Can avocado act as an egg replacement for vegan bread

I think this is not possible. Avocado is a great source of high quality fat, but does not contain any protein. Egg contains copious amount of protein which enables it as 'binding' agent. When protein coagulates it 'binds' the ingredients together, giving them a different texture.

So, avocado - having a completely different taste, texture and macro nutrient composition could not act as egg substitute anywhere.

On a side note - egg is not a vital ingredient in bread. Bread gets it's elastic consistency from wheat protein, while the CO2 bubbles from yeast make it spongy and airy. If anything, adding the avocado would be like adding potato and oil to your bread. It would have a harder time rising and the texture would be moister. Don't know about the taste, though...

It really depends on the kind of bread you're making, and what the eggs are used for (leavening, binding, etc). For example, a pizza dough or baguette doesn't need egg. A quick bread such as banana bread might call for eggs in the recipe, and may or may not need an egg replacer (the bananas themselves are actually are a great egg replacer in that case). A bread recipe calling for an egg wash can just have that step skipped. Other recipes might have have eggs serving another function. This website and this website both have lists of egg replacements and their function.

Egg replacers I've used include: silken tofu, applesauce, bananas (usually in baked goods like muffins or quick breads); flax seeds, commercial egg replacer (Ener-G), and tapioca starch.

The best egg replacement is ground flax seed. Mix one tsp of ground flax with three tsp of water. Let sit for 5-10 minutes. You'll get the consistency you need and will still be vegan.