PSII-7 Development and assessment of a mobility scoring system for beef cattle

Lameness is a disruption of normal gait due to infection, injury, or abnormal conformation, causing pain and discomfort. Several scoring systems have been developed to determine lameness severity; a key indicator in deciding if an animal is fit to withstand transport. However, most scoring systems were developed for dairy cattle and may not be suited for use in feedlot cattle due to the large genetic variation between beef breeds as well as the highly variable environment in which they are housed. Lack of consistency when scoring lameness and reduced ability to detect early lame cattle can result in poor animal welfare and increased costs. The objectives of this study were 1) to develop a mobility scoring system that aids in transport decisions for beef cattle, and 2) to determine observer repeatability using this scoring system. Over a 7-mo period, video cameras were placed in an alley to record the ambulation of individual cattle exiting the processing barn at 4 commercial feedlots in Southern Alberta. Cameras were set to record whole-body videos of cattle walking, running, or trotting. Five researchers trained to use this mobility scoring system, individually evaluated 174 cattle from the collected videos, for fitness for transport and the presence/absence of gait abnormalities: shortness of stride, stiffness (mild, moderate, or severe), limp (mild, moderate, or severe), hip hike, head dropped, head bob, arched back, non-weight bearing, or reluctance to move. The mobility scoring system used was a modified (NCBA and Zinpro) 4-point scale (0-3) for locomotion: 0) an animal with no gait abnormalities; 1) an animal with mild stiffness and shortness of stride; 2) an animal with difficulty taking some steps and one or more of the following: severe stiffness, limp favoring affected limb, limps with a head bob when walking but still bears weight; and 3) an animal reluctant or unable to move, bearing little or no weight on affected limb, the head of the animal is dropped and back arched with pronounced head bob and severe limp detected, or incoordination. Fitness for transport was scored as fit, compromised, or unfit according to the humane transportation guidelines of the Canadian Food Inspection Agency. A kappa statistic was calculated to assess inter-observer reliability for both mobility and transport fitness scoring systems as well as gait abnormalities. The combined mobility scores had substantial agreement between observers (Κ = 0.63; P < 0.001). Mobility score of 2 had the highest agreement among all variables (Κ = 0.88; P < 0.001), followed by head bob (Κ = 0.85; P < 0.001), and arched back (Κ = 0.76; P < 0.001). Results of this study will aid in the development of a mobility score that improves industry stakeholder agreement regarding lameness severity and transport loading decisions.