[in Japanese]

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Body (vaginal) temperature was recorded continuously to determine a reliable method of measuring body temperature for detecting estrus in dairy cattle. Three Holstein heifers, 11 to 15 months of age and each with a portable dataloger attached to their backs, were released in an outside paddock. The vaginal temperature was recorded by the datalogger at two-minute intervals. During the 50-day experimental period, estrus was observed eight timcs, and the lowest vaginal temperature (LVT) in the morning showed a characteristic change between days immediately before estrus, as follows. (1) The LVT in the morning began to decrease two or three days before estrus and reached its minimum level on the day before estrus. The decrease in LVT between days before estrus varied from 0.1 to 0.8℃. (2) The LVT increased 0.3 to 0.6℃ on the day of estrus compared to the previous day. (3) When estrus extended to the next day, LVT remained at a high level. (4) LVT returned to normal level after estrus. The LVT was found most frequently around 0800h and 87% of the LVT were observed between 0500 and 0900h. The LVT often appeared 30 to 60 minutes after the heifers stood up. It is, therefore reasonable to measure body temperature in the morning and before feeding, while the animal is standing, to detect estrus in dairy cattle, Key words : vaginal temperature, dairy cattle, estrus detection, heifer Jpn. J. Livest. Management, 28(2) : 50-54. 1992. Received November 25,1991.

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Detailed behavior of dairy cow in case of free-stall housing is still unknown. In this study, the effects of season and stocking density on animal behavior ; frequency and duration of lying, standing, ruminating, drinking and eating in addition to stall utilization of the lactating cows (Holstein, Jersey and Guernsey) were examined under free-stall housing. Scan sampling were performed during two days at ten minutes intervals in three socioenviromental cases ; 8 cows to 25 stalls in winter (low density in winter : WL), 16 and 17 cows to 24 stalls in summer (high density in summer : SH), and 8 cows to 25 stalls (low density in summer : SL). Lying behavior was longer in winter than summer, but the frequencies of lying did not differ among both seasons and stocking densities, while the lying time tended to decrease in SH. Within a 24 hour period, the peak of lying was found between 03 : 00 and 04 : 00h. Standing tended to increase with SH as compared to WL. Frequencies of ruminating and eating episodes did not differ among both seasons and stocking densities, but its duration tended to be longer in winter than in summer. Ruminations were longer in lying form in winter but in standing form in summer, Stalls used by cows for rest throughought 24h period were 6.5 to 7.1 per head, but its duration tended to decrease in summer. In free-stall housing, cows seemed to avoid to face each other at stall in low density, as every instance of frequent usage in one particular stall less usage was observed in opposite stall. Stall usage by the cows seemed to be more even under high density feeding. Jpn. J. Livest Management, 28(2) : 55-61. 1992. Received February 15,1992.

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The effects of parity and environmental temperature on milking performance were investigated during the summer months of 1982,involving 4 primiparous and 4 multiparous dairy lactating cows. The cows were separated into two groups. One group involving 2 primiparous and 2 multiparous cows stayed outside during the entire day except for milking time and 1600h-2030h of sampling periods (Group N). The other group involving 2 primiparous and 2 multiparous cows was air conditioned from 0800h to 2030h and stayed out side from 2030h to 0830h (Group A). The temperature in the air-conditioned barn was controlled at 23±1℃. The results are as follows : 1) The body temperature and respiration rate of Group N paralleled with the change in ambient temperature and increased markedly in early August during which the ambient temperature at 1400h exceeded 30℃. The body temperature and respiration rate of multiparous cows had a tendency to be higher compared with those of primiparous cows in Group N. But those of Croup A were around 38.6℃ and 40 resp./min, respectively. 2) The estimated dry matter intake of Croup A was higher than that of Group N. The estimated dry matter intake per body weight of primiparous cows was not different from that of multiparous cows. 3) The rate of decrease in milk yield of primiparous and multiparous cows in Group N was about 4 and 9 % , respectively, as compared with each yield expected by the normal lactation curve from late June to middle September. Although the rate of decrease in milk yield of Group N was not different from that of Group A for primiparous cows, the former was higher than the latter in the case of multiparous cows. 4) The change in milk fat percent of Group N was different for primiparous and multiparous cows according to the degree of decrease in milk yield. 5) These results suggest that the effect of high temperatures on milk yield was higher in multiparous cows compared with primiparous cows, and that air-conditioning during a hot summer was more effective for the milk yield of multiparous cows. Jpn. J. Livest Management, 28(2) : 62-70. 1992. Received February 28,1992.

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[in Japanese]

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