The impact of an oral distraction in cattle during a painful procedure
A total of 288 steers (274 ± 19 kg) were randomly allotted in a 2x2 design to investigate the effectiveness of an oral distraction at minimizing an animal's struggle during a painful procedure (i.e. freeze branding). The heart rate of 12 focal steers per treatment group was recorded using a remote recording system (Vmed PC-Vet). The oral insert consisted of a stainless steel oesophageal probe (25cm in length) modified with a handle and metal frame to hold it in place. Steers were restrained in an instrumented headgate to measure the maximum and average force exerted by each animal. Immediately after being caught in the headgate, a 10s settling period was allowed to elapse, after which the oral insert was placed in the animal's mouth or sham inserted. Immediately after insertion, a 10s baseline period of heart rate and exertion force was recorded. The area to be branded was then clipped of hair and saturated with methyl hydrate. The animal was branded with three separate irons cooled in liquid nitrogen or maintained at room temperature that were held on the animal for 15 seconds each. A square root transformation was applied to the exertion force to obtain normality. Exertion force and heart rate were analysed using a One-Way ANOVA. Steers with the oral insert exerted less force during restraint compared to steers receiving the sham insert treatment (means ± SE: 487 ± 43 mV and 709 ± 61 mV, respectively; p < 0.01), but freeze branding had no effect. No treatment differences in heart rate were observed. Animals given an oral distraction struggled less during restraint, which has the potential to not only reduce the stress on the animal during handling, but also improve the ease of handling animals.