Focal sampling of cow lying behaviour for automated welfare assessment

the objective of the current study was to determine the number of focal animals required to represent the daily lying behaviour of a herd of lactating dairy cows. the study was carried out at 3 commercial dairy farms. the lying time (h/d) and number of lying bouts (n/d) of 15 ± 3 focal dairy cows, continuously recorded by electronic recording devices,were analysed using a resampling method for sample size determination. estimates of lying behaviour based on five or six cows per focal group provided an accurate estimate of the overall means for each focal group monitored. an accurate estimate of the daily lying behaviour on commercial dairy farms might be generated using continuous recording of at least 40% of the cows in the herd. The sampling methods applied to the automated monitoring systems are time- and labour-saving tools that can be used to assess cow comfort and welfare in relation to lying behaviour.