Utah study: The right poop helps packrats eat poisonous plants
By Lisa Schencker
The Salt Lake TribuneFirst published Jul 21 2014 08:13AM
Poop, packrats and poisonous plants may seem like a repellent combination for University of Utah biologists to study.
But the results could help feed livestock in developing countries, improve care for endangered species and even tackle the spread of unwanted juniper plants in Utah.
U. scientists found that woodrats, also known as packrats, were able to eat toxic creosote bushes for the first time, thanks to fecal transplants from other rats accustomed to eating the yellow-flowered bush.
The key? Gut bacteria in the fecal transplants, according to the authors of the study, published Monday in the journal Ecology Letters. The authors say it proves something that’s long been suspected by scientists — that gut bacteria can help animals munch poisonous plants.
"Our work demonstrates on several fronts microbes are important for animals that consume toxic plants," said Denise Dearing, a senior author of the study and a chairwoman of the biology department at the U.
It may all sound pretty gross, but it might lead to expanded ways of feeding livestock, among other benefits.
"In the wild, bacteria probably play a big role in allowing mammals to eat poisonous plants," said Kevin Kohl, a postdoctoral researcher at the U. and lead author of the paper. "This might be a way we could help agricultural animals eat toxic plants."
Juniper plants, for example, have been spreading in Utah, a concern of ecologists and others. If livestock could eat juniper, that would help control its spread, in addition to providing another cheap food source for the livestock, Kohl said.
He said being able to transfer gut bacteria to livestock so they can eat otherwise toxic plants might also be useful in developing countries, where those plants may be the sole food source.
Kohl said scientists must see next if successfully transferring such bacteria to livestock is possible.
Dearing said the findings also raise other questions. For example, because endangered species might lose the diversity of their gut microbes when bred in captivity, does that leave them unable to consume certain plants that they otherwise would have eaten once released into the wild?
Also, do the antibiotics often fed to livestock to improve growth hurt their ability to eat toxic plants when drought reduces available grass? For this study, the scientists conducted three experiments with two types of woodrats — juniper eaters from the Great Basin desert and creosote eaters from the Mojave Desert.
In the first experiment, one group of Mojave rats was fed rabbit chow with creosote resin and another group was fed plain rabbit chow. Scientists found that the rats who ate the creosote had much higher levels of gut microbes that may degrade creosote, showing that the rats’ diets determined the makeup of their gut microbes.
In the second experiment, scientists gave antibiotics to two groups of rats to kill their gut microbes. They then gave creosote to one group, but not the other. The group that got the creosote was unable to eat it and lost weight, while the other group lost no weight.
In the third experiment, scientists transplanted fecal matter from creosote-eating rats into juniper-eating rats and found that it helped them eat creosote diets without losing much weight.
But juniper-eating rats that didn’t get the fecal matter lost significant amounts of weight when fed creosote.
Dearing and Kohl conducted the research with three other U. faculty members: human geneticist Robert Weiss, biochemist James Cox and biologist Colin Dale. The National Science Foundation funded the study.