甜叶菊秆与玉米秸秆混合青贮品质和体外瘤胃发酵特性

Silage quality and in vitro rumen fermentation characteristics of stevia and corn stalks

为探讨不同比例甜叶菊(Stevia rebaudiana)秆与玉米(Zea mays)秸秆混贮的青贮品质和发酵特性,本研究设计6个处理,即玉米秸秆与甜叶菊秆的混合比例为100:0 (CK)、90:10 (A)、80:20 (B)、70:30 (C)、60:40 (D)及50:50(E),各处理原料充分混合后,装桶密封发酵60 d,开桶取样,进行青贮品质及其发酵特性测定。结果表明:不同混合比例青贮饲料感官品质均优良;相较于青贮前,青贮后各处理的干物质(DM)、钙(Ca)和粗蛋白(CP)含量增加(除CK组和D组Ca含量外),各组青贮饲料单糖(ESC)、磷(P)、中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)含量均降低,但随甜叶菊秆添加量的增加,各组NDF和ADF含量增加。青贮后,C组DM、Ca和CP含量较CK组分别提高1.92%、18.46%和42.15%;D组CP含量显著低于其他组(P <0.05),除A组和B组外,其他处理组ADF含量较CK组差异显著(P <0.05)。青贮后的pH介于3.68~4.14;氨态氮/总氮(NH3-N/TN)随甜叶菊秆量的增加而增加(E组除外);各组间的乳酸(LA)含量均有显著差异(P <0.05),且CK组LA和乙酸含量最低;体外产气试验表明,A组总产气量最高(157.92 mL·g-1);A、B、C和D组干物质降解率(DMD)和中性洗涤纤维降解率(NDFD)均显著高于E组(P <0.05)。发酵液pH介于6.52~6.84;D组NH3-N浓度低于其他组;CK组的异丁酸和戊酸含量均高于处理组。综合分析结果表明,玉米秸秆和甜叶菊秆以90:10的比例混合可以更好地改善青贮品质,可在生产实践中推广应用。

We evaluated the silage quality and fermentation characteristics of different proportions of stevia stalk and corn stalk.Six treatment combinations with varied ratios of corn stalk and stevia stalk 100꞉0(CK),90꞉10(A),80꞉20(B),70꞉30(C),60꞉40(D),and 50꞉50(E)were prepared.The materials in each group were mixed,sealed,and fermented for 60 days,after which their silage quality and fermentation characteristics were determined.The sensory quality of silage with different mixing ratios was excellent.The dry matter(DM),Ca,and crude protein(CP)contents were increased after ensilage(except for in the CK group and Ca in group D).Additionally,the monosaccharide(ESC),P,neutral detergent fiber(NDF),and acid detergent fiber(ADF)contents decreased in each group,although NDF and ADF increased with increasing Stevia rebaudiana.After ensilaging,DM,Ca,and CP contents in group C increased by 1.92%,18.46%,and 42.15%,respectively,compared with those in group CK.The CP content in group D was significantly lower than that in the other groups(P<0.05).Except for groups A and B,the ADF content in all groups significantly differed from that in the CK group(P<0.05).The pH of the forage after silage was 3.68~4.14.The ammonia nitrogen/total nitrogen(NH_(3)-N/TN)level increased as the proportion of stevia stalk increased,except for in group E.The lactic acid content in the CK group was significantly lower than that in the other groups(P<0.05).In vitro gas production was highest in group A(157.92 mL·g^(-1)).The DMD and NDFD in groups A,B,C,and D were higher,respectively,than that in group E(P<0.05).The range fermentation pH values was 6.52~6.84,and the NH_(3)-N concentration in group D was significantly lower than those in the other groups.The content of isobutyric acid and valeric acid in CK group was higher than that in the other groups.These results show that the quality of maize silage can be improved by mixing with corn stalk and stevia stalk in a 90꞉10 ratio.