How to Feed Cats: Examining the Nutrition of Feral Cats

Paper Review: The Nutrition of Feral Cats 

Estimation of the dietary nutrient profile of free-roaming feral cats: possible implications for nutrition of domestic cats. 

British Journal of Nutrition 2011;106 Suppl 1:S35-48. 

by E.A. Plantinga, G. Bosch, and W.H. Hendriks 

Abstract
Cats are strict carnivores and in the wild rely on a diet solely based on animal tissues to meet their specific and unique nutritional requirements. Although the feeding ecology of cats in the wild has been well documented in the literature, there is no information on the precise nutrient profile to which the cat's metabolism has adapted.

The present study aimed to derive the dietary nutrient profile of free-living cats. Studies reporting the feeding habits of cats in the wild were reviewed and data on the nutrient composition of the consumed prey items was obtained from the literature.

Fifty-five studies reported feeding strategy data of cats in the wild. After specific exclusion criteria, twenty-seven studies were used to derive thirty individual dietary nutrient profiles. The results show that feral cats are obligatory carnivores, with their daily energy intake from crude protein being 52%, from crude fat 46% and from N-free extract (i.e., carbohydrates) only 2%. Minerals and trace elements are consumed in relatively high concentrations compared with recommended allowances determined using empirical methods.

The calculated nutrient profile may be considered the nutrient intake to which the cat's metabolic system has adapted. The present study provides insight into the nutritive, as well as possible non-nutritive aspects of a natural diet of whole prey for cats and provides novel ways to further improve feline diets to increase health and longevity.

My Comments 
In this excellent study (1), the researchers reviewed 27 published studies reporting the feeding habits of feral cats and obtained data on the nutrient composition of the cats’ prey. The results showed that feral cats are obligatory carnivores with a diet high in protein (52% of daily energy) and fat (46% of daily energy) content, but low in carbohydrates (2% of daily energy). The results of this study should be expected since it has long been recognized that cats are strict carnivores, with a high dietary need for protein and fat but no dietary need for carbohydrates (2-5).

The typical prey diet of cats is low in carbohydrate (<10% of metabolizable energy (ME) (6-9). However, most commercially available cat foods are moderate to high in carbohydrate content (> 25 – 55 % ME), partly because of the difficulty in formulating extruded, dry diets that are low in carbohydrate. But higher carbohydrates are also used in cat food diets because cereal is a relatively inexpensive ingredient, and there is demand for lower-cost diets in the pet food market.

I believe strongly that many of the present-day diseases of the domestic cat are related to an "unnatural" diet, one too high in carbohydrates and too low in protein and fat. I believe we should be feeding our cats closer to what they would be eating in the wild, at least if they do not have special nutritional needs because of diseases such as kidney disease. Future research should focus on the value of feeding a natural diet of whole prey as a means of enhancing both feline health and longevity.

The authors should be commended for doing this excellent study and publishing the results. Hopefully, the pet food industry will pay attention.

References:

1. Plantinga EA, Bosch G, Hendriks WH. Estimation of the dietary nutrient profile of free-roaming feral cats: possible implications for nutrition of domestic cats. British Journal of Nutrition 2011;106 (Suppl 1):S35-48.
2. MacDonald ML, Rogers QR, Morris JG. Nutrition of the domestic cat, a mammalian carnivore. Annual Review of Nutrition 1984;4:521-562.
3. Zoran DL. The carnivore connection to nutrition in cats. Journal of the American Veterinary Medical Association 2002;221:1559-1567. 
4. Morris JG. Idiosyncratic nutrient requirements of cats appear to be diet-induced evolutionary adaptations. Nutrition Research Reviews 2002;15:153-168. 
5. Bradshaw JWS. The evolutionary basis for the feeding behavior of domestic dogs (Canis familiaris) and cats (Felis catus). Journal of Nutrition 2006;136:1927S–1931S.
6. Myrcha A, Pinowski J. Weights, body composition and caloric value of post-juvenile molting European tree sparrows. Condor 1970;72:175–178.
7. Vondruska JF. The effect of a rat carcass diet on the urinary pH of the cat. Companion Animal Practice 1987;1:5-9.
8. Crissey SD, Slifka KA, Lintzenich BA. Whole body cholesterol, fat, and fatty acid concentrations of mice (Mus domesticus) used as a food source. Journal of Zoo and Wildlife Medicine 1999;30:222-227.
9. Eisert R. Hypercarnivory and the brain: protein requirements of cats reconsidered. Journal of Comparative Physiology B, 2011;181:1-17.