quality of BMR sorghum-sudangrass, teff grass, and cool-season grasses during 2013 at the University of Minnesota-WCROC dairy.


Grass Species
Description (% of DM) BMR sorghum-sudangrass Teff grass Cool-season grasses
Dry Matter 17.0 29.0 27
Crude Protein 12.9 13.7 19.9
Acid Detergent Fiber (ADF) 37.6 40.2 35.5
Neutral Detergent Fiber (NDF) 58.1 61.8 52.7
TTNDF Digestibility 53.9 46.4 52.5
Lignin 5.4 3.6 5.7
Sugar 6.3 5.8 7.3
Non-Fiber Carbohydrates (NFC) 18.8 14.1 18.1
Net Energy for Lactation (Mcal) 0.56 0.53 0.59
Milk per Ton 2476 2028 2450

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