If I had access to a grain mill with those prices (and I probably do, just haven't looked around) I would buy wheat and barley, and whole or cracked corn. They don't eat much of the milo I've given them, so I wouldn't bother to buy that. That would be a lot less expensive than the $8.00 or so I am now paying for 50# of Corn/Oats/Barley. For twice the normal price, I could get four times the volume. As far as how much food, it's cost, etc, to raise a mouse up to full sized, I have never computed that. One trip to the petstore with excess mice and rats usually nets me between $30 and $100, and I would say that I make that kind of trip every six weeks or so. Since this works out equitably, with the mice paying the cost of the food and bedding I use, I consider that it's FREE to raise a mouse or a rat to adult size. Mice are omnivores, and I use a dogfood to get the protein and fat content of their food up to a decent level for lactating and pregnant mom mice. The grains alone are far too low in protein and fat to sustain a colony of feeder mice. The dog food I buy has no dyes, don't know about preservatives etc, but it's cheap, so it has less extra ingredients. Being cheap it has more grain meal than meat meal. The mice love it and flourish. Since they are outdoors in their own air conditioned building, I don't really care too much about the smell. It's not obvious outside the building (so no neighbor would complain) and even inside it's not that bad. I tend to put the dog food and the grain on the substrate itself. Any grains they don't eat goes with the bedding to the compost heap. Any extra whole kernels of dog food go into the "weanling bin" of mice. My typical colony of 1.4 mice, with 20 babies receives 3/4 cup of dog food (Grreat Choice Adult Dog Food from Petsmart) and 3/4 cup of mixed grains and black oil sunflower seeds. That lasts 3 to 4 days until I clean cages and start all over again.
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~Sasheena