A combination of non-invasive endocrine monitoring and predictive models to assess pregnancy status in wild guanacos: a population approach.

MAROZZI A; CARMANCHAHI P; CANTARELLI VI; GOMEZ FM; PANEBIANCO A; GREGORIO P; LEGGIERI LR; PONZIO MF

Conferencia; 7th Conference of the International Society of Wildlife Endocrinology; 2019

The use of non-invasive methods and predictive models is an opportunity to incorporate pregnancy status information on population studies. Usually, this data is not included due to the limitations of pregnancy detection in free-ranging individuals. With the objective of developing a predictive model to diagnose pregnancy status in free-ranging wild guanacos (Lama guanicoe), we measured fecal progesterone and estrogens metabolite concentrations in pregnant (n=35) and non-pregnant (n=34) females used for live shearing management (capture, shear and release). Hormonal data was combined with data on abdominal ballottement as an independent factor of pregnancy diagnosis, to develop a logistic regression model which was then applied to assess pregnancy status in unhandled individuals in La Payunia Reserve (Mendoza, Argentina; n=69 females).To build up the predictive model, extracts from dry fecal samples were analyzed to determine pregnanediol glucuronides and conjugated estrogens concentrations by enzimeimmunoassays (PdG R13904 and EC R522-2 respectively, C. Munro). As expected, PdG and EC concentrations were significantly higher in samples obtained from pregnant females under live shearing management (PdG pregnant vs. non-pregnant females: 81.9±58.5 and 45.4±24.4 μg/g respectively, EC pregnant vs. non-pregnant females: 485.6±412.0 and 76.2±47.9 ng/g respectively).The model was applied to hormonal data obtained in free-ranging guanacos to predict percentages of pregnant females in the population (46% in 2016 and 19% in 2017). PdG concentration in free-ranging individuals varies between 15.1-312.0 μg/g in pregnant females, and between 18.8-83.5 μg/g in non-pregnant females. EC concentration extends from 43.6-1119.7 ng/g in pregnant and from 10.6-98.7 ng/g in non-pregnant females. These results will be used to incorporate pregnancy status on guanaco population dynamic studies. Moreover, this study approach might be applicable in other wild species in order to monitor pregnancy in large scale studies.