Also |I just read that an independent study has shown dogs can digest grains.
Some dogs can digest grains - others not, that is why grain-free foods are available, same with everything else, dairy, beef, chicken etc., some are ok on these things - others cannot cope with them. I go more on my own experience of my dogs than studies/experts, who it is fair to say are rather like studies/opinions on human food and health. Just like you said in another post not all dogs can eat all things.