Abstract
The aim of the present study was to develop a technique that is able to estimate marbling score on live beef cattle (Japanese Black) by ultrasound diagnosis. Diagnostic ultrasound images were evaluated according to values of image features (entropy, area uniformity, contrast, and average brightness), and the relationships between these values and the actual beef marbling standard (BMS) numbers in carcass were examined. One week or less before slaughter, ultrasound scanograms around the 7th vertebra thoracica were done in 56 Japanese Black steers. The position on scanograms was decided by observing the position of the M. longissimus thoracic and its peripheral tissue. In the longissimus muscle area, correlation coefficient between values in the scanograms and actual measurement values of the carcass sections were 0.98 (P < 0.01). Using the brightness density of optional regions, the M. longissimus thoracic, M. trapezius, and M. spinalis thoracic regions were calculated on diagnostic ultrasound images by texture analysis, and the resultant image feature values were compared with the actual BMS numbers. Although there was a nonlinear relationship between the image features values of the M. longissimus thoracic region and the actual BMS number, different tendencies were recognized between image features of the M.longissimus thoracic region and other regions on the same ultrasound image. Differences in image features between the M.longissimus thoracic and M. trapezius regions, and superficial measure of MLTA obtained by ultrasound were employed as predictor variables, and the actual BMS number as a response variable. A coefficient of determination of 0.73 between the predictor variables and the response variable was revealed by multiple regression analysis. In the present study, it was proven that an imaging analysis technology using an ultrasound diagnosis is capable of evaluating the marbling score in live fattening cattle.
