Effect of ambient temperature on physiological responses of lactating cows [Holstein crossbred and Brown Swiss crossbred]
1981
Taveedaje Prajaksakul
A switch-back design was used for determining the effect of ambient temperature on a physiological reaction between six lactating cows which were divided into two groups (three of each consisting of one Holstein crossbred and two Brown Swiss crossbreds). The experiment consisted of two periods. The first and second periods were six and three weeks respectively. In the first period, one group was fed in an air conditioned room where the average air temperature was between 24.9 degrees-27 degrees Centigrade and the average relative humidity was between 66.7-71.5 percent. The other group was fed under normal conditions where the average air temperature was between 28.8 degrees - 30.3 degrees Centigrade and the average relative humidity was between 57.0-73.8 percent. In the second period, the first group was fed under normal conditions where the average air temperature was between 28.9 degrees - 29.9 degrees Centigrade and the average relative humidity was between 60.0-70.5 percent. Alternatively, the second group was fed in an air conditioned room where the average air temperature was between 26.7 degrees - 27.3 degrees Centigrade and the average relative humidity was between 72.6-74.0 percent. Adaptation period was one week in each period before collecting the data The high temperatures caused a significant increase in respiration rate and decrease in hemoglobin concentration. Lower environmental temperatures tended to increase the number of red blood cells, body weight, milk yield and voluntary forage intake but decreased water intake
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