Associations between temperament, performance and immune function in cattle entering a commercial feedlot

Behavioural, endocrine and immunological measures made at weaning or feedlo t entry were examined for associations amongst them and with feedlot perfor mance with a view to identifying predictors of the suitability of cattle fo r feedlot finishing. The 24 animals used in this experiment were chosen to represent the extremes of temperament amongst 209 beef steer calves that we re weaned at 7-9 months of age. From a subgroup of 50 animals that were pad dock-weaned without handling or supplementary feeding, the 12 animals with the worst temperament were selected on the basis of flight time and crush b ehaviour assessment. From a matched subgroup of 100 animals that were weane d in yards and hand fed for 10 days, the 12 animals with the best temperame nt were selected on the basis of flight time, crush score and a novel behav ioural test performed as follows. Each morning, fresh hay and a small amoun t of grain were offered in an adjacent pen and calves were scored on their willingness to walk past an observer standing by the gateway between the 2 pens. These 2 experimental groups were designated as 'nervous' and 'calm', respectively. Blood samples were collected at the start and end of weaning for cortisol assay. On entry to a commercial feedlot 6 months later, blood samples were collected for cortisol and immunological assays on day 1 (imme diately after induction processing) and day 5 (after 4 days in the feedlot pen). The nervous group had significantly higher cortisol levels at weaning and at the feedlot and, after 85 days on feed, had significantly lower ave rage daily gain and significantly higher morbidity than the calm group. Gro ups did not differ in total and differential leucocyte counts, lymphocyte p roliferation, production of the cytokine interferon, natural killer cell ac tivity, neutrophil myeloperoxidase activity, lymphocyte subsets (CD4, CD8 o r WC1), and serum concentrations of IgA, but IgM was lower in the calm grou p. Significant correlations were found between cortisol and a number of hae matological variables, flight time, and average daily gain. The correlation s suggest that desirable traits at feedlot entry may include slow flight ti me, low crush score and high confidence score, low cortisol, low total whit e cell count, low neutrophil count, high CD8(+) lymphocyte percentage, high lymphocyte proliferative activity and high IgA concentration. Relationship s between behavioural traits and immunological measures may have utility in predicting the suitability of individuals for the feedlot environment.