Accuracy of Thoracic Tape-Based Live-Weight Estimation in Minhota Calves: Effects of Age, Sex and Dam Parity

Accurate live-weight monitoring is important for calf management, but calibrated scales are not always available under farm conditions. This study evaluated the accuracy of a thoracic measuring tape for estimating live weight in Minhota calves and examined whether tape error was influenced by age, sex and dam parity. The dataset included 210 repeated weighing records from 68 biologically distinct calves. Scale-measured live weight was used as the reference value, and tape accuracy was assessed using signed error, absolute error, percentage error, absolute percentage error, correlation and Bland–Altman analysis. Repeated-measures regression models were used to account for multiple records from the same calf. Tape-estimated live weight was very strongly correlated with scale-measured live weight (r = 0.997). The tape showed a small average underestimation of live weight, with a mean signed error of −3.02 kg, mean absolute error of 7.79 kg, root mean squared error of 11.92 kg and mean absolute percentage error of 4.97%. Age was the main factor associated with tape accuracy. For every additional 100 days of age, signed error decreased by 5.74 kg, indicating increasing underestimation in older calves. Sex and dam parity had limited effects. The thoracic measuring tape is a useful practical tool for routine monitoring of Minhota calf growth, but age-related bias should be considered, especially in older and heavier calves.