牛の呼吸数，心搏数，体温および肉生産に対する気動の影響

The study was designed to investigate the effect of air movement on respiration rate,heart rate and rectal temperature,using six Holstein steers,avereging 9 months of age and 375.0kg of body weight at the beginning of the study and 10 monhts and 402kg at the end.The investigation was carried out in the days in July and August when abbient temperature were over 28℃.Either cooled air using a pad-and-fan sysytem or natural air was sent by electric fan to the back of each steer from distributing hole of vinyl film duct set 1 meter upside from the back of cattle in the shelter.The fannig caused a decrease in heart rate and respiration rate,but not in rectal temperature.Decrease in ambient temperature also caused a decrease in respiration rate.On reduction of the respiration rate,the fanning in the study had the effect same with that of decrease in ambieit temparature as much as 4℃.Fannnig using the wet pad system was more effective on reduction of respiration rate than the fanning without the pad.Respiration rate had a positive correlation with dry bulb temperature and dry kata cooling power,and a negative correlation with wet kata cooling power.On the basis of the relation between heart rate and energy con-sumption,the effect of the fanninng beaf production was estimated.The fanning for 5 hours a steer economized energy equiv alent to the Calorie in 60 grams of beaf with standard quality at ambient temperature of 28-32℃,and of beef in above 32℃.

この研究は開始時平均9ヶ月令、体重375kg、終了時10ヶ月令、体重420kgのホルスタイン種去勢牛6頭を用い呼吸数、心搏数、体温に対する気動の効果を調べるために計画した。研究は7,8月で気温が28℃以上の日に実施した。自然の空気またはパッドアンドファン方式による冷気を送風機により牛舎内の牛の背部から1ｍの高さに設置したビニールフィルム管の送風口から牛の背部に送風した。本研究の送風は乾球温度および乾カタ冷却力と正相関、湿カタ冷却力と負相関があった。心搏数とエネルギー消費の関係に基づき牛肉生産に対する送風効果の概算評価を行った。5時間の送風により去勢牛1頭（400kg）当り、28～32℃の環境では標準的肉質の牛肉60ｇ中のカロリーに相当するエネルギーの節約になった。