Estimativa de peso e mensurações morfométricas com o uso de câmera de profundidade em novilhas da raça nelore

Abstract

The objective of this study was to evaluate the body weight estimate and morphometric measurements of Nellore heifers using a depth sensor as a tool. An Intel® RealSense d435i depth camera was used to acquire dorsal images of the of 405 heifers aged 8 to 18 months. The data were acquired in the experimental area of Embrapa Agrossilvipastoril in Sinop, Mato Grosso, in addition to two other properties in the state, one located in the municipality of Itaúba and the other also in Sinop from March to December 2019. images were manually associated with the electronic ear tag of each animal, being converted into png format and text file (.csv). With the animal contained in the trunk, weight was collected by electronic scale and the following morphometric measurements were performed using a hypometer: distance from withers to the ground (withers height), distance from the rump to the ground (height from the rump), distance between the edge anterior hip to ischial tuberosity (croup length), distance between the coxofemoral joints (croup width) and distance between the two shoulders (chest width). The volume was determined by means of the product of the height by the area of the animal in pixels estimated in the processed images. The volume value was later converted from pixels to m3. The adjusted linear regression model, for real weight measured on the scale and estimated volume3, presented a high coefficient of determination of R2 = 0.97. The mean absolute percentage error (EPAM) was 3.13% for the model. The mean absolute error (AME) was ± 8.85Kg. The mean quadratic error (NDE) was 10.07 kg. The correlations found for the 93 animals measured analogously with the aid of a hypometer and digitally through the processed images that were captured with the depth camera and the values calculated for absolute error mean (EAM), mean square error (EMQ) and mean percentage error (EPAM), were: R2 = 0.56, 4.23cm, 5.34cm and 18% for chest width; R2 = 0.86, 4.4 cm, 5.1 cm and 13.9% croup width; R2 = 0.75, 6.0 cm, 8.0 cm and 19.3% for croup length; R2 = 0.9, 4.7 cm, 6.6 cm and 3.8% for croup height; R2 = 0.92, 3.5 cm, 5.1 cm and 2.9% for withers height.