Transition Matrix Model to Evaluate the Effect of a Hoofbath Used to Cure and Prevent Digital Dermatitis in a Class-Structured Populations of Cows

Preventing the onset of a digital dermatitis (DD) outbreak in a dairy farm is a desirable tool for claw health managers. Designing such tools requires identification of DD lesion stages and their change in frequencies to develop indicators of changes in disease prevalence in the herd. A non-mechanistic transition matrix model was used to evaluate the effect of 2 hoofbath products, DeLaval Hoofcare DA (DA) and an experimental formula (DAX), at curing and preventing DD lesions in a herd of 73 dairy cows.
The split hoofbath design included hind feet parlor scoring of all cows at regular intervals of 2 weeks for a period of 4 months. Feet were assessed based on a scoring system comprising 5 classes of lesions as observed at the digital skin close to the coronary band.
The classes were: no lesion (O), hyperkeratotic (H), ulcerative (U), granulomatous (G), or papillomatous (P). The number of transitions between the different stages of disease per time interval were used to calculate the transition probabilities for a class structured population. Based on the transition frequencies, a Markov Chain model was constructed to predict the relative prevalences of the 5 disease class lesions after a long period of time ...