Behavior of 20 (17 lactating and 3 dry) high-producing Holstein cattle (30kg/head/day of average milk yield and approximately 9000kg of rolling herd average of milk production/head/year) was observed at 5-min. intervals during 24 hours in tie stall barn.Enough amount (24.4kg of DM/head/day) of mixed ration and long grass hay were fed evenly to lactating cattle. Behavior of them was different among daily milk yield, lactation period and parity classes. Higher producing cattle had longer ingesting and shorter resting time.Those in early lactation period had longer resting with standing, greater frequency of standing and lying and ingesting than in other lactation periods.The average of continuously lying durations in early lactation period was 45min. and was only half of that in late lactation period.In the midlactation period, ruminating time was longer and resting time was shorter than in other periods.These behavioral characteristics agree with the known time lag between peak of feed intake and milk yield after calving.It is supposed that cattle in early lactation period supplement rapid increase of nutritive requirement after calving by increasing frequency of ingesting and also ingesting at the period from midnight to dawn to compensate inability of ingesting much amount of ration at once because of declined appetite after calving.And first calving heifers were greater in frequency of standing and lying and shorter in average of continuously ingesting durations than multiparous cows. High producing cows, those in early lactation period and first calving heifers are likely to be the most susceptible to stress and will require delicate and careful management.
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