Precision Livestock Farming and animal welfare: is the numerical revolution of agriculture able to take into account animals' and farmers' needs?

Precision Livestock Farming techniques have been developed essentially to increase profitability and reduce workload by applying automatic processes to monitor animals and their environment. For instance detecting oestrus allows timely insemination, while detecting lameness at an early stage or imbalance in the nutritional status or even abnormal ambiance parameters in the barn can help take remedial actions quickly. The data generated by Precision Livestock Farming sensors could also support animal welfare. A system detecting health problems (e.g. mastitis, ketosis in dairycows)can be part of welfare management. In addition and maybe more importantly, some Precision Livestock Farming devices are based on animal behaviour detection directly, or indirectly through the position of animals: time spent feeding, ruminating, resting, walking, etc. Subtle changes in behaviour can indicate the mental state of an animal hyper-reactivity vs. apathy, social isolation, changes in the daily rhythm of activity, reduction in play behaviour and grooming, hyper-agressivity. These changes can be all signs of malaise due to disease, stress, social instability, etc. We argue that Precision Livestock Farming techniques offer a wide range of possibilities to use animal behavioural signs to address animal welfare in modern livestock farming, be the welfare related to health status, social relations, human-animal relationship or more general effects of a stressful environment. At present, these possibilities have been little explored, and they deserve more research. In addition, the use of Precision Livestock Farming is changing farmers' work and potentially their interactions with animals. It is necessary that the animals remain at the centre of attention if one wants to address adequately their welfare in harmony with the farmer.