Welfare indicators for young dairy heifers managed with virtual fencing in northern Sweden.

This study investigated the effects of virtual fencing (VF) on welfare indicators (i.e., BW, behavior, and hair cortisol) of young dairy heifers under northern Swedish conditions. Thirty heifers aged 126 to 294 d at the beginning of the experiment were allocated into 2 groups (n = 15): a control group managed with physical electric fencing, and a VF group. All heifers were fitted with VF collars before acclimatization on pasture. The 110-d experiment included a 5-d acclimatization period followed by three 35-d grazing periods conducted in different paddock areas (full paddock, one side, and the opposite side), each comprising a 6-d learning phase and a 29-d post-learning phase. Collar data for the VF group were analyzed for each learning phase and subsequent days in each period. Animal behavior was evaluated as scan sampling observations. Herbage samples were collected at the start and end of each period to evaluate herbage mass and chemical composition for potential pasture utilization assessment for both groups. The heifers were weighed at the beginning and at the end of the trial, and tail hair samples were collected at the end of the experiment for cortisol analysis. Over the course of the experiment the number of recorded audio cues increased and electrical pulses decreased. No significant differences were observed in behaviors such as grazing or lying down ruminating between the VF and control groups, nor were there significant differences in herbage mass or composition. Body weight gain was lower and hair cortisol concentrations were significantly higher for heifers managed with VF. Virtual fencing collars maintained reliable functionality throughout the 110-d trial under summer grazing conditions, and heifers aged 6 to 9 mo rapidly learned and adapted to the system. Although slightly higher cortisol concentrations and differences in growth were observed in the VF group, no behavioral evidence of impaired welfare was detected. Overall, VF demonstrated functional reliability under practical conditions; however, further research is needed to clarify the physiological and welfare implications of VF use in young heifers.