Assessing cognitive performance in dairy calves using a modified hole-board test.

The hole-board test has been used to assess working and reference memory in a variety of species, but not in cattle. We developed and applied a modified hole-board test for dairy calves. Fifteen bottles were evenly spaced along three walls of a test arena; 11 of these were empty and 4 were 'baited' with milk. Calves were exposed daily (over an 11-day learning period) to the test arena with the location of the baited bottles held constant; the location of the 4 baited bottles was then changed and calves were re-trained on these new locations (over a 7-day re-learning period). Working memory (no. of revisits to the baited set), general working memory (no. of revisits to the whole set), and reference memory (avoidance of non-baited bottles) were assessed daily. Performance significantly improved during the learning period for reference and general working memory. Working memory tended to improve, albeit non-significantly. The change in bottle location initially reduced all performance measures, but these subsequently improved during the 7-day re-learning period. These results indicate that a modified hole-board test can be used to assess calf cognition, and thus may be helpful in future research designed to investigate the effects of housing and rearing conditions on cognition.