While I'd expect the manufacturers to skimp on details, even other food cites lack any citations. If someone is playing scientist and decides not to cite their sources, I am going to go and ignore everything you have to say on the topic. Are you talking about personal observations? Other websites? Making things up as you go along? Why is it important: In one case the Dog Food Project cites a source, it turns out it uses the information incorrectly. Under digestiblility, the cite lists protein sources by the digestibility in percent. http://www.dogfoodproject.com/index.php?page=labelinfo101 Unfortunately, the cite it links to is also not referenced except by "Nutrition Sources" and and "personal communications with nutrition experts" http://www.thepetcenter.com/imtop/nbasics.html Whats different? THOSE ARE NOT "PERCENTAGES". They are a score with the most digestible material given an arbitrary value of one. They are all based off that, and egg whites are not 100% digestible. This is really a small error, since the ratios should still be related, but errors like this do begin to cast doubt on sites... and posts.