Because cloth udder towels (CUT) may function as a fomite for mastitis-causing pathogens, most udder health laboratories offer towel culture services as a tool to monitor towel hygiene. However, no studies have investigated if an association exists between bacteria levels in CUT and udder health outcomes. The objectives of this cross-sectional study were to (1) describe associations between herd-level measures of towel bacteria count (ToBC) and quarter-level intramammary infection (IMI) status in late-lactation cows, (2) establish pathogen-specific target levels of bacteria in CUT to aid the interpretation of towel culture reports, and (3) identify laundering-related risk factors for high ToBC. The study was conducted in 67 herds from 10 dairy states in the United States that used CUT. These 67 herds were originally recruited as part of a larger (80 herd) cross-sectional study of bedding management. Each herd was visited once during December 2017 to April 2018 and quarter-milk samples (n = 4,656) were collected from late-gestation (>180 d pregnant) cows (n = 1,313). Two recently laundered CUT were collected and a questionnaire was used to collect information about pre-milking teat preparation and CUT management practices. Quarter-level IMI status was determined using standard bacteriologic methods. In addition, colony-forming units of all bacteria (total bacteria), Staphylococcus spp., Streptococcus spp. or Streptococcus-like organisms (SSLO), coliforms, noncoliform gram-negatives, and Bacillus spp. were determined for each pair of CUT (log10 cfu/cm2). The association between ToBC and IMI was determined using multivariable logistic regression with mixed effects. After dichotomizing ToBC into high and low categories, associations between towel management practices and ToBC category were determined using unconditional logistic regression. The quarter-level prevalence of IMI was 19.6%, which was predominantly caused by non-aureus Staphylococcus spp. (NAS; 10.2%) and SSLO (5.1%). The predominant bacteria in CUT were Bacillus spp. (median = 3.13 log10 cfu/cm2). Total bacteria count was not associated with odds of IMI (odds ratio = 1.06), likely due to the predominance of Bacillus spp. in CUT and low number of IMI caused by Bacillus spp. In contrast, counts of Staphylococcus spp. and SSLO were positively associated with odds of IMI caused by NAS (odds ratio = 1.33) and SSLO (odds ratio = 1.45), respectively. Of 12 CUT management practices evaluated, only the failure to use a dryer was identified as a clear predictor of risk for a high ToBC (risk ratio of high coliform count = 8.17). Our study findings suggest that CUT may act as a fomite for NAS and SSLO. We recommend that herds aim to keep counts of Staphylococcus spp. and SSLO in CUT below 32 cfu/cm2 (or 5 cfu/in2), and that laundered towels be completely dried in a hot air dryer.
Bibliographical noteFunding Information:
We thank the Zoetis Quality Milk Specialist and Dairy Technical Services teams (Julio Alcantar, Michele Barrett, Karthryn Browning, Ruben Gonzalez, Samuel Herrera, Bernard Kwaku, Shawn Hull, Doris Ledwith, John Lee, Francisco Rivas, and Bill Sullivan), who conducted the fieldwork in herds located outside of Minnesota. We also thank doctor of veterinary medicine students from the University of Minnesota, Samuel Basquin, Edouard Cotten, Wanda Weber, and Aaron Rendahl. M. Boyle is an employee of Zoetis. He was involved in the study design and conceptualization, and with review of the manuscript. He was not involved with any analyses of data. All others have no competing interests to declare. S. M. Rowe was involved in fieldwork, laboratory work, data management, analysis, and manuscript preparation. S. M. Godden was involved in supervision, study conceptualization, fieldwork, and manuscript editing. E. Royster was involved in study conceptualization and manuscript editing. J. Timmerman was involved in laboratory work and manuscript editing. M. Boyle was involved in study conceptualization, fieldwork coordination, and manuscript editing. This study was funded by Zoetis (Parsippany, NJ).
- cloth udder towel
- intramammary infection
- pre-milking teat preparation
- towel bacteria count
- towel laundering