7WIENER G, HAN J L, LONG R J. The yak [ M ]. 3nd ed. Bangkok: RAP Publication, 2003 : 1-18.
8PERRY J M, ZHAO Y, MARLETTA M A, et al.Cu2+ and Zn2+ inhibit nitric-oxide synthase through an inter- action with the reductase domain [ J ]. The Journal of Biological Chemistry,2000,275(19) :14070-14076.
9MENKE K H,RAAB L,SALEWSKI A,et al.The Esti- mation of the digestibility and metabolizable energy con- tent of ruminant feedingstuffs from the gas production when they are incubated with rumen liquor in vitro [ J ]. Journal of Agriculture Science,1979,93(1) :217-222.
10MENKE K H, STEINGASS H.Estimation of the ener- getic feed value obtained from chemical analysis and in vitro gas production using rumen fluid[ J ]. Animal Research and Development, 1988,28 : 7-55.