A heck of a lot of science goes into dog food. It must be balanced, providing sufficient protein, carbohydrate and other nutrition for the average dog, a sick dog or perhaps a puppy. It must withstand the process of turning ingredients into kibble without losing their food value. It must sit in a bag on a shelf for quite a period of time without going stale and while retaining its stability.
Turns out it’s not so simple.
To complicate it further, there’s another piece to the dog food science puzzle – making sure dogs will eat it, something called “palatability.” After all, you can create the most nourishing, healthy, stable food in the world, but if dogs won’t eat it, you’ve wasted a lot of time and money.
George Collings, Ph.D., knows something about building dog food. He’s been around the pet industry since the late 1970s. His doctorate is in nutritional sciences, and he’s been involved in creating more than 1,000 products for pets, he told a group of pet product retailers at SuperZoo, a pet products show held in Las Vegas in September 2012.
“The pet food industry that I’ve lived through has changed a lot,” he said. “Today we see a sea of products out there. When I started, there were just a few basic products in the marketplace. We fed [dogs] well, but today we have a totally different market.”
In the early days, all pet food was “brown and round,” he said. “Now we’re moving into pet foods that are like human foods.” From “homogenized nuggets in a box in the ‘40s,” we’ve gone to the super-premium food of the ‘80s, and today, it’s all about feeding dogs like people with everything from grain-free to natural to organic to “human-edible,” though, he says, the U.S. Food and Drug Administration is “putting their hands up” against that.
And kibble alone doesn’t cut it anymore. He points out that we have “soft-moist, soft-dry, pouches, trays, refrigerated” and a host of other options. At one time, most diets were based on corn or wheat, but today there’s “rice, peas, potatoes, tapioca, quinoa and garbanzo beans.” For fat, we’ve gone from “tallow to chicken fat to fish oil and canola oil. We’ve added egg, flaxseed, vegetable fibers, herbs, fruits and vegetables.
“This is a totally changed market,” he said.
It’s not the dogs driving it, though. It’s the dog food buyers – you and me.
Nonetheless, if dogs won’t it eat, it won’t sell.
An interesting thing about palatability, Collings said, is that a more palatable food doesn’t necessarily mean a dog will eat more of it. It also doesn’t make the food more nutritious than, or even as nutritious as, other, less palatable foods.
So, what is it? It’s simply making nutrition edible, he said.
Ten major factors affect a food’s palatability, according to Collings:
- • Fats and oils, including their quality, how they’re applied, how consistent the source is, whether the “fat vats” are cleaned regularly, their stability and the temperature at which the food is coated with them. Chicken, beef, pork, canola, turkey and fish “are all different,” Collings said, “having both positive and negative effects on palatability.”
- • Meat proteins used in the food, whether beef, chicken, lamb, fish, egg or whatever, and their source, how they’re heated and handled.
- • Digests, which can be dry, hydrolyzed meat or liver or liquid, hydrolyzed meat or liver; coatings of soy, milk, cheese, liver or yeast; a gravy or broth; and “spikes, reaction flavors added to ingredients.”
- • Acids, which are used mostly in cat food.
- • Processing, which includes “grind size,” or how big granules within a kibble are; the “degree of cook,” which “explodes out” starches so they can be digested; the “cell structure” so that applied fat can be absorbed; the coating system used to apply fat; and the temperature because if you heat to burning, palatability plummets.
- • Shape and size, with shape being more important to cats and pet owners, and the size determining whether a dog of a certain size will gulp the food or chew it.
- • Preservation systems, such as natural vs. synthetic antioxidants, the level of rancidity, antimicrobials and sugar.
- • Packaging choices, including the types of plastic used, whether the container blocks light, the types of paper, whether the container is re-sealable. “You can go out and build the best tasting product and put it in a plastic bag of the wrong plastics, and lose the palatability,” Collings said. If you store your dogs’ food in a container other than the bag it comes in, that can deteriorate palatability as well.
- • Nutritional content can affect palatability too. Protein levels are more important to cats, while fat levels are key with dogs. Too much ash causes a drop in palatability, and, as fiber levels climb, palatability falls. The source of minerals is very important, Collings said. “You can change the palatability really quickly by using the wrong mineral sources.”
- • The ingredients in a food make a big difference in palatability. Dogs tend not to like the smell of foods containing lamb meal, Collings said, while cats like the taste of food that contains wheat. Both dogs and cats prefer brewer’s yeast over other yeast types.
The big question for a dog food, he said, is “does it turn on the nose?” That’s the dog’s nose, not yours. As humans, “We want it to smell like turkey coming off the product.” But that won’t necessarily do it for a dog.
Cats care about taste and how the food feels in the mouth.
This difference is likely due to anatomy. A cat has 60 million olfactory epithelia cells in its nose. Your dog has 4 billion. We have only 12 million.
An older study of intact dogs found that they preferred pork to lamb, pork to horsemeat, lamb to horsemeat, beef to lamb and beef to horsemeat, Collings said. When the dogs’ noses were rendered useless, they had no preference at all.
Dogs have 1,700 taste buds on their tongues, each made up of 50 cells with a life span of just 10 to 10.5 days. The replacement of those cells is affected by age, hormones, nutrition and pharmaceuticals, Collings said. So, while taste isn’t as important as smell is to dogs, it’s easy to see how an older, medicated dog might not care all that much about eating. Just in case you’re wondering, you and I have 9,000 taste buds on our tongues.
While cats are “highly attractive” to certain acids,” he said, “A dog is not.” Dogs like sugar and salt, with female dogs more receptive to sweetness than males. Both dogs and cats can perceive a bitter taste, but cats use them to distinguish toxins. “Meat taste is perceived by both.”
“Taste perception and sensitivity decrease with age,” Collings said, so you’d think that senior diets would be most palatable. “But generally they’re not.”
So, how do dog food designers test a new product’s palatability?
“A palatablity test compares two foods – which one is eaten first, which one is one is eaten most,” Collings explained. The first such test was invented by Ralston Purina in the ‘60s.
In the following decade, the two-bowl test developed. Two bowls were overfilled with two different foods and offered for a designated amount of time, he explained, usually under an hour. Foods were switched between bowls each day, ideally for a full week. “Odor preference was observed by watching which food they eat first,” he explained. But food preference depends on which food the dog eats the most of.
In addition to whether the food will attract a dog, other factors affect whether it will eat it at home. For example, “palatability goes down when canned food temperature goes down.” So, when you open a fresh can and serve it to our dog, he might gobble it up. At the next meal, when the can’s been in your refrigerator, he may be much less interested in eating. Drops in barometric pressure can affect how well a dog eats, as does frequency of feeding. If your dog eats with other dogs, depending on his place in the group, he may eat more or less than the others, Collings said.
I, myself, have never had a dog who wouldn’t eat anything put in front of him, or dropped under the dining room table, or found on the sidewalk, for that matter. But there certainly are dogs that are more particular about their food, especially as they age and take medications.
So, while dog food manufacturers have their hands full just building the right food that adheres to current guidelines and regulations, it’s a very good thing that they’re also figuring out how to get our dogs to eat it.