Evaluation of bedding treatments to inhibit Klebsiella pneumoniae growth in wood shavings and sand

Mastitis caused by Klebsiella spp. leads to significant milk losses and increased rates of culling and mortality in affected cows on dairy farms. Control of environmental bacterial loads in bedding is critical to prevent intramammary infections caused by Klebsiella spp. However, little is known about how commercially available disinfectants and bedding conditioners perform against this pathogen. To determine the efficacy of a bedding conditioner and a surface disinfectant against Klebsiella pneumoniae in wood shavings and sand, a controlled laboratory study using bedding experimentally inoculated with bacteria and randomized allocation of bedding samples to treatments was conducted using a 2 × 3 factorial design. Bedding material (wood shavings, sand) and treatment (control, conditioner, disinfectant) were fixed factors, and Escherichia coli was used as the control species. Bacterial recovery from inoculated bedding samples was quantified, and the effect of treatment on bacterial counts was estimated using linear mixed models. Counts of E. coli were reduced in wood shavings treated with bedding conditioner. This is consistent with previously reported effects of the conditioner and supports the validity of the bedding inoculation model, but counts were not reduced in sand. In contrast, the conditioner significantly reduced K. pneumoniae counts in sand only. The disinfectant significantly decreased E. coli and K. pneumoniae counts in sand but increased K. pneumoniae counts in wood shavings. Overall, treatment effects were dependent on bacterial species and bedding material, indicating that their performance cannot be generalized across substrates or pathogen groups. Field studies incorporating on-farm bedding conditions are required to validate these laboratory findings and account for variability in responses among bacterial species of concern in mastitis management.