Five sets of rising five year old Holstein-Friesian non-lactating identical twin cows were studied from February to April 1994. One member from each twin pair had been tail docked at 18 months of age while the other member had its tail intact. The animals were observed weekly at three different times of day; 7am, 12 noon and 3pm. At low fly levels there were no significant differences in the frequencies of either front (eg. leg stamping) or rear (eg. tail flicking) focused fly- induced behaviours between the two treatments. At high fly levels there were no significant differences in front focused behaviours but the docked animals performed significantly more rear focused behaviours than the non-docked cows (eg. 96 vs 34 tailflicks at 12 noon, p<0.05). The adrenocorticol responses to intravenous injection of 0.05mg ACTH (Synachthen, CIBA-GEIGY) or saline was assessed four times throughout the experiment. The animals were blood sampled at time - 1min, 50 and 120 min relative to the time of injection of ACTH or saline. There were no significant differences in plasma cortisol concentrations in response to ACTH injection between treatments. Tail docked cows had elevated levels of fly induced behaviour but did not have an altered adrenal cortex function. This suggests that behaviour is a more sensitive indicator of the effects of fly predation than adrenal response to ACTH. Sensitive physiological indicators of chronic stress need to be developed for the assessment of husbandry practices.

TB, McFadden, MR Callaghan, and SR Davis

Proceedings of the New Zealand Society of Animal Production, Volume 55, , 17-20, 1995
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