Cattle in high social order spend more time eating than those in low order, since the former can eat without being disturbed. This paper describes the results of an investigation made in 1984 and 1985 at the livestock farm (Hokkaido) of Tamagawa Univ. Two groups of three Holstein steers each, not dehorned, were used in eight experiments to determine the time spent in eating supplementary feed under the condition of varying the length of trough allotted each animal. The frequency of eat-breaking was also observed. Each experiment was carried out for three days in succession. Animals were selected so as to represent each herd in live weight, but their exact ages were unknown. The steers were kept in an enclosure 1Om by 30m and had continuous access to high quality hay and water. At about 4 : OOpm, 1kg of commercial fattening feed (Table 1) per animal was placed in each trough. The results obtained are summarized as follows : 1. The mean rate of eating (mean time spent in eating 1kg feed given separately) of the steers averaging 519kg live weight was 3min. 53s., and that of the steers averaging 305kg live weight was 5min. 29s. (Tables 6and7). The large animals ate more rapidly. In these expeiments the steers were never noted to break eating. 2. When the ratio of trough length to chest width (T/C ratio) was less than about 1.0,that is, when trough length allotted per animal was less than the mean chest width of steers, competition for feed in side-by-side eating was intense. Differences in time spent eating were large as shown in Tables 3,4,and 8. 3. When the T/C ratio was over about 1.6,competition for feed in side-by-side feeding was very mild, and differences in time spent eating were very small as shown in Tables 2 and 5. When the trough was not devided, the length of the trough required to allotted to each animal appeared to be approximately 1.6 times the mean chest width of steers. 4. Setting up angle iron posts vertically just in front of the trough at intervals almost equal to the mean chest width of the steers (T/C ratio=40.0cm/38.7cm=1.03) without providing any head protection as shown in Fig. 1,made the time spent eating by one group (average body weight=305kg) essentially the same, being about 5min. 33s. -5min. 40s. (Table 9). This time was almost the same as that of cattle eating separately (Table 7). 5. The frequency of eat-breaking tended to be inversely proportional to the T/C ratio (Tables 2-5).

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[in Japanese]

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Measurements of the body surface temperature of a Japanese-Shorthorn beef cow were made in both indoor and out-door environments throughout the summer and winter seasons. In an unheated room, the temperature distribution of the skin surface and radiative hair at 22 sites on one side of the cow body was measured as a function of air temperature. The effects of net radiation and wind speed on skin surface and radiative hair temperature of the cow when exposed to the open air were measured. The skin surface and radiative hair temperature increased linearly with net radiation, and decreased non-1inearly with wind speed. The interrelationships between body surface temperature, net radiation, and wind speed were analyzed using a sensible heat balance. Measurable local sensible heat loss was determined from a graph indicating the relationship between body surface temperature and net radiation. The temperature distribution of the skin surface in the unheated room increased with decrease in air temperature. Skin surface temperature in the area of the ribs and belly exceeded that of other trunk area at an air temperature of O℃. Differences in the surface temperature of the trunk and limbs were also clearly apparent. Mean skin surface and mean radiative hair temperature was related to air temperature, and the differences being remarkable at an air temperature of about 12℃. In a cold environment, hair and tissue insulation may be increase a possibility indicated by temperature differences of rectal areas, skin, hair, and air.

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