The English word you're looking for is an impaction, but we know what you mean!
I've been using white millet seed for nearly two years with no problems at all. They eat it a little, but not much on purpose. The seeds are so smooth, they pass through. If they crack the seed before swallowing, it gets digested, so no problems there, either.
Some folks have problems with little moths in the millet, but they're more an annoyance than a problem. You should be able to prevent that by freezing the millet to kill any larvae in the seed.
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Torey
Eugene, Oregon, USA
1.1 Uromastyx geyri (Joe and Arthur)
3.0 Uromastyx dispar maliensis (Tank, Turtle, and Spike)
1.0 Uromastyx ornata (Scuttlebutt)
2.1 Anolis carolinensis (Bowser, Sprocket, and Leeloo)
0.1 African dwarf frog (Sheila)
1.0 Betta splendens (Mr. Miagi)
1.1 Felis domesticus (Roscolux and Jenny)
