Ultrasonic imaging of marbling at feedlot entry as a predictor of carcass quality grade

Abstract

This study evaluated the ability of ultrasonic examination at entry into the feedlot to predict carcass traits. Feeder calves (487) from eight Prince Edward Island feedlots were examined with an Aloka 500 ultrasound and Critical Vision® image analysis software to determine carcass attributes (backfat, ribeye area and intramuscular fat) at feedlot entry. These measures, along with potential confounders, were evaluated for their ability to predict carcass grade. Three statistical procedures (multinomial logistic regression, constrained multinomial logistic regression and a proportional odds logistic regression) were used to evaluate the data. After evaluation, final analyses were performed using the constrained multinomial logistic regression (adjacent category) procedure. All three ultrasound determined carcass attributes were significantly associated with slaughter grade. The odds of being one grade category higher (e.g., AAA) versus the adjacent category (e.g., AA) were 1.74, 1.37 and 0.98 per percentage point intramuscular fat, mm of backfat or cm 2 of ribeye area, respectively. Heifers were 2.1 times more likely to be in the next higher grade category than steers. Feedlot of origin, days on feed and carcass weight were also significant predictors of final grade.