The impact of factors, that are independent of environmental stimuli, need to be determined, so the value of vocalizations in the assessment of welfare in cattle can be decided upon. The effect that parental differences, sex, age and weight have on the vocal response of calves to one minute of isolation at 166 (day of weaning), 167 , 278 and 350 days of age were examined. The amount of movement during isolation was also observed to determine if a relationship between movement and rate of vocalizations exists. Of the 130 beef calves used in the test, they originated from one of 17 full-sibling families. These families were created by breeding five sires with thirteen superovulated dams. The embryos were then transfer into unrelated cows, who raised the calves until weaning. The number of calves that vocalized on the day of and day after weaning were 33.3% and 34.8% respectively. On day 278, 27.8% and on day 350, 38.6% of the calves vocalized while isolated. The sire and family had a significant effect on the number of vocalizations, the acoustic properties of the vocalizations and movements made during isolation. However, there was not a significant relationship between the vocal responses and movement during isolation. Age and therefore body weight had numerous effects on vocalizations. The older calves tended to produce longer vocalizations. At 350 days of age, age and weight were positively correlated with fundamental frequency and sound pressure level at the frequency of greatest intensity, while they were negatively correlated with the loudest harmonic. Heifer vocalized more than bulls at 278 and 350 days of age, however, there was little difference between sexes in terms of the acoustic properties of the vocalizations. The results of this study show that when calves are raised similar environmental conditions, the parental genetics influence vocalizations. However, the vocalizations may also be affected by sex, age, and weight. This study also found that there is not a relationship between vocalizations and amount of body movement.