Rating: 
Hill’s Science Diet Mature Adult dry dog food earns the Advisor’s lowest rating of 1 star.
The Hill’s Science Diet Mature Adult product line includes four dry dog foods.
Although we found no AAFCO nutritional adequacy statements for these dog foods on the Hill’s Science Diet website, each product appears to be designed for senior pets.
- Hill’s Science Diet Mature Adult Small and Toy Breed
- Hill’s Science Diet Mature Adult Active Longevity
- Hill’s Science Diet Mature Adult Large Breed
- Hill’s Science Diet Mature Adult Small Bites
Hill’s Science Diet Mature Adult Active Longevity dry dog food was selected to represent the others in the line for this review.
Hill's Science Diet Mature Adult Active Longevity
Dry Dog Food
Estimated Dry Matter Nutrient Content
Ingredients: Whole grain corn, chicken by-product meal, animal fat (preserved with mixed tocopherols and citric acid), soybean mill run, flaxseed, chicken liver flavor, lactic acid, corn gluten meal, potassium chloride, l-lysine, choline chloride, vitamin E supplement, iodized salt, vitamins (l-ascorbyl-2-polyphosphate (source of vitamin C), vitamin E supplement, niacin, thiamine mononitrate, vitamin A supplement, calcium pantothenate, biotin, vitamin B12 supplement, pyridoxine hydrochloride, riboflavin, folic acid, vitamin D3 supplement), calcium carbonate, dicalcium phosphate, minerals (ferrous sulfate, zinc oxide, copper sulfate, manganous oxide, calcium iodate, sodium selenite), l-tryptophan, taurine, glucosamine hydrochloride, l-carnitine, preserved with mixed tocopherols and citric acid, chondroitin sulfate, phosphoric acid, beta-carotene, rosemary extract
Fiber (estimated dry matter content) = 3.6%
Red items when present indicate controversial ingredients
The first ingredient in this dog food is corn. Corn is an inexpensive and controversial cereal grain of only modest nutritional value to a dog.
For this reason, we do not consider corn a preferred component in any dog food.
The second item lists chicken by-product meal, a dry rendered product of slaughterhouse waste. It’s made from what’s left of a slaughtered chicken after all the prime cuts have been removed.
In a nutshell, chicken by-products are those unsavory leftovers usually considered “unfit for human consumption”.
In addition to organs (the nourishing part), this stuff can contain almost anything — feet, beaks, undeveloped eggs — anything except quality skeletal muscle (real meat).
On the brighter side, by-product meals are meat concentrates and contain nearly 300% more protein than fresh chicken.
The third item is animal fat. Animal fat is a generic by-product of rendering, the same high-temperature process used to make meat meals.
Since there’s no mention of a specific animal, this item could come from almost anywhere: restaurant grease, slaughterhouse waste, diseased cattle — even euthanized pets.
We do not consider generic animal fat a quality ingredient.
The fourth item lists soybean mill run. Mill run is a by-product, mostly the hulls of soybeans remaining after processing the beans into meal. This is nothing more than a cheap, low-quality filler more commonly found in cattle feeds.
The fifth ingredient is flaxseed, one of the best plant sources of healthy omega-3 fatty acids. Provided they’ve first been ground into a meal, flax seeds are also rich in soluble fiber.
After the chicken liver flavor, we find lactic acid, a nutrient found naturally in many living organisms.
It’s difficult to say with certainty why lactic acid is present here except to assume it’s added to balance the pH of the recipe.
The eighth ingredient is corn gluten meal. Gluten is the rubbery residue remaining once corn has had most of its starchy carbohydrate washed out of it.
Compared to meat, glutens are inferior grain-based proteins lower in many of the essential amino acids dogs need for life.
This inexpensive plant-based ingredient can significantly boost the total protein content reported in this dog food.
From here, the list goes on to include a number of other items.
But to be realistic, ingredients located this far down the list (other than nutritional supplements) are not likely to affect the overall rating of this product.
With two notable exceptions…
First, we find no evidence of probiotics, friendly bacteria applied to the surface of the kibble after processing.
And finally, the minerals here do not appear to be chelated. And that can make them more difficult to absorb. Non-chelated minerals are usually associated with lower quality dog foods.
Hill’s Science Diet Mature Adult Dry Dog Food
The Bottom Line
Judging by its ingredients alone, Hill’s Science Diet Mature Adult dry dog food appears to be a below-average kibble.
But ingredient quality by itself cannot tell the whole story. We still need to estimate the product’s meat content before determining a final rating.
The dashboard displays a dry matter protein reading of 20%, a fat level of 16% and an estimated carbohydrate content of 57%.
As a group, the brand features an average protein content of 20% and a mean fat level of 16%. Together, these figures suggest a carbohydrate content of 57% for the overall product line.
Low protein. Average fat. And above-average carbohydrates when compared to a typical dry dog food.
In addition, when you consider the protein-boosting effect of the corn gluten meal, this looks like the profile of a kibble containing only a modest amount of meat.
Bottom line?
Hill’s Science Diet Mature Adult is a plant-based dry dog food using a modest amount of chicken by-product meal as its main source of animal protein, thus earning the brand 1 star.
Not recommended.
Those looking for a review of the rest of the kibbles in this line may wish to visit our review of Hill’s Science Diet Adult dry dog food.
A Final Word
This review is designed to help you make a more informed decision when buying dog food. However, our rating system is not intended to suggest feeding a particular product will result in specific health benefits for your pet.
For a better understanding of how we analyzed this product, please be sure to read our article, “The Problem with Dog Food Reviews”
Remember, no dog food can possibly be appropriate for every life stage, lifestyle or health condition. So, choose wisely. And when in doubt consult a veterinarian for help.
Have an opinion about this dog food? Or maybe the review itself? Please know we welcome your comments.
Notes and Updates
12/28/2009 Original review
08/01/2010 Review updated
11/14/2011 Review updated, no changes
The Dog Food Advisor publishes independent reviews to help pet owners make better choices when shopping for dog food.