Global livestock production must be intensified to meet the demand from a growing human population. However, this must not be at the expense of reduced animal health and deteriorated animal welfare. Infection with parasitic worms of ruminants is a major constraint on an efficient pasture-based livestock production. The challenge is to develop indicators that detect welfare impact of helminth parasites on farms in order to target control measures. The aim of the project is to develop improved welfare indicators based on automatic registration of weight gain and activity patterns and complemented with tests to detect parasites with current molecular techniques. Secondly we will examine how antiparasitic measures such as targeted treatment can alleviate unnecessary suffering of affected animals. It will not only lead to the development and implementation of measures to actively enhance animal welfare but also strengthen animal health by sustainable methods of parasite control.