Evaluating the efficacy of two footbath concentrates to control digital dermatitis in free-stall dairy cows using a non-inferiority study

Objective

Our primary objective is to determine if a commercial footbath concentrate (Healmax®) is non- inferior to a copper sulfate concentrate in the prevention of new cases of digital dermatitis (DD) As a secondary objective, we will investigate the comparative efficacies of the two products in the control of chronic DD cases.

Materials and methods

Five Holstein and Holstein-cross herds ranging from 1323-2292 cows/herd were enrolled in the study starting December 2021. Treatments were allocated randomly at the pen level to the test product (HM; 2.5% concentration) or to a Copper Sulfate (CS; 5% concentration) footbath solution. Footbaths are run 4d/wk, once per day, for a 4-month time period, with footbaths changed after every 200-400 cows. All lactating cows are scored in the milking parlor every two weeks for DD by trained observers, including baseline evaluations prior to the study start. Using the M-based scoring system, a score of 0 denotes no lesion being present and 4H, 4P, and 2P being lesion categories of increasing severity. Herd-level data is extracted during each farm visit from farm DairyComp 305 software. Outcomes for DD will be measured at the leg level (rear legs only). For the study sample size calculations, a 5% incidence risk of new DD infections and a 25% non-inferiority margin has been used. Data will be analyzed using a linear mixed model to account for cow and herd level effects. [...]