> have the feeling that the dearer the food the better ..
Not
always the case.
If you feel your dogs have done well on both then this ->
> so feel i might be doing my dogs an injustice cant be the case ;)
Just for you to consider, I'll ping up some 'breed specific' points:
1)With Siberians the ingredients that most commonly cause problems are Soy, Corn and Beet pulp.
Autarky is a cereal high diet in terms of protein source (bear in mind that Prairie Meal is a dried by-product of Maize starch consisting principally of gluten) and the form of protein in Maize 'Lipid transfer protein' is an undigestible protein... so when looking at the % for protein it may not be as high as it may appear. (Important if your Sibes are not sedentary?) the prairie meal has been listed separately to disguise the actual high quantity of a low digestible protein source.
Ok so for a Siberian its a low protein source...... Is this a problem?
2) Zinc deficiency is also a health issue within the breed. It is a recessive gene trait, a defect in absorption ( so necessarily dietary but genetic), But the research papers do comment that:
'diets with low digestibility = reduced Zinc bioavailability'
I don't know if this helps but if money is the decider, I've found a link to a supplier offering Arden Grange at only £23 a bag! Bargain!! and Mucccch superior protein quality for a comparable price. HOWEVER this is cheaper than AG normally sells for so might be worth asking supplier first if this is just a limited time offer?
Link to AG supplier for £23 bagHope this helps you come to your decision :)