Buijs, S., Weller, J., Budan, A. 2023. When the measurement affects the object – Impact of a multi-part head/neck mounted wearable device on dairy cow behaviour, health and productivity. Applied Animal Behaviour Science 263, 105937.

Wearable technology is increasingly used in both dairy research and commercial dairy farming. Assessment of how such wearables affect cows is of major importance to rule out reductions in welfare and productivity that would hamper commercial implementation. Furthermore, if devices intended to measure behaviour affect behaviour, data can no longer be extrapolated to a larger (unequipped) population, hampering their use as research tools. Lack of published research on this topic may cause an underestimation of effects on cows and research findings. We assessed the effects of a head/neck mounted wearable intended to capture methane and measure activity on dairy cow behaviour, health and productivity. The device consisted of a nose-piece covering the nostrils, held in place by a halter and a 4 kg neck-rig (31 × 19 × 23 cm at the widest points). We performed a 2 × 3-week cross-over trial involving 44 cows. Whereas many variables were not found to be affected, the wearable significantly (P < 0.05) affected bald spots (2.3-fold increase), social grooming (initiated: 41% decrease, received: 34% decrease) and drinking time (10% increase). Furthermore, milk yield and lactose content were significantly decreased, and partial mixed ration intake tended to be decreased (P < 0.10), but all three to a minor extent (<2% decrease). During the initial 6 h only, the wearable significantly increased transitions (standing up and lying down) and tended to increase the probability of a lowered head. During the first week only, the wearable significantly affected step counts (14% increase). During the last (third) week only it affected displacements with physical contact in the feeder area (initiated: 29% increase, P < 0.10, received: 34% increase, P < 0.05). This study showed that wearable technology can affect several parameters of dairy cow welfare. Whilst some effects were minor or short-lived, others were larger and persisted or increased throughout the 3-week deployment phase. This suggests that a habituation period of approximately one week should be observed before collecting data with the wearable. In addition, further product development would be advisable to reduce skin abrasions and improve its suitability for long-term application.