A research project financed in part by Dairy Farmers of Canada and its partners under the Organic Science Cluster investigated sustainable alternative sources of bedding for dairy cows. The research team led by Dr. Renée Bergeron (University of Guelph), and collaborators the University of Guelph (Dr. Trevor De Vries), Université Laval (Dr. Doris Pellerin, Dr. Anne Vanasse, Anick Raby) and McGill University (Dr. Elsa Vasseur, Dr. Philippe Séguin, Tania Wolfe) found that switchgrass is a promising alternative to wheat straw as bedding material for dairy cows. They discovered that cows preferred switchgrass over the straw and there were no negative effects on cow comfort, cleanliness and teat end contamination. Switchgrass may also be a more economically advantageous choice for some dairy farmers.
In their study, they assessed cow preference, lying behavior, stall and cow cleanliness and potential bacterial contamination of teat ends. They also analyzed the economic impact of the use of Switchgrass and the best harvesting practices for performance and quality as a bedding.
Switchgrass (Panicum virgatum L.) is a high-yielding, long-term perennial grass grown on marginal land (Sanderson et al., 2006). It is well adapted for growth under temperate climate, is disease and pest resistant, requires low fertilizer applications and is relatively inexpensive to grow and harvest (Frigon et al. 2012).
In a first experiment, nine cows were housed individually in pens with three stalls with different lying surfaces. They were submitted to a preference test for three types of bedding: deep-bedded chopped switchgrass (SG), “switchgrass-lime” mattress (mixture of chopped switchgrass, water and carbonic magnesium lime – farms using organic bedding commonly add lime to reduce bacterial growth), and wheat straw on a rubber mat (control). The cows had been previously exposed to stalls with sawdust covered mattresses. Lying times were recorded and the cows filmed.
In a second experiment, 24 cows in a free-stall housing were offered the same three bedding treatments. Researchers tested the effects of the three types of bedding on lying behavior, cow cleanliness and teat end bacterial contamination. Stall usage was recorded and samples were taken of teat ends and tested for bacteria (coliforms, Klebsiella spp., and Streptococcus spp.).
The researchers found that the cows preferred the switchgrass bedding compared to the other two bedding types when given equal access and choice. The results also showed that the switchgrass and switchgrass-lime deep bedded options were equivalent in terms of lying behavior and cow cleanliness, but the higher moisture content and teat end coliform counts on the switchgrass-lime surface make it a less favorable option. A longer term study would be required to confirm the latter finding.
When wheat-straw and switchgrass were compared for lying time, cleanliness, injury, SCC and teat end bacteria, they were equivalent in terms of comfort and cleanliness.
Harvest and use of switchgrass
The research team also investigated the economic impact of using switchgrass as an alternative bedding and identified harvesting practices to optimize its performance and conservation.
Switchgrass was grown, harvested and dried on two sites in Quebec – at Université Laval and McGill University. The field experiments showed that yields are much higher when switchgrass is harvested in the fall compared to the spring. However, the spring harvest resulted in lower moisture content. Harvesting before or after the first frost in the fall does not seem to affect winter survival or regrowth in the spring and drying efficiency is higher when switchgrass is harvested before frost, compared to after the fall frost. However, the final moisture content of switchgrass remains higher before frost than after frost.
To assess the economic impact of using switchgrass as bedding, ten Quebec dairy farms in five regions of the province were surveyed. For most, it was an economically advantageous choice. Farmers reported that yields and persistence are advantages and other benefits cited included smaller storage space required.
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