Estimation of bull live weight through thermographically measured body dimensions

Estimating the live weight of bulls by measurement of body dimensions with thermography and thermal image analysis was studied during progeny testing of the Simmental breed. The experimental group of bulls was measured seven times every 60 days from housing at the average age of 139 days (181 kg) till slaughtering (449 days, 594 kg). Each bull was weighed, manually measured and captured by the thermal camera. This device, together with the image analysis algorithm, proved to be a successful tool for estimating the wither height (Wh) and hip height (Hh) during all seven age classes. The SEE values for Wh decreased significantly during all weighing from 5.49 cm at day 139 to 1.11 cm at day 449 and from 4.99 to 1.76 cm for Hh, respectively. Two linear models for estimating current body weight at different ages were also developed on the basis of the long-term herd data of the Wh (BW1) and Hh (BW2) measurements. A statistically significant relationship (P < 0.05) was found for all seven age classes, whereby the Radj2 was varying with the age from 0.11 to 0.66 (BW1) and from 0.15 to 0.74 (BW2). Since the SEE values increased a little from 24.96 kg at day 139 to 33.59 kg at last weighing for the BW1 and from 21.76 to 32.69 kg for the BW2, both models expressed high accuracies. Therefore the thermal camera shows to be a useful tool in estimating live BW, which is of significant importance in reducing stress during progeny testing and beef production.