Hair Cortisol and Testosterone Concentrations in Relation to Maturity and Breeding Status of Male Feral Horses

Medill, Sarah A.; Janz, David M.; McLoughlin, Philip D.

doi:10.3390/ani13132129

Cited by 5 publications

(1 citation statement)

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“…, 2007 ). Another study showed that cortisol levels in reproductively competent adult male wild horses were negatively correlated with testosterone levels, while in non-reproductive males, they were positively correlated ( Medill et al. , 2023 ).…”

Section: Discussionmentioning

confidence: 99%

Assessment of stress levels and reproductive condition in giant pandas: insights from hair, faecal and saliva samples

Yan,

Liu,

Liu

et al. 2024

Conservation Physiology

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Concerted conservation efforts have brought the giant panda (Ailuropoda melanoleuca) back from the brink of extinction, but pandas continue to face anthropogenic threats in the wild and breeding success in captivity remains low. Because stress can have detrimental impacts on reproduction, monitoring stress- and sex-steroid levels would help assess the effectiveness of conservation mitigation measures in panda populations as well as monitor the welfare and reproductive health of captive animals. In this proof-of-concept study, we used faecal sex steroid and cortisol concentrations (n = 867 samples collected from five males and five females at Beijing Zoo every 4 days over the course of 12 months) as a reference to investigate if testosterone, estradiol, progesterone and cortisol can be meaningfully measured in panda hair (n = 10) using radio-immuno-assays. Additionally, we calculated the ratio of testosterone to cortisol (T:C ratio) for each male, which can provide a biomarker of stress and physical performance. Our findings revealed distinct monthly variations in faecal sex-steroid and cortisol concentrations, reflecting reproductive seasonality and visitor-related stress among individual pandas. Notably, the oldest male had a significantly lower T:C ratio than other males. Our results confirm that the level of sex steroids and cortisol can be assayed by panda hair, and the hair cortisol concentrations correlate significantly with that in faeces with one month lag behind (r = 0.68, P = 0.03). However, the concentrations of hormones detected in saliva are lower than those in faeces by two orders of magnitude, making it difficult to ensure accuracy. By assessing the applicability of hair, faecal and salivary sampling, we can infer their utility in monitoring the reproductive status and acute and chronic stress levels of giant pandas, thereby providing a means to gauge the success of ongoing habitat restoration efforts and to discuss the feasibility of sample collection from wild populations.

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Section: Discussionmentioning

confidence: 99%

Assessment of stress levels and reproductive condition in giant pandas: insights from hair, faecal and saliva samples

Yan,

Liu,

Liu

et al. 2024

Conservation Physiology

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Non-invasive hormone assessment of Australian Merino Rams (Ovis aries): A pilot investigation of cortisol, testosterone and heat stress

Fox,

Wilson,

Narayan

2024

Preprint

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Non-invasive hormone assessment is growing in interest as producers and livestock researchers seek new methods to assess animal welfare. Conventional matrices used for hormone assessment include blood serum, saliva, urine and faeces, typically involving invasive human-animal interaction, which is known to initiate an acute stress response and thus confound studies assessing cortisol. As such, these matrices are most appropriate as short-term, point measures as they reflect circulating concentrations at the level of the minute and hour. Alternatively, non-invasive hair and wool assessment offer long-term, historic reflections of hormone concentration at the scale of weeks and months – and are not limited by sampling stress – thus making wool an appropriate tissue for hormone analysis. This pilot study quantified cortisol and testosterone concentrations of ram fleece and determine if there is a significant difference between segments of the sample staple, and whether there is a correlation between hormones. Cortisol is a glucocorticoid produced within the adrenal glands and secreted in anticipation of or in response to a stressor. Testosterone is an androgen mainly synthesised within the testes of males and responsible for several critical functions including regulation of muscle growth, libido and spermatogenesis. In our study, 70 topknot wool samples were collected from rams on a commercial stud property in Dirranbandi, Queensland, Australia. Of these animals, 12 samples were selected at random to undergo cortisol and testosterone quantification. In the laboratory, a single, intact staple was isolated from the total sample, divided into 10 mm segments and prepared for their respective (cortisol or testosterone) immunoassays. No significant difference (p>0.05) was found between wool segments for either cortisol or testosterone, however, statistical differences (p<0.05) were found between individuals for both hormones. A strong correlation (R2=0.9173) was found between wool cortisol and testosterone concentrations, which was a first-time discovery in rams. Furthermore, climate loggers (n=6) were installed in proximity to the rams to collect daily maximum temperature (°C) and relative humidity (RH%) data to calculate the temperature-humidity index (THI) as an indicator of potential heat stress. Under this method, rams were deemed ‘comfortable’ at a THI<72; under ‘mild’ stress at a THI of between 72 and 78; ‘moderate’ stress between 79 and 80; and ‘severe’ stress at a THI of >81. Mean weekly THI peaked in late summer (February), remained high in early autumn (March), decreased throughout the remainder of autumn and the duration of winter before increasing slightly as temperatures rose in early spring (September). Over the trial, 90.36% or 4,706 h were marked by ‘comfortable’ conditions, 8.95% or 466 h by ‘mild’ stress, 0.60% or 31 h by ‘moderate’, and 0.10% or 5 h by ‘severe’ stress. It was determined that THI is most valuable when combined with other methods of measuring heat stress, including non-invasive wool hormone assessment. Whilst most of the findings in this study were previously confirmed by other studies, the strong correlation between wool cortisol and testosterone concentrations appears to be a first. In summary, this study reveals the major future possibilities for non-invasive wool hormone assessment and the possible applications of combining this with temperature-humidity index scores to provide further insight into heat stress within the context of production animal agriculture.

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Fiber quality and fertility in male alpacas in the Cusco region of Peru

Pacheco,

Bengtsson,

Killander

et al. 2024

Front. Vet. Sci.

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IntroductionHigh testosterone levels might be associated with coarser fiber in alpacas, affecting fiber quality. In the husbandry systems employed in the Andes, males with higher libido might have an increased frequency of successful matings than males with lower libido. This study aimed to determine some of the factors affecting fiber quality in Peruvian alpacas and to evaluate the association between fiber quality and male mating behavior.MethodsThe study population consisted of 189 adult male alpacas at La Raya, Cusco, Peru, at 4,400 m above sea level, belonging to the National University of San Marcos, Lima, and the National University of San Antonio Abad of Cusco. Fiber samples were collected from male alpacas in September 2015; body condition score (BCS) was evaluated. After washing and drying, the fiber samples were analyzed using an Optical Fiber Diameter Analyser 2000; linear regression analysis between predictor variables (location of alpacas, age, BCS, and fiber color) and fiber quality outcomes was conducted. Fertility data were available only for some males belonging to San Marcos University, consisting of hand-written records from the breeding season January to April 2015; individual fertility quotients were calculated for each male.ResultsAge was associated with fiber quality, young alpacas having the finest fibers (p < 0.05). An increased BCS was associated with increased fiber length, fiber diameter and spinning fineness, but decreased comfort factor (p < 0.05). White fibers were thinner (p = 0.05) than colored fibers, with lower comfort factor and spinning fineness. A significant association between the fertility quotient and fiber curvature was observed (p = 0.018).DiscussionThese results suggest that careful selection of breeding individuals and attention to husbandry could result in improved fiber quality among alpaca herds in Peru. However, it would be advisable to increase the number of males studied, using more reliable methods for evaluating male fertility and pregnancy diagnosis than were available for this study.

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Hair Cortisol and Testosterone Concentrations in Relation to Maturity and Breeding Status of Male Feral Horses

Cited by 5 publications

References 69 publications

Assessment of stress levels and reproductive condition in giant pandas: insights from hair, faecal and saliva samples

Assessment of stress levels and reproductive condition in giant pandas: insights from hair, faecal and saliva samples

Non-invasive hormone assessment of Australian Merino Rams (Ovis aries): A pilot investigation of cortisol, testosterone and heat stress

Fiber quality and fertility in male alpacas in the Cusco region of Peru

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