Prediction of marbling in musculus longissimus dorsi of bulls by ultrasonographic method. (Literature review and results of preliminary experiment

We analysed the possibilities of prediction of marbling in meat by means of ultrasonographic pictures and photograph of musculus longissimus dorsi area in live bulls. We used 120 bulls of Holstein breed and 35 bulls of the Slovak Spotted breed in our experiment. We processed preliminary the results of experimental comparison of the sonographic and laboratory evaluation of 3 bulls. The animals were fed by standard way and they were killed at different age of 12, 15 and 18 months. We took sonographic picture of mld area at the point of last rib before killing. Approximately 20 minutes before killing the bulls were administered the sedative Rometar in 2 % concentration and dose 0.25 ml per 100 kg l.w. to reduce the movement of animals. The place for sonography was prepared by shaving off the hairs and applying the acoustic gel. Three pictures were taken from each bull at the same frequency, however, at different intensity of sound, 60, 65 and 70 % out of the total intensification of the sonograph. During the dissection we photographed the transversal cut of m.l.d. and took a sample for laboratory determination of intramuscular fat from each bull. Samples were taken precisely from that place at which we photographed and sonographed before. We estimated the marbling degree in meat after the American marbling score in the sonograph pictures and photographs. Then we confronted them with the content of i.m. fat determined in laboratory. Our hitherto results show that the estimated degree of marbling in sonograph pictures and photographs correspond with the content of i.m. fat determined in laboratory. For instance the content of i.m. fat determined in laboratory was 4.2 % in the sample of m.l.d. in bull No. 72722 and in the sonograph picture of the same bull we estimated the marbling degree 7 which corresponds with the content of i.m. fat from 4 to 5 %. In spite of the fact that our results are not final, the method seems to be very precise to predict the marbling in meat