Over the course of the last few decades, huge strides have been made in the realm of udder health, and specifically, in managing somatic cell counts and contagious mastitis pathogens. While there is still room for improvement in these areas, more focus has shifted to confronting environmental causes of mastitis.

Research conducted by the University of Minnesota and Washington State University aimed to identify benchmark coliform counts to monitor bedding hygiene. As published in the Journal of Dairy Science, the group compiled bedding characteristics, udder hygiene scores, and bulk tank milk quality for 168 herds from 17 states.

In comparison to reclaimed sand bedding, new sand bedding, and organic nonmanure materials, manure solid bedding was associated with more udder health issues. It was tied to higher bedding bacteria counts, dirtier udders, and higher coliform and streptococci or streptococci-like organisms in bulk tank milk.

Although manure solids were tied to the highest risks, the other three types of beddings were still at times at risk for high counts of coliforms, Klebsiella spp., and streptococci or streptococci-like organisms. When these were present either in used or unused bedding, it was directly associated with higher levels of udder health measures such as higher test day linear scores, more cases of intramammary infections, new intramammary infections, and greater proportions of cows with chronic infections.

Set benchmarks
No matter the type of bedding, the researchers emphasized the importance of knowing where bedding bacteria counts are in order to better understand environmental risks for cows. To that end, they shared eight benchmarks for farms to measure bedding against.

1. Coliform counts in unused bedding: less than or equal to 500 colony forming units/cubic centimeter (cfu/cm³)
2. Coliform counts in used bedding: less than or equal to 10,000 cfu/cm³
3. Klebsiella spp. in unused bedding: 0 cfu/cm³
4. Klebsiella spp. in used bedding: 0 cfu/cm³
5. Staphylococcus spp. in unused bedding: 0 cfu/cm³
6. Staphylococcus spp. in used bedding: 0 cfu/cm³
7. Streptococci or streptococci-like organisms in unused bedding: 0 cfu/cm³ (for manure solids unused bedding should be below 1,000 cfu/ cm³)
8. Streptococci or streptococci-like organisms in unused bedding: 500,000 cfu/cm³