視覚遮断と電気柵の併用が牛の脱柵行動に及ぼす影響：予備的研究

Developing cost-effective and easily deployable fencing systems for cattle to mitigate escape risk is essential to promote the creation of grazing enclosures in abandoned fields. Visual perception of the environment outside a fence may trigger escape behavior of cattle. We investigated the impact of obstructing visual information on escape-related behaviors in four Japanese black cows and six Holstein non-lactating cows. In Experiment 1, we evaluated the frequency and time of escape-related behaviors in cows placed in an electric fence enclosure when the electricity was turned off and highly palatable feed was visible beyond the fence. In Experiment 2, we installed opaque sheets outside the electric fence to prevent the cows from recognizing any palatable feed and evaluated the effect on escape-related behaviors in cows using the recorded data (Experiments 1 and 2:1872 h in total). In Experiment 1, five cows exhibited escape-related behaviors and escaped from the electric fence (average escape time: 4.6 ± 1.3 days (mean ± SE)). In Experiment 2, the escape-related behaviors of the cows were significantly reduced by visual blockage of the environment outside the fence (p < 0.01).