季節性變化對圈養射紋陸龜菌相、食物滯留時間及利用之影響

Abstract

本研究旨在探討環境溫度變化對射紋陸龜之腸道菌相、食物滯留時間及食物利用情形的影響，藉以協助改善臺北市立動物園野生動物收容中心圈養之射紋陸龜於飼養過程中之腸胃道問題，保護此類瀕臨絕種動物。 本試驗分為三部分。試驗一，主要為比較射紋陸龜、蘇卡達陸龜及紅腿陸龜於不同季節之菌相變化；試驗二，為測量射紋陸龜食物滯留時間；試驗三，則藉由體外發酵檢測不同食物之發酵作用，並測定產氣量、短鏈脂肪酸生成等，以評估不同食物導致快速發酵之能力。 腸道菌相之結果顯示射紋陸龜於冬季具顯著較低之乳酸桿菌及雙岐桿菌 (P < 0.05)，與蘇卡達及紅腿陸龜相比，其於季節變換間之菌相較不穩定。個體間之食物滯留時間差異極大，最短為12天，最長則可達80天。體外發酵試驗之結果顯示冬季腸道菌相於發酵過程中產生較多氣體，尤以桑葉、精料 Mazuri及精料混合（ T-rex, Rep-cal 及Versele以1:1:1比例混合）組別為多，整體產氣則較快速。短鏈脂肪酸生成主要為乙酸、丙酸及丁酸，夏季腸道微生物較冬季產生較多乙酸，丁酸生成量則以冬季腸道微生物較高。 綜觀以上結果，射紋陸龜於冬季菌相情形較差，滯留時間長，體外發酵結果則顯示紅蘿蔔、桑葉、精料 Mazuri及精料混合組別有高的產氣特性，為了避免脹氣的發生，此類食物於冬季之給予量應予以限制。

The objective of our research was to study the effect of environmental temperature on microbiota , food retention time and utilization of Radiated tortoise to help alleviate the urgency of protecting these endangered animals. Our experiment was divided into three parts. First we compared the microbiota in different seasons for respective species, Radiated tortoises, Sulcata tortoises (Geochelone sulcata) and Redfooted tortoises (Chelonoidis carbonaria). Secondly, we tested the food retention time in radiated tortoises. Thirdly, we evaluated different types of food with in vitro fermentation. In this part, testing of end products such as gas, short chain fatty acids (SCFA) would provide information about which type of food has higher potential for rapid fermentation. The microbiota results showed that the Radiated tortoises had significant lower amount of probiotics (Lactobacillus and Bifidobacterium spp.) present in the GI tract in the winter than in the summer. Compared with Sulcata and Redfooted tortoises, the Radiated tortoises had less stable microbiota during season transitions. In the retention time experiment, the overall patterns of markers varied among individual animals. The shortest total transit time was 12 days while the longest was over 80 days. In the study of in vitro fermentation, the animal’s daily feed was provided to microorganisms in both summer and winter as nutrient source.. The result showed that winter microbiota had more gas production than that of the summer microbiota especially in the MB (Mulberry leaves), Cg (Concentrate Mazuri), and Cmix (Concentrate mix)groups. Additionally, the gas production in the V4 (Carrot), MB, Cg, and Cmix groups was faster than those of the other vegetable groups. The SCFA production is mainly composed of acetate, propionate and butyrate. Summer microbiota usually produced more acetate than winter microbiota. However, butyrate production was higher in winter microbiota group. It is worth noticing that butyrate seemed to induce colonic hypersensitivity to distension. Moreover, when it is oxidized to CO2, it may produce much more gas leading to flatulence. In conclusion, the microbiota in Radiated tortoises in the winter seemed to be in a less favorable condition than in the summer. Furthermore, the retention time in some Radiated tortoises was very long which could cause longer fermentation. On the other hand, the V4, MB, Cg and Cmix also showed potential in causing flatulence. Thus, to protect Radiated tortoises from flatulence, we may need to limit the supply of these types of food