We investigated whether phenotype affects vocal and behavioural responses of newly-weaned beef calves during handling situations and whether vocal response differs between two types of handling situation. The phenotypic characteristic chosen was hair colour. Steers were classified into four groups, completely black animals (designated “Type 1A”, N=121), black animals with white markings (“Type 1B”, N=35), completely white animals (“Type 2A”, N=114) and white-faced animals with some degree of tan or light brown body colouration (“Type 2B”, N=37). In trial 1, vocalisations of all 307 steers were individually recorded for 1 min, while each was restrained for ear-tagging, ear-implantation of a growth promotant, rectal temperature measurement, vaccination and placement of electrodes for subsequent heart rate measurement. The proportion of calves vocalising was 36.2%. This proportion varied among phenotype groups ( P=0.042). More Type 1A (45.4%) than Type 2A animals (29.8%) vocalised ( P=0.014). Calls did not differ between phenotype groupings in any acoustic properties. In trial 2, conducted on days 2 and 3 after trial 1, 111 of the steers tested in trial 1 were confined individually, in visual isolation on a scale platform for 1 min. Heart rate was measured at the beginning and end of this period. Vocal behaviour was recorded and movement was measured using an electronic device connected to the load sensing circuit of the scale. During isolation 16.2% of steers vocalised; a smaller proportion than in trial 1 ( P=0.0001). Type 1 cattle (1A and 1B combined) tended to be more vocal than Type 2 (22.4 and 9.4%, respectively, vocalised, P=0.0639) There were no phenotype-related differences in movement. Type 1 cattle tended to have higher initial heart rates (151.4±3.7 versus 140.7±2.8 beats/min, P=0.063) and greater reduction in heart rate (27.4±1.9 versus 22.9±1.7 beats/min, P=0.076) over the 1 min than Type 2. The amount of movement positively correlated with heart rate. Calves that vocalised showed greater reduction in heart rates than silent calves (32.4±2.1 versus 24.5±1.4 beats/min, P=0.0373). Cattle that vocalised during trial 1 were more likely to vocalise during trial 2 ( P=0.0373). Calls recorded during trial 2 were shorter (1.29±0.16 s versus 1.80±0.1 s, P=0.0075) with lower fundamental frequencies (88.1±2.8 Hz versus 136.8±10.9 Hz, P=0.001) than during trial 1. These results indicate that there are differences in the propensity to vocalise between phenotypic groups. This should be considered when making welfare judgements based on a proportion of animals that vocalise. Acoustic properties of calls differ between conditions and may provide information about how those conditions affect the internal states of the animals.
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