台灣山羌胃腸道特徵與瘤胃生態之研究

Abstract

本研究目的為探討圈養台灣山羌（Muntiacus reevesi micrurus）之瘤胃生態及飼糧消化率，並比較圈養與野生山羌胃腸道之異同與瘤胃乳突於組織學上之差異，藉以瞭解圈養對動物之消化生理及利用狀態之影響。試驗I個別飼養之雌山羌於餵飼後四小時以胃管抽取胃液，記錄攝食量並分析胃液，分析項目包括胃液酸鹼值及揮發性脂肪酸濃度以及體外瘤胃細菌之培養與原蟲計數。試驗II測量圈養山羌與野生山羌之消化道長度和觀察胃腸道之特徵並截取瘤胃乳突進行組織切片。試驗III進行圈養山羌飼糧消化率測定並分析瘤胃內容物與皺胃內容物之營養成分，藉以探討山羌於圈養環境或野外地區其食性之差異。 圈養山羌之胃液酸鹼值介於6.1∼6.8，且胃液中乙酸、丙酸與丁酸濃度偏低。每毫升胃液其菌數約0.03∼120.33 x 107，而總菌、纖維素分解菌與澱粉分解菌數目之間呈正相關（r >0.9）。周身纖毛原蟲佔總原蟲數30％以下，而局部纖毛原蟲則大於70％。圈養山羌瘤胃乳突為線性形狀，野生山羌其乳突為扁平舌狀，此為顯著差異處，而圈養山羌之小腸有較長之趨勢。山羌對於粗蛋白質（CP）、中洗纖維（NDF）與無氮萃取物（NFE）之消化率表現最佳，乙醚萃取物（EE）與灰分（Ash）則較差。再者，圈養與野生山羌其瘤胃內容物之CP、NDF、NFE與酸洗纖維（ADF）含量均相當，唯圈養山羌之EE有較高趨勢。 本研究結果顯示，試驗中圈養山羌所給飼之飼糧可使胃液酸鹼值維持在正常範圍，唯瘤胃中細菌數較一般畜養之反芻動物低，此導致揮發性脂肪酸之濃度亦降低，而小體型局部纖毛原蟲則為主要原蟲種別。山羌之腸道長度為體長之13.9∼15.1倍，此與“精緻性”攝食之反芻動物相似。圈養與野生山羌之瘤胃乳突形態具明顯差異，此與飼糧刺激乳突發育之影響具相關性。

The aim of this study is to investigate the rumen ecology and feed digestion in Formosan Reeves’ muntjac（Muntiacus reevesi micrurus）. We also observed the effect of captive environment on animal digestive physiology by comparing the characteristics of gastrointestinal tract and tissue samples of ruminal papillae between captive and wild muntjac. In experiment I, the rumen fluid of female muntjacs was taken through a stomach tube at 4 hours after feeding for further analysis. The items analyzed include pH value, concentration of volatile fatty acids (VFA), counts of rumen bacteria and protozoa. In experiment II, we measured the length of intestinal tract of muntjac and observed gastrointestinal characteristics of it which was dissected; a portion of ruminal papillae was cut off for tissue sample. In Experiment III, we analyzed the feed digestibility ration of captive muntjac and compositions of nutrients in captive muntjac rumen and abomasum content which are correlated to muntjac feeding type and living environment. Results reveal that the pH value of rumen fluids of captive muntjac ranges between 6.1∼6.8 and the concentration of VFA is lower than that of the domestic animal. The rumen bacteria count is between 0.03∼120.33 x 107 colony counts / ml rumen fluids. There is positive correlation among the quantity of total bacteria, cellulolytic bacteria and amylolytic bacteria. The percentage of Isotrichidae’s quantity among all protozoa is lower than 30%, whereas the quantity of Ophryoscolecidae is greater than 70%. The morphology of ruminal papillae between captive muntjac and wild muntjac showed distinct difference and the length of small intestinal tract tends to be longer than that of the wild. The muntjac had better digestibility on crude protein (CP), acid-detergent fiber (NDF) and nitrogen free extract (NFE). The CP, NDF, NFE and acid-detergent fiber of rumen content between captive and wild muntjac were similar whereas EE was higher in captive muntjac. In conclusion, the pH value of rumen fluid was within normal ranges, and the quantity of rumen bacteria is lower than that of the domestic ruminants, resulting in lower concentration of VFA in captive muntjac. Furthermore, study indicates that small Ophryoscolecidae is the major protozoa species in the rumen. The ratio of intestinal length to body length is approximately 13.9∼15.1 which is similar to concentrate selector. Finally, the morphology of ruminal papillae showed significant difference between captive and wild muntjac which could be related to the diets that stimulate the growth of papillae.