“…This finding is consistent with earlier findings that higher levels of intake of a particular roughage were associated with reduced digestibility (Dong et al, , 2003bLong et al, 2004) or that high feeding levels led to low digestibility by ruminants because of the more rapid passage of digesta from the rumen (Ørskov and Ryle, 1990;Ørskov, 1992;Han et al, 1992;Hao et al, 2000;Long et al, 2004) in yaks. These yak findings also reflect results in cattle and water buffalo (Levy et al, 1986;Jewell and Campling, 1986;Rule et al, 1986;Huhtanen, 1988;Elizalde et al, 1996;Hussain and Cheeke, 1996;Mulligan et al, 2002;Shane Gadberry et al, 2005), and indicate a reduction in the time available for rumen fermentation and intestinal digestion (Han et al, 1997b;Liu et al, 1997;Xue and Han, 1997). As the experiment progressed, however, new rumen microorganisms adapted gradually to high-CP and -ME diets; thus, apparent digestibility continually increased during the study.…”