【摘要】 选择泌乳中期的黑白花乳牛八头,配对分为试验和对照两组,分两期进行交叉试验,每期四周。试验组牛装电风扇三台,气温到达22℃以上时启动。27℃以上每隔30—50分钟每牛洒水7.5升。两组牛白天舍饲,夜间放在运动场上。两个试验期的平均干球温度、相对湿度和THI分别为29.17℃、76.29％和80.81。试验组的直肠温度和呼吸频率显著(P<0.01)低于对照组,分别为38.97和39.61℃及60.87和78.53次/分。试验组的青草采食量较对照组高20.9％,产乳量高16.85％,每日体重减轻少0.94公斤,差异均极显著(P<0.01)。试验组包括维持在内的产乳的饲料利用率较对照组高22.7％。结果表明,这些防暑措施能显著减轻乳牛的热应激,提高采食量和产乳量,减少体重损失和提高饲料利用率。据经济效益分析,试验组每日每牛的净收入较对照组高1.3964元。更多还原

【Abstract】 Eight lactating Holstein cows were selected and paired into two groups (treatment and control) in a double-reversal design with two periods of 4 weeks each. The treatment group was equipped with three electric fans, which were operating as the air temperature rising to and above 22℃; and when the temperature rose further to and above 27℃, it was sprinkled with water by 7.5L/cow at 30—50 minute intervals. The animals of two groups were housed at daytime and set on yard at night. During the two trail periods the average air temperature, relative humidity and temperature-humidity index were 29.17℃, 76.29% and 80.81, respectively. The rectal temperature and respiratory rate of the treatment group were significantly lower than those of the control (P<0.01),they were 38.97 and 39.61℃,and 60.87 and 78.53/min., respectively (P<0.01). The treatment group consumed 20.9% more grass and produced 16.85% more milk than those of control (P<0.01). The body-weight loss of the treatment group was less than that of control by 0.94 kg/day. cow (P<0.01). The results suggested that the treatment measures could relieve cows from heat stress, and consequantly increase feed consumption and milk yeild, and decrease body-weight loss. The net gain of the treatment group increased by 1.3964 yuan/day per cow.更多还原