Source: National Mastitis Council, Sam Rowe, University of Minnesota PhD candidate
Researchers from the University of Minnesota recently published an article in the Journal of Dairy Science, which reports findings from an observational study of cloth udder towel management and intramammary infection (IMI) in latelactation cows. The objectives of their study were to:
1) Investigate the relationship between towel bacteria counts and IMI risk,
2) Establish target levels for bacteria counts in towels and
3) Investigate towel management practices that might impact bacteria counts.
Sixty-seven farms from 10 dairy states were visited once in the winter of 2017-18. Recently laundered (ready-to-use) cloth udder towels were collected from the milking parlor, along with quarter-milk samples (n=4,656) from 1,313 cows approaching dry-off (>180 days pregnant). Towel management and laundering practices of each farm were recorded using a questionnaire. Quarter-level IMI status was determined using standard bacteriologic methods, recommended by the National Mastitis Council. In addition, colony forming units of all bacteria (total bacteria), Staphylococcus spp., Streptococcus spp. or Strep-like organisms (SSLO), coliforms, non-coliform Gram-negatives and Bacillus spp. were determined for towels (log10 CFU/cm2 ).
Counts of Staphylococcus spp. and SSLO were positively associated with IMI risk
Statistical analysis found that odds of IMI caused by non-aureus Staphylococcus spp. (NAS) increased by 33 percent for every 1 log unit increase in Staphylococcus spp. counts in towels (OR=1.33). Likewise, the odds of SSLO IMI increased by 45 percent for each 1 log unit increase on SSLO counts (OR=1.45). In contrast, total bacteria counts (all bacteria types combined) in towels were not associated with IMI caused by all pathogens (OR=1.06), possibly because the predominant bacteria found in towels was Bacillus spp., which is an uncommon cause of IMI and mastitis. These findings suggest that managing counts of Staphylococcus spp. and SSLO on towels may help prevent new infections caused by those bacteria. However, more research is needed to demonstrate this.
The authors recommended that herds aim to keep Staphylococcus spp., SSLO and coliform counts each <32 cfu/cm2 (<5 cfu/ in2 ), which was achieved in 51 percent, 46 percent and 88 percent of herds in the study, respectively. These findings indicate that these targets are likely to be achievable for commercial herds in the United States.
Failure to dry towels associated with high coliform counts
Towel management practices evaluated included washing water temperature, sanitizer use, dryer use, laundering site (on site vs. professional service) and laundering equipment. Of these, failure to dry towels was a clear predictor of coliform counts, with undried towels being eight times more likely to have coliform counts above the target of 32 cfu/cm2 . Furthermore, all towels that were laundered by a professional, off-site service had coliform counts below the target level, while 15 percent of towels laundered on site were above the target levels.
The authors acknowledge that larger studies are needed to better investigate laundering practices, as only 67 herds were enrolled in the current study. A previous study by Fox (1997) found that towel bacteria counts could be minimized by practicing at least one of the following: 1) use sanitizer, 2) use hot-air drier and 3) use hot water during washing.
Funding for the study was provided by Zoetis, Parsippany, N.J., USA.
Fox, L.K. 1997. Recovery of mastitis pathogens from udder cloths following several laundering methods. Dairy Food Environ. Sanit. 17:14-19.
Rowe, S.M., S.M. Godden, E. Royster, J. Timmerman, and M. Boyle. 2019. Crosssectional study of the relationship between cloth udder towel management, towel bacteria counts, and intramammary infection in late-lactation dairy cows. J. Dairy Sci. 102(12), 11401-11413.
Thompson, R.S. 2006. How can we ensure our udder prep cloth towels are truly clean and sanitized? Progressive Dairyman. Accessed: November 2018. https:// www.progressivedairy.com/topics/barns-equipment/0906-pd-how-can-weensure-our-udder-prep-cloth-towels-are-truly-clean-and-sanitized