6Hofmann R R.Adaptive changes of gastric and intestinal morphology in response to different fiber content in ruminant diets,in fibre in humen and animal nutrition[J]. The Royal Society of New Zealand, 1983,20:51-58.
7Van Soest P J.Development of a comprehensive system of feed analyses and its application to forages[J].J Anim Sci,1967,26:119-128.
8Allen M S.Effeets of diet on short-term regulation of feed intake by lactating dairy cattle [J].J Dairy Sci, 2000,83(7):1598-1624.
9NRC.Nutrient Requirements of Dairy Cattle (10th Ed) (M).Wasgington,DC:National cademy Press,2001.
