Abstract: In order to determine the appropriate level of the crush process of alfalfa hay in field,this study used alfalfa as research material with the process of crushing stalk in varying degrees,and analyzed the rule of the moisture loss,and the characteristic in drying process and nutrients content in the modulation process,and used the in vitro digestion experiments to validate the result.The results showed that the content of moisture demonstrated the tendency which was decreased fast at first and then slow down,the speed of the process of crushing was significantly faster than unflattened treatment during alfalfa drying process (P<0.05),the degree of crushing was greater,the speed of drying was faster.The treatment of crushed made the stem and leaf went synchronous during the process of drying,and the rate of leaf reservation was higher.Moderate flattening alfalfa was drying faster,and the better preservation of nutrients,and it had higher DM,CP in vitro digestion rate,it was concluded that the moderate crushed was the appropriate degree of flattening alfalfa hay in feild.

Key words: alfalfa; crushed; hay nutritional ingredient; in vitro digestibility