斜め空中写真法による放牧牛の行動解析

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書誌事項

タイトル別名
  • A Behavioural Study of Grazing Cows and Heifers by Oblique Aerophotography
  • ナナメ クウチュウ シャシンホウ ニ ヨル ホウボク ウシ ノ コウドウ カイ

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The location of grazing cows and heifers in pasture was estimated by oblique aerophotography. Two herds of grazing cows and heifers were observed and photographed at 3 minute intervals for 3.5 hours. Timed observations and photographic records using a 35mm single-lens reflex camera were undertaken from the top of a tower standing by the side of the pasture. The angle of depression of the optical axis was about 40 degress; the furthest animals in the photographp were at a distance of 70m from the tower. The relation between coordinates in the photographs and coordinates in the pasture was given in the form of a non-linear equation, which included six parameters concerning the rotations and location of the camera in three dimensional space. The actual positions of the grazing animals in the pasture were estimated from coordinates in the photographs. Since the error of estimation was less than 2m in most cases, the accuracy of the estimation was sufficient for behavioural study in the pasture. The distribution of the animals was not homogeneous within the pasture: preferences were shown for the corner of the fence and around the watering place. Inter-pair distances (IPDs) for all combinations of individual animals were calculated with estimated positions in the pasture. When the distribution of IPDs was asymmetrical and similar to Gamma distribution, IPDs were then analyzed by nonparametrical method. In session 1, twelve heifers and eight cows grazed pasture 1 of 15 a. In most cases there was no distinction between simulated IPDs and real IPDs of cow to heifer; IPDs of heifer to heifer and of cow to cow were significantly less than IPDs of cow to heifer. In the heifer group, there were some cases in which clear distinction between IPDs was confirmed. The IPDs of a pivot animal to certain animals were significantly less than IPDs of pivot animal to residual members. The relation which the two animals illustrated could be expressed as "intimate". Some heifers had more than three "intimate" companions, while all the cows had less than two. The relationship among the cows enabled the construction of a linear frame which the members in the subgroup formed like chains, while a reticular frame in which the members were connected like a mesh formed in the heifer group. Some "outsiders" which had no "intimate" companions were found in this session. In session 2, eight heifers grazed pasture 2 of 33 a. Only a reticular frame was recognized in the group, and "outsiders" were not found.

収録刊行物

  • 日本畜産学会報

    日本畜産学会報 56 (6), 439-446, 1985

    公益社団法人 日本畜産学会

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