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Eric - Got Cats? Get Worms!


When you read my work, you may not think of it as a nature study, but the ultimate purpose of my experiment is to find an environmentally friendly solution to animal wastes. My family has a lot of animals and, specifically, 10 cats. I see the problems with animal wastes daily. The cats live happily in a very large, specially equipped pen. The only problem is that I hate to clean four smelly litter pans. There are no words that adequately express my dislike for this chore. Tired of my complaints, Mom challenged me to design a better system. For years I've observed worms in the compost piles in the woods behind our house. Why not borrow some worms from the woods and have them clean the cat pans for me? Having worms clean up cat mess is my idea of how work should be done.

One of the cats from the author's experiment
One of the cats from the Eric's experiment
I knew nothing about vermicomposting and needed to educate myself. I read 12 volumes of Worm Digest, a few books, and watched a video. I spoke with Dr. TK Carney, a soil and compost specialist with the Louisiana State University Cooperative Extension Service. He discouraged worm-composting cat waste because of the potential pathogens, but he referred me to an expert in vermicomposting, Dr. Rhonda Sherman, with the North Carolina State University Cooperative Extension Service. She did not discourage me, but told me to make certain my cats had no pathogens or chemicals in their systems. She told me to read references on the vermicomposting systems used for reducing pathogens in bio-solid mass from city sewage. Her Web site and its links were the most helpful; they contained information that was more scientific than on many other sites.

It was clear that my experiment would have to be designed in stages; the answers to the first questions would be used to design the next stages. To determine in a scientific manner if a composting cat litter pan was a practical cat pan would ultimately take two years.

The next part of the essay is the scientific method: the basis of my design, my questions, hypotheses, methods, variables, and controls. It's not too interesting to read because it is methodical, but method is necessary to a valid experiment.

Photo of vermicompost.
The vermicompost
Question: Can a vermicomposting system be a practical alternative to the traditional cat litter pan? Hypothesis Year 1: Vermicomposting cat wastes will break down the solid waste and reduce the number of pathogens in cat wastes.

I decided that my experiment was workable; I could overcome the problems I had read about. I would have my cats screened for intestinal parasites and fecal pathogens, and take them off flea medications and wormers for four months. I theorized that vermicomposting the wastes of my meat-eating cats would not create the heat problem that manures from grass-eating animals generate. The final product of the vermicomposting cat litter pan would be a beneficial soil amendment for the woods and the landscape around my house.

Working at a vermicompost container
Working at a vermicompost container
Purpose Year 1, Part 1: To produce a vermicomposting system for cat feces by determining the optimum ratio of carbon to nitrogen for the worms, the ideal food-to-worms ratio, and the ideal end point of the vermicomposting. Part 2: To determine if cats would adapt to the vermicomposting system. Part 3: To determine how to protect the worms from predation by the cats.

The author working in the lab.
In the lab
Question Year 2: Can a vermicomposting system survive, adapt, and work when antiparasite drugs are used on the cats? Hypothesis Year 2: A vermicomposting system is a viable alternative to a traditional litter pan if cat predation can be avoided and the worms can adapt to the chemical metabolites of commonly used feline products.

Cats are exposed to parasites from the time they are born. External parasites include fleas, ticks, ear mites, and mosquitoes; internal parasites include hookworms, roundworms, tapeworms, and heartworms. It is possible with today's feline products to have a parasite-free cat; contemporary cat owners use a variety of products. The metabolites of these antiparasite products will be passed into the vermicomposting cat pan. To learn about the metabolites of the popular feline products, I read the package inserts and contacted the manufacturing companies.

Purpose Year 2, Part I: To test the effects of commonly used feline antiparasitics (antihelminics and insecticides) on a vermicomposting system. Part 2: To introduce the system into a normal home to see if it is practical.

1. Controlled Variables Years 1 and 2

The following variables are kept as constant as possible in the experimental design. Environment of worms, Eisenia fetida:
a. Containers (10-gallon bins with lids; air and drainage holes drilled)
b. Bedding (soaked peat moss—all systems weighed 20 pounds initially)
c. Moisture (should be "9" on moisture meter)
d. Light
e. Air flow
f. Bedding temperature (regulated with heating pads to a constant temperature of 70° F)
g. Water (tap water from city system)
h. Worm adaptation (Before feeding, allow worms to adjust to new environment for one week; after first feeding, allow one week before taking weight, soil tests, pH, and E. coli counts.)

Eric with several vermicompost bins.
Eric with several vermicompost bins
2. Environment and social structure of cats
a. Housing (normal living area, covered and shaded)
b. Ambient temperature and humidity
c. Diet (Science Diet Adult Dry, regular formula—one cup daily, fed in their normal bowls in their normal place)
d. Water (tap water from city system, provided by a continuous-flow delivery system)
e. Composition of cat "family" (10 cats that have long lived together)
f. People interacting with cat "family" (limited to Eric and Mom)
g. Litter pans (four, each covered with their regular litter—recycled newspaper in pellets)

Photo of worms used for vermicomposting.
Worms used for vermicomposting
3. Manure worms, Eisenia fetida, all about same size.

4. Carbon source for worms (shredded moist newspaper; slick supplements not used. The shredded paper was moistened with water equal to three times the paper's weight.)

5. Water (tap water from city system)




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