Development of practical method in the early stage discovery of the heat stressed dairy cows and proof of its effective countermeasures

For the purpose of the establishment of technology which the execution period of countermeasure is judged and the effective way of employing the countermeasure against heat stress of dairy cows, respiration rate(RR), rectal temperature (RT), mean body temperature(MT), behavior time of dairy cows were measured on some farms from April to October. Then, relations between the physiological response and milk production , the number of childbirth, effective temperature(ET), the cowshed environment were examined. Relations between RR and ET varied in the milk production. As for the dairy cows producing milk 35kg/day under, it was about 25 degree ET that the RR increased, and exceeded all the means of RR (48 times/min.). But, as for the dairy cows producing milk 35kg/day and more. it was about 21 degree ET that the RR increased, and exceeded all the means of RR. There was most number of the RR of the dairy cow which turned childbirth by 3 when it was compared in the number of childbirth. RR of dairy cows increased caused by the progress of the milking days. RR and RT decreased as it followed in wind speed's becoming fast and the open area of cowshed became wide. It thought that the wind speed beyond 0.5m/min. and making the open area of the cowshed wall more than 0.06 square m toward the capacity 1 cubic m of the cowshed were effective against heat stress reduction of dairy cows. The machines which controlled operation such as a ventilator based on ET inside the cowshed were manufactured as an experiment, and installed in the dairy farmer's cowshed.As a result.put it on October from April, the propagation record improved, and 4-6% of the amounts of milk increased. In the dairy management of breeding 25 milking cows and producing the milk of a milking cow 25kg/day and selling the milk for 98 yen/kg, income increased about 400,000 yen (it is about 18,000 yen/a milking cow) in a year as a result of making a trial calculation.