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

Abstract

Behavioural, endocrine and immunological measures made at weaning or feedlot entry were examined for associations amongst them and with feedlot performance with a view to identifying predictors of the suitability of cattle for feedlot finishing. The 24 animals used in this experiment were chosen to represent the extremes of temperament amongst 209 beef steer calves that were weaned at 7–9 months of age. From a subgroup of 50 animals that were paddock-weaned without handling or supplementary feeding, the 12 animals with the worst temperament were selected on the basis of flight time and crush behaviour assessment. From a matched subgroup of 100 animals that were weaned in yards and hand fed for 10 days, the 12 animals with the best temperament were selected on the basis of flight time, crush score and a novel behavioural test performed as follows. Each morning, fresh hay and a small amount 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 (immediately 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 average daily gain and significantly higher morbidity than the calm group. Groups did not differ in total and differential leucocyte counts, lymphocyte proliferation, production of the cytokine interferon, natural killer cell activity, neutrophil myeloperoxidase activity, lymphocyte subsets (CD4, CD8 or WC1), and serum concentrations of IgA, but IgM was lower in the calm group. Significant correlations were found between cortisol and a number of haematological variables, flight time, and average daily gain. The correlations suggest that desirable traits at feedlot entry may include slow flight time, low crush score and high confidence score, low cortisol, low total white cell count, low neutrophil count, high CD8 + lymphocyte percentage, high lymphocyte proliferative activity and high IgA concentration. Relationships between behavioural traits and immunological measures may have utility in predicting the suitability of individuals for the feedlot environment.