Photo shows  milker washing cow udder in parlor.

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-aureus Staphylococcus 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.

The paper:

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:

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:

developing udder on a Jersey heifer
She’ll be in the parlor soon.
photo: Spirited Rose Homestead Dairy Farm

  • 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.

Another good resource is the National Mastitis Council’s Heifer Mastitis Prevention and Control Plan.

A cow in an automated milking unit.
All teat cups still on so far.

Swedish researchers shaved one minute off milking times in an automated milking system (robot) when they increased the setting for milk flow at take-off from 0.06 kg/min (0.13 lb/min) to 0.48 kg/min (1.06 lb/min). Well yeah, you’re thinking, of course it would. These researchers also measured milk composition, harvested milk yield, and the amount of residual milk left in the udder. And none of those things was significantly different between the take-off milk flow rates. (They also looked at a take-off flow level of 0.3 kg/min [0.66 lb/min]).

A similar study was conducted in New Zealand, where researchers looked at 0.2, 0.4, 0.6, and 0.8 kg/min (0.44, 0.88, 1.3, and 1.8 lb/min, respectively) milk flow rates for determining take-off. Here, the cows were milked in a rotary parlor, and take-off flow rates were for the unit rather than by quarter. They, too, found no differences in milk yield or milk composition.

So, you may want to check the minimum milk flow settings on your automatic takeoffs. Bumping that number up should decrease individual milking times without sacrificing milk production or altering composition. Getting cows through the robot faster is good for pounds of milk per robot. And who’s going to complain if (parlor) milking finishes a little earlier?

the articles:

Krawczel et al. 2017. Milking time and risk of over-milking can be decreased with early teat cup removal based on udder quarter milk flow without loss in milk yield. Journal of Dairy Science 100:6640–6647.

Edwards et al. 2013. Milking efficiency for grazing dairy cows can be improved by increasing automatic cluster remover thresholds without applying premilking stimulation. Journal of Dairy Science 96:3766–3773.