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Abstract :

The aim of this PhD thesis was to assess the effectiveness of different promising measures to durably decrease the prevalence of digital dermatitis (DD) in dairy herds. The treatment modalities to be studied should be acceptable for farmers and not toxic both for Human and the Environment. A first part was dedicated to investigate the motivations and limits of French dairy farmers towards the implementation of different treatments against DD. The need for evidence of optimal frequency of application of collective treatments with footbath or another way of application was enlighten. After the development and the assessment of a simple method for scoring of DD lesions in the milking parlor, a clinical trial was conducted in 52 dairy herds. This clinical trial aimed at assessing, using survival analysis, the relative effectiveness of 4 different treatment regimens and herd practices to decrease the incidence and increase the cure rate of DD lesion. The implementation of walk-through footbath and collective spraying using a solution of chelated minerals were effective to significantly decrease the incidence and improve cure rate of DD lesions when applied over 2 days every fortnight. Legs hygiene and hoof trimming before DD detection were also found crucial to control DD. Lastly, the impact of DD on milk yield was estimated to 0,6 to 0,9 kg/day. These results highlight the need of combining several control measures, including both treatments and herd practices to design relevant control strategies of DD in dairy herds.

Key words :

dairy cattle, digital dermatitis, epidemiology, control measures, scoring method, treatment,
hygiene, milk yield, survival analysis