by Bretaigne Jones, DVM

Recent research completed at the Waltham Center in the United Kingdom has revealed that cats choose from available diets that which most closely meets an innate, instinctive preference for specific energy sources proportions. In addition, these instinctive preferences adjust according to the Lifestage of the cat. The proportion of energy sources for early kittenhood is different from adolescence, as well as adulthood.

This new research result is called Macro Nutrient Profile (MNP). It encapsulates vital considerations such as nutritional and physiological needs, digestibility, and palatability. The research concentrated on wet diets for cats. The terms "macro nutrient profile" defines those nutrients that are present in large quantities, and that yield energy. Energy can come from protein, fat and carbohydrates. The proportion of the energy amounts from each of these macronutrient sources preferred, changes as the cat grows and matures.

Animal nutritionists have long recognized that taste is not a strong consideration in palatability preferences in cats. Compared to humans who have 9,000 taste buds, and dogs who have 1,700, cats trail a distant third with only 500 taste buds! Instead of taste, other factors such as food texture and temperature, kibble size and shape (mouth feel) and the smell of the food are more important to the cat. Cat breeders can readily acknowledge that when cats can't smell well due to upper respiratory infections, they tend to be anorexic. When their noses are cleared of the discharge and occlusion, their appetite improves. This strong reliance on smell also explains why cats prefer to have food that is at least at room temperature as the warmer temperatures improve the aromatic effect.

Palatability can be a tricky science with cats, as many will eagerly eat new canned products when offered. Understandably, the owners draw conclusions that this ready acceptance of new foods or flavors supports a desire for variety. That premise is wrong. The Waltham research clearly demonstrated that over time, cats will preferentially eat a diet that most closely matches their instinctive nutritional needs, even if that diet is flavored with a taste and smell that they ordinarily find unattractive. It further revealed that the appropriate MNP ensures long-term preference, virtually removing the risk of monotony of particular food, clearly showing that there is no need for variety. In effect, MNP completes the other factors of palatability.

During the Waltham research, cats were offered three diets, each of which had different proportions of energy from protein and fat and different aromas.

The flavor utilized as unattractive was orange. The orange flavored food had 70% of the total energy from protein, the remaining 30% from fat. The second diet had a rabbit aroma with 40% energy from protein and 60% from fat. The third diet had a fish aroma and only 10% of the energy from protein, and 90% from fat.

Initially, most of the cats chose the fish-flavored food ( high in fat, low in protein), while rejecting the rabbit and orange flavored foods (both of which had higher protein and lower fat energy). Over the course of 38 days, almost all of the cats were eating the higher protein, lower fat diet, even though it was the orange-flavored food!

That is obviously an extremely simplified overview, but the results are the same. These findings can help explain why cats may initially eat a new canned diet only to turn up their noses at it later. The nutritional profile, more specifically the macro nutrient profile, was not meeting their long-term needs.

The younger kittens have a instinctive preference for a diet that has a higher percentage of energy from fats. This makes sense as they have a higher energy demand with rapid growth and maturing nervous system. Fats yield over two and a half more energy per gram than either protein or carbohydrates. The diet that matches this MNP is more energy dense, meaning the kittens can eat less volume and still meet their energy needs. For tiny stomachs and immature digestive systems, this makes a big difference. Then as the kitten goes into adolescence, their instinctive needs gradually shift to a more equal proportion of protein to fat energy. Their growth rate has slowed down, and while their energy needs are still higher than needed for adults, it is not as demanding as early kittenhood. When the kitten has transitioned fully to adulthood, its nutritional needs shift again to the higher protein energy, lower fat energy proportion diets. Adult cats have a very efficient digestive process from which they harvest energy from protein preferentially.

An added value to wet diets is meeting the needs of very young and older cats, who have tender mouths or teeth. Kittens as young as four weeks just starting to wean will prefer a soft textured food. Older, senior, cats frequently deal with sore mouth or dental issues making a dry diet difficult.

There is no advantage nutritionally to a wet food over a dry diet, or vice versa. It largely depends on the individual cat's needs, be that from age, health considerations, or just preference. It helps to have a cat that will eat either wet or dry foods in case a situation arises in which they need a diet that is only available in one form.

Ongoing research will continue to identify and explore the special needs of cats.