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Wild Food vs. Zoo Food

Bai Yun enjoys a bamboo meal.

In the wild, one to five percent of a giant panda’s diet is non-bamboo food items. This may include wild fruits or berries, scavenged meat, and opportunistically caught small mammals. So why don’t we offer in-season berries and fruits to the San Diego Zoo’s pandas, just as they might snack on in the wild?

Keep in mind that the fruits these animals eat in the wild are very different from those that are cultivated for human consumption. In fact, wild fruits are much, much higher in fiber and lower in sugar than those we eat, since humans have bred cultivated produce for thousands of years to match our own tastes and preferences. We always strive to do our best to match each species’ wild diet, so we try to use fruits sparingly, mainly as a training tool or reward. Our pandas like apples, yams, and carrots just fine, so we usually stick to those as our “go-to” training items, though we do occasionally use applesauce and other extra-desirable foods to make sure they take any needed medications. But above all, we try to keep in mind that 95 percent or more of their wild diet is bamboo and copy that as closely as we can.

In addition to their bamboo, they also get a high-fiber commercial biscuit that supplies their vitamins and minerals. In the wild, of course, pandas don’t have access to such supplements, nor would they need them. Wild pandas are able to eat fresh bamboo growing straight out of the ground, full of all of the nutrients they need. We don’t have the luxury of growing a bamboo forest in the Zoo, so we have to cut their food from elsewhere and transport it. Just as vegetables are more nutritious for us when they’re fresh, bamboo loses some of its nutrients once it’s cut and transported, so we need to make sure we’re meeting all of the nutritional needs of our panda family.

Jennifer Parsons is an associate nutritionist for San Diego Zoo Global.

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Analyzing Bamboo and other Foods

Bai Yun analyzes her nutritious bamboo.

What, if any, analysis is conducted at the San Diego Zoo to check the nutritional value of the different kinds of bamboos given to the pandas? The Nutritional Services departments at the Zoo and San Diego Zoo Safari Park routinely sample our animals’ foods for nutrient analysis. We do not have a complete nutrient laboratory onsite, but we send feed and forage samples to multiple laboratories around the country to get complete nutrient profiles as needed. What our nutrition laboratory can do is prepare samples for analysis through oven- or freeze-drying techniques and grind the samples to 1 millimeter to ensure a representative sample.

It has been a number of years since bamboo has been analyzed for the giant pandas. Joyce Nickley, a former keeper at the San Diego Zoo Safari Park, completed her masters of science research by looking at the nutrient content of bamboo, with the results published in her thesis as well as in a chapter in Giant Pandas: Biology, Veterinary Medicine, and Management (2006, edited by D.E. Wildt, et al.). Additional browse plant analysis has been completed on multiple primate browse species, four of the many species of eucalyptus grown for koalas, four species of acacia browse, and pennisetum used for the elephants. Every load of hay (Bermuda grass, Sudan grass, and alfalfa) is sampled for nutrient analysis, and our custom feeds, commercial feeds, and prey items (insects, fish, rodents) are routinely analyzed.

Our typical analysis includes moisture, protein, fiber (neutral detergent fiber, acid detergent fiber), and minerals (calcium, phosphorus, magnesium, potassium, sodium, iron, zinc, copper, manganese, molybdenum, sulfur chloride, and cobalt). In addition to these basic analyses, we often have lignin, sugar, starch, and fat analyzed. Due to the increased cost, we only analyze vitamins (A, D, E, C, and B vitamins), fatty acids, amino acids, selenium, and iodine for specific projects or clinical cases.

Routine nutrient analysis of the feeds we use at the Zoo and Park has allowed us to build a database of feed nutrient profiles that help us formulate diets for all of our animals, including our popular pandas, to keep them healthy and satisfied.

Michael Schlegel is the director of nutritional services for San Diego Zoo Global.

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Hello, Gao Gao

No large bamboo culm for Gao Gao anymore!

After a good recovery from exploratory surgery on October 6, our giant panda Gao Gao is back in the main panda viewing exhibit at the San Diego Zoo and doing very well. For those of you who follow the giant pandas at the Zoo in person or online, I know that there was much anticipation about when he would be back on exhibit. I’m happy to report that he’s doing very well!

Gao Gao spent that first morning roaming his exhibit scenting the walls, trees, and rocks to cover up son Yun Zi’s scent. The first day he really just spent readjusting to being outside for longer periods of time and not having a keeper right outside the door keeping a careful eye on him. In no way was he uncomfortable or uncertain of himself on this first day, and he got back to eating and taking it easy rather quickly.

As I was narrating for panda viewers that morning when he first came out, I watched him and listened for any vocalizations that he would make. I’m happy to report that he really had no stress his first day back, and our guests were so happy to see him. For now he will be eating more leafy bamboo that has a thin stalk, meaning that our keepers are breaking the bamboo into smaller pieces for easy chewing and easy digesting.

We are very happy to have him back on exhibit and encourage you to come take a look over the next few weeks and say hello!

Anastasia Horning is a panda narrator at the San Diego Zoo. Read her previous post, Rain for Pandas.

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Pandas, Bamboo, and Biomimicry

Bai Yu shows off a paw adapted for bamboo holding.

This summer the San Diego Zoo’s gates stay open a little later, and guests have the opportunity to hang out with their favorite animal friends longer than usual. Our Nighttime Zoo theme, China Celebration, offers a great opportunity to explore the inspirational adaptations of Chinese plants and animals. The process of studying biology in order to gain inspiration to be applied to human design is known as biomimicry or bioinspiration.

Starting with the most popular ambassador of China that we have at the Zoo, our giant pandas are quite the anomaly of the Animal Kingdom. Though their digestive systems and taxonomic classification hint that they should be carnivorous, they are instead so famously partial to bamboo. They even have a specially adapted “thumb” to grasp bamboo stalks as they strip the leaves. This “thumb” is not really a thumb at all but a modified wrist bone, giving pandas the odd appearance of having six fingers on their front paws. Astronauts, with their puffy space gloves, can’t grip nearly as well as our furry black-and-white bears. Just think how effective a robotic panda paw would be when repairing structures in space.

Almost as interesting as the pandas in the realm of biomimicry is their staple diet item, bamboo. Bamboo is a sustainable wood resource AND a source of inspiration for stability in structure. The round, hollow tube of bamboo provides support that allows the stalks to grow very tall and thin without snapping in half. As bamboo bends, the circular cross section bends into an oval, allowing flexibility in order to keep the stalk intact. Bamboo, unlike other plants, has a unique site of photosynthesis. While most plants use leaves as their solar collectors (bamboo included) bamboo plants also have chloroplasts on their stalks. Taking hints from bamboo’s strong structure and efficient use of space can provide inspiration for the design of future buildings.

Another creature from China, just as important to the ecosystem but significantly less cuddly than the panda, is the Mang Mountain pit viper, which will soon be exhibited in the Zoo’s new Panda Trek habitat. This venomous snake is part of a subfamily known and named for its infrared-sensing tissue contained in pits located between their eye and nostril. The Mang Mountain pit viper is a beautifully colored snake with alternating ragged bands of green and brown with the last ten inches or so of its tail a very light blue, an adaptation used to lure in prey. Once prey is unfortunately close (from its perspective) the pit viper strikes and pierces its prey with its almost inch-long fangs. Vipers have astonishing control over their venom secretion, a beneficial trait to conserve a precious and energy-intensive resource. They can release venom through the left fang only, the right fang only, both fangs at once, or none at all. They do so by flexing a muscle near the venom sac that expels the liquid out of the sac and down a tube ending in the fang. Snake locomotion has already inspired several different robot prototypes, but studying venomous snakes and their venom injection system could also inspire new responsive, resource-conscious liquid dispensers.

There are many other inspiring animals from China and from around the world at the San Diego Zoo and San Diego Zoo Safari Park. Who knows, maybe for your next invention you will be crediting a panda as a consultant!

Dena Emmerson is a biomimicry research assistant at the San Diego Zoo. Read her previous post, Nano-inspiration: Small Size, Big Potential.

Be sure to visit our Biomimicry section for more information about this exciting field of study.