Here's some ingredients I use:
oatmeal
pressed barley
"green" drink mix (has spirulina, dried wheatgrass juice, blue-green algae, alfalfa, stuff like that in it)
Soy protein supplement powder (w/vitamins and minerals in it)
ground flax seed (for omega-3 fatty acids)
carrots
greens (dark green leaf lettuce, kale, broccoli leaves etc...)
calcium
a little herp vitamins
Basically, IMO you want make sure your gutload contains carbs, protein, a bit of "good" fats (omega-three fatty acids), calcium, and vitamins. Vitamins can come from produce, food powders (like the green drink and soy supplement I use), or herp vitamins, or all of the above. I try to provide a varied diet that offers a borad range of nutrition from vegetable sources as well as supplements.
Others have recommended ...what is the name...search for ICB and you'll find it, it's a complete vitamin/protein/carb.mineral formula you dust on feeders and can replace an elaborate gutload.
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Sarah Stettler aka Starling
Sarah@stargecko.com
StarGecko.Com COMING SOON! Star Quality Leopard Geckos
Specializing in Hypotangerine Tremper Albinos