Resurrecting this thread because after 2 years of rat-keeping, I think I've finally settled on a feeding regime that works for everyone involved.
I make my rat mix out of ingredients that I get at supermarkets and RatRations. The ingredients get split between 4 sub-mixes: most of it goes into the standard mix, which is scatter fed as normal in the main cage. High value, low detritus foods go into the free range mix, which gets hidden around the free range area to encourage exploring. High value, low density foods go into the scatter mix, which gets buried in the digging box. And very high value foods go into the treat mix, which is hand fed and also keeps rats entertained while they get health checks and nail trims.
The downside of this is that I have to make sure I feed the 4 sub-mixes in the right proportions to each other, so there's a bit more calculating and weighing to do than there would be with just one big mix. But the upside is that I have a sub-mix to suit every situation, and I know exactly how many treats I can give out without them being extra-budgetary. I make all the sub-mixes at the same time as part of the same batch (since they all get finished at the same time), so it's actually not much more work than making one big mix.
The treat mix, containing fruit and larger nuts and seeds:
The scatter mix, containing lighter puffed and flaked foods:
The free range mix, containing the rats' favourite remaining low-mess foods:
The standard mix, containing everything else:
Here is the composition of the mix as a whole (i.e. all the sub-mixes rolled in together):
77% grains
100g pearl millet
100g proso millet
100g paddy rice
100g red sorghum
100g white sorghum
75g pearl barley
75g pot barley flakes
75g white hominy
75g yellow hominy
75g rye flakes
50g barley groats with husk
50g barley flakes
50g buckwheat groats
50g buckwheat groats with husk
50g roasted buckwheat
50g Job's tears groats
50g cornflakes
50g popcorn kernels
50g rolled oats
50g brown rice
50g white rice
25g puffed brown rice
25g bulgur wheat
25g giant wholewheat couscous
25g wheat flakes
15g puffed Job's tears
12.5% pulses (all soaked and microwaved)
130g soya beans
20g split black gram
20g split chickpeas
20g puy-style lentils
20g split mung beans
20g split green peas
20g split yellow peas
5% nuts and seeds
15g flaked coconut
15g sunflower seeds in shell
10g almond flakes
10g cashew nuts
10g hemp seeds
10g linseeds
10g pumpkin seeds in shell
10g walnuts
2g caraway seeds
2g coriander seeds
2g cumin seeds
2g fennel seeds
2g sesame seeds
0.5% invertebrates
10g mealworms
1.5% fruits and vegetables
10g carob pod
10g carrot
10g celery
10g diced dates
10g leek
10g parsley
10g parsnip
5g beetroot
5g currants
5g mixed bell peppers
5g sultanas
5g tomato
5g wakame
2kg total: 1.3kg standard mix, 500g free range mix, 100g scatter mix, 100g treat mix
~13% protein, ~6.3% fat
In addition to this, they get fresh veg (usually cooked 'cause they're picky sods) 6 days a week, animal protein once a week (usually egg or oily fish), bones once a month, hay or other dried forage every so often, and 0.8g DailyRat3 per rat per week.
Poo-shoveller to: Xeltan, Calyn, and Din.
Fondly remembering: Lita (NLA32), Lia (NLA28), Zephyr Delanynder (NLA28), Falere (NLA36), Mirala (NLA36), Zephyr Opold, and Rila.
Good night my little angels, sleep tight 
