6Owens V N, Albrecht K A, Muck R E, et al. Protein degradation and fermentation characteristics of red clover and alfalfa silage harvested with varying levels of total nonstructural carbohydrates [J]. Crop Science,1999,39(6):1873-1880.
7Playne M J, McDonald P. The buffering constituents of herbage and silage [J]. Journal of the Science of Food and Agriculture,1966,17(6):264-267.
8Broderica GA, Kang J H. Automated simultaneous determination of ammonia and amino acids in ruminal fluid and in vitro media [J]. Journal of Dairy Science,1980,63(1):64-75.