Predicting birth in Asian elephants using faecal progesterone levels
As part of her PhD in human nutrition at the University of Surrey, which is funded by the Biotechnology and Biological Sciences Research Council (BBRSC) doctoral training programme, Eleanor Healing was required to do a three-month Professional Internship for PhD Students and chose to do hers at Chester Zoo analysing faecal progesterone levels in our herd of Asian elephants.
Eleanor tells us more below:
Basically, you do three months in an area outside your research, so I wanted to do something that was quite different and interesting. I contacted Chester Zoo because I looked on the website and found that there was a lot going on with endocrinology research which I thought was quite interesting!
At Chester Zoo, since 2007, we’ve routinely monitored the faecal hormones metabolites in Asian elephants; providing Eleanor with faecal samples from three individuals over a combined total of seven pregnancies. This frequency of data sampling is actually greater than in any other published data.
"There was so much data! It’s like years of data for every single day for these elephants. So I just put them all together and started having a look at the data to see if there were any patterns that could predict when the calves might be born."
0.5g of faecal samples ready for extraction
Adding methanol to the faecal samples
Having a tool to predict birth of Asian elephants is especially important in this species due to their predisposition to dystocia, a foetal malposition, which can trigger difficult birth deliveries.
They tend to have difficult births and can retain foetuses so it’s good to have an idea of when they should give birth to allow for rapid veterinary intervention if necessary.
Using faecal samples instead of blood samples to determine this date has the advantage of being relatively easy but more importantly is a non-invasive method.
The analysis of the faecal hormone metabolites showed that pregnancy progesterone profiles from our elephants all followed a similar pattern. The average faecal progesterone levels were recorded as increasing following conception and reaching a peak between the fifth and seventh month of gestation. Following this increase, a gradual decrease was observed until 50 days before birth when levels were then sharply dropping.
Centrifuging the samples
Preparing to run an Enzyme Immuno Assay (EIA)
Weighing out 0.5g of a faecal sample
Eleanor’s main finding though is the fact that she observed a drop in progesterone levels 11 days before birth:
The conclusions I drew here were that that could indicate a parturition date in 9 to 11 days time. Then when it drops after that, it drops to about double of what the baseline is for that individual elephant so that normally shows that the elephant will give birth on the next day.
Eleanor also found an association between maternal age and overall progesterone profile. As individuals grew older their overall progesterone levels were recorded as generally lower. This indicates that maternal age should be taken into account when comparing progesterone levels of individuals to diagnose their pregnancies as older elephants may have lower levels than expected.
This study is novel in the number of elephant pregnancies that were assessed but also in the fact that it was able to compare multiple pregnancies in the same individual providing new information about the endocrinology of these incredible mammals. The huge amount of samples analysed provides high quality and reliable data allowing the development of a new set of guidelines to predict Asian elephants’ parturition dates using progesterone metabolites levels using faecal samples.