Determination Of Grading Index Of Forages For Dairy Cows In Inner Mongolia And Study Of Dietary Associative Effects

The objective of current research was to study the effects of roughages quality and their combination effects on milk cow productivity by using GI (Grading Index) and RFV (Relative Feed Value) analyzing methods for optimizing roughages utilization in Inner Mongolia.Through GI and RFV analyzing, 12 roughages were selected from 159 different forages and the values of CP, NDF, ADF, DM, DMI, NE, GI and RFV were detected. The results indicated that quality of roughages was different based on conventional nutrient analyzing method, but quality of roughages exhibited the consistent tendency by GI and RFV test.Roughage combination effects was conducted through vitro incubation method, and the results showed that feeding animal with mixing forages exhibited positive effect on milk cow productivities. Comparing with control groups, experimental group of removing 50% of corn stalk by corn silage, Chinese wildrye and prairie milk vetch respectively exhibited the positive effect of animal productivities, and the same results was also seen by using corn stalk replacing corn silage, Chinese wildrye and prairie milk vetch, respectively. The sequence of MFAEI was melilot/corn stalk (1.447), prairie milk vetch/corn stalk (1.421), Chinese wildrye/corn stalk, damp-dry silage/corn stalk (1.191) and silage/corn stalk (1.187).Milk productivities and composition and digestibility of twelve Holstein dairy cows with same body condition were measured by feeding conventional and GI ration respectively. The results indicated that milk yield, milk fat, protein and dry matter of experimental group significantly (P<0.05) higher than that of control group, but lactose content had no significant difference. Experimental groups had the significant (P<0.05) higher digestibility of CP, NDF and P with no difference in digestibility of DM, ADF and Ca comparing with control group.