摘要
本试验旨在研究膨化预处理对玉米秸秆木质纤维结构的降解作用以及菌酶协同发酵对膨化玉米秸秆微贮饲料感官评定、发酵品质和营养价值的影响。根据膨化机出料口间隙的不同,设置4个组,其中对照组为未膨化玉米秸秆,3个膨化组出料口间隙分别为1.5(E1.5组)、2.5(E2.5组)和4.0 mm(E4.0组),每组5个重复。根据膨化预处理试验结果,确定秸秆膨化预处理优化参数,并进一步开展微贮试验。微贮试验设置4个组,分别为对照组(膨化玉米秸秆无任何添加剂,CK组)、膨化玉米秸秆+4 mg/kg植物乳杆菌组(LP组)、膨化玉米秸秆+1.0 g/kg纤维素酶组(EC组)以及膨化玉米秸秆+4 mg/kg植物乳杆菌+1.0 g/kg纤维素酶组(LP+EC组),每组5重复,每个重复1袋,30℃条件下密封发酵45 d。结果表明:1)与对照组相比,膨化组玉米秸秆粗蛋白质(CP)、粗脂肪(EE)和可溶性碳水化合物(WSC)含量显著提高(P<0.05),中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)、半纤维素和纤维素含量显著降低(P<0.05)。其中,E4.0组膨化预处理效果最佳,用于后续微贮试验。2)扫描电镜观察微观结构结果表明,膨化预处理后玉米秸秆细胞壁结构被破坏和降解,且秸秆表面细菌总数显著降低(P<0.05)。3)与CK组相比,试验组膨化预处理玉米秸秆微贮饲料pH均降低,具有酸香味,感官品质较好,综合评价均为优等,且感官评定总得分从高到低依次为LP+EC组(87分)>LP组(86分)>EC组(82分)。4)与CK组相比,各试验组微贮饲料pH均显著降低(P<0.05);LP组和LP+EC组乙酸含量和氨态氮(NH_(3)-N)/总氮(TN)值均显著降低(P<0.05),乳酸含量和乳酸/乙酸值均显著提高(P<0.05)。5)与CK组相比,试验组微贮饲料NDF和ADF含量显著降低(P<0.05),阿魏酸含量显著提高(P<0.05);EC组和LP+EC组CP和EE含量显著提高(P<0.05)。同时,LP+EC组CP、EE和阿魏酸含量显著高于LP组(P<0.05),NDF和ADF含量显著低于LP组(P<0.05)。综上所述,膨化机出料口间隙为4.0 mm时,膨化预处理能够降解玉米秸秆的木质纤维结构,释放更多的WSC,从而提升其营养价值;膨化预处理再与微贮结合处理,菌酶协同发酵的效果最佳,能够有效降低玉米秸秆的纤维含量,并释放更多的阿魏酸活性物质,从而改善玉米秸秆微贮饲料的发酵品质。
The purpose of this experiment was to study the effects of extrusion pretreatment on the degradation of lignocellulosic structure of corn stalk and the effects of bacteria-enzyme cooperative fermentation on sensory evaluation,fermentation quality and nutritional value of expanded corn stalk microbial ensilage.Four groups were set up according to the difference of outlet clearance of extruder with 5 replicates in each group,in which the control group was unexpanded corn stalk,and the outlet clearance of the three extrusion groups was 1.5(E1.5 group),2.5(E2.5 group)and 4.0 mm(E4.0 group),respectively.According to the results of the extrusion pretreatment test,the optimized parameters of stalk extrusion pretreatment were determined,and the microbial ensilage test was further carried out.The microbial ensilage test was set up in 4 groups,which were control group(extruded corn stalk without any additives,CK group),extruded corn stalk+4 mg/kg Lactobacillus plantarum group(LP group),extruded corn stalk+1.0 g/kg cellulase group(EC group)and extruded corn stalk+4 mg/kg Lactobacillus plantarum+1.0 g/kg cellulase group(LP+EC group),with 5 replicates per group and 1 bag per replicate,respectively,and sealed for fermentation at 30℃for 45 days.The results showed as follows:1)compared with the control group,the contents of crude protein(CP),ether extract(EE)and water soluble carbohydrate(WSC)of corn stalk in extrusion groups were significantly increased(P<0.05),while the contents of neutral detergent fiber(NDF),acid detergent fiber(ADF),hemicellulose and cellulose were significantly decreased(P<0.05).Among them,E4.0 group had the best extrusion pretreatment effect and was used for subsequent microbial ensilage test.2)Scanning electron microscopy showed that the cell wall structure of corn stalk was destroyed and degraded after expansion pretreatment,and the total bacterial count on stalk surface was significantly decreased(P<0.05).3)Compared with CK group,the pH in extrusion pretreatment corn stalk microbial ensilage in experimental groups was reduced with sour flavor and better sensory quality,the comprehensive evaluation was excellent,and the total sensory evaluation scores were in the order of LP+EC group(87 points)>LP group(86 points)>EC group(82 points)from high to low.4)Compared with CK group,the pH in microbial ensilage in experimental groups was significantly decreased(P<0.05);the acetic acid content and ammonia nitrogen(NH_(3)-N)to total nitrogen(TN)ratio in LP and LP+EC groups were significantly decreased(P<0.05),and the lactic acid content and lactic acid to acetic acid ratio were significantly increased(P<0.05).5)Compared with CK group,the contents of NDF and ADF in microbial ensilage in experimental groups were significantly decreased(P<0.05),and the ferulic acid content was significantly increased(P<0.05);the contents of CP and EE in EC group and LP+EC group were significantly increased(P<0.05).Meanwhile,the contents of CP,EE and ferulic acid in LP+EC group were significantly higher than those in LP group(P<0.05),while the contents of NDF and ADF were significantly lower than those in LP group(P<0.05).In summary,when the outlet clearance of extruder is 4.0 mm,the extrusion pretreatment can degrade the lignocellulosic structure of corn stalk,release more WSC,and thus improve its nutritional value.When the expansion pretreatment is combined with microbial ensilage,the bacteria-enzyme cooperative fermentation has the best fermentation effect,which can effectively reduce the fiber content of corn stalk and release more active substance as ferulic acid,so as to improve the fermentation quality of corn stalk microbial ensilage.
作者
王红梅
母宇辉
宋跃君
章海欧
司丙文
WANG Hongmei;MU Yuhui;SONG Yuejun;ZHANG Haiou;SI Bingwen(Feed Research Institute,Chinese Academy of Agricultural Sciences,Beijing 100081,China;China Certification&Inspection Group Industrial Co.,Ltd.,Beijing 100028,China;Liaoyuan City Muxing Machinery Co.,Ltd.,Liaoyuan 136299,China)
出处
《动物营养学报》
北大核心
2025年第4期2739-2749,共11页
CHINESE JOURNAL OF ANIMAL NUTRITION
基金
国家重点研发计划项目(2021YFD1300300)。
关键词
玉米秸秆
膨化
微贮
菌酶协同
阿魏酸
corn stalk
extrusion
microbial ensilage
bacteria-enzyme cooperative
ferulic acid
