Great thread and a complex subject so apologies if this turns into a lengthy post.
Personally I have no problem with grains per se and like many of you, I have always found certain forms (especially whole brown rice) to be very beneficial for a lot of dogs.
Other grains like wheat and, to a lesser extent, maize do cause problems for some dogs but from my experience, for dogs without intolerance to these specific grains, they can be fine and (particularly in their whole form) might actually be beneficial.
Regarding the rating algorithm, being grain free does not increase a food’s score. The fact that most of the ‘best’ foods out there are grain free is more to do with manufacturers driving and responding to consumer trends than any proven nutritional benefit. I’ll go more into this below but for now back to the algorithm:
Brown rice scores well; Oats, barley etc are more or less neutral; Maize is downgraded slightly; Wheat is downgraded more. This is because the scores are intended to indicate how healthy a food will be for the majority of dogs.
Scores for all ingredients (not just grains) also depend on the percentages present and high levels of any ingredient that could be regarded as a ‘filler’ reduces a food’s score. For example, 5% white rice will score a lot better than 50% white rice and despite brown rice being a ‘good’ ingredient, a very high percentage will cost points.
So why are all of the top rated foods grain free? Well, in order to be successful a manufacturer has to give its customers what they want and right now most of the people buying the very top end foods are looking specifically for grain free foods. Grain has developed such a bad reputation over the last few years that putting it into a food immediately eliminates a huge section of the market. Even if a high-end producer found that adding grain to their foods would be beneficial to dogs, they just couldn’t do it as it would mean virtual commercial suicide.
It is a positive feed back loop that probably started with some clever marketing by the early grain free manufacturers and has now resulted in grain being the bogey man of pet food.
I completely acknowledge that I too play my part in the loop. As you’ll all know, one of the five ‘at a glance’ symbols on the site is whether a food is grain free or not. This wasn’t originally the plan but with so many people specifically looking for grain free foods, I added the symbol to make their searches easier. This obviously creates the false impression that grain-free is an important characteristic to look for in a food on a par with natural or clearly labelled but this is not the case at all. Sadly, the balance between giving visitors what they want and what I think they should want is a difficult one.