A study in the Journal of Animal Sciences (J. Anim. Sci. 2013.91:225–237) claims that raw diets aren’t quite the cat’s meow.
Researchers from the University of Illinois and an Omaha zoo fed raw diets to domestic cats as well as African wildcats, jaguars, and Malayan tigers. Let’s see what happened:
Our objective was to evaluate raw meat diets for captive exotic and domestic carnivores containing traditional and alternative raw meat sources, speciﬁcally, beef trimmings, bison trimmings, elk muscle meat, and horse trimmings. We aimed to examine diet composition and protein quality; apparent total tract energy and macronutrient digestibility in domestic cats, African wildcats, jaguars, and Malayan tigers; and ME and fecal fermentative end-products in domestic cats. Because of variation in the meat sources, dietary proximate, AA, and long-chain fatty acid composition were variable. Our analyses indicated that all diets had essential fatty acid deﬁciencies, and the elk diet (i.e., trimmed muscle meat) was deﬁcient in total fat.
More specifically, the researchers stated:
All diets fed herein were adequate sources of ALA [alpha-linolenic acid]; however, for all lifestages, none met the recommended levels of LA [linoleic acid, which is essential for all mammals]. The elk and horse diets were also less than the combined recommendation for EPA and DHA. The horse diet had less ARA [arachadonic acid] than that recommended for kittens, gestation, and lactation.
What’s wrong with this picture?
- The paper notes that all diets were deficient in fat (specifically linoleic acid). But it was the researchers themselves who formulated the diets. They added a vitamin-mineral premix (contents not specified), but no extra fat. If the food was deficient in fat, they have only themselves to blame.
- They hypothesized that the four meats used would vary in composition, which they did. So what? All four meats provided an abundance of protein and essential amino acids…except for taurine, which was inexplicably left out of the analysis, even though it is essential for cats.
- None of the researchers was a veterinarian; not that a DVM is necessary to do good research, but in this case, a veterinary perspective would have been helpful. For example, a vet would have included taurine in the analysis.
- The the elk meat they used was muscle meat that they admitted was too closely trimmed of fat–yet they did not compensate by adding back any fat.
- In the cats’ bloodwork, sodium was too high in all but one diet; the paper made no mention of this.
- The researchers used the 2006 NRC standards for kittens, rather than either feline AAFCO Nutrient Profile. Commercial raw diets sold in the U.S. that claim to be complete and balanced must follow the AAFCO standards.
- The paper noted that the diets were also deficient in the Omega-3s EPA and DHA. We don’t know the source of their meat; but most food animals are ranch-raised and grain-fed or grain-finished. This process shifts the natural fatty acid balance of the animal from being rich in Omega-3s to being almost entirely Omega-6s.
- Reputable raw commercial diets and homemade foods do not use “trimmings.” They use wholesome meat fit for human consumption–typically poultry or other commonly available meats, most of which are relatively high in fat.
- I personally checked a dozen commercial raw food diets, and every one of them contained one or more additional sources of fat, such as ground flaxseed, salmon oil, cod liver oil, or chicken fat. Moreover, their guaranteed analyses showed dry matter fat content around 40%. The experimental diets were ranged from 6.5% (clearly deficient) to 36.6%. Knowing this, they failed to correct the deficiency, then complained about it later.
- There were only four each of the captive exotic cats and an unspecified number of domestic cats (but likely four). The small sample size limits the utility of the data.
- The study period was very short–only 5 days–again limiting the usefulness of the results.
- The intent of the study was not to assess the long-term suitability of a raw diet for any cat, even though that’s what it implied in its findings:
In conclusion, although the raw meat diets were highly digestible, because of variation in raw meat sources the nutrient composition of the diets was variable. Thus, compositional analysis of raw meat sources is necessary for proper diet formulation. The types of meat commonly used in raw meat diets may be deficient in total fat (trimmed muscle meat) and essential fatty acids (trimmings and muscle meats).
What they’re saying is that you have to send all your meat out for lab analysis, otherwise you can’t possibly balance the diet.
Bottom line: This study was poorly designed and executed, and so is not applicable to our kitties at home. A properly-balanced homemade diet (or a commercial raw diet formulated for cats) remains a natural and healthy alternative to commercial pet foods.