Use of Images of Standing and Lying Dairy Cows (Bos taurus) to Estimate Body Weight with Body Shape Indices

Abstract

The purpose of this study was to estimate the body weights (BWs) of cattle (Bos taurus) under free-posture conditions, with no movement or restraint of the animals. Dairy cows at different life stages were photographed from above in both lying and standing positions. Several body-shape indices were measured based on the captured images, and relationships with BWs were analyzed. From these relationships, we created models to estimate BWs using shape indices based on all of the data for each life stage of multiparous cows and heifers of more/less than 250 kg. In both standing and lying positions, area measurements of the upper portion of the body had the highest correlations with BW. In the model using all of the data, predicted BWs varied most for cattle that were multiparous, and were underestimated for low-BW cattle. In the models of the standing and lying positions created for each life stage, BW was estimated with high accuracy, except in the case of multiparous cattle. No bias was shown between BWs in the standing and lying positions. These results imply that cow BWs can be estimated using photographs of standing and lying cattle.