|With sawdust in short supply, corncobs or soybean straw can work in compost barns.
While dairy compost barns may be unmatched for cow comfort, finding a reliable, reasonably priced supply of sawdust bedding can be challenging.
When the economy was booming and sawmills and wood manufacturers were working 24/7, competition for sawdust was fierce among dairy producers and manufacturers who use sawdust as composite material or burn it for energy. Now that the economy has tanked, simply finding available sawdust—at any price—is a challenge.
Researchers at the University of Minnesota (U of M) have conducted several studies evaluating sawdust substitutes and partial substitutes at the West Central Research and Outreach Center in Morris, Minn.
Using sawdust as a control, a team led by U of M dairy specialist Marcia Endres compared corncobs, woodchip fines and soybean straw.
"Some of these materials were evaluated as mixtures on a 2:1 volume-to-volume ratio,” Endres says. "These mixtures included woodchips/sawdust, woodchips/soybean straw and soybean straw/sawdust.” Both the corncobs and soybean straw were processed to reduce particle size, with 96% of the corncobs and 80% of the soybean straw processed to less than 1⁄3".
"Cow comfort [based on the number of cows lying down] was similar among materials,” Endres says. Eighty percent of cows on sawdust had no hock lesions. But 53% of cows on soybean straw and 62% of cows on soybean straw mixed with woodchips had lesions, with hair loss.
Body condition scores averaged 3.0, hygiene scores averaged 2.5 and somatic cell counts averaged 157,000.
"It appears that any of the materials tested can work in a compost barn, as long as excellent management of the bedding pack and appropriate milking prep procedures are followed on a consistent basis,” Endres says.