Maud Coignard

Abstract :

The aim of this PhD thesis was to produce epidemiological knowledge related to the health of the dairy cows, as considered and defined within the Welfare Quality® Protocol. The main expected result is to contribute to the adaptation of this protocol to allow its use for on-farm intervention and thus contribute to the improvement of the level of health of dairy cows. A first part aimed at describing the level of welfare and of health in French dairy herds and at identifying the associated at risk factors. Despite a low variability for the health score observed in the study sample, several at risk practices were identified such as a lack of cleanliness, a high percentage of thin cows or the absence of pain management regarding dehorning procedures in calves. Moreover, some indicators to detect herds with impaired health were identified. The second part aimed at investigating the informative value, in addition to the Welfare Quality protocol®, of cow based indicators to discriminate long vs short lasing lameness within the frame of a single visit. Several indicators of interest were identified, such as low body condition score or the existence of several skin lesions or hairless patches in different part of the body. Lastly, the association between the level of welfare and the milk yield at herd level was assessed in order to provide putative economic arguments to support further investments to improve the welfare of dairy cows. In herds with low aggressions between cows and good emotional state of the herd, dairy cows produce more milk.

Key words :

Cattle, epidemiology, welfare, health, prevalence, lameness, milk yield