肉用牛の成長と生産に関するシステム分析

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書誌事項

タイトル別名
  • Systems Analysis of Beef Cattle Growth and Production
  • ニクヨウギュウ ノ セイチョウ ト セイサン ニ カンスル システム ブンセキ
  • (2) Validity Check of the Model
  • II.モデルの妥当性検討

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抄録

A simulation model developped by Hirooka and Yamada (1985) to predict growth, whole body and carcass compositions of beef steer from the information on feed quality and quantity as well as genetic size of the breed has been evaluated.(1) Time series observations for growth and feed intake of Japanese Black steers, based on 15 fattening experiments with various feeding conditions, were compared with simulated output obtained from the model. Discrepancies between actual and simulated values for body weight change were small, although simulated values tended to be slightly less than actual ones. The overall average of simulated daily gain was about 5% less than the actual gain.(2) To test the generality of our model, expected daily gain described in the Japanese Feeding Standard for Japanese Black and Holstein steers was compared with simulated daily gain under 3 levels of metabolizability and ME intake which was required to obtain the expected daily gain in the Japanese Feeding Standard.Expected daily gain in the Feeding Standard was within the range of simulated daily gain obtaind from high and low levels of metabolizability.(3) Carcass composition was compared with carcass data of 35 Japanese Black and 22 Holstein steers. In Japanese Black, simulated values for muscle and fat weight agreed fairly well with actual values, but they were overestimated for bone weight. This overestimation may be due to the fact that genetic size of the breed was not taken into account for estimating ash weight. Indeed, by considering Japanese Black as a small-size breed, simulated values for ash weight were reduced by 10% according to the literature values, and then, not only bone weight but also all carcass tissue weights agreed well with actual values. In the medium-size Holstein, simulated values for all carcass tissue weights agreed with the actual values without any adjustment. In conclusion, this simulation model appears to be quite adequate not only for Japanese conditions but also appricable to a variety of breeds and feeding conditions which might be encountered in other countries, because the model took the genetic size of breeds and various feeding conditions into its account.

収録刊行物

  • 日本畜産学会報

    日本畜産学会報 58 (2), 138-146, 1987

    公益社団法人 日本畜産学会

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