BACK TO QUEBEC CITY 2002 TITLES
Physiological and behavioural
responses to mixing with strange steers in finished steers
M.E. Booth1, G.J. Mears1,
K. Schwartzkoph-Genswein2, F.A. Brown1, C.L. Holmes1, T. Entz1, A.L. Schaefer3
and T.A.
McAllister1
1,3Agriculture and Agri-Food
Canada, 1Lehtbridge, Canada; 2Alberta Agriculture, Food and Rural Development,
Lethbridge, Canada; 3Lacombe, Canada
This study investigated the social and physiological responses of finished crossbred steers to mixing with unfamiliar animals. Cattle were penned as 4 established groups totaling 19 steers (622.67±46.34 (SD) kg). Within pen, animals were paired randomly and each pair was exposed to 4 different treatments. All pairs were either Home Boys in their home group in holding pen 1, HB(H) or mixed, with 2 strangers added to their home group in the larger holding pen 2, HB(M); or Strangers in their home group in holding pen 2, S(H) or mixed as 2 strangers added to a different established home group in holding pen 2, S(M). Animals were identified by grease-stick marks on their hind-quarters. Blood samples for plasma cortisol analysis were taken at 0, 20, 60, 120 and 240 minutes via indwelling jugular catheters. Behaviour observations started immediately after the 0 sample. All occurrences of some interactive events were recorded for every animal in any group with the aggressor and recipient being noted except in the case of head-to-head. In comparison to non-mixing days there were significant (Wilcoxon signed rank tests; P<0.01) increases in total number of interactive behaviours; of head-to-head and interactions given for HB(M) and S(M); also for S(M) in total number of interactions received. There was no change in the number of interactions received by HB(M). S(M) steers received 1/3 rd more of the interactions given by HB(M) animals than did HB(M) penmates. Plasma cortisol showed some handling effects at sample 0 min but by the 60 min sample had decreased significantly across all treatments. Whilst there was a clear increase in aggressive interactions when cattle were mixed the cortisol response was relatively short.