Prediction of lamb carcass backfat thickness by skinfold measurement

Abstract Text: Skinfold measurement is a common method for determining body fat composition and nutritional status in humans for athletic and health goals. Many subjective and objective methods are available for prediction of sheep carcass composition, with more accuracy for automated methods. The objective of this preliminary study was to start the assessment of the use of skinfold measurement as predictor of lamb carcass composition. The first trial evaluated the use of skinfold measurement to predict carcass backfat thickness (BF) and rib eye area (REA). Were used twenty market lambs (29.73 ± 3.15 kg of BW) chosen randomly at slaughterhouse floor. Skinfold measurement (mm) was taken in vivo with a clinical plicometer with sensibility of 2 mm, reading range of 80 mm and pressure of ± 10 g/mm², including: skinfold on sternal bone (SSF); skinfold on m. Longissimus between first and least lumbar vertebra (LSF); skinfold on rump backfat thickness location (RSF); and average skinfold (ASF), with the three measurement. After slaughter, carcasses were chilled over 24h at 4°C. Hot and cold carcass weights (HCW and CCW) were recorded. BF and REA were taken in the cold carcass on m. Longissimus between 12^th and 13^th ribs. A stepwise regression was performed with BW, skinfold measurement, and carcass weights to predict BF and REA. A two steps model was obtained for BF prediction with SSF and HCW (P < 0.01). SSF and HCW were responsible by 39.97, and 48.72%, respectively, of BF variation, resulting in a model R² = 0.89 (RSD = 0.40). A stepwise model for REA used SSF and BF (P = 0.0847). SSF and BF had a partial R² of 0.34, and 0.29, respectively, which model representing 63% of REA variation. In conclusion, skinfold measurement can be used to predict lamb carcass BF and REA, and show potential to be used in the estimation of carcass composition.

Keywords: backfat prediction, lamb, plicometer