VARIABILITY WITHIN INTRAMUSCULAR FAT-CONTENT OF PIGS AS MEASURED BY GRAVIMETRY, FTIR AND NMR-SPECTROSCOPY

In order to determine in vivo intramuscular fat content of pigs' biceps femoris, three methods were compared. Gravimetry and FTIR spectroscopy after total fat extraction from a biopsy (about 400 mg skeletal muscle tissue) and in vivo H-1 NMR spectroscopy after imaging and volume of interest selection were used. Mean values (g fat/100 g fresh tissue) were, respectively, 1.47 +/- 0.35 (gravimetry), 1.26 +/- 0.33 (FTIR) and 0.51 +/- 0.19 (NMR); but NMR-values represented only triglycerides. Within an intramuscular fat range from 1.1 to 2.7 g per 100 g fresh muscle tissue, it was possible to estimate a calibration line between the in vitro and in vivo data for hybrid piglets of about 18 kg. Repeated in vivo NMR measurements on the same muscle Volume showed a mean coefficient of variation of 5.5 +/- 2.7%. The coefficient of variation of measurements on different volumes within the same muscle was 14 +/- 10%. The mean intramuscular fat content of 18 kg or 100 kg pigs was, respectively, 1.64 +/- 0.46 (biceps femoris) and 1.32 +/- 0.1 (longissimus dorsi) g per 100 g fresh muscle tissue.