Glaeser Sharon S, Edwards Katie L, Paris Stephen, Scarlata Candace, Lee Bob, Wielebnowski Nadja, Finnell Shawn, Somgird Chaleamchat, Brown Janine L
Oregon Zoo, 4001 SW Canyon Rd., Portland, OR 97221, USA.
North of England Zoological Society, Chester Zoo, Upton-by-Chester, Chester CH2 1EU, UK.
Animals (Basel). 2022 May 23;12(10):1332. doi: 10.3390/ani12101332.
The conservation of endangered species and sustainability of managed populations requires considerations to ensure the health and welfare of individuals. Male elephants experience a biological phenomenon called "musth", which is characterized by increased testosterone production, temporal gland secretion and urine dribbling, heightened aggression and sexual behavior, and therefore can pose unique challenges for human safety and animal welfare. This study characterized longitudinal (9 to 22 years) patterns of circulating testosterone and cortisol in relation to musth in four adult Asian elephant bulls spanning ages from 12 to 54 years. Age-related effects on musth activity and adrenal responses to social changes and clinical health events were also examined. All bulls exhibited regular annual musth cycles. Circulating cortisol covaried positively with testosterone and musth, highlighting intrinsic patterns that should be considered when evaluating the impact of social, health, and environmental changes on adrenal glucocorticoid activity. Except for an end-of-life cortisol increase in one bull, there was no clear evidence of chronically elevated cortisol secretion outside of musth in any individual. Testosterone decreased with age in sexually mature bulls, whereas age-related changes in cortisol varied across individuals, with the three older bulls showing the greatest rate of change during musth versus inter-musth periods. In contrast to physiological factors, there was no evidence of social factors, such as addition of a new male and death of male herdmates, impacting adrenal glucocorticoid activity in these bulls in the short term. Changes in cortisol were associated with treatment for () in two bulls, increasing after start of treatment and decreasing with cessation of treatment, but were not clearly associated with activation of disease. This study highlights the importance of longitudinal hormone monitoring to track changes in physiological function and responses to social, health, and environmental change in elephant bulls, which is important for making more informed decisions on how to manage male elephants under varying degrees of human care to ensure welfare and safety.
濒危物种的保护和管理种群的可持续性需要考虑确保个体的健康和福祉。雄性大象会经历一种名为“狂暴期”的生理现象，其特征是睾酮分泌增加、颞腺分泌和尿液滴流、攻击性和性行为增强，因此会对人类安全和动物福利构成独特挑战。本研究描述了4头年龄在12至54岁之间的成年亚洲象公牛体内循环睾酮和皮质醇的纵向（9至22年）模式及其与狂暴期的关系。还研究了年龄对狂暴期活动以及肾上腺对社会变化和临床健康事件反应的影响。所有公牛都表现出规律的年度狂暴期周期。循环皮质醇与睾酮和狂暴期呈正相关，这突出了在评估社会、健康和环境变化对肾上腺糖皮质激素活性的影响时应考虑的内在模式。除了一头公牛在生命末期皮质醇升高外，没有明显证据表明任何个体在狂暴期之外皮质醇分泌长期升高。性成熟公牛的睾酮水平随年龄下降，而皮质醇与年龄相关的变化因个体而异，三头年龄较大的公牛在狂暴期与非狂暴期之间显示出最大的变化率。与生理因素相反，没有证据表明社会因素，如新雄性的加入和雄性同伴的死亡，在短期内会影响这些公牛的肾上腺糖皮质激素活性。两头公牛的皮质醇变化与（）治疗有关，治疗开始后升高，治疗停止后下降，但与疾病激活没有明显关联。本研究强调了纵向激素监测对于追踪雄象生理功能变化以及对社会、健康和环境变化反应的重要性，这对于在不同程度的人类照料下如何管理雄象以确保福利和安全做出更明智的决策至关重要。
