Relationships between in vivo measurements of backfat thickness and several carcass and ham traits in heavy pigs

This study investigated the relationships between ultrasound measurements of backfat thickness (UBF) taken on live heavy pigs and several carcass composition and ham quality traits. Before slaughter 240 pigs were weighed (average BW: 167 ± 10 kg) and assessed for UBF using an A-mode ultrasonic device (placed above the last rib at approximately 5.5 to 8.0 cm from midline, with increasing distance with increasing BW). At slaughterhouse backfat thickness and weight of carcass and of commercial lean and fat cuts were collected. After 24-h chilling, hams were trimmed, weighed, scored and measured for several quality traits. A sample of trimmed fat was taken to assess iodine number and linoleic acid content. All hams were cured, and weight losses during curing were recorded. The measures of UBF were correlated with all carcass and ham traits available. The strongest relationships with UBF were detected for backfat depth at loin (0.54), backfat weight and yield (0.69), overall yield of lean and fat cuts (-0.59 and 0.51, respectively), score or measure of ham fat covering thickness (0.62 and 0.53, respectively), and linoleic acid content of ham subcutaneous fat (- 0.48). Magnitude of correlations does not provide reliable prediction of carcass, but ultrasound assessment on live animals could be useful to support selection programs of heavy pigs aimed to dry-cured ham production. Further studies are needed to investigate genetic relationships between these traits and UBF.