Taking students on a walk to the wild side

Lemurs were just one of the many exotic animals Cheryl Morris formulated diets for at…


Lemurs were just one of the many exotic animals Cheryl Morris formulated diets for at Omaha’s Henry Doorly Zoo and Aquarium in Omaha, Nebraska. Her expertise in comparative nutrition was essential to carrying out her work.

By Amber Friedrichsen

If you’ve ever been to a zoo, you’ll recall how an animal’s enclosure resembles its natural habitat. Zoo animals’ diets are similar to what they would eat in the wild, too; however, there is little information about nutritional requirements for many exotic species. So, how do zoos ensure their animals are being properly fed?

This situation calls for a skilled comparative nutritionist, and Iowa State University is lucky to call one of these hard-to-find scientists its own. Cheryl Morris, associate professor of animal science, spent the last 15 years working as the vice president of conservation sciences at Omaha’s Henry Doorly Zoo and Aquarium in Omaha, Nebraska. She returned to Iowa State this year and currently has an appointment in teaching and outreach.

While nutritional requirements have been established for horses, chickens, beef, and pigs, the same cannot be said for exotic species. In her position at the zoo, Morris formulated zoo animal diets by using her knowledge of production and companion animal physiology and nutrient needs. She crafted feeding plans for exotic species by comparing them to their domesticated counterparts.

 “A cat is anatomically set up like a tiger, therefore I could extrapolate a cat’s requirements to a tiger,” Morris said. “Or for instance, I didn’t know for sure what the nutrient requirements were for a rhinoceros, but I knew their digestive physiology looks like that of a horse.”

Despite their similarities, a key difference between production and exotic animals is how they are managed. Zoo animals are managed for longevity, so if they develop a chronic disease, they receive specialized care to help them live in spite of it. Oftentimes, this could be accomplished by adjusting what they eat.

“A lot of my work focused on clinical diets,” Morris said. “If we had a gorilla with heart disease, a lemur with diabetes, or a big cat with inflammatory bowel disease, I focused on those individual cases and formulated diets specific to them.”

Understanding nutritional requirements and addressing medical issues made Morris’s job complex. Another challenge Morris faced was finding the right ingredients to make each diet. Whether an herbivore, omnivore, or carnivore, the food a zoo animal consumes in its native environment is likely hard to come by in the Midwest.

To overcome this, Morris studied what these species eat in the wild and searched for suitable substitutes. “I had to look at the nutrients that are in feeds that we can get here in the central part of the U.S. and see how they can be matched to a species’ needs,” Morris said. “Alfalfa hay, for example, is not going to be something grown in Africa, but we used it to help formulate the diet of a giraffe. It was like a big puzzle.”

When zoos have limited options for ingredients in animals’ diets, it is important they make the most of what they have access to. Jake Sterle, graduate student in business administration, learned how to do this during his internship at Omaha’s Henry Doorly Zoo and Aquarium three summers ago. A project he worked on involved manipulating what shrimp eat in order to enhance the diets of the jellyfish.

“Jellyfish technically don’t eat shrimp in the wild, but in captivity it’s the most efficient way to feed them,” Sterle said. “I was working in an aquarium to see how you can feed baby brine shrimp to give jellyfish the most nutrition.”

This semester, Sterle is a teaching assistant for Animal Science 320: Animal Feeds and Feeding – one of the classes Morris instructs. While there likely won’t be any lessons on jellyfish and shrimp, he said feed efficiency is a key concept students learn in this class, and it can be applied to all kinds of species in a variety of settings.

Another course Morris is teaching this fall is Animal Science 224: Companion Animal Science. In this class, Morris emphasizes the importance of animal training, and she offers students examples from her time at the zoo. In mixed species exhibits, such as an aquarium, Morris said animals were trained to eat the correct food so they would receive the appropriate nutrients.

“With multiple species of sharks, sea turtles, and other fish all in a big tank, you’re having to get everyone fed, and some of those animals have unique requirements,” Morris said. “There is animal training that has to go into it, and animals are essentially separated for feeding.”

Ava Frase, graduate student in animal science, is the teaching assistant for this course. She admires Morris’s enthusiasm and her ability to share her expertise with students. Frase also interned at Omaha’s Henry Doorly Zoo and Aquarium and is happy to continue working alongside Morris. She hopes to pursue a career in wildlife conservation and exotic animal nutrition, and said Morris has been influential in helping her attain her professional goals.

“It’s really hard to get into a zoo career, and I think Dr. Morris is a really good resource for students who are interested in that because she is super knowledgeable about the industry and she has so much experience,” Frase said. “I’m very excited to see what she is going to do in her classes and how she is going to introduce exotic nutrition and exotic everything to the students. She does a good job with that.”

Although Morris is still settling in, she has plans for a new animal science course in the making. The basis of this class would be to examine how nutrition and reproduction techniques practiced on farms can be integrated into zoos. While it might be a few years before this course takes shape, Morris already has an idea of what it will look like.

“The world of zoo management needs a lot of the same scientific disciplines that we need in animal science,” Morris said. “The point of this class would be to show how all the disciplines we teach students about – cows and pigs and sheep – are beneficial to our zoo animals, too.”