4Wilkins R J. The preservation of forage. In E. R. Orskov(ed) Feed Science[M]. Elsevier Science Publ., New York, 1988:231 -255.
5Sheaffer C C, Martin N P, Lamb J F S. Leaf and stem properties of alfalfa entries[J]. Agronomy Journal, 2000, 92(4): 733-739.
6Buckmaster D R, Heinrichs A J. Losses and quality changes during harvest and storage of preservative treated alfalfa hay[J]. Transaction of the ASAE, 1993, 36(2): 349-353.
7Rotz C A, Abrams S M, Davis R J. Alfalfa drying loss and quality as influenced by mechanical and chemical conditioning[J]. Transaction of the ASAE, 1987, 30(3): 630-635.
9Woolford M K, Tetiow R M. The effect of anhydrous ammonia and moisture content on the preservation and chemical composition of perennial ryegrass hay[J]. Anim Feed Sci Technol, 1984, 11(3): 159- 166.
10Rotz C A, Davis R J, Buckmaster D R, et al. Preservation of alfalfa hay with propipnic acid[J]. Appl Eng Agric, 1991, 7(1): 33"40.