放牧牛の生理・生態に関する研究(II-2) : 春放牧初期における和牛の休息時ガス代謝・心肺機能ならびに血中乳酸量・血糖量の変化について

Physiological and Ecological Studies on the Grazing Cattle : II-2 On the Changes of Resting Gas-metabolism, Cardio-respiratory Functions, Blood Lactic Acid and Blood Sugar in Japanese Black Breed of Cattle during the Early Part of the Grazing Period in Spring

In our previous report, we found that the change of resting gas-metabolism and cardiorespiratory functions of Wagyu(Japanese Black Breed of Cattle) were most remakable in the early 10days of the grazing period in spring.
In this report we studied in detail only this early grazing period. The principal results obtained were as follows:
(1) O_2 consumption, CO_2 production and heat output at rest of grazing cattle increased with grazing and each reached the maximum value(about 170% of its initial resting value) on the 6th day after grazing was started.
Then the value fell to some degree and seemed to keep about 40-60% over its initial value.
(2) Pulse rate increased 30-70% witt grazing, and its changing curve was in parallel with that of O_2 consumption or heat output, this suggested that pulse rate could coveniently be used in a field work as an indirect index in calorimetric studies.
(3) Respiration rate ana pulmonary ventilation rate increased 30-70% with grazing, though the daily values seemed to be greatly under the influence of the enviromental temperature.
(4) Each of R.Q., percentage of oxygen decrement, oxygen pulse and tidal air differed a little among individual cattle. The changes of these four with grazing were not great and showed no distinct tendency.
(5) Blood lactic acid increased on the first day of the grazing period, but suddenly decreased after that. Considering this fact, blood lactic acid acctmulation did not seem to increase with grazing.
(6) Blood sugar was not found to change with grazing, and its value showed a considerable variation in individual cattle. There were no cattle with an abnormally Iow value of blood sugar during the grazing period.
In conclusion a remarkably rapid increase of relative metabolic rate (R.M.R.) appears in the early 6 days of the grazing period―― a little earlier than that previously reported. Considered from the adolve-mentioned changes of oxygen pulse, blood lactic acid, blood sugar, etc., fatigue does not occur in grazing cattle if they are kept in good health before put to grazing and the grass on a range is in good conditions.