The effect of ultrasound probe on accuracy of intramuscular fat content and marbling prediction in beef longissimus dorsi muscle

The accuracy of prediction of intramuscular fat content was evaluated using two ultrasound probes (5 MHz/64 mm and 3.5 MHz/172 mm). The study was carried out on 142 bulls (74 Slovak Spotted, 6 Pinzgauer, 22 Holstein, 20 Beef Simmental and 20 Charolais bulls). Ultrasound images of rib eye area were taken between 12th and 13th rib one week before slaughter. After slaughter, photographs of rib eye area were taken in order to determine level of marbling. Computer image analyses using a special software package and statistical analyses using SAS/STAT package were done. No statistically significant differences in level of marbling and intramuscular fat content were found between 5 MHz and 3.5 MHz probes. Correlation coefficients between level of marbling and ultrasound image values were 0.26 (5 MHz) and 0.25 (3.5 MHz). With Slovak Spotted bulls, correlations between SONO and MARB values ranged from 0.52 to 0.69 (3.5 MHz) and from 0.19 to 0.28 (5 MHz probe). The effect of ultrasound probe on intramuscular fat content and marbling prediction accuracy was not shown with whole data set considered. The possible influence of ultrasound probe used is shown with findings for Slovak Spotted bulls considered. The optimal performance for ultrasound machine ALOKA SSD-500 was proposed: 65% (5 MHz probe) and 80 - 90% (3.5 MHz probe).