I have a 3/4 acre city plot where I raise heritage meat rabbits, and game birds. I have been operating in this location for 4 years. Before starting this practice I composted all of the animal waste produced here and added it to our personal vegetable plots.
Gamebirds require a high-protein diet (27 – 30%) resulting in a higher feed cost than more conventional poultry species. The higher diet cost coupled with an extended grow-out period and my inability to store larger, bulk quantities of feed result in smaller profit margins for my products.
My current open composting system cannot support increased farm production or be used for wasted grain. As I live in an urban area, pests are a major concern to me and my neighbors. Grain attracts rodents and other pests so I currently compost it in sealed plastic drums, a very slow process. I would like a more accelerated, less wasteful and more ecologically friendly way to utilize wasted feed and other farm wastes like food scraps and rabbit manure. Black Soldier Fly Larvae (BSFL) is a potential solution that would allow me to manage the aforementioned waste products in a beneficial and conscientious manner that would increase profit margins and contribute to the nutrition of my animals. BSFL can quickly process my manure and other waste products while at the same time producing a protein-rich larvae that can be fed to poultry. This could also be valuable teaching tool for other small-scale farmers in my area.
- How much of the partridge and coturnix quail diet could be replaced by BSFL while maintaining a quality carcass, and the cost reduction of this replacement.
- How quickly and efficiently can grain and manure waste be composted by BSFL in the central Ohio climate.
- How much spent food and rabbit manure is required to sustain a BSFL feeding regimen at the farm and is it sustainable.
- What are the labor costs associated with the BSFL.
First I set up two bins, and added BSFL larvae which I purchased from Northwest Redworms. I did this in order to jumpstart the project, instead of waiting for a native BSFL population to colonize my bins. I then added a regular amount of rabbit manure to each bin and took notes on how long it took the BSFL to consume it, and also how many mature BSFL actually self harvested out of the bin. I wanted to get an idea of my input to output ratio. I also added waste like kits who died at birth, and post processing in order to assess how well the larvae went through them.
The first few harvests of BSFL, I released on the ground near the bins so that they could mature to adult BSFL and continue laying eggs in the bins. I also fed some to the partridge and quail. I found that the birds enjoyed the larvae as long as they had been fed from a few days old, rather than introducing them to older flocks, who were skeptical of them (partridge in particular).
The bins were placed in a run enclosed in 1/2 inch hardware wire and metal roofing. I consulted some fellow BSFL raisers who said this setup would be ideal since larvae are often a tasty treat for raccoons and other wildlife. They also assured me that the flies would have no trouble finding their way through the barrier. The run also had grapevines growing up the sides, and adult BSFL need foliage to perch on in order to mate.
I found that the larvae did consume manure, spent feed, and processing waste, however they did it at different speeds. They much preferred the processing waste (organs, heads, feet, etc). Manure was second fastest, and spent feed was last.
I found that the moisture level of the bins is very weather dependent, and needs to be monitored daily. The material added to the bins also effected the moisture levels, and waste from processing, which contains the most moisture was best at keeping the bins wet enough for larvae to move around and stay active.
However, I was not able to coax the adult flies into laying eggs into the bins again. I observed many adult flies around the farm, some of whom decided to colonize under one of the rabbit hutches instead. I used egg traps made of fermented poultry feed set near the bins, and provided eggs traps of corrugated cardboard inside the bins with no success.
I input 50 pounds of rabbit manure and 50 pounds of processing waste, and in total harvested about 1 pound of larvae.
I spent about 20 minutes per day adding manure/waste, adjusting the moisture level, and observing the colony.
Educational & Outreach Activities
I also showed several visitors to the farm the bin setup, how it works, and what the larvae and adult flies look like. Some of these visitors were farmers and some were general public and neighbors.
I have a series of instagram and facebook posts that explain the project and follow its trajectory. They include photos and videos of bin design and set up, and also video of the birds eating BSFL, explaining the process, why they are a beneficial food source, and how they contribute to the sustainability of the farm as a whole.
Due to low yields of BSFL, I will adjust some of the elements of the project going forward.
I will move one BSFL bin out of the enclosed run and under a shady tree, leaving the wooden lid attached to protect against weather. I will leave the other in the enclosed run, and remove the wood lid in order to create greater access to the colony for adult flies to lay eggs in.
I learned that birds needs to be fed BSFL from day 1 in order to accommodate their feeding preferences. I also learned that I need to monitor the moisture level inside the bins very carefully.
The project is time consuming on a daily basis as it adds about 20 minutes to daily chores, however, I am still convinced that with more tweaking, BSFL could be a productive way to mitigate waste.