Effect of single versus group housing and space allowance on responses of calves druing open-field tests (1997)

Jensen MB, Krohn CC, Munksgaard L, et al.

Abstract

32 dairy heifer calves were housed in one of four pen types: (1) a small single pen (0.9 m × 1.5 m); (2) a large single pen (1.8 m × 3.0 m); (3) a small group-pen (1.8 m × 3.0 m for four calves); and (4) a large group-pen (3.0 m × 5.4 m for four calves) until three months of age. Thereafter, all calves were housed individually in tether stalls which were 0.9m wide. Each calf was subjected to two test-sessions: one before tethering at three months of age and one at six months of age. Each test session included two tests. The first test was an open-field test with an unfamiliar calf present and the second was an open-field test in an empty arena. Behaviour and heart rate were recorded. Based on the data for the open-field test with an unfamiliar calf present, two principal components reflecting exploratory motivation and fear of unfamiliar calves, respectively, were defined. At three months of age, individually reared calves had higher scores for the principal component reflecting fear of unfamiliar calves. Principal components reflecting exploratory motivation and fear, respectively, were also defined based on data for the open-field test in an empty arena. At three months of age, individually reared calves had higher scores for the principal component reflecting fear in this test. The results suggest that individually reared calves are more fearful when introduced to a novel social situation and when isolated in a novel arena. Differences in space allowance did not affect the measured responses during the tests at three months of age. At six months of age, no effects of either social rearing or space were found.