December 2020

Bedding. Bacteria. Better management.

According to Dr. Sandra Godden, professor with the department of veterinary population medicine at the University of Minnesota, these are the “three ‘B’s’ of udder health.” She outlined the relationship between bedding bacteria counts (BBC) and udder health, bedding management practices and monitoring bedding hygiene in the Nov. 19 webinar from the National Mastitis Council.

“Bedding functions as a source of comfort, traction, absorbency and keeps cows clean,” Godden said. “Bedding then impacts how comfortable cows are and when they lie down, if cows become lame or develop hock lesions and their overall udder health.”

Relationship between BBC and udder health

The type of bedding used on a farm can greatly impact the exposure that a cow may have to environmental mastitis pathogens. Numerous studies since 1975 have demonstrated a positive relationship between BBC, bacteria count on teat skin and increased intramammary infection in cows. Godden referred to a 2019 cross-sectional study conducted by her student, Kruthika Patel, that analyzed the association between BBC and Dairy Herd Improvement Association (DHIA) herd measures of udder health. A total of 168 herds were studied across 17 states and used the following bedding types: new sand, recycled sand, manure solids and organic non-manure materials.

With all bedding materials combined, the study found that as coliform and strep counts in unused bedding increased, udder health progressively declined. Therefore, two conclusions were drawn from this study: 1.) As BBC increases, so does impaired udder health and 2.) Bacteria of concern that affect udder health include coliforms, klebsiella spp., streptococci and streptococci-like organisms (SSLO) and staph spp.

Bedding management

Understanding the relationship between BBC and udder health determines the best and worst bedding types to use on farms. Godden said that sand is generally the best choice for udder health, and while manure solids can present concerns, “not all manure-solids herds have high BBC or poor udder health.”

Those herds that maintain udder health with manure solids as their bedding source start with clean, fresh bedding and incorporate proper management factors, such as processing, storage, season and region.

Management of recycled manure solids

A high dry matter percentage (DM%) and low organic matter percentage (OM%) are associated with reduced BBC and better udder health in unused manure solids. Suggested DM% goals for unused manure-solids bedding aims for greater than or equal to 65% to reduce overall coliform and SSLO counts.

Godden also referenced a study, funded by the Upper Midwest Agricultural Safety and Health (UMASH) and McLanahan, which investigated the impact of recycled solid processing methods on Midwest dairy farms and how they affected BBC, udder health and other outcomes like milk quality, udder hygiene, air quality and economics.

Of the four processing methods studied (green, digested, drum composted and dried), it was concluded that:

  • Mechanical drying and drum composting reduced BBC for one or more groups of bacteria associated with increased mastitis risk.
  • Udder health was better in herds using dried or drum composted recycled solids.
  • Milk production was better in herds using dried, recycled manure solids.

For Midwest dairy producers using this bedding, herds with mechanical dryers or drum composting may have better success achieving lower BBC and better udder health.

Management of sand

A low OM% and high DM% are also associated with reduced BBC in unused sand, but with goals of OM equal to or less than 1.5% and DM greater than 95% for new and recycled sand. When selecting new sand, factors such as low organic matter, dryness, no debris or stones and a consistent particle size between 0.1 millimeters and 1.0 millimeter are important factors to consider to reduce BBC and improve udder health. Other recommendations for sand bedding to increase DM% include washing sand and increasing time in storage for new sand, as well as using covered storage for recycled sand.

For housing situations on farms, Godden had similar recommendations for bedding management in both freestall and compost barns, such as avoiding overcrowding and providing excellent ventilation. She also suggested specific practices for each housing type:

Bedding management in free stall barns:

  • Daily additions of organic bedding to stalls
  • Correct stall design and dimensions to avoid cows defecating in stalls
  • Removal of wet materials at least twice daily
  • Scrape alleyways during each milking
  • Prevent standing water and manure in alleyways

Bedding management in compost barns:

  • Appropriate bedding: Sawdust or fine, dry wood shavings are best
  • Aerate twice daily and dig down 10 inches into bedding
  • Add fresh bedding when bedding begins to stick to cows
  • Clean out completely in the spring/fall
  • Use excellent udder prep at milking

Monitoring bedding hygiene

Finally, bedding hygiene can be monitored through bedding culture reports. These may be useful tools in mastitis control programs on farms and involve sending a sample of unused and used bedding to be tested in a laboratory, Godden adivsed. Results are determined from suggested benchmarks for BBC in bedding.

More information for submitting a bedding sample test can be found here.

While the results of this study are conclusive and very helpful for farmers determining the best bedding choices and management practices on their farms, there is still much left to learn. There has been discussion concerning studies to be conducted on areas such as lower-input static composting approaches, testing parameters associated with OM% in unused sand bedding and using bedding conditioners to alter pH.


Ashley Hagenow for Progressive Dairy