The Walden Effect: Farming, simple living, permaculture, and invention.

How many chickens will a black soldier fly bin feed?

Black soldier fly bin"How much chicken feed will [your black soldier fly bin] produce?  How many grubs are you expecting per week?  Will it be enough to be a substantial caloric addition or is this just for a treat?  Will this replace any supplements you may currently use?"

This is a good question, but the answer is a bit complicated.  As a starting point, the number of grubs you get from a unit like ours will depend on how much food you provide and on how well colonized your unit is.  Best-case scenario is that our six-gallon unit can handle 2 pounds of food scraps per day, which will be converted into 0.2 to 0.4 pounds of black soldier fly larvae per day.  Of course, if you don't do everything perfectly, you'll get less.

Mass Production of Beneficial Organisms: Invertebrates and Entomopathogens suggests that black soldier fly larvae (fresh, I think, but the table is a bit unclear) provide 1,994 calories per kilogram.  That would mean that our daily 0.2 to 0.4 pounds of black soldier fly larvae would provide 180 to 360 calories, equivalent to the daily energy needs of half to one chicken.

Pastured chicken flockBut that doesn't mean our bin will only feed half a chicken.  Protein makes up about 35% of the calories in black soldier fly larvae, meaning that you should consider the grubs to be more like soybeans than like the 16%-protein feed mixtures from the store.  Since soybeans often make up about a third of the weight of store-bought chicken feed, it's conceivable that our bin's daily output could equate to supplemental protein for 1.5 to 3 chickens.

But how do you work around having this supplemental protein source on hand?  You might get away with mixing one of these homemade layer feeds and simply substituting black soldier fly larvae for soybeans (figuring that a pound of dry roasted soybeans is equivalent to about 2.24 pounds of fresh black soldier fly larvae).  Or, on a smaller scale, you could simply provide your chickens with all the black soldier fly larvae you have available and then also provide an automatic feeder full of store-bought feed and another of grain so the chickens can lower the overall protein level of their diet (by eating more grain) as they see fit.

No matter how you figure it, having a high-protein, animal-based feed available for chickens should cut feed costs and improve the birds' health, along with boosting the nutritional density of the eggs and meat the chickens provide.  The real question will be --- is the positive impact greater than if we simply fed our food scraps to the chickens (as we currently do) instead of to the black soldier fly larvae?

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About us: Anna Hess and Mark Hamilton spent over a decade living self-sufficiently in the mountains of Virginia before moving north to start over from scratch in the foothills of Ohio. They've experimented with permaculture, no-till gardening, trailersteading, home-based microbusinesses and much more, writing about their adventures in both blogs and books.

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Dear Anna, I was the happy recipient of a box of walking onions from your sweet father last year. I planted the small bulbs and was pleasantly surprised at how prolific they grew! Unfortunately, my family is having a hard time liking the taste the consistency of the bulbs. The greens are great and I've added them to many dishes and have begun freezing/ drying for use through the winter. But the bulbs are tough and bitter. Even after cooking the bulbs are chewy and fibrous. What did I do wrong? Did I leave them in the ground too long?

Comment by Elizabeth Sun Sep 7 14:23:13 2014
Elizabeth --- Several things might be going on. First, I take off quite a few outer leaves before cooking with just the tender center. (The parts of the bulb that are hard to cut up are going to be tough when cooked.) Second, the bulbs aren't going to taste exactly like onions --- more like a mixture of onions and garlic, although I've never felt they were bitter. Finally, I've actually mostly cooked with them in the winter since that's when I'm lower on other vegetables, so I can't promise they taste good in the summer! Hope that helps jumpstart your experimentation.
Comment by anna Sun Sep 7 18:41:37 2014
I've found I need to cut off the tough portion of the bulb, near the roots, in summer. Forget the tops in hot weather, unless you peel away the outer parts. Don't eat what doesn't cut easily.
Comment by Errol Hess Mon Sep 8 14:02:27 2014

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