The occupancy ratio (ratio of animal time spent inside per day) has been studied in relation to various meteorological environmental factors in summer (July to September) in Hokkaido. The behavior of eight calves was investigated being housed in four types of calf hutches : three in white painted plywood calf hutches with backwall open ; one in a nomal type white painted plywood calf hutch ; one in an FRP calf hutch ; and three in a chained hutch with capacity of four calves. Two eight millimeter cameras were used and pictures were taken for two seconds at interval of five minutes. Since lightings were not used, the observation was made only in the day time (from sunrise to sunset). The average occupancy ratios for three types of calf hutches other than the chained hutch ranged from 52% to 61% and were considerably lower than those in winter (about 80%). Calves in the chained hutch stayed inside much longer (78% to 80%) than those in the other calf hutches. Although the occupancy ratios in winter were strongly related to wind velocity, little correlation was observed in summer. On the other hand, the occupancy ratios in summer were strongly affected by rainfall. On rainy days they were quite high (68% to 75%) compared with those on non-rainy days (46% to 56%). The positive correlation coefficients (P<0.05) between the occupancy ratios and outside temperature and black-globe temperature were observed on non-rainy days for two calves out of four housed in the white painted plywood calf hutches. It seems to be because the average inside globe temperature is 2.7℃ lower than the average outside globe temperature and also because the difference tends to increase according to the increase of the outside globe temperature. These results indicate the calf hutch in summer in Hokkaido has the role of protection from rainfall. The role of protection from heat stress in a hot climate was also estimated in the white painted plywood calf hutches.

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A study was made of the water consumption of growing Holstein steers given orchardgrass first cut hay, orchardgrass soilage or corn silage with small amounts of concentrate. The following results were obtained : 1) The eating of succulent feed such as soilage and corn silage reduced free water intake. Total water intake (the sum of free water intake plus that in the feed), however, was the same as in the case of eating dry feed such as hay, provided live weight and dry-matter intake were the same.2) There was a significant positive correlation between total water intake and dry-matter intake. 3) Free water consumption (Y, kg/day)was posotively correlated with the dry-matter concentration of soilage (X, %) (r=0.851,P<0.01) when daily variation in dry-matter concentration of soilage ranged from 17 to 33%. The regression equation obtained was : Y=1.53X-20.1,(P<0.01). 4) Siguificant positive correlation was observed between average daily barn temperature (X, ℃) and total water intake per kg of dry-matter intake (Y, kg). The following regression equation was obtained : Y=0.10X+3.20,(P<0.01). 5) Based on the above findings, the moisture content of feed may be concluded to have no effect on total water intake but to do so on drinking water intake, provided factors such as live weight, dry-matter intake and ambient temperature are constant.

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