Correlations of visual scores, carcass traits, feed efficiency and retail product yield in Nellore cattle

ABSTRACT

The growing use of visual scores (VS) and ultrasound (US) for carcass evaluation inbreeding programs, calls for a knowledge of the relationships between these traits and other relevantcharacteristics, such as feed effi ciency and production of commercial cuts. The objectiveof this study was to evaluate correlations between body visual scores and carcass traits identi-fi ed by ultrasound (US) and feed effi ciency (FE), carcass weight (HCW), dressing percentage (DP)and retail product yield (RPY) in beef cattle. Nellore cattle (male), 42 non-castrated [NCAST] and44 castrated [CAST]) were evaluated by both VS and US, at the postweaning (15-month old) andfi nishing phases (21-month old). Visual scores of conformation (C), precocity (P) and muscling(M) were assessed and the backfat thickness (UBFT), rump fat thickness (URFT) and ribeye area(UREA) were measured by ultrasound. Gain-to-feed (GF) ratio and residual feed intake (RFI) weremeasured in feedlot. Hot carcass weight, DP and RPY were determined at harvest. Non-castratedcattle had greater HCW and RPY but lower UBFT and URFT than CAST. Postweaning VS and USwere poorly correlated with FE in both sexual conditions. Finishing VS were negatively correlatedwith GF in CAST and fi nishing URFT was negatively correlated with RPY in NCAST. The relationshipof VS and US with feed effi ciency and meat yield is affected by age at the date of evaluationand by castration. Feed effi ciency is not related to the yield of meat cuts in Nellore cattle.