June 6, 2016


By: Susan Jojola

From research in people, rats and horses, we know food variety tends to result in greater food intake versus a single type of food. At AFB, we wanted to know if that tendency is also true in kittens—and also better understand how flavor variety in early food experiences might impact their food intake over time.

At the April 2016 Petfood Forum, I had the opportunity to present the results of a long-term study we conducted over nine months that helped answer those questions. In some cases, our results defied expectations, leading to insights that have implications for our customers, pet parents and their kittens.


In the five-month first phase of our study, we looked at whether flavor variety, or lack of it, influenced food intake among 50 kittens who were used to eating fat-coated kibble. Our goal was to understand the role of sensory-specific satiety: when a person or animal is satiated with one food, but still motivated to eat another. As humans, we’re familiar with this short-term effect. It’s the reason we can’t eat another bite of lettuce, but still might have keen interest in eating a chocolate bar!

Similarly, a long-term effect of sensory-specific satiety documented in people and rats is “monotony.” Imagine you ate cheesecake for dessert for a year. After 12 months, you might change your opinion of how much you like cheesecake—and really enjoy ice cream as an alternative. Because of this monotony effect, we anticipated kittens on a single-flavor diet would consume less than those on a varied-flavor diet.

But our research yielded some surprising results. The kittens on a single-flavor diet actually ate more than those on the varied-flavor diet over five months of free feeding. However, this doesn’t mean the kittens began to like the food more, but rather that their threshold for tiring of a flavor became higher. How is this possible? It appears monotony can inhibit the sensory-specific satiety alert normally triggered in kitten brains that says, “I don’t want to eat any more of this.”

To understand this phenomenon, imagine you ate only cheese pizza for breakfast, lunch and dinner for a month. By the end of the month, you would likely eat more than you did at the beginning of the month because cheese pizza would no longer satisfy your appetite as it initially did. While the pleasantness of the food would likely be reduced, the drive to eat would remain—and food intake of the only available option would increase.

In this study, kitten growth rates were used as an indicator of food intake. Of the kittens studied, male kittens fed the single-flavor diet had the highest growth rate, suggesting the decreased sensory-specific satiety that leads to increased intake is more prevalent in males—an insight that has implications for weight management in young male cats. This is an area where more study is warranted.


The next phase of our study looked at whether cats that had long-term exposure to a single flavor as kittens preferred that flavor (the primacy effect) or preferred an alternative flavor (the novelty effect) when given a choice in two-bowl tests. In this study, we used a basic kibble formula that met cats’ nutritional requirements as obligate carnivores and applied “parity palatants” across all food options presented. That meant all foods were equally nutritious and palatable to the cats, regardless of flavor (chicken, pork, fish or vegetable), allowing us to rule out innate nutrition-seeking and palatability as variables.

Over two weeks, in two-bowl tests all 50 now-adult cats received a daily rotation of the four flavors (that only half of the cats were exposed to in the previous seven months) in equal combinations. What we found was neither the primacy effect nor the novelty effect. In this case, based on the intake ratio, the cats exposed long-term to a single flavor showed similar preference for the new flavor variety and the familiar single flavor, suggesting any palatable food was enjoyable.


At AFB, we continue to develop palatants that cater to cats’ flavor preferences to provide them a pleasurable feeding experience as their nutritional requirements are met.

For more study details, including related data and graphics, download free my Petfood Forum 2016 presentation, “Does flavor variety stimulate food intake in kittens?” on our afbinternational.com website. If you have questions, I look forward to hearing from you at sjojola@afbinternational.com.


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