It’s impossible to keep much sterile on a dairy, but could clean udder cloths be transmitting mastitis-causing bacteria in the milking parlor? A recent study of 67 U.S. dairies in ten states investigated whether there is an association between the bacteria levels in (clean) cloth towels and the health of the udders those towels were used on. The authors measured bacteria on clean towels and in milk samples. They also looked at towel use and laundering practices.
What did they discover?
~20% of udder quarters were infected
10% non-aureusStaphylococcus species
4% Staphylococcus aureus
5% Streptococcus or Strep-like organisms
4% other gram-positive bacteria
2% gram-negative bacteria (includes coliforms)
No towels were free of bacteria. The mean overall bacterial count was 3.77 log10 cfu/cm2 (cfu=colony forming units).
Bacillus species were the most commonly found (95% of cloths). Approximately half the towels contained Staph and/or Strep species.
Only Staphylococcus species and Streptococcus species counts on towels were associated with mammary infection rate.
No towels laundered off-site by a service had high coliform counts. Also, undried towels had higher coliform counts.
Now, the study authors note that they have not demonstrated that new infections are necessarily being introduced from bacteria on clean towels, just that they found a positive association between Staph and Strep infections and the presence of those organisms on clean towels. However, given their findings, they suggest getting clean towels tested and then working to get those bacteria levels to essentially undetectable for Staph, Strep, and coliform species. Changes in laundering or storage practices could help. (When was the last time the clean towel bin was washed?)
The bottom line: Dry udder cloth towels after washing. Get clean towels tested periodically to see if they may be carrying mastitis-causing bacteria.
Rowe et al. Cross-sectional study of the relationship between cloth udder towel management, towel bacteria counts, and intramammary infection in late-lactation dairy cows. Journal of Dairy Science, December 2019, 102:11401-11413. DOI: https://doi.org/10.3168/jds.2019-17075
Are too many heifers on your farm showing up with mastitis early in that first lactation? You may want to examine your prevention strategies. A review paper that examined the effectiveness of various precalving treatments in heifers was published earlier this summer. Here are the key take-a-ways:
When the infection is caused by contagious bacteria (e.g., Streptococcus agalactiae, Staphylococcus aureus), antibiotics, teat sealants, and vaccines can improve udder health outcomes.
Particularly if you are considering using antimicrobial treatments, culture quarter milk so you know who the enemy is. We want to minimize the development of antibiotic resistance.
When environmental pathogens (e.g., Escherichia coli, non-agalactiae streptococci) are the problem, teat sealants and combination therapies are effective at reducing mastitis risk.
When coagulase-negative staphs (CNS) are infecting heifer udders, antibiotics, teat-sealants, and combination therapies offer the most help.
When employing any of these treatment options, be sure they are delivered by a well-trained person.
On farms with effective fly control and that minimize stress for late-gestation heifers, there may be little benefit from preventative medical treatment.
The paper: Naqvi, Nobrega, Ronksley, & Barkema. June 2018. Effectiveness of precalving treatment on postcalving udder health in nulliparous dairy heifers: A systematic review and meta-analysis. Journal of Dairy Science 101:4707-4728.
Researchers from Oregon State University investigated the blood serum profiles of Holstein cows before and after calving and compared those that developed clinical mastitis with those that did not. To do so, they used ultra-performance liquid chromatography high resolution mass spectrometry plus statistics to identify differences in concentration of metabolites, lipids, minerals, and inflammatory markers in blood serum. It’s OK if you read that last sentence and went, “Huh?” The short version is that they ran blood serum samples from dry cows through some fancy laboratory equipment to see if there were any indicators associated with developing clinical mastitis after calving. And yes, there are!
For example, alpha-tocopherol (a form of vitamin E) levels were significantly higher in the blood of cows that did not develop clinical mastitis compared to those that did (Figure 1). Another difference was in the overall profile of metabolites (molecules that participate in or are produced during metabolism); they were quite different for cows that remained healthy and those with post-calving mastitis (Figure 2).
While no dairies have liquid chromatography mass spec technology in their on-farm lab, these results may lead the way to identifying one or two highly reliable blood markers that could be easily measured on the dairy. And forewarned is forearmed, right? Knowing which cows were likely to develop mastitis could allow proactive treatment to prevent the more expensive and damaging clinical mastitis.