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Genetic merits of sires serving in Okinawa were estimated in terms of expected progeny difference (EPD) applying BLUP procedure to field carcass records of 572 steers from 14 sires of Japanese Black breed. Eleven out of 14 sires were produced by line breeding of lines from several prefectures. Two sires produced in Shimane Prefecture and sired by Dai-Nana-Itozakura were ranked high in both meat production and meat quality traits. However, the genetic evaluation of the other sires varied: some sires were ranked high in meat production traits and the others high in meat quality traits. Comparing the genetic evaluation of the sires in the present study with those in progeny testing carried out at the progeny testing station in Okinawa, the ranks of sires in meat production traits were similar in both of the sire evaluations, although the ranks of the sires in meat quality traits were considerably different. This discrepancy in meat quality traits is likely due to the difference in meat grading method and fattening system between commercial feeders and the progeny testing station.

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There are many small islands in South-Western Islands of Japan. It is considered that the grazing of beef cattle in native grasslands of the South-Western Islands is one of the useful way in order to utilize these islands or steep slope-lands without the destruction of nature. This study was conducted to obtain fundamental knowledge on the utilization of these native grasslands for cattle grazing.
The native grassland of 5 ha dominated by silvergrass (Miscanthus sinensis Anderss.) was divided into 3 paddocks and grazed by 3 Japanese Black steers of 10-11 months old. We investigated the vegetation before and after grazing and after burning, and the number of the established plant of bahiagrass after sowing.
The vegetation before grazing was dominated by silvergrass and Ipomoea indica Merr. which twined the former. Ipomoea indica Merr. and Pueraria lobata Ohwi were almost eaten by grazing steers, but silvergrass remained uneaten because it was too tall. Silvergrass showed the highest summed dominant ratio (SDR₂) before and after grazing respectively. The vegetation was changed after burning, then the grassland was dominated by creeping wood (Oxalis corniculate L.) . The number of the established plant of bahiagrass in the burned plots was not significantly different from that in the unburned plots.
Since the grassland is located in tropical area, bahiagrass sown in December germinated in January. Daily gain in each paddocks during grazing periods ranged from 0.17 to 0.74 kg. We found that Ipomoea indica Merr. has high nutritive value.
From the results described above, it is considered that burning has almost no influence on the establishment of bahiagrass. However it is dangerous to burn native grasslands because of the possibility of explosion of unexploded bombs buried in the grasslands during World War II. In native grasslands there are useful wild grasses which contribute to body weight gain of the cattle, and we must continue to study proper grazing management in order to keep the coexistence of herbage and wild grasses.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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