A similar protocol was followed in three experiments: a trainer cow was randomly assigned to half the pens of recently weaned calves. Data on physiology, behaviour and performance were collected. Trainer cows did not affect rectal temperatures, requirements for antibiotic therapy, white blood cell counts, neutrophil:lymphocyte ratios, or leukotoxin antibody titers. There were no overall differences in weight gain. Trainer cows did not affect the frequency and duration of visits to the bunk. The number of calves observed eating increased. The presence of a trainer cow resulted in less calves lying and more walking, than when no cow was present. The authors concluded that trainer cows did not improve calf health, time spent at the feed bunk or performance of newly weaned calves.