Non-invasive endocrine monitoring applied to conservation, welfare and animal behavioral studies

PONZIO MF; CANTARELLI VI

Conferencia; Animal Behaviour Live: annual online conference 2021; 2021

Traditionally, studies on reproductive biology and the response to stress have been based on the determination of endocrine activity of hormones associated with these processes in plasma, along with behavioral studies. However, the collection of blood samples itself constitutes a procedure that can modify plasma glucocorticoid levels and negatively impact the expression of the hypothalamic-pituitary-gonadal/adrenal axis and consequently the behavioral activity of the studied animals. In addition, plasma levels of certain hormones fluctuate widely as a result of pulsatile secretion and/or circadian rhythms and therefore, each blood sample provides a static data of a parameter that is changing, so multiple samples would be needed to have a reliable notion of long-term hormonal secretory activity. Non-invasive hormonal monitoring allows us to measure the metabolites of steroid hormones in different matrices, such as feces, urine, saliva, hair, feathers, egg yolk etc. The steroids of interest are extracted from the matrices using methanol and/or ether, and the resulting supernatant is assayed using polyclonal antibodies in an enzyme immunoassay. The main benefit of these techniques lies in the fact that its use completely avoids the stress of animal handling and restraint associated with the collection of blood samples and the risks related with repetitive venipuncture. This is particularly important when dealing with wild animals or when also recording behavioral data. Furthermore, sample collection can be performed during long periods of time and finally, the type of assay used is relatively simple, efficient and easy to adapt from one species to another.Using these techniques, we are able to evaluate, both in the wild and in captivity, aspects as diverse as reproductive cycles, seasonal variations, sexual and behavioral differences associated with hormones, association between hierarchical positions, effects of environmental toxins on the endocrine function, stress and, even more, human activities impact on animal welfare.