本试验的目的是在卢德勋2001年提出的粗饲料分级指数（GI2001）的基础上筛选一些新指标在奶牛粗饲料中建立新一代分级指数（grading index-2008，GI2008），并用GI2008、GI2001和饲料相对值（RFV）对4种粗饲料品质进行分级比较。根据公式分别计算4种粗饲料的GI2008、GI2001和RFV值。结果表明，4种粗饲料（苜蓿干草、玉米青贮饲料、羊草、玉米秸秆）的GI2008值分别为145.50、108.44、20.10和12.09 MJ/d；GI2001值分别为32.11、19.70、9.39和3.98 MJ/d；RFV值分别为109.20、100.12、91.55和69.93 MJ/d。三者对粗饲料品质划分次序一致。GI2008和GI2001对粗饲料品质分级均优于RFV，二者比较，GI2008与GI2001均能科学地对粗饲料品质进行评定，GI2001值（X，MJ）与GI2008值（Y，MJ）存在如下回归关系：Y=5.166 9X-12.683（R2=0.946 3，P＜0.000 1，n=4）。结果提示，在实际应用中，GI2001指标简便易行，而GI2008主要用于研究目的，科学性比较强。在今后的研究中使用GI2008能更准确而科学地对粗饲料品质进行分级划分。
Based on forage grading index（GI2001）proposed by Prof. LU Dexun in 2001, this study selected new parameters and try to establish a new forage grading index (GI2008) for cows in 2008.To demonstrate the rationality of GI2008, we used GI2001, GI2008 and RFV to evaluate four forages quality and made a comparison of the results. The values of GI2001, GI2008 and RFV were calculated according to their formulas, respectively. The results showed that 1) the values of GI2008 for the 4 forages ranked as follows：alfalfa (145.50) > corn silage (108.44) > cheninsis (20.10) > corn stalk (12.09); the values of GI2001 ranked as follows: alfalfa (32.11)> corn silage (19.70) > cheninsis (9.39) >corn stalk (3.98); the values of RFV ranked as follows: alfalfa (109.2) > corn silage (100.12) > cheninsis (91.55) > corn stalk (69.93). The sequences of the four forages quality were identical by GI2008, GI2001 and RFV methods. GI2008 and GI2001 were superior to RFV, and both of them could give evaluating results for the forage quality more scientifically. The regression equation obtained between GI2001 and GI2008 as follows: Y=5.166 9X-12.683（R2=0.946 3，P<0.000 1，n=4）. GI2001 is simple and easy to operate, but GI2008 is more scientific than GI2001 when using for the field of research. Thus, GI2008 can more accurately and scientifically evaluate the quality of forages on research in future.［Chinese Journal of Animal Nutrition, 2011, 23（8）：1296 -1302］
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