Abstract
Bovine digital dermatitis (DD) is an important infectious cause of cattle lameness worldwide that has become increasingly prevalent in New Zealand pastoral dairy herds. In this study, a simplified DD scoring system after considering both M and Iowa DD scoring systems was applied to explore the transmission dynamics of DD in a typical spring-calving pastoral New Zealand dairy herd. The modified model only included three compartments: normal skin, early stage lesions and advanced lesions. Lesions regressing after treatment were excluded as DD lesions are rarely treated in New Zealand. Furthermore, sub-classes within each lesion class were not defined due to the lack of variability in DD lesion presentations within New Zealand. The model was validated based on longitudinal field data from three dairy herds in the Waikato region during one lactation season (2017–18). The model suggested that in infected dairy herds, although DD prevalence will tend to increase year-on-year it is likely to remain relatively low (< 18%) even after 10 years of within-herd transmission. It is likely that the low transmission rate during the late lactation (model assumption) results in more cases resolving than developing during this period and therefore results in the low prevalence of infectious cattle at the start of each subsequent lactation. Cattle with advanced lesions had a stronger influence on the establishment and maintenance of DD than cattle with early stage lesions highlighting the importance of targeting these animals for intervention. On-going monitoring of DD is highly recommended to assess the long-term progression of the disease in affected dairy herds.
Highlights
Bovine digital dermatitis (DD) is an infectious foot disease that causes varying levels of pain, discomfort, and lameness in dairy cattle [1] and has been increasingly found in dairy production systems worldwide [2, 3]
DD dynamics Based on the model predictions, given the presence of one advanced lesion at the start of lactation, DD prevalence would increase to a peak in mid-lactation and decrease during the late lactation and dry periods
If advanced lesions were absent at the beginning of the lactation in the first year (Figure 4, panels C and D), DD prevalence declined in the second year and remained at a similar level in the third year before starting to increase from the fourth year
Summary
Bovine digital dermatitis (DD) is an infectious foot disease that causes varying levels of pain, discomfort, and lameness in dairy cattle [1] and has been increasingly found in dairy production systems worldwide [2, 3]. In countries where cows are housed indoors, DD can be a major infectious cause of cattle lameness as well as a significant problem for the dairy industry due to losses in milk production [4], increased treatment costs [5], and negative impacts on animal welfare [6]. In pasture-based systems, such as those that predominate in New Zealand, DD lesions are typically less commonly seen than in housed cattle [11]. Clinical lameness was rarely associated with DD under New Zealand conditions [12], it is likely that DD will have only limited impacts on herd-level production [13].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
