The lying position and body-direction of calves on sloped floor were observed individual pens and a group pen, and preference of the grandient of sloped floor for lying in a group of calves were deternined by cafeteria type trials. In experiment 1,body-directions in lying of 12 calves kept in individual pens having a 1/10 sloped floor (1.5×3.0m) and a flat floor (1.5×2.5m) were recorded throughout 24 h when calves were at 2 months old and at 5 months old. There-after, lying positions and body directions in 6 calves of 6 months old keot in a pen(3.0×90.m) in which floor had a 1/10 sloped were observed throughout 24 h. In experiment 2,lying positions of 6 calves of 6 months old were observed in a 27.×14.4m shelter which was in a 14.4×28.8m dry-lot. The floor under the shelter were divided equally into two parts of 2.7×7.2m, as control and treated parts. The control part was flatfloor, and the gradient of treated part was changedat one week intervals from 0(flat), 1/14,1/9 to 1/7. The lying positions of each calves undder the shelter were recorded in later 3 days in each week. In the 5th week, the floor under the shelter was divided into 4 parts of 2.7×3.6m, respectively. The gradient of each quarter was 0(control), 1/14,1/9 and 1/7,and lying positions of calves were recorded in later 3 days in the week. In individual pens of experiment 1,the proportion of lying frequency to the total observations of calves at 2 months old was 73.0%, while it was 57.5% at 5 months old(P<0.01). In both ages, calves were hardly lying on the flat floor. Lying frequency of calves in the group pen was 62.5%. The most of the body-direction of lying calves at 2 months old was parallel to the contour line, though at 5 months old, the most calves were lying obliquely as their heads were higher than tail heads. In the group pen, parallel lying to the contour line occupied 68.1% in all lying(P<0.05). Four calves preferred to lie down on upperpart of floor and two preferred in front of hay rack in the group pen(P<0.01). In the 1st week of experiment 2,calves were lying more frequently on the flat floor of the treated part than the flat floor of the control part(P<0.01). From the 2nd to the 4th week, there was no significant difference of lying frequency between the control part(flat) and treated parts(1/14,1/9 or 1/7). In the 5th week, the lying on the control part was 20.4%, was signficantly low than other 3 treated quarters. The most frequent lying was observed on 1/9 sloped quarter(39.9%), and followed by 1/14 quarter(37.2%). In both quarters, the upper half was mainly used for lying by calves. Only 2.5% of lying in calves was observed in the quarter of 1/7 gradient.

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[in Japanese]

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[in Japanese]

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