Abstract
In order to clarify the relationships between milk yield and seasonal fluctuations in grass growth, this investigation was carried out deal with pasturing cows parturition in spring and summer. The milk yield of summer parturition cows was about 20 per cent lowered as compared with that of spring parturition cows, even eliminate high temperature in summer. Under the condition of independent of temperature for milk yield, i.e. below 27℃, it was recognized significant possitive correlation between milk yield and grass standing crop in pasture. Consequently, the highest milk yield showed when the peak of grass growth, i.e. spring flush, corresponded to the peak of lactation curve. On the other hand, the more deviate these two peaks each other, the lower the milk yield. From these results, it became clear that animal output of dairy pasture within arable land was more depended on pasture output than that of permanent pasture without arable land.
