應用糞類固醇內泌素監控台灣黑熊、馬來熊及無尾熊之生殖與緊迫生理

外文標題: 
Monitoring the reproductive and stress status of Formosan black bear (Ursus thibetanus formosanus)、Malayan sun bear (Ursus malayanus) and Koala(Phascolarctos cinereus) by fecal steroid
校院系所: 
國立臺灣大學畜產學研究所
指導教授: 
林仁壽
吳兩新
楊寧蓀
出版年份: 
2003年
主題類別: 
摘要: 

圈養野生動物的保種計畫中,人工繁殖技術為重要的策略應用,然先決條件需先行瞭解物種的繁殖模式,並進行長期監控。傳統採血檢測動物生殖內泌素的方法,容易對神經質的野生動物造成緊迫傷害,且影響檢測的精確性,因此利用動物自然排泄的糞尿檢測,極具開發潛力。本研究乃應用自行建立之非侵入性糞類固醇檢測技術,探討台北市立動物園在圈養環境下之台灣黑熊(Ursus thibetanus formosanus)、馬來熊(Ursus malayanus)及無尾熊 (Phascolarctos cinereus),其生殖與緊迫生理上的變化,期以長期監控動物生理狀態,提供有效的繁殖策略,透過緊迫指標的建立,作為環境良窳之評量,提升動物福利之水平。本研究共分五個部份:
試驗一、動物糞類固醇日節律變化之研究
每2小時1次全日追蹤動物之排遺,檢測內泌素含量。結果顯示台灣黑熊糞孕酮(P4)、睪固酮(T)及皮質醇(F)濃度,日夜時段均無顯著變化,雌二醇(E2)白天時段之濃度較高;馬來熊糞T日夜時段均無顯著變化,P4及F白天時段濃度較高。無尾熊於白天糞類固醇濃度並無明顯變化。
試驗二、熊科動物生殖內泌素與行為之變化
每週採集糞樣2次,檢測糞類固醇代謝物之含量變化,並進行台灣黑熊之行為觀察。結果顯示台灣黑熊繁殖季之糞T濃度顯著高於非繁殖季,P4變化則相反,E2差異不顯著。母獸無論交配與否,均有類似圖像變化,於10-12月P4濃度出現高峰。對照台灣地區之產仔記錄,顯示母熊係於3月交配,12月分娩,仔熊贏弱,推測有胚延遲埋殖的情形。母熊於發情時,E2呈現規則性的起伏變化,約5-8天/週期,連續5個週期,應屬多次性發情者,具有誘發性排卵動物的生理變化,交配前3週E2持續維持高濃度,交配當週P4迅速上升,旋即下降,糞P4濃度於交配前1個月至後2個月差異不顯著,11月有顯著升高;E2濃度交配於前1個月顯著升高,交配後兩個月差異不顯著,11月顯著升高。社會行為於交配前2個月有逐增現象,交配尖峰時高達白天行為的40%。馬來熊母熊糞P4無季節性變化,糞E2可以反映母獸生理狀況,如發情;公熊糞T濃度變化受母熊發情之影響。
試驗三、無尾熊生殖內泌素之變化
每週採集糞樣3次,未交配無尾熊之動情週期約7-10天,交配後未懷孕者約52天再發情,其糞P4之圖像變化與懷孕者相似。懷孕期約35天,可利用糞P4維持低濃度之現象作為育幼之判定,母獸於仔獸夭折後10天再發情。公獸在台灣全年都有配種記錄,其糞T濃度有季節性變化,但與南半球之時辰相反,可作為適應指標。
試驗四、外源性刺激對熊科動物之血液及糞皮質醇的影響
麻醉後血液F濃度激增3-5倍,於120分鐘後回復,給予ACTH刺激後F濃度旋即上升,120分鐘後仍維持高濃度。糞F於麻醉後連續3日維持高濃度,但麻醉後給予ACTH刺激,則於1日後回復至基礎值。吹箭生理鹽水與吹箭ACTH刺激,糞F濃度均無顯著變化,可能為ACTH劑量不足。
試驗五、環境豐富化對台灣黑熊之行為及糞皮質醇的影響
糞F濃度於改變配對1個月間顯著升高,唯有個體差異。母獸長期於室內隔離,糞F濃度於1個月內升高2倍,之後驟降至基礎值以下,顯示緊迫極大,於恢復外放後半個月稍增。環境豐富化能大幅降低刻板行為,移動探索行為則有明顯增加,但持續時間不長,需適作更新之舉。母熊之糞F濃度於環境改變後1個月間顯著降低。
本研究係首次應用糞類固醇內泌素對台灣黑熊及無尾熊進行長期生殖生理探討,並評估圈養環境下之各種緊迫因子,包括麻醉、長期隔離、更換配對及模擬急性緊迫對動物之影響,應可提供明確之生理參數和指標,以供飼養管理之參考。

外文摘要: 

Monitoring the reproductive and stress status of Formosan black bear (Ursus thibetanus formosanus)、Malayan sun bear (Ursus malayanus) and Koala (Phascolarctos cinereus) by fecal steroid
Yang Chien Jen
Abstract:
The purpose of the study was to use a non-invasive technique to understand the reproductive and stress physiology of bears and koala under captivity. Physiological level of crucial sex steroids and cortisol was determined to investigate the stress-induced effect on reproduction under captivity over a long period of time. Under mentioned are the investigations undertaken and their results:
Fecal samples from bears and koala were collected every two hours for three consecutive days and assayed for the level of steroids to determine the circadian rhythm over a twenty-four hours period. The results showed that progesterone (P4), testosterone (T) and cortisol (F) did not had any significant change throughout the cycle, but estrogen (E2) level was significantly high during the day in Formosan black bear. In Sun bear there was no significant change in fecal T, but P4 and F were in higher levels during the daytime. There were no obvious changes in the level of different steroids in the fecal sample of koala collected every two hours over the whole day range (9AM-3PM).
The reproductive steroid status and social behavior of Formosan black bears were investigated. The fecal samples were collected biweekly to monitor the variation of steroids level over a long period. The social behavior of Formosan black bears was observed bimonthly for a year with more frequent observations during the breeding season. Our findings revealed that fecal T level was significantly higher in breeding season in male bears and fecal P4 level in females was lower during breeding season. There was no significant change in fecal E2 level both during breeding and non-breeding seasons.
Regardless of mating status, the level of fecal P4 was found to be significantly higher during the month of October to December in similar pattern in all female Formosan black bears.
Abailable information of breeding in Taiwan revealed that the Formosan black bear conceived in March and parturated in November to December, delivering a small cub. This unique feature indicates the phenomenon of delayed implantation. Three weeks before mating there was significant increase in fecal E2, while at the period of mating there was a spike of fecal P4. However, there was no significant change in fecal P4 level, one month before and two months after mating, while fecal E2 level changed significantly a month prior to mating with no change in months that followed. It was also found that levels of P4 and E2 were significantly higher in the month of November compared to other months of the year. The social behavior gradually increased to 15~20% two weeks before mating, occupying approximately 40% of daily activity at peak during the mating period. There was no seasonal variation in the level of P4 in Sun bear, while E2 level was reflected with the changing reproductive status. The T levels of male Sun bears were influenced by the presence of females, with significant increase when they were in estrus.
The female koala returned to estrous 52 days after previous mating in non-parturient animal, with similar pattern of P4 level to that of parturient ones. It was found that level of P4, 52 days post mating remained at low level in parturient female. This valuable information can help us predict the presence of joey in the pouch of female Koala, which can provide basis for advance managerial approaches.
In spite of the changes in seasonal fecal T levels, the male Koalas were found to be a year round breeders, indicating weak reflection of fecal steroid level and existing reproductive status.
The influence of exogenous stimulation of anesthetic agent and adrenocorticotropic hormone (ACTH) on the blood and fecal F levels were investigated. Post administration of anesthetic agent, the blood steroid level increased three to five times within 40 minutes and then dropped gradually reaching normal status after two hours. When ACTH was administered immediately after it, the blood F level increased rapidly and maintained high level even after two hours. When the anesthetized bear’s fecal F level was monitored, it remained at higher level for three consecutive days, but when anesthesia was immediately followed by ACTH treatment, the level of F remained at higher level only for a day.
The influences of environmental factors to the behavioral and fecal steroid of Formosan black bear were also investigated. The switch in the place of the female Formosan black bears induced different effects on individual animals. It was observed that individual animals were under different degree of stress reflected in fecal F level.
A female Formosan black bear suspected for being pregnant was isolated for a period of four months, first month in isolation saw the level of fecal F increased by about two times. Then, there was a sharp drop in F level, even below the pre isolation level, which remained for around three months. The bear was released from isolation as no further signs of pregnancy noticed, instead estrus signs were manifested. Environment enrichment decreased the larger stereotyped behavior in male black bear while exploratory behavior was found to increase obviously. However, we found that after some time the bear regained it stereotyped behavior with adjustment to the new environment, requiring further intervene to enrich the surrounding to suppress it. There was difference in the fecal F level in male and female bears subjected to environment enrichment. The male did not show any significant change while the female had a decreased level of F.
This is the first study of its type that has employed non-invasive study over a long term on bears and koalas relating the investigation of fecal steroids and physiology. The sex steroids and F level in the feces was monitored to obtain a daily circadian rhythm, yearlong reproductive status, and changes as a result of isolation and environment enrichment. We conclude that this novel non-invasive technique will be of important help in understanding the physiological status of animals under captivity. The informations obtained by this technique can be a useful tool to enhance the health, procreation and welfare of the animals under captive condition.