Individual differences in the reaction of beef cattle to situations involving social isolation, close proximity of humans, restraint and novelty

Abstract

Forty-eight steers and 46 heifers were each subjected to a series of 11 behavioural tests on 3 occasions, separated by intervals of 3 and 4 weeks. The tests performed were restraint in a crush, flight time, fear of humans, flight distance, ease of sorting, following, lateralisation, open field, novel object, startle and restraint test. On the second and third occasions, the animals were also subjected to a test of human proximity. The data were then subjected to a principal components analysis (PCA), which identified two components that explained 42% of the total variation. These two components were named general agitation and avoidance of humans. General agitation was mostly influenced by variables from the restraint test, the open-field test, the following test and flight time. Avoidance of humans was mostly influenced by variables from the fear of humans test and flight distance. A third principal component, which explained 9% of the variation was also identified, and was mostly influenced by the lateralisation and crush tests. Heart rate increases in the human proximity test were lowly correlated with the variables measured in the other 11 tests. The conclusion is that, in order to assess individual differences in beef cattle to conditions of social isolation, human proximity, novelty and restraint, the tests that best do this are the restraint test, the open-field test, the following test, flight time, the fear of humans test and flight distance.