Display of a peer's face picture enhances the preference for a pen in preference testing in cows.

Using preference testing, we investigated the effect of a brush and a peer's face picture on the welfare of breeding beef cows. Four cows were used in experiment 1 and another four cows were used in experiment 2. An experimental barn consisted of two 3.5 square-meter pens, and a corridor measuring 1.6 m wide and 1.3 m long. During the experiment, either side of the pens were treated. In experiment 1, straw bedding was placed in a treated pen (condition B) in the first two trials, a brush was added in the treated pen (condition BB) in the next two trials, and a peer's face picture was displayed in the treated pen (condition BBF) in the last two trials. In experiment 2, condition B was applied for the first two trials, a peer's face picture was displayed in the treated pen (condition BF) in the next two trials, and condition BBF was applied for the last two trials. Each cow was housed alone from 09.00 hour to 15.00 h in the experimental barn during the six trials. The cows stayed in the treatment pen longer than in the non-treatment pen under all conditions in experiments 1 and 2. In experiment 1, the mean total time spent in the treatment pen was longer under condition BBF than under conditions B and BB. In experiment 2, the mean total time spent in the treatment pen was shorter under condition B than under conditions BF and BBF. The mean percentage of time spent ruminating was greater under condition BBF than under condition B. It is concluded that the cows preferred the peer's face picture in the isolated condition of preference testing in this study.