Development of the laser remote caliper as a method to estimate surface area and body weight in beef cattle

Abstract

Linear measurements combined with surface area and volume calculations were used to develop formulas to estimate body weight (BW) in beef cattle. These measurements were evaluated directly or estimated using a laser remote caliper (LRC) and digital imaging software. Seventy-two dry, late gestation beef cows aged 3-13 years were measured and weighed Six measurements for each cow were taken; the cattle were weighed, a body condition score (BCS) was assigned, heart girth (HG), hip width (HW), and hip height (HH) were measured directly and 3 digital pictures were taken. The digital pictures portrayed three different views; side view (restrained), rear view (restrained), and side view (free-stall). Body length, HW, HH, surface area and volume were indirectly calculated from the digital images. For each view a complete (C-) formula (direct and indirect measures) and remote (R-) formula (only indirect measures) to estimate BW was developed. The R-squared values 0.7459, 0.7937, 0.8078, 0.5016, 0.611, 0.5553 were attained for C-side view free-stall, C-side view (restrained), C-rear view (restrained), R-side view free-stall, R-side view (restrained), and R-rear view (restrained). The accuracy of these formulas was 81% on average. BCS, HG and HW were the most significant factors when developing a formula for BW (p-value < 0.001). Side view (restrained) image measurements were most accurate in estimating BW. These measurements were highly correlated with the direct measurements and digital linear body measurements were not distorted (due to poor posture/positioning) as seen with the other views. The results or this study show that linear measurements collected by digital imaging methods can be a useful tool for estimating BW.