Fischer J M, Buchanan-Smith J G, Campbell C, Grieve D G, Allen O B
Department of Animal and Poultry Science, University of Guelph, ON, Canada.
J Dairy Sci. 1994 Jan;77(1):217-29. doi: 10.3168/jds.S0022-0302(94)76944-7.
A 2 x 2 factorial arrangement of treatments, in which particle length of alfalfa silage in the TMR and supplementary long alfalfa-grass hay were the factors, was used to determine whether hay benefits lactating cows and whether its effects depend on fibrosity of the main forage source. Without supplementary hay, TMR contained 45% forage, including corn silage, and 26 to 27.5% NDF. When hay was fed, the amount of alfalfa silage in the corresponding TMR was reduced. In the production trial, 40 cows (20 multiparous) were fed the diets for 8 wk in early lactation. No interactions of silage length and hay occurred on any production variables except lactose concentration in the milk of multiparous cows. Addition of hay to the diet enhanced DMI, without effect on production, so efficiency of milk production was reduced. Shorter alfalfa silage enhanced DMI by multiparous cows, reduced SCM and FCM in primiparous cows, and depressed fat test in both groups. Milk composition and component production generally were unaffected. Five rumen-fistulated cows in early to midlactation each were given the four treatments during four 3-wk periods. Hay enhanced rumination when short alfalfa silage was fed but tended to reduce it on long alfalfa silage. Hay also depressed rumen pH and enhanced VFA concentrations. Alfalfa silage length had minimal effects on rumination and no effect on fermentation, and neither hay nor silage length affected digestion of silage DM or NDF in the rumen. Addition of hay to the diet may not be beneficial for cows fed TMR, but longer term feeding studies are needed.
采用2×2析因处理安排，其中全混合日粮（TMR）中苜蓿青贮的颗粒长度和补充的长苜蓿干草为因素，以确定干草是否对泌乳奶牛有益以及其效果是否取决于主要饲料来源的纤维性。不补充干草时，TMR含有45%的饲料，包括玉米青贮，中性洗涤纤维（NDF）含量为26%至27.5%。饲喂干草时，相应TMR中苜蓿青贮的量减少。在生产试验中，40头奶牛（20头经产牛）在泌乳早期饲喂这些日粮8周。除经产牛牛奶中的乳糖浓度外，青贮长度和干草对任何生产变量均无交互作用。日粮中添加干草可提高干物质采食量（DMI），但对生产无影响，因此牛奶生产效率降低。较短的苜蓿青贮提高了经产牛的DMI，降低了初产牛的标准乳（SCM）和校正乳（FCM），并降低了两组的乳脂率。牛奶成分和成分产量一般不受影响。5头处于泌乳早期至中期的瘤胃瘘管牛，在四个3周期间分别接受四种处理。饲喂短苜蓿青贮时，干草可增加反刍，但饲喂长苜蓿青贮时则有降低反刍的趋势。干草还会降低瘤胃pH值并提高挥发性脂肪酸（VFA）浓度。苜蓿青贮长度对反刍影响极小，对发酵无影响，干草和青贮长度均不影响青贮干物质或NDF在瘤胃中的消化。日粮中添加干草可能对饲喂TMR的奶牛无益处，但需要进行更长期的饲喂研究。
