Those orange cubes are good for hydration and that's about it as far as gutloading goes. The cubes are designed to keep crickets alive, not to be a wholesome gutload for your reptile's sake or they would be much more expensive. While it does have some nutrients, they are a very low ratio to the gelatin part (or whatever they're made of) of the cube, so you're only getting a tiny bit of what you need. They are not a complete diet and should definitely be supplemented with fresh fruits and veggies as well as a regular dusting schedule.
Good Wet Gutloading Ingredients: dandelion leaves, collard greens, mustard greens, turnip greens, escarole lettuce, butternut squash, carrots, mango, alfalfa sprouts, oranges, blueberries, raspberries, sweet potato, strawberries, hibiscus leaves and flowers, papaya
Good Dry Gutload Ingredients: bee pollen, alfalfa powder, kelp powder, brewer’s yeast, wheat germ, raw uncooked sunflower seeds, raw uncooked pumpkin seeds, hemp seeds, small amounts of whole grain cereals, spirulina algae, tortoise pellets
Foods to AVOID: Broccoli, spinach, beets, and parsley, have large amounts of oxalic acids which bind calcium absorption. Lettuces and cabbage do not have any significant nutritional value. Also, avoid things like dog food, cat food, and fish flakes which are high in animal protein.
This site has nutritional info on many commonly available fruits and veggies to help guide you in choosing good gut loading ingredients:
http://www.greenigsociety.org/foodchart.htm. Gutloading ingredients should be chosen that are higher in calcium than phosphorus. High phosphorus levels in the food impedes calcium absorption, as do oxalates and goitrogens.
Sandrachameleon has many more blog entries on gut loading and nutrition.
