Phosphorus/calcium content of cat food

[Mark]

Surely the more calcium cancel out the phosphurus?  as binders are calcium, that must be the case. Therefore something that says it's 1.4% phos but it's 4:1(calc to phos) is actually much lower in amount on phos absorbed than something that says it's 1% phos but 1:1 (calc to phos) ?   

Re: protein, the "experts" say that high protein is bad but orijen say it's not the anmount but the quality of protein that counts.

[Gillian Harvey]

the calcium "cancels out" the phosphorus - so a food that appears to be higher in phosphorus could also have a high calcium content making less of the phosphorus absorbable than one with a lower phos content and less calcium - if that makes sense?.

Had to read through that one several times LOL!

Whatever the calc/phos contents - they should always be in the correct ratios to each other, which can be between 1:1 (calc to phos) to 1:4 (calc to phos). Apparently an adult mouse has a calc to phos ratio of 1:4!

A high quality protein doesnt necessarily mean its high in phos - is that what you mean about Orjen? I may not have understood the question completely LOL! 

[Mark]

I was thinking about ca food this morning (what else  ) it occured to me that people with CRF cats watch the phos content of cat food - even Tanya's CRF site lists foods in order of phos content. Surely the calclium content also has a bearing. Ie the calcium "cancels out" the phosphorus - so a food that appears to be higher in phosphorus could also have a high calcium content making less of the phosphorus absorbable than one with a lower phos content and less calcium - if that makes sense?. One of the reasons I thought about it is because Orijen has quite a high phos content but the makers recommend it for CRF cats. One of the reasons they give is because although it doen't have restricted protein, it is high quality protein which is good.

Any thoughts?