Choice of probing site for estimation of carcass lean percentage in Pitrain pig using the real-time ultrasound

Abstract

Real-time ultrasound data of backfat thickness, longissimus thoracis muscle depth and longissimus thoracis muscle area were obtained from 210 Piétrain pigs (98 gilts and 112 barrows) using the Pie Medical Scanner 200 equipped with an animal science probe (ASP-18) and frequency of 3.5 MHz. They were fed ad libitum and slaughtered at an average age of 213 days for an average weight of 101 kg. The day before slaughter, four longitudinal and transverse images were taken on the level of the last rib and the tenth rib from each animal. The repeatability of ultrasound last rib backfat (ULRBF) measurements was similar to that of tenth rib backfat (UTRBF) (t = 0.87). Ultrasound last rib longissimus thoracis muscle depth (ULRMD) and area (ULRMA) measurements were more repeatable than those corresponding to the tenth rib. The best correlation between carcass lean percentage estimated by the Fat Lean Meter (CGM lean) and ultrasound carcass measurements was obtained with backfat thickness (r = -0.51). The correlation between CGM lean percentage and ULRMD and between CGM lean percentage and ULRMA were higher than those between CGM lean percentage and UTRMD and between CGM lean percentage and UTRMArespectively. When the CGM lean percentage was predicted from ultrasound backfat thickness, the accuracy of the regression equation was the same regardless of the probing site (last or tenth rib). On the other hand, when longissimus thoracis muscle measurements (depth and area) are included together with backfat thickness in prediction equations, the last rib was more accuracy. Therefore, the last rib site can serve as the probing site for CGM lean percentage prediction.

Keywords

• Swine
• pork
• ultrasound
• longissimus thoracis muscle
• backfat
• carcass lean
• carcass composition