title: Relation between observed locomotion traits and locomotion score in dairy cows.
abstract: Lameness is still an important problem in modern dairy farming. Human observation of locomotion, by looking at different traits in one go, is used in practice to assess locomotion. The objectives of this article were to determine which individual locomotion traits are most related to locomotion scores in dairy cows, and whether experienced raters are capable of scoring these individual traits consistently. Locomotion and 5 individual locomotion traits (arched back, asymmetric gait, head bobbing, reluctance to bear weight, and tracking up) were scored independently on a 5-level scale for 58 videos of different cows. Videos were shown to 10 experienced raters in 2 different scoring sessions. Relations between locomotion score and traits were estimated by 3 logistic regression models aiming to calculate the size of the fixed effects on the probability of scoring a cow in 1 of the 5 levels of the scale (model 1) and the probability of classifying a cow as lame (locomotion score ≥3; model 2) or as severely lame (locomotion score ≥4; model 3). Fixed effects were rater, session, traits, and interactions among fixed effects. Odds ratios were calculated to estimate the relative probability to classify a cow as lame when an altered (trait score ≥3) or severely altered trait (trait score ≥4) was present. Overall intrarater and interrater reliability and agreement were calculated as weighted kappa coefficient (κw) and percentage of agreement, respectively. Specific intrarater and interrater agreement for individual levels within a 5-level scale were calculated. All traits were significantly related to the locomotion score when scored with a 5-level scale and when classified as (severely) lame or nonlame. Odds ratios for altered and severely altered traits were 10.8 and 14.5 for reluctance to bear weight, 6.5 and 7.2 for asymmetric gait, and 4.8 and 3.2 for arched back, respectively. Raters showed substantial variation in reliability and agreement values when scoring traits. The acceptance threshold for overall intrarater reliability (κw ≥0.60) was exceeded by locomotion scoring and all traits. Overall interrater reliability values ranged from κw=0.53 for tracking up to κw=0.61 for reluctance to bear weight. Intrarater and interrater agreement were below the acceptance threshold (percentage of agreement <75%). Most traits tended to have lower specific intrarater and interrater agreement in level 3 and 5 of the scale. In conclusion, raters had difficulties in scoring locomotion traits consistently, especially slight alterations were difficult to detect by experienced raters. Yet, the locomotion traits reluctance to bear weight, asymmetric gait, and arched back had the strongest relation with the locomotion score. These traits should have priority in locomotion-scoring-system guidelines and are the best to be used for the development of automated locomotion scoring systems.
authors.affiliation: Wageningen UR Livestock Research, Wageningen University, PO Box 338, 6700 AH, Wageningen, the Netherlands. Electronic address: andres_schlageter@yahoo.com.
authors.forename: Andrés
authors.initials: A
authors.lastname: Schlageter-Tello
authors.affiliation: Animal Production Systems Group, Wageningen University, PO Box 338, 6700 AH, Wageningen, the Netherlands.
authors.forename: Eddie A M
authors.initials: EA
authors.lastname: Bokkers
authors.affiliation: Farm Technology Group, Wageningen University, PO Box 36, 6700 AA, Wageningen, the Netherlands.
authors.forename: Peter W G
authors.initials: PW
authors.lastname: Groot Koerkamp
authors.affiliation: Division Measure, Model and Manage Bioresponses, Katholieke Universiteit Leuven, PO Box 2456, 3001 Heverlee, Belgium.
authors.forename: Tom
authors.initials: T
authors.lastname: Van Hertem
authors.affiliation: Division Measure, Model and Manage Bioresponses, Katholieke Universiteit Leuven, PO Box 2456, 3001 Heverlee, Belgium.
authors.forename: Stefano
authors.initials: S
authors.lastname: Viazzi
authors.affiliation: Division Measure, Model and Manage Bioresponses, Katholieke Universiteit Leuven, PO Box 2456, 3001 Heverlee, Belgium.
authors.forename: Carlos E B
authors.initials: CE
authors.lastname: Romanini
authors.affiliation: Institute of Agricultural Engineering-Agricultural Research Organization, PO Box 6, Bet-Dagan 50250, Israel.
authors.forename: Ilan
authors.initials: I
authors.lastname: Halachmi
authors.affiliation: Division Measure, Model and Manage Bioresponses, Katholieke Universiteit Leuven, PO Box 2456, 3001 Heverlee, Belgium.
authors.forename: Claudia
authors.initials: C
authors.lastname: Bahr
authors.affiliation: Division Measure, Model and Manage Bioresponses, Katholieke Universiteit Leuven, PO Box 2456, 3001 Heverlee, Belgium.
authors.forename: Daniël
authors.initials: D
authors.lastname: Berckmans
authors.affiliation: Wageningen UR Livestock Research, Wageningen University, PO Box 338, 6700 AH, Wageningen, the Netherlands.
authors.forename: Kees
authors.initials: K
authors.lastname: Lokhorst
mesh_terms: D000818:Animals; D002417:Cattle / Q000502:physiology*; D005260:Female; D005684:Gait / Q000502:physiology; D008124:Locomotion / Q000502:physiology*; D016015:Logistic Models; D010641:Phenotype; D015203:Reproducibility of Results; D014743:Videotape Recording
keywords: agreement; lameness; locomotion; observer; reliability