Validation of a High Frequency Radio Frequency Identification (HF RFID) system for registering feeding patterns of growing-finishing pigs

• A HF RFID system was validated for registering feeding pigs.
• The system was used in simulated commercial farm conditions.
• Specificity for individual pigs with one or two tags was always above 85%.
• Sensitivity varied for individual pigs, tags and different time windows used.
• A sensitivity of 88.58% and a specificity of 98.34% can be reached.

Automated monitoring of the feeding patterns of growing-finishing pigs would allow detecting problems with individual pigs or groups of pigs and thus improving health, welfare and productivity of the farm. In this paper a High Frequency Radio Frequency Identification (HF RFID) system was validated for its suitability to register individual pigs’ feeding patterns at a round trough in a group-housing context. High Frequency RFID antennas were installed above the troughs of a commercially available type of round feeder to identify feeding pigs fitted with one or two passive RFID tags on their ears. A multiplexer was used to connect multiple antennas to a single reader. During 11.5 h, video observations of 20 focal pigs (equipped with two tags) at an age of 16 weeks were performed to validate the system. A large variation in feeding patterns of the 20 focal pigs was found. Correlation between the number of registrations per pig and the feeding duration on video was low (R2 = 0.53) mainly due to four pigs with specific feeding behaviour (with the four pigs excluded: R2 = 0.88). The RFID registrations of the 20 focal pigs – with irregular time gaps between them – were compared with instantaneous video samples using several time window sizes around the video sample. The specificity for individual pigs with one or two tags was always above 85%, but sensitivity varied for individual pigs, tags and with different time windows used. A quantitative comparison between the use of one or two tags per pig was made based on a receiver operating characteristic (ROC) curve. For two tags per pig a sensitivity of 88.58% and a specificity of 98.34% can be reached with a time window size of 9 s. For one tag per pig, sensitivity is only above 85% at a time window of size 31 s. Of the total number of RFID registrations 77.11% occurred during feeding visits, and 92.23% occurred during or within 10 s of feeding visits on video. This system showed good potential for measuring feeding patterns of growing-finishing pigs in commercial pig houses, for research purposes, or to detect potential problems with pigs by signalling changes in the registered feeding patterns.