Merah and her baby Ginger have an orangutan picnic

Courtesy of Robin Winkelman/Saint Louis Zoo

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Zoo Cuisine

Animal nutritionists use math to create healthy diets for zoo animals

September 26, 2016
By Jacqueline Barba

Have you ever turned up your nose at an unappetizing dish you were served for dinner? If so, you’re not alone. And it’s not just humans who have favorite and least favorite foods—so do some other species!

Merah, a female orangutan at the Saint Louis Zoo in Missouri, is one such picky eater. Her least favorite food is protein biscuits. Resembling long pieces of dog food, these biscuits are specially designed to give apes the protein they need. But nothing zookeepers do can convince Merah to eat a full serving.  

Ray Meibaum 2016

Nate Oliveira, a keeper at the Saint Louis Zoo, packs up leafy greens for feeding time.

Luckily for Merah, the Saint Louis Zoo has an animal nutritionist on staff. Zoo nutritionists design healthy diets for wild animals and make sure that choosy creatures get the nutrients they need. At the Saint Louis Zoo, Debra Schmidt creates diets for more than 14,000 animals.

Schmidt relies on a lot of math to calculate the animals’ nutritional needs. She uses an equation based on body weight to provide the animals with the right balance of vitamins, minerals, proteins, and fats. She’s also responsible for keeping track of the zoo’s enormous grocery list. It includes 13,000 bales of hay, 675,000 waxworms, and 1,200,000 crickets a year.

Animal nutrition requires creative thinking too. That was the case with Merah’s diet. “Merah is by far the pickiest animal I’ve ever worked with,” says Schmidt.

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Using orangutans’ dietary needs as a guide, Schmidt created a menu that would please Merah’s finicky taste buds. Her new diet features a variety of proteins, including kidney beans, hard-boiled eggs, and tofu.

“Tofu is one of her favorites,” says Kim Emerson, one of Merah’s keepers. “She takes it right out of the package.”

Luckily for Schmidt, not all of the zoo’s animals are as fussy as Merah. Asked to describe the other orangutans’ appetites, Emerson laughs: “They’re vacuum cleaners!”

WRITING PROPORTIONS

A proportion is an equation that states that two ratios are equivalent. Zoo nutritionists like Debra Schmidt can use proportions to scale quantities of food up or down to find the exact amount they will need for a certain number of animals.

Set up and solve proportions to answer the following questions about animal diets at the Saint Louis Zoo.

The zoo’s 7 adult female Asian elephants are fed 1,092 pounds of elephant pellets (the elephant version of protein biscuits) every 3 weeks. How many pounds of elephant pellets are they fed over the course of 8 weeks? 

The same 7 elephants receive a total of 80.5 bales of grass hay each week. How many bales would be needed for 10 elephants?

The zoo’s 3 female giraffes receive 37.5 pounds of alfalfa hay each day. How many pounds would 2 giraffes need each day? 

Each year, the 3 giraffes eat a combined total of 13,290 pounds of giraffe pellets. How many giraffes could 22,150 pounds of pellets feed for a year?

The zoo’s 18 flamingos share about 17.3 pounds of krill per day. How many pounds of krill per day would be needed for 24 flamingos? Round your answer to the nearest tenth.

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