Predicting farrowing of sows housed in crates and pens using accelerometers and CUSUM charts

Accelerometer collar to measure the activity in sows before farrowing.Used a dynamic linear model to extract trend from data with diurnal components.Used a CUSUM chart to detect a raise in activity.A single model to detect approaching farrowing in both pens and crates. Piglet mortality is a continuing problem in modern pig production. It is high especially during the first few days after birth and can be reduced by supervision of farrowing.There is currently a trend to move towards housing without crates due to animal welfare concerns. Thus, automatic systems that can predict farrowing equally well in different housing systems would have wider applicability than ones developed for crated systems only. A method that works with same parameters in different housing systems would be easier to maintain and reuse in different conditions. The aim of this study was to develop a new accelerometer based system to measure sow activity before farrowing. This data was then used to build a model to predict the approach of farrowing, based on increased activity, within 24h before the start of farrowing.We used a wireless 3D accelerometer to measure the activity of sows in order to detect farrowing. The accelerometer collars were attached to neck collars of 29 sows farrowing in crates and 33 sows farrowing in pens. We expected sows in pens to show higher activity, but a similar rise in the level.We used a single model to detect farrowing in both crates and pens. A dynamic linear model was used to model the activity of the sows before farrowing and to extract trend component from seasonal components and a CUSUM chart was used to detect activity increase.The model detected a rise in activity on average 13ź4.8h (meanźstandard deviation) before farrowing in sows housed in crates and pens with sensitivity of 96.7% and specificity of 100%. The fact that we were able to use a single model with a constant set of parameters gives indication that the method has potential to become a robust indicator of farrowing in different housing systems, even though pre-farrowing activity was higher in sows housed in pens than in crates.