Effect of alley-floor scraping frequency on Escherichia coli, Klebsiella species, environmental Streptococcus species, and coliform counts

The objective of this study, conducted at the University of Kentucky Cold-stream Dairy, was to determine whether increased alley-floor scraping frequency decreased environmental mastitis-causing pathogen counts. Sixteen Holstein cows were monitored during two 3-wk treatments: removing manure from the alley floors once (1 ×) or twice daily (2 ×) by a skid steer equipped with a tire scraper. Bedding, milk, and teat-end swab samples were collected twice weekly to observe changes in streptococci, Klebsiella spp., coliform, and Escherichia coli counts and SCS. Increasing alley-floor scraping frequency to 2 × decreased all bedding pathogen counts (P = 0.01); teat-end coliform, E. coli, and streptococci counts (P < 0.01); and milk coliform counts (P = 0.04). Increased scraping frequency did not significantly affect milk E. coli, streptococci, or Klebsiella spp. counts; SCS; or teat-end Klebsiella spp. counts. Correlation coefficients indicated bedding bacterial counts were moderately positively correlated with teat-end bacterial counts (r = 0.37, 0.43, 0.56, and 0.45 for coliforms, E. coli, streptococci, and Klebsiella spp., respectively; P < 0.05). Teat-end coliform and streptococci counts were moderately correlated with milk coliform and streptococci counts (r = 0.53, 0.53; P < 0.01). Intramammary infections are caused by pathogenic bacteria traversing the teat canal and infecting the udder. Bedding bacteria counts are positively related to teat-end bacteria counts, which are positively correlated with intramammary infections; therefore, decreased pathogen counts in the external environment of the cows are a likely method for decreasing the risk of intramammary infection.