The only justification we have for using and killing animals is for food, clothing and entertainment. Mass production (ie breeding and slaughtering en masse) is for our own personal pleasure, convenience or tradition, and these uses are unnecessary.
In the past, and in certain areas, eating animals was essential for survival, but today, in civilised society with supermarkets everywhere, there is no reason to harm animals.
That being the case Veganism is the best alternative, especially given that we have the tools necessary to produce and distribute wholesome vegetarian products en masse. Not only because of easy distribution etc. but also because it is wholesome and healthy for the individual. In fact, many people I know who are vegan are healtheir now as a result of changed diet.
Not only would we be sparing other sentient beings of pain (ie. animals) we'd also be improving our health thus improving our overall performace. We'd have more energy and less lethargy. Our excuses would likely then be less (or at the very least, less convincing).