The behavior of cattle during an injection of doramectin 1% injectable solution or ivermectin 1% injectable solution in an attempt to measure small differences in aversiveness in 61 red Angus-cross, 2-year-old heifers. Each animal was held in a squeeze chute and given a 9 ml s.c. injection of doramectin, ivermectin or sterile saline. To separate the behavioural effects of needle insertion from the animal's reaction to each substance a 19 gauge butterfly needle with a 30 cm tube was used to prevent the pressure of the syringe from affecting behaviour. Two observers, who were blind to the treatment, scored the reactions to the injections. The aversiveness of the injection was scored on a scale, 1 = no reaction, stood still, 2 = slight movement during injection, 3 = shaking the chute, and 4 = vigorous shaking. The cattle were also scored for willingness to re-enter the squeeze chute. Cattle in the doramectin group had significantly more animals with a score of 1 compared to cattle injected with ivermectin. Re-entry scores into the chute were significantly different between treatments for one observer and not significantly different for the other observer. None of the products caused a sufficient nociceptive stimulus to prevent cattle from re-entering the squeeze chute. Doramectin causes significantly less discomfort during injection than ivermectin. It is possible to measure differences in animal discomfort with a numerical scoring system.
|Publication Title||Applied Animal Behaviour Science|
|Author Address||Department of Animal Sciences, Colorado State University, Fort Collins, CO 80523-1171, USA.|
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