The Relationship Between Facial Hair Whorls and Milking Parlor Side Preferences M. Tanner, T. Grandin, M. Cattell, M. Deesing Colorado State University, Fort Collins, Colorado Preference for milking parlor side was compared to facial hair whorl patterns on the forehead to determine if there was a relationship. Anecdotal reports from horse trainers indicate the hair whorl patterns on the forehead are correlated with handedness.
Some horses have a very strong tendency to perform better when turning towards their preferred side.
Trainers have also observed that side preference is weak in some horses and strong in others. Since hair whorls form in the fetus during the same time the brain forms, our hypothesis is that relationships between handedness and hair whorls may be similar in many mammals. Dairy cows were used as subjects because large numbers of cows could be monitored for milking parlor side preference with a computerized identification system. Side preference data was collected at a large commercial dairy on 1379 Holstein cows for 90 milkings. They were milked three times daily in a Surge Double 24 stall parallel parlor.