October 20, 2015
This is a summary of the experiment. For a more detailed account, see The Rabbit Colony Experiment A Detailed Report.
The rabbits at Windward are kept in elevated or suspended rabbit cages. We wanted to learn the effects of keeping the rabbits in outdoor colonies, so a litter of 8 New Zealand White rabbits was separated into a colony and a cage.
The colony is a 20' by 11' area surrounded by an 8' tall fence made from cattle panels and chicken wire. We also buried chicken wire under the surface to prevent the rabbits from burrowing, so that we could observe them and catch them for weighing. The area was surrounded by trees and included two 10"x18"x14" wooden nesting boxes, which provided shade and shelter.
Our primary goal was to measure the weights of the rabbits in each group and the ratio of commercial feed to rabbit weight. Other goals included comparing the labor involved in taking care of each group and determining the health and safety of the rabbits in the colony.
We measured the commercial feed added each day and the rabbits' weights each week. We slaughtered the rabbits at 19.5 weeks and weighed the skinned and gutted carcasses as well as the edible meat (the carcass minus the bones).
The caged rabbits on average weighed more than the colony rabbits (7lb-9oz vs 6lb-6oz). The colony rabbits, however, required 20% less feed per pound of weight.
I used the feed and weight records to extrapolate the results if we had slaughtered the rabbits earlier. Both the cage and the colony rabbits had a significantly lower feed/weight ratio at 10 weeks then at the slaughter time of 19.5 weeks.
The colony rabbits handled high temperatures (over 100 degrees Fahrenheit) better than the caged rabbits, since they could use the ground to cool down. It took slightly less time each day to take care of the colony than it did to take care of one cage. The colony rabbits had no observable health problems.
These results indicate that it is more cost effective to raise rabbits in colonies than in cages. It's also more cost effective to slaughter rabbits at a younger age. Combining those two considerations, the cost (in terms of commercial feed) per pound of meat from a colony rabbit slaughtered at 10 weeks is 30-35% of the cost per pound of meat from a caged rabbit slaughtered at 19.5 weeks.
Caring for one colony takes less time than caring for one cage, and more rabbits can live in a colony than in one cage. In addition to the savings in feed, by my qualitative assessment we could reduce the daily rabbit chore's time by perhaps 50%. There are difficulties involved in keeping rabbits in large groups, many of which I'm still unaware of. But given the potential savings, I think the possibility is worth investigating.