Manure happens: Sanitation machine may stress zoo animals


    They don’t have to face midterms, so why would animals at the Dallas Zoo be stressed?

    Christine Bertz, a graduate biology student, is studying stress levels of okapi, the only other animal in the giraffe family besides the giraffe.

    Below the stalls in the zoo, a manure machine with a heavy chain and big metal teeth churns away everyday. Researchers at the zoo thought it might be affecting the okapi.

    “This was a special study the zoo wanted done,” said Jeanette Boylan, research advisor at the Dallas Zoo. “From previous results we hypothesized that our manure handler might be affecting the okapi and we wanted to test that hypothesis.”

    Bertz focuses on the impact the machine has on the stress levels of okapi.

    “The okapi have always had a high profile in the international species survival plan,” said Gary Ferguson, a TCU professor and thesis advisor to Bertz. “Lots of records are kept and a lot of monitoring is done on aspects of the animals’ lives in captivity.”

    Unknown in the western hemisphere until 1901, okapi are not considered endangered, but are rare in the wild and in captivity. The only place they can be found in the wild is in Zaire, Africa. There is concern that the shy, somewhat reclusive okapi might have increased levels of stress due to noise.

    “From a zookeeper’s standpoint, this is a very important piece of machinery,” Bertz said. “It removes and processes manure; a job, which not long ago, required many hours of zookeepers’ time.”

    However, the manure handler makes a lot of noise and runs 45 minutes every day.

    “By knowing what factors influence the stress levels of the animals, we can adjust our husbandry practices for optimal animal care,” Boylan said.

    In order to determine stress levels, Bertz measures cortisol. Cortisol is a steroid hormone excreted by the adrenal cortex when okapi experience stress. There are several methods of determining cortisol levels.

    “We measure cortisol from urine samples because it is the least invasive method,” Bertz said.

    Bertz has completed the field testing phase of her research and now is in the process of analyzing data and compiling results for her thesis, Ferguson said.

    If the noise from the machine proves to cause increased stress, zookeepers will probably move new calves and sick animals to enclosures away from the noise of the manure handler, Bertz said.