Abstract
The purpose of this study is to investigate the influence of heifers sociability on their liveweight gains in Holstein breed being grazed on public pasture. 81 raising Holstein heifers were used for this investigation, at Itayama pasture Shibata-shi in Niigata prefecture from May to October in 1973. The agonistic behaviour in the herd was observed and the relationships between the liveweight gains during the grazing season and the social order and the number of cows fed in the owners' barn were examined. The results are summarized as follows: 1. A significant positive correlation (r=0.503^<**>, r=0.423^<***>) was recognized between percentage of victories and age in month in early and later term of grazing. 2. A significant positive correlation (r=0.466^<***>) was recognized between percentage of victories and bodyweight in later term of grazing only. 3. The percentage of victories and the ranking of the heifers which have experienced grazing in the preceding year were higher than the newly grazed heifers. 4. The percentage of victories and the ranking of the heifers introduced later were lower than the other heifers introduced earlier. 5. A significant positive correlation (r=0.670^<***>) was recognized between liveweight gains during the first month after grazing and the gains throughout the grazing season. 6. As the number of cows and heifers fed in owners' barn before grazing increased, the liveweight gains of these heifers showed a tendency to increase after grazing implying that the liveweight gains could be promoted when heifers, having been fed in fewer herd in owners' barn, would be fed outside of the barn in small groups for a certain period before grazing to pasture.
