The propensity of cattle to vocalise during handling and isolation is affected by phenotype

We investigated whether phenotype affects vocal and behavioural responses o f newly-weaned beef calves during handling situations and whether vocal res ponse differs between two types of handling situation. The phenotypic chara cteristic chosen was hair colour. Steers were classified into four groups, completely black animals (designated "Type 1A", N = 121), black animals wit h white markings ("Tape 1B", N = 35), completely white animals ("Type 2A", N = 114) and white-faced animals with some degree of tan or light brown bod y 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 gro wth 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 = 0.0 14). Calls did not differ between phenotype groupings in any acoustic prope rties. In trial 2, conducted on days 2 and 3 after trial 1, 111 of the steers test ed in trial I were confined individually, in visual isolation on a scale pl atform for I min. Heart rate was measured at the beginning and end of this period. Vocal behaviour was recorded and movement was measured using an ele ctronic device connected to the load sensing circuit of the scale. During i solation 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 I cattle tended to have hig her 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 I 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 I were more likely to vocalise during tr ial 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 voca lise between phenotypic groups. This should be considered when making welfa re judgements based on a proportion of animals that vocalise. Acoustic prop erties of calls differ between conditions and may provide information about how those conditions affect the internal states of the animals. (C) 2001 E lsevier Science B.V. All rights reserved.