228 Hind Leg Angle and Stride Length Measured by 3-D Imaging Account for Variance of Locomotion Score and Growth Performance of Cattle in Slatted Feeding Facilities

Abstract

Abstract The objective was to determine the variance of locomotion score (LS) and growth performance attributable to hind leg angle and stride length (SL) measured by 3-D image analysis for cattle in slatted feeding facilities. Inherent individual differences in structural conformation may be related to cattle mobility and growth performance in indoor slatted facilities. Angus × Simmental steers (n = 189; BW = 352 ± 43 kg) were blocked by initial BW and assigned to 21 pens. Pens were randomly assigned to 1 of 3 treatments (TRT): concrete slats with no matting, 15-year-old Animat Pebble matting, and new Animat Pebble matting. Steers were fed for 152 d. Individual steers videos were recorded on d 0 using an Intel RealSense depth camera and processed using MATLAB to estimate hind leg angle, SL, and body length (BL). Locomotion scores were assigned using a 0-3 scale (Zinpro Step-Up Locomotion Scoring System) throughout the finishing phase. The MIVQUE0 option of the MIXED procedure of SAS 9.4 was utilized to estimate the proportion of variance in average LS, overall ADG, and final BW. Variance of average LS was attributed to SL and SL × BL × TRT at 64% and 28%, respectively. For overall ADG, variance was attributable to SL × BL, SL × BL × TRT, and TRT at 38%, 35%, and 25%, respectively. Variables of SL, BL, SL × BL × TRT, and TRT accounted for 38%, 23%, 23%, and 15% of the variance in final BW, respectively. Hind leg angle did not account for variance in average LS, ADG, or final BW. Overall, variance of average LS, overall ADG, and final BW were primarily attributed to stride length, body length, flooring type, and their interactions. Individual animal differences in structural conformation are related to cattle mobility and growth performance in slatted indoor facilities.