Innovative magnetic sweeper safeguards animal health
University of Pretoria engineering student Thashan Govender puts his new invention, a magnetic sweeper, to the test in the lucerne shed at the NZG.
Aubrey Tselapedi sweeps the Wattled crane enclosure where a new fence has been erected against the brick wall.
Aubrey shows the underside of the sweeper with numerous pieces of wire from the enclosure sticking to the magnet. Thashan's sweeper has proved to be a success!
When new enclosures are built, or others renovated in the NZG there is always "rubbish" generated by the construction process, which needs to be cleaned away before animals are put into the enclosure.
Potential health hazards
It is not always easy to remove all potentially hazardous objects such as small off-cuts of wire, nails, screws or pins or other metallic objects from the enclosure. Small pieces of wire which are inadvertently left in an enclosure can easily go undetected to the human eye, but may pose a serious health hazard to an animal that may pick up the wire and swallow it.
The condition "foreign body reticulitis" is well known to cattle farmers where small pieces of wire are sometimes ingested by cows. Bales of lucerne used to be tied with baling wire, where the chances of small off-cuts of the wire contaminating the bales were high. This had severe consequences to stock if ingested. Now lucerne bales are tied with baling rope, which can also be hazardous if ingested, but being long and more visible it can easily be seen and removed from the feed.
Ingested wire lodges in one of the stomachs where it may penetrate through the stomach wall and may further penetrate into the heart or liver and kill the cow. In the NZG, the same condition has been diagnosed in the African buffalo, Bald ibis and Waldrapp ibis. When ibises are brought to the animal hospital for examination, they are routinely X-rayed to see if there is a foreign body such as a wire in their intestinal tract. If the condition has not progressed too far and complications are minor, the wire is removed surgically.
There is therefore a need to ensure that animals in our care are not exposed to potential threats such as small pieces of wire lying around in their enclosures. The NZG needed to find a way to scan each enclosure, especially the new enclosures which have had structural enhancements made to them. As most of these hazardous objects are metallic, it was suggested that we use a magnet to sweep the enclosures.
Robynn Ingle-Möller is the coordinator for the Engineers@Zoo programme at the NZG. Each year, engineering students from the University of Pretoria have the opportunity to work on a project in the zoo. The projects are a formal part of the student's course and they are assessed on them. Projects are selected which have a positive impact on the husbandry and environmental enrichment of animals in the zoo.
It was proposed that a magnetic sweeper be made and Robynn submitted this request, amongst others, to the University of Pretoria. The project invoked some interest at the university and Mr Thashan Govender came forward to work on the project. I had a meeting with him explaining what was required and a few weeks later he brought two prototypes of the "magnetic sweeper" to the zoo for testing.
Thashan's magnetic sweeper is mounted on wheels and can be easily pushed around. A piece of wire lying on the ground, or just below the surface of the soil, will shoot up and stick to the magnet. He made a second sweeper, lighter and without wheels which is better suited for sweeping in tight corners and between plants.
Aubrey Tselapedi, a conservator from the Bird Section had recently fitted a new wire mesh barrier in the Wattled crane enclosure. This was a good opportunity to try out the two magnetic sweepers.
After a few minutes of sweeping the ground along the newly erected fence line, numerous small pieces of wire were picked up. Although Wattled cranes are not prone to ingesting these foreign objects, it is still good practice to remove all objects that may potentially cause harm to an animal - "prevention is better than cure".
By Dr Ian Espie, Chief Veterinarian, NZG
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