This holiday season, animals in Tucson's Reid Park Zoo get to munch on a rare treat: scraps from the University of Arizona's research into renewable energy sources.

Researchers from the UA's department of agricultural and biosystems engineering, who are growing sweet sorghum for the production of environmentally friendly biofuel, have found a new way of disposing of the leftovers without throwing them away.

After harvesting, the plant's 10-foot stalks are ground up to extract its sugary juice and process it into ethanol, which can be used as biofuel. The crushed stalks, along with any unused parts such as leaves and the seed-containing heads, end up in a waste pile.

"A while ago, the keepers at Reid Park Zoo approached us about corn stalks to feed to their animals," said Carl Schmalzel, a senior research specialist in the department of plant sciences in the UA's College of Agriculture and Life Sciences, who grows and helps harvest all sorts of crops used in the department's various research projects.

"That made me think of the sweet sorghum stalks, because they're more palatable than the corn stalks. So I asked them if they were interested in those, too."

Since he already had a trailer loaded up with several hundred pounds of sweet sorghum material, Schmalzel took it to the zoo.

"We were delighted," said Leslie Waters, area supervisor at Reid Park Zoo. "Not only was it already cut up and loaded, but Carl was kind enough to deliver it, too. We don't have the resources to always be able to take advantage of outside opportunities such as a downed tree, so this made us very happy."