[Endocrinologic studies of male psittacine birds for the evaluation of their reproductive status]. / Endokrinologische Untersuchung männlicher Papageienvögel zur Beurteilung ihres Reproduktionsstatus.

OBJECTIVE: Evaluating methods of hormone measurement in different specimens of male parrots in order to assess their reproductive status and stress axis. MATERIAL AND METHODS: Cockatiels and rose-ringed parakeets were chosen as psittaciforme representatives and their endocrine profiles were examined. In various pre-experiments, suitable techniques for the determination of testosterone in plasma, saliva and faeces of male parrots were established. Before analysing the samples by enzyme immunoassay, blood and faeces were extracted using diethyl ether, while saliva could be tested without extraction. Based on the excretion of mainly conjugated testosterone metabolites, parrots' faecal samples were also hydrolysed with ß-glucuronidase/arylsulfatase before extraction. In addition, the levels of the stress hormone corticosterone were determined by radioimmunoassay in order to assess possible relationships between stress and the secretion of testosterone. RESULTS: The examined psittacine species displayed different seasonal secretion patterns for both testosterone and corticosterone. Cockatiels had maximum plasma testosterone levels in February, in contrast, rose-ringed parakeets showed highest concentrations in November. As a consequence of cumulative excretion, both species showed much higher faecal than plasma testosterone concentrations. In rose-ringed parakeets, the levels of corticosterone in plasma were exceptionally high compared to the cockatiels. CONCLUSION: According to this study, we have been able to establish suitable methods for testosterone analysis in blood and faeces of cockatiels and rose-ringed parakeets, supporting the assessment of their reproductive status. At present saliva does not appear to be an ideal medium for reliable hormone level measurement, thus further investigations are required concerning this subject. CLINICAL RELEVANCE: By means of process analysis, it will be possible to detect increasing testosterone levels and/or pathological alterations, which could be considered in breeding programmes.

Sexing domestic chicken before hatch: a new method for in ovo gender identification.

Male chicks are an unwanted by-product when producing laying hens. The common practice to kill them directly after they have hatched gives rise to ethical concerns worldwide. The aim of this study was to develop an endocrine method to determine the sex of domestic chicken before hatch. On Days 7 to 10 of incubation, the allantoic fluid from brown layers' eggs (n = 750) was analyzed via enzyme immunoassay for their content of estradiol, estrone sulfate, and testosterone in order to detect gender differences. We successfully established a reliable method for in ovo sex identification on Day 9 of incubation by estrone sulfate measurement in the allantoic fluid. Female embryos displayed significantly higher hormone levels in the allantoic fluid than males (female: median = 0.312 ng/mL; male: median = 0.110 ng/mL; P ≤ 0.001). Our method allows the sexing of domestic chicken at a very early stage of embryonic development, even before the onset of pain perception. The possibility to eliminate eggs containing male embryos on Day 9 of incubation represents a vast improvement compared with culling day-old chicks.