Wednesday, January 20, 2016

Good Fat Bears

You calling me fat? - MDC
I was just reading an article in Connections on A Quest for the Missouri Black Bear by Jennifer Conner.  It mentioned "Body mass index (BMI) is measured using a contraption that measures electrical waves throughout the bear's body and can determine muscle/fat ratio which in turn determines the overall fitness of the individual bear."   I contacted Jeff Beringer of MDC to get more information.
"We are using an instrument that measures electrical resistance in bears. We fasten an alligator clip on the lip and a probe near the anus, then turn on the machine to measure resistance. The program considers body weight and other factors. It could be akin to BMI as used for humans. We are looking at this as another body condition index to see how it varies by sex, age, time or year, etc."
Denning bears do not eat or drink and don't take bathroom breaks to urinate or defecate.  Females that are inseminated carry their fertilized eggs for months before delayed implantation in the uterus starts the development of cubs.  Once she delivers, a mother bear will return to sleep, occasionally awaken to lick the cubs.  Otherwise the cubs nurse on their own - human mothers, eat your heart out!

Males lose 15-25% of their weight while pregnant females lose up to 40% as they lactate to feed newborn cubs over 3 months.  The stored weight and nutritional status correlate with reproductive success and offspring survival.  Bears burn their stored fat for energy and water, and their muscle and organs for protein just like you and I would in starvation.  Muscle atrophy is estimated at 10-20%.  Unlike humans, they will rapidly restore their muscle mass when they start eating in the spring.

Imagine the implications this would have on humans if we could unlock these secrets.  Kidney failure for months without harm, prolonged bedrest or starvation corrected rapidly, maybe even suspended animation during space flight.  Metabolic studies such as BMI and protein and body fat metabolism in bears will help unlock these secrets.

I couldn't find much on the measurement of BMI in black bears.  I suspect that once the technique (see "alligator clip on lip and a probe near the anus") gets out in the bear community, the enthusiasm of the bear volunteers diminishes dramatically. 

This and much more about bear hibernation is at this Nova site.

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