"The pig industry has intensified in recent years, esulting in farms with bigger herds and fewer employees. Sensor technology can be a vital tool under these new conditions to ensure animal welfare, as it permits continuous and simultaneous monitoring of various indicators.
Currently, several sensors are available in the market or under development that can monitor animal welfare on farms. Examples include a 3D camera, accelerometers, microphones, climate sensors, and RFID (radio frequency identification) ear-tags, amongst others. These sensors can collect information from the animals and/or the housing environment based on the technology they use.
Information about the environment can include variables such as room temperature, humidity, or air quality, while information about animals may incorporate body temperature, activity level, feeder visits, spatial distribution in the pen, coughing, or lameness, to name a few.
In the ClearFarm project, we used a sensor device that can measure information from the animals (hereafter referred to as animal-based parameters): activity level, spatial distribution and posture, to be precise.
*Measuring the activity levels*
Research has shown that the activity level of pigs can vary substantially due to incidents like leg injury (lameness), diseases or stress. In addition, the spatial distribution and posture of pigs can indicate their behavioural patterns during the day, including their resting and feeding habits and the level of comfort while resting in the pen.
The aim of the trial was, firstly, to validate the sensor data against manually collected data (the so-called ‘ground truth’ or ‘gold standard’) and, secondly, to investigate whether these animal-based parameters could be used in practice to measure the welfare status of pigs.
Four sensor devices were installed on commercial farms, and three batches of nursery and fattening pigs were monitored. Our study results showed a high level of agreement between computer vision and human observation for spatial distribution and posture.
However, it was not possible to validate the activity level data collected by the sensor device due to significant differences in the way the camera and the human observer recorded the activity. Moreover, it was found that changes in the environment caused alterations in the activity level.
For example, an increase in temperature or a decrease in humidity, CO2, and NH3 led to an increased level of activity. Furthermore, the increase in activity was linked to higher levels of aggression, stress, and inflammation, as determined by skin lesion counts and salivary biomarkers. The activity level also varied between days and production stages.
Despite the inability to confirm the activity level through human observation, our study shows a correlation between events that could adversely affect pig welfare (e.g. changing environment, air quality, aggression level, and physiological status in pigs). To summarise, our findings indicate that sensor-collected activity levels could be used as a tool for pig welfare monitoring."