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Little research has taken place on the effect of euthanasia methods on biophysical and biochemical changes at the time of euthanasia in fish. These changes are used in multiple species to determine stress levels before death. Koi (Cyprinus carpio) are an important fish species often used in laboratory research, kept in backyard ponds, and managed in zoological and aquarium collections. The current study evaluated euthanasia of koi by immersion in 0.5 g/L tricaine methanesulfonate (MS-222) (n = 10), 0.5 g/L clove oil (n = 8), 1 g/L clove oil (n = 10), and CO2 (n = 7) on time to cessation of opercular movement, plasma lactate levels, and plasma cortisol levels. CO2 had the longest mean time to cessation of opercular movement, and MS-222 had the shortest (mean CO2: 24.9 min, range 13.18–31.35 min; MS-222: 2.68 min, range 1.33–4.5 min). The difference was not significant between any of the groups for plasma cortisol or lactate levels. MS-222 demonstrated the highest cortisol levels, and CO2 had the lowest (mean CO2: 108.7 ng/ml, range 33.9–195.8 ng/ml; MS-222: 650.6 ng/ml, range 77.3–2374.9 ng/ml). Average lactate levels were highest for 1 g/L clove oil and lowest for 0.5 g/L clove oil (mean 0.5 g/L clove oil: 5.1 mmol/L, range 1.8–8.1 mmol/L; 1 g/L clove oil: 7.4 mmol/L, range 5.6–10.5 mmol/L). [ABSTRACT FROM AUTHOR]

Fecal glucocorticoid metabolite (FGM) concentrations, activity, and personality were assessed for 35 fennec foxes (Vulpes zerda) to determine whether animals managed as ambassadors differed from exhibit or off-exhibit animals. A FGM assay, pedometer, and personality assessment tool were validated. Then, fecal samples and movement data were collected during winter and summer periods. Handling was recorded, and the personality of each fox was evaluated. Generalized linear mixed models assessed the relationships between FGM concentrations, activity, personality, handling, sex, season, rearing type, and role. FGM concentrations did not differ in relation to role or handling. Foxes were most active at night; the time of peak activity did not vary with role or handling. Foxes were more active in winter; males were more active than females, and ambassador foxes were more active than off-exhibit animals. Hand-reared foxes were more sociable, and, at one institution, ambassador foxes were more sociable than foxes in other roles. These results suggest that management for ambassador programs is not associated with changes in glucocorticoid production or circadian patterns but may increase activity and be associated with greater sociability. [ABSTRACT FROM AUTHOR]

Although reproduction in the domestic horse has been well described, less is known about reproduction in wild equids. This study describes endocrine patterns associated with estrous cycles and pregnancy for Somali wild asses (Equus africanus somaliensis), an endangered African equid. Fecal samples were collected three times per week for more than 2 years from five female Somali wild asses at the Saint Louis Zoo; progestagen and estrogen metabolites were quantified using commercially available immunoassays. Progestagen analysis indicated that cycle lengths were 27.2 ± 1.2 days and females cycled throughout the year. Progestagen levels during early pregnancy were low and not sustained above baseline until approximately 40 weeks prior to partition. Concentrations increased markedly around 16 weeks prior to delivery and peaked 2–3 weeks before birth. Fecal estrogen levels also increased significantly starting 40–45 weeks before parturition and reached their maximal value approximately 20 weeks prior to birth. Neither foal heat nor lactational suppression of estrus was observed, and females cycled within 45 days after delivery. These data are the first to describe the reproductive physiology of Somali wild asses. As the species faces increasing threats in the wild, this information may support conservation efforts by assisting with ex situ breeding programs. [ABSTRACT FROM AUTHOR]

Female birds deposit significant amounts of steroid hormones into the yolks of their eggs. Studies have demonstrated that these hormones, particularly androgens, affect nestling growth and development. In order to measure androgen concentrations in avian egg yolks, most authors follow the extraction methods outlined by Schwabl (1993. Proc. Nat. Acad. Sci. USA 90:11446-11450). We describe a simplified method for extracting androgens from avian egg yolks. Our method, which has been validated through recovery and linearity experiments, consists of a single ethanol precipitation that produces substantially higher recoveries than those reported by Schwabl (1993. Proc. Nat. Acad. Sci. USA 90:11446-11450). Zoo Biol 28:137-143, 2009. © 2008 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

A variety of factors influences the formation of hierarchical structures, and can include an altered aggressive state, an ability to physically dominate, and previous agonistic experience. Using male Orconectes rusticus, we tested the duration of the winner effect by varying the time between a winning encounter and a subsequent encounter by a 20, 40 or 60-minute interval. Varying the time between the two fights significantly altered the probabilities of initiating fight behaviour and of winning a fight. A crayfish with a 20-minute delay between its winning experience and its subsequent fight was significantly less likely to initiate fight behaviour and significantly more likely to win its next fight than was an animal whose next fight was delayed for 40 or 60 minutes. We then investigated whether the dynamics of this winner effect were influenced by perception of odour signals during agonistic interactions by blocking the chemo- and mechanoreceptors on the antennae and antennules to prevent reception of relevant cues communicating social status. Individuals fighting an opponent with this loss of sensory information were significantly more likely to initiate a fight, but then escalated at a slower rate to a higher fight intensity level. In addition, individuals had a decreased chance of winning an agonistic bout against an opponent deprived of sensory input from the antennae and antennules. [ABSTRACT FROM AUTHOR]

Clouded leopards are notoriously difficult to manage under human care due to their tendency toward high stress, intersex aggression, and limited reproductive success. This case study investigated the endocrinological interplay between adrenal and ovarian steroids and describes a positive correlation between concentrations of fecal estrogen and glucocorticoid metabolites in a female clouded leopard. The female was monitored through two sampling periods approximately 16 months apart, and each data set yielded similar results using a simple linear regression model. The finding of a significant positive correlation between the two steroids represents a novel finding in felids and a hitherto unidentified potential interplay between adrenal and ovarian steroid activity. It also adds to our collective understanding of the effects of estrus on female clouded leopards, impacting conservation efforts as we encourage reproduction in this vulnerable species., (© 2024 The Author(s). Zoo Biology published by Wiley Periodicals LLC.)