8Nelson, W. F., and L. D. Satter. Effect of stage of maturity and method of preservation of alfalfa on production by lactating dairy cows[J].J. Dairy Sci., 1990,73:1800-1811.
9Terry R A,Tilley J M A,Outen G E. Effect of pH on cellulose digestion under in vitro conditions[J].J. Sci. Food Agri. , 1969,20 : 317-320.
10Mould F L,Orskov E R,Mana S O. Associative effects of mixed feeds. I. Effects of type and level of supplementation and the influence of the rumen fluid pH on cellulolysis in vivo and dry matter digestion of various roughages[J]. Anita. Feed Sci. Technol. , 1983 ( 10 ) : 15- 30.
