Description of the main attributes (origin, gender, age, body condition, and slaughter weight) at slaughter house arrival and their impact on carcass characteristics from cull Quarter Horse

In order to describe the effects of origin (Mexico and United States of America), sex, age at slaughter (AS, 4categories), body condition score (BCS, 5 categories) and slaughter weight (SW, 4 categories) on carcass characteristics of culled quarter horses, data from 235 horses sacrificed in the same slaughter facility within a 150 days period wereanalyzed. Overall, 74.5% were from the US, 80% were < 15 years of age and had BCS ≤ 4, and sex proportion was similar(51.5% female vs 48.5% males). Horses from USA had heavierSW (27%), leg circumference (4%), carcass weight (4.2%) and carcass yield (2.9%). Sex did not affect any characteristics evaluated. Horses from 3 to 8 years had greater rib eye area(REA) and backfat thickness. Except for leg length, as BCS and SW improved, all carcass characteristics linearly increased as BCS and SW increased. It is concluded that origin, sex, and age, explained very little on the carcass characteristics. The slaughter weight mainly explained changes in linear measures,carcass weight, and compact index, while BCS mainly explained carcass yield and REA.