Reliability of an ordinal rating system for assessing the amount of mud and feces (tag) on cattle hides at slaughter

A study was conducted to provide a quantitative description of the amount o f tag (mud, soil, and bedding) adhered to the hides of feedlot beef cattle and to appraise the statistical reliability of a subjective rating system f or assessing this trait, Initially, a single rater obtained baseline data b y assessing 2,417 cattle for 1 month at an Ontario beef processing plant. A nalysis revealed that there was a strong tendency for animals within sale-l ots to have a similar total tag score (intralot correlation = 0.42), Baseli ne data were summarized by fitting a linear model describing an individual' s total tag score as the sum of their lot mean tag score (LMTS) plus an amo unt representing normal variation within the lot. LMTSs predicted by the li near model were adequately described by a beta distribution with parameters nu = 3.12 and omega = 5.82 scaled to fit on the 0-to-9 interval. Five rate rs, trained in use of the tag scoring system, made 1,334 tag score observat ions in a commercial abattoir, allowing reliability to be assessed at the i ndividual level and at the lot level. High values for reliability were obta ined for individual total tag score (0.84) and lot total tag score (0.83); these values suggest that the tag scoring system could be used in the marke ting and slaughter of Ontario beef cattle to improve the cleanliness of ani mals presented for slaughter in an effort to control the entry of microbial contamination into abattoirs. Implications for the use of the tag scoring system in research are discussed.