【摘要】 试验选择泌乳中期的黑白花乳牛8头,按产犊月份、泌乳量和胎次等配对分为两组。试验组精料含粗蛋白质21.15%和产奶净能(NE_L)1.767兆卡/公斤;对照组含粗蛋白质15.92%和 NE_L1.584兆卡/公斤。每公斤乳最高精料喂量为0.5公斤,野青草任吃。试验自7月12日起至9月5日止共8周,分两期交叉进行。两试验期平均气温分别为26.9℃和25.8℃,相对湿度为87.6和83.0%,温湿度指标(THI)为78.7和76.5。试验期两组牛的直肠温度和呼吸频率无显著差异,但试验组的产乳量显著高于对照组(P<0.05),每牛每日平均分别为23.77和22.39公斤;试验组精料消耗量显著低于对照组(P<0.01),每牛每日平均分别为11.85和12.64公斤,产乳的精料利用率和体重变化两组无显著差异。结果表明高温季节提高日粮的蛋白质和能量水平能显著提高产乳量。更多还原

【Abstract】 Eight Holstein cows of mid-lactation were selected and paired into twogroups(treatment and control)according to calving dates,milk yields and numberof lactations.The concentrate mixture of the treatment group contained 21.15%crude protein and 1,767 Mcal.net energy for lactation(NEL)/kg,while those ofthe control group was 15.92% and 1,584 Mcal.NEL/kg,respectively.The maximumallowance of concentrate mixture was 0.5 kg for one kg of milk.Wild grasswas fed adlibitum.This trial was carried out from July 12 to September 5 ina double-reversal design with two periods of 4 weeks each.The average air temperature,relative humidity and temperature-humidityindex(THI)during the two trial periods were 26.9℃ and 25.8℃;87.6% and83.0%;and 78.7 and 76.5,respectively.The results showed that the average rectaltemperatures and respiration rates of the two groups were not significantlydifferent,however the milk yield of the treatment group was significantly higerthan that of the control group(P<0.05).They were 23.77 and 22.39 kg/day peranimal,respectively,and the mixed concentrate consumption of the treatmentgroup was significantly lower than that of the control group(P<0.01).Theywere 11.85 and 12.64kg/day per animal,respectively.The results of this studysuggested that by increasing the protein and energy level in diet for lactatingcows during the hot season,milk production can be improved significantly.更多还原