Harada Hiroshi
University of Miyazaki

In Japan, the individual sire has large genetic influences in the improvements of meat production performance because more than 90% of progeny are produced by artificial insemination. The selections of superior breeding sires of Japanese Black cattle are done by use of performance, and progeny testing records at official stations and also field progeny testing records. The bulls will be selected with relatively strong selection intensity on growth characteristics and feed efficiency at performance testing.
Recently the breeding value estimate is one of the good indicators for selecting superior breeding stock on carcass traits. However, some unexpected defects will be in this program when we place the first emphasis on the improvement of carcass traits directly. We may lose superior bulls, which may be excellent in carcass traits at the first step of selection based on the performance testing records. Numerous approaches including statistical, anatomical and high technological analysis are used to evaluate the meat production performance. The technology using ultrasound would be used for obtaining the estimates of carcass trait directly and is one of the effective approaches to improve the meat production performance of beef cattle. The techniques for estimating carcass characteristics in live animals have been used since the late 1950s to measure fat depth of cattle and pigs by A-mode pulse-echo scanners (Hazel and Kline, 1959). B-mode instruments, which were manifactured with single element of transducer, scanning scope and color scanning scope USL-21 (Harada et al., 1988 and 1989, Kaijo Denki Co. Ltd., Japan) and were improved to multi-elements transducer. The electrical scanner Super-eye MEAT ("SEM500", FHK Co. Ltd., Japan) was designed (1989) and was also improved as "SEM900" (1999) by Harada and is capable of producing two-dimensional images of cross-sectional view of the body.
The newest machine “HS-2100” (FHK Co. Ltd., Japan) was also improved (2009) by Harada. Use of the ultrasound in meat animal improvement programs have increased largely as the results of the perceived accuracy of such instruments in measuring longissimus muscle thoracis area and fat depth (Forrest et al., 1989). On the other hand, carcass traits of beef cattle in foreign countries are usually measured between the 12th and 13th ribs but at present measurement is done between the 6th and 7th ribs of the cattle in Japan.
Real-time ultrasound equipment is used with 3 or 3.5 MHz frequency in foreign countries because of low marbled beef. However, the frequency of 2 MHz is needed to obtain the good image of M. longissimus thoracis area and beef marbling score because it is difficult to estimate these carcass traits of high marbled beef which affects interpretation of the boundary line of M. longissimus thoracis between ribs by using more than 2.5 MHz frequency.
Then experiments were carried out to compare the carcass trait estimates within breeds and prefectures on Japanese Black and Brown cattle. Then experiments were tried to predict the carcass traits of fattening cattle after slaughter at early stages. The third experiments were made to elucidate estimated breeding value of ultrasonic estimates of carcass traits of Japanese Black cattle.