Ready for the Switch? The Dairy Merits of Switchgrass
What was once a humble placeholder crop to prevent soil erosion – and before that, a native prairie grass -- is emerging as an important TMR element and bedding option for dairies.
Switchgrass is proving to be steady staple on some dairy farms, thanks to its versatility and environmentally friendly attributes. Researchers at the University of Guelph, Ontario, have explored the potential of the warm-season grass for the past several years, as a potential tool to reduce the environmental footprint of dairy production.
Because it can thrive on marginal land, University of Guelph researcher Abigail Carpenter said growing switchgrass as a dairy crop can reduce land competition, curb soil erosion, and help hold nutrients in place.
Roger Samson, Executive Director of Resource Efficient Agricultural Production (REAP)-Canada, has championed the merits of switchgrass for decades. He said the nutritional potential of the native grass for dairy rations are just beginning to be appreciated. Options include:
An effective fiber source – A small quantity (2 pounds per cow per day or less) of chopped switchgrass can be used similarly to straw in lactating TMRs – particularly fresh-cow rations -- to increase effective fiber and slow the ration passage rate.
A low-energy dry-cow feed – Switchgrass can be used at a rate of about 6-12 pounds per cow per day to help create a bulky, low-energy TMR for dry cows.
A low-potassium transition feed – Because potassium in forages can lead to a cascade of metabolic problems in fresh cows, the low potassium content of switchgrass makes it an attractive forage source to reduce dietary potassium and cation-anion difference. Compared to wheat straw, switchgrass also has a lower fungal load.
Samson recommends harvesting switchgrass for dairy feed in late summer or early fall. In this window, biomass yields are high and dry-down time is low.
Additionally, Samson noted switchgrass is proving to be a superior dairy bedding source compared to wheat straw, because its plant structure allows for less matting and a softer, more comfortable resting surface. It evaporates water more effectively from the bedding pack, promoting cow comfort; lower bacterial growth; and potentially reduced mastitis incidence.
Producers report having to change switchgrass bedding less frequently than straw, and fewer hock injuries, as shown in this video. And because switchgrass has a lower nitrogen content than straw, it decomposes more slowly.
Much of the recent dairy switchgrass work has been performed in Canada. But as as a native grass, adaptable varieties of switchgrass -- which vary according to latitude -- can grow throughout most of North America. University of Wisconsin researchers advise planting switchgrass varieties no more than one hardiness zone from their origin.
A good stand of switchgrass once was notoriously difficult to establish, but Samson said that is changing, thanks to the development of new varieties. He shared this video, in which he displays a newly planted switchgrass stand, which he said now is similar in ease to growing alfalfa. Once established, its perennial native grass qualities mean a well-managed switchgrass stand can endure for decades.
October 13, 2022