This is a recommended home-cooked cat food recipe using easily sourced ingredients. The recipe comes from The Encyclopedia Of The Cat by Dr Bruce Fogle DVM, MRCVS.

The Recipe
- cook the rice, bonemeal, salt and corn oil in twice their combined volume of water for 20 minutes;
- stir in the chicken and the liver;
- leave to simmer for a further 10 minutes;
- blend it thoroughly and refrigerate.
It should feed an average sized domestic cat for three days. The chicken is medium-fat but could be leaner if the cat is being dieted.
Probably because it contains a lot of good stuff 😉 LOL. Not a very accurate answer.
Nutritional value per 100 g (3.5 oz) (from Wikipedia)
Energy 1,527 kJ (365 kcal)
Carbohydrates 80 g
– Sugars 0.12 g
– Dietary fiber 1.3 g
Fat 0.66 g
Protein 7.13 g
Water 11.61 g
Thiamine (vit. B1) 0.0701 mg (6%)
Riboflavin (vit. B2) 0.0149 mg (1%)
Niacin (vit. B3) 1.62 mg (11%)
Pantothenic acid (B5) 1.014 mg (20%)
Vitamin B6 0.164 mg (13%)
Calcium 28 mg (3%)
Iron 0.80 mg (6%)
Magnesium 25 mg (7%)
Manganese 1.088 mg (52%)
Phosphorus 115 mg (16%)
Potassium 115 mg (2%)
Zinc 1.09 mg (11%)
Wild cats do eat the contents of the stomach of animals that are herbivores and mice consume any kind of fruit or grain from plants. Perhaps this is a factor in its inclusion.
Why so much rice?