French N, Kennelly J J
Department of Animal Science, University of Alberta, Edmonton, Canada.
J Dairy Sci. 1990 Jul;73(7):1857-63. doi: 10.3168/jds.S0022-0302(90)78866-2.
Two experiments were conducted to determine the effects of frequency of feeding on ruminal fermentation, blood parameters, milk yield, and milk composition in cows fed a 60% pelleted concentrate and 40% chopped alfalfa hay (DM basis) diet. In Experiment 1, four ruminally cannulated cows were fed concentrates in 12 equal portions at 2-h intervals or in two equal portions at 0500 and 1500 h in a crossover design. In Experiment 2, treatments were as in Experiment 1 plus an additional treatment consisting of a total mixed diet fed at 2-h intervals in a 3 x 3 Latin square design. All treatment periods were 2 wk. In Experiment 1, increased frequency of concentrate feeding tended to result in elevated ruminal pH and increased acetate to propionate ratio. Plasma insulin concentration tended to be higher (1.54 vs. 1.04 ng/ml) and milk fat percentage increased from 2.21 to 2.60% for 2 and 12 times daily feeding, respectively. In Experiment 2, frequency of feeding concentrate or total mixed diet did not affect ruminal and blood parameters or milk yield. In both experiments, milk protein and lactose concentrations were not influenced by feeding frequency. Results suggest that where intake is kept constant, increased feeding frequency will not influence milk yield but could result in elevated milk fat percent in animals fed fat-depressing diets.
进行了两项试验，以确定饲喂频率对采食60%颗粒精料和40%苜蓿干草（干物质基础）日粮奶牛的瘤胃发酵、血液参数、产奶量及乳成分的影响。在试验1中，4头安装了瘤胃瘘管的奶牛采用交叉设计，每隔2小时等量饲喂12次精料，或在0500时和1500时各等量饲喂1次。在试验2中，处理方式同试验1，外加一种处理，即采用3×3拉丁方设计每隔2小时饲喂一次全混合日粮。所有处理期均为2周。在试验1中，增加精料饲喂频率往往会使瘤胃pH值升高，乙酸与丙酸比例增加。血浆胰岛素浓度往往更高（分别为1.54和1.04纳克/毫升），每日饲喂2次和12次时，乳脂率分别从2.21%增至2.60%。在试验2中，精料或全混合日粮的饲喂频率不影响瘤胃和血液参数或产奶量。在两项试验中，乳蛋白和乳糖浓度均不受饲喂频率影响。结果表明，在采食量保持恒定的情况下，增加饲喂频率不会影响产奶量，但可能会使采食低脂肪日粮动物的乳脂率提高。
