泌乳量の変動要因としての環境温度に関する研究 : II. 泌乳量の変動と泌乳牛の生理現象

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Interrelationships among environmental temperature, physiological conditions ofanimal, milk yield, and milk composition were discussed in lactating Holstein cows.The present experiment was carried out on the Livestock Farm, University ofTokyo, in Ibaraki Prefecture from May 26, 1964, to May 25, 1965, using 7 Holstein cows.To estimate the physiological conditions of animals, the following items were examined:the heart rate, the respiration rate, the rectal temperature, tlae packed cell volume, thewhite blood count, and the differential leucocyte count. The data obtained were analysedstatistically by using the technique of time serial analysis.The results obtained were summarized as follows.l) The milk yield was affected by ambiextt temperature. When the ambient ten-perature was higher than 20C, the milk yield decreased, being inversely proportionalto the rise of temperature. However, in autumn and winter when the ambient tem-perature was lower than 2OC, the milk yield increased in proportion to the rise oftemperature. This relationship was not clear in spring.2) Among those physiological phenomena, which were affected by ambient tem-perature, the heart rate, the rectal temperature, and the packed cell volume were closelyrelated to milk yield.3) Partial corrlation coefficients were calculated in order to eliminate the influenceof temperature from these complicated interrelationships. The heart rate was directlyproportional to the milk yield. The rectal temperature and the packed cell volumewere inversely proportional to the milk yield.4) The milk yield was influenced distinctly by the change of environmental term-perature. In this case, the milk yield was affected also by the blood circulation andwater metabolism.It was presumed that these functional changes showing the seasonal fluctuationmight be direct causes of variation in milk yield.
社団法人日本獣医学会の論文
1968-10-20

泌乳量の変動要因としての環境温度に関する研究 : II. 泌乳量の変動と泌乳牛の生理現象

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