CAJ | 학술논문

本试验旨在研究瘤胃微生物对苜蓿茎降解特性及超微结构的影响。选用长势和株高相近的初花期苜蓿茎进行尼龙袋降解率试验,并截取第2节茎均分为6份,在瘤胃中分别降解6、12、24、48和72 h,利用扫描电镜和透射电镜观察其超微结构变化。结果表明：1)苜蓿茎干物质和中性洗涤纤维在瘤胃中的降解主要发生在24 h内,且在48 h后中性洗涤纤维只有很少部分被降解。2)非木质化的表皮、厚角组织、绿色组织、形成层、初生韧皮部和初生木质部薄壁组织均可在瘤胃微生物作用下快速降解,且在24 h时已完全降解,但木质化程度高的次生木质部纤维及导管几乎不能被降解。3)带荚膜球菌和不规则形状菌是降解纤维组织的主要细菌,且不同组织结构在微生物作用下的降解规律存在差异。由此可见,苜蓿茎在瘤胃微生物作用下可快速降解,但降解速率及程度受其组织结构及组分的影响,而高度木质化的结构在瘤胃中难以降解,提示了降低高度木质化组分含量是提高苜蓿茎降解率的有效途径。
본시험지재연구류위미생물대목숙경강해특성급초미결구적영향。선용장세화주고상근적초화기목숙경진행니룡대강해솔시험,병절취제2절경균분위6빈,재류위중분별강해6、12、24、48화72 h,이용소묘전경화투사전경관찰기초미결구변화。결과표명：1)목숙경간물질화중성세조섬유재류위중적강해주요발생재24 h내,차재48 h후중성세조섬유지유흔소부분피강해。2)비목질화적표피、후각조직、록색조직、형성층、초생인피부화초생목질부박벽조직균가재류위미생물작용하쾌속강해,차재24 h시이완전강해,단목질화정도고적차생목질부섬유급도관궤호불능피강해。3)대협막구균화불규칙형상균시강해섬유조직적주요세균,차불동조직결구재미생물작용하적강해규률존재차이。유차가견,목숙경재류위미생물작용하가쾌속강해,단강해속솔급정도수기조직결구급조분적영향,이고도목질화적결구재류위중난이강해,제시료강저고도목질화조분함량시제고목숙경강해솔적유효도경。
This study was conducted to investigate the effects of rumen microorganisms on degradation charac-teristics and ultrastructure of alfalfa stem. Alfalfa stems with similar growth profile and plant height were har-vested at early flowering to carried out a degradation rate experiment using nylon bags, at the same time, the second internode was longitudinally cut to six equal parts for samples which were incubated for 6 , 12 , 24 , 48 and 72 h in the rumen, repectively. The changes of ultrastructure of alfalfa stem were observed under scanning and transmission electron microscopes. The results showed as follows:1 ) dry matter and neutral detergent fi-ber were mostly degraded within 24 h of fermentation in rumen, and only a small part of neutral detergent fiber was degraded after 48 h. 2) The non-lignified epidermis, collencyma, chlorenchyma, cambium and primary xylem parenchyma were all quickly degraded, and completely degraded within 24 h of fermentation in rumen, but the lignified secondary xylem fiber and vessels remained undegraded. 3) Encapsulated cocci and irregularly shaped bacteria were the majorities of fiber digesters, and the degradation regularity was various with different structure of tissues. In conclusion, alfalfa stem can be rapidly degraded under the effects of rumen microorgan-isms, but the rate and content of degradation are related to the structure and composition of alfalfa stem, in ad-dition, the highly lignified structures are difficult to be degraded in the rumen. Therefore, reducing the content of lignification composition is an effective method to improve degradation rate of alfalfa stem.