Protein in commercial mixes

[asthehind]

Today I am somewhat annoyed to discover that my boys' current and usual mixes are too high in protein. Every single mix I've been able to find information on has the same problem. The closest to the ideal protein range that I can find is this food at 13.5%:
www.vitalpetproducts.co.uk/products/index.php?store=Foods&cat=Small%20Animal&search=gerbil&tab=Subcategories&display=15&page=1&sort=price&sortasc=false&code=5364

I'm not particularly worried about this while they are young and growing, but soon they will be a year old and I feel they shouldn't be on this high a protein level for much longer. Can anyone else in the UK recommend a food with a more appropriate protein level for the adult gerbil? Or is there anything good I could add to their mix to reduce the protein proportion?

[blanknote]

How much is the protein level in their current food?

[asthehind]

Their normal Burgess Supagerbil is 14%, and the food they're on right now is Nature's Touch at 14.7%.

[blanknote]

A breeder once told me that at least a year old gerbils should be getting 15-16% protein. I didn't realise to discuss when they think that it would be good to lower the amounts!

It's a bit difficult when you get mixed opinions, but they seem to be very knowledgeable about things, so I am not worried at the moment about the higher protein compared to what a lot of websites states.

[asthehind]

I expect you're right! I just worry. It's what I do best...