Cost per 100 kilocalories

This chart provides an interesting comparison. It shows the cost of 100 kilo- calories of energy for several brands.

Unfortunately, it doesn’t tell you anything about the quality of the ingredients, or the amount of nutrients your dog will get from a food. Ultimately, you need to balance the quality of ingredients, the price per calorie, the digestibility of the food, the level of performance of the food in your dog, and your level of trust in the manufacturer to decide which food is best for your dog.

Prices used in our calculations were checked in Austin, TX at PETsMART, PET-CO, and local supermarkets, mid-December 1998. For foods not available in the Austin market, the manufacturer provided a typical price for a 40 or 50 lb. bag of food in a typical market. The price used was neither the high-est nor the lowest price the product sells for. Remember, prices vary based on competition, distance from the manufacturing plant, sales, and other factors.

We used ME calculations provided by the manufacturers. Where none were available, we calculated ME based on the Modified At-water formula and Guaranteed Analysis data.

Animal Food Services Meat Eater Frozen Patties   .2364
Wysong Maintenance II/Synorgon   .1238
Riplees Ranch Original Dog Food   .0601
Dr. Ballard Maintenance   .0537
Bil-Jac Select   .0519
Nutro Natural Choice   .0509
Nutro Max    .0462
Blackwood 3000   .0455
Sensible Choice Lamb Meal and Rice   .0451
Sensible Choice Chicken and Rice   .0437
Regal Active Bites  .0434
Eukanuba Original Performance   .0432
Eukanuba Adult Maintenance   .0431
Waltham Conditioning Adult   .0417
Nature’s Recipe Original Lamb Meal/Rice   .0415
Science Diet Canine Maintenance Sm Bites    .0415
Pro Plan Chicken & Rice Adult   .0406
Purina O.N.E. Chicken & Rice Adult   .0380
Excel Lamb Meal & Rice   .0359
Blackwood 2000   .0353
Iams Chunks   .0351
Authority Adult Chicken Meal/Rice    .0311
Cycle Adult   .0303
National Training X-TRA   .0293
Nurture Adult   .0287
Pedigree Mealtime Small Bites   .0261

What’s Age Got To Do With

Activity isn’t everything. Age plays a big part. Those were the findings of two studies by Dr. Mark D. Finke in 1991 and 1994. At the time, Dr. Finke was at the ALPO Pet Center in Allentown, PA. Now he works for PETsMART, handling all petfood-related issues.

The first study was conducted with Beagles, Siberian Huskies, and Labrador Retrievers. All were kennel dogs. The second test was done with 19 unspayed, adult female Beagles, over a 60-week period. These also were kennel dogs, with a high activity level..

Detailed measurements were taken of caloric intake, and of urine and feces, to determine the energy requirements of each dog. The data were analyzed using regression analysis, a statistical method, and a formula was generated which gives a result consistent with the data.

Dr. Finke found that as dogs age from 1 to 7 years, their energy requirements drop by 24%. That’s similar to the 20% to 25% drop in adult human energy requirements from age 19 to 51 years.

Weather plays an important part, too. A house dog can have a 10% to 15% variation in calorie needs between summer and winter. Outdoor dogs will have an even bigger variation. Arctic breeds, with well-insulated coats, will have a smaller variation based on weather.

Adjustment will also be necessary if your dog is extremely active, or not very active. These figures are based on dogs who, for the most part, were quite active in their kennel runs.
Individual variations also will mean up to 10% difference in calorie requirements from these numbers.

Dr. Finke’s chart follows, and is called Chart II.

Use these numbers as a starting point, and adjust your dog’s caloric intake as necessary.

The Guaranteed Analysis and Metabolizable Energy Numbers: How Close to Reality Are They?

As I’ve been updating this book, I’ve taken a hard look at the numbers involved. I’ve also developed spreadsheets to calculate some of the more complicated formulas. I’ve learned a few things about the numbers that I’d like to share.

Let’s first look at the Guaranteed Analysis. Want to know why every pet food company tries to steer you away from using these numbers? The reality is that there’s a huge “fudge factor” built in. The pet food manufacturing process isn’t very precise or consistent, even using the latest computer manufacturing technology (which not every company uses). The biggest variations come in the ingredients. Mother Nature isn’t consistent, so ingredients like corn can have different nutrient content, and different moisture content. Suffice it to say that  there are plenty of variables, and they all come into play to make each batch of food slightly different than  the last one.

Because of these differences, there has to be enough room in the Guaranteed Analysis so the manufacturer doesn’t bust out beyond the limit he’s guaranteeing and violate the law. In other words, if the protein level in the final product ranges from 26.8% to 27.8%, the manufacturer will give himself some breathing room and put 26% on the label as the guaranteed minimum. The same goes for the minimum level of fat, and the maximum levels of fiber and moisture.

Here are some examples of the Guaranteed Analysis and the reality, which is the Average Analysis – several samples analyzed and averaged:

Those discrepancies affect other numbers, too. The best way to determine the Metabolizable Energy (kilocalories) for example, is to feed several dogs the food, collect urine and feces, and calculate what goes in versus what comes out. But that’s an expensive proposition, and generally only the larger companies will run this test. It’s much easier to use a slightly-complicated formula, called the Modified Atwater Formula, which is based on some basic knowledge of how much energy protein, fat, and carbohydrates contain.

To show you how these figures can vary, I plugged the two sets of numbers for Iams Chunks/MiniChunks into the Modified Atwater Formula. I used the ash content from the Average Anal-ysis, and the 3.3 oz. weight of a cup of the food that Iams uses.

Based on the Guaranteed Analysis, ME is 327.5 Kilocalories/cup.
Based on the Average Analysis, ME is 347.8 Kilocalories/cup.
Based on Animal Tests by Iams, ME is really 381 Kilocalories/cup.

Just to add another layer of confusion, two formulas can be used. The Atwater Formula is the one used to calculate the ME of foods for people. It assumes a high level of digestibility. The Modified Atwater Formula includes adjustments for lower quality ingredients, such as those traditionally included in pet food. The problem is that some foods (especially raw meat diets, high meat content commercial foods, most canned petfoods and baked foods) are more digestible than ever before. Should we use the Atwater Formula or the Modified Atwater Formula? Here’s what the Atwater numbers look like. You can compare them to the Modified Atwater numbers above.

Based on the Guaranteed Analysis, ME is 364.3 Kilocalories/cup.
Based on the Average Analysis, ME is 386.6 Kilocalories/cup.

As you can see, the Atwater Formula using the Actual Analy-sis figures is almost exactly what the Animal Tests showed the real ME is. To me, that says that this food is made with the equivalent of human-grade food, at least when it comes to providing ME.

The moral of this story is that the Guaranteed Analysis has a wide margin of error built in, and isn’t a great set of numbers to use for comparison. The Average Analysis is much more accurate, but much harder to extract from the petfood companies. Iams has their numbers and plenty of other data on their website (www. iams.com), but you may have to call the other companies to get the Average Analysis for other brands.

The other moral of the story is that the ME should also be considered a guideline, and another piece of the puzzle. In the example above, there was a 14% difference between the standard calculation and the real, Average Analysis-based ME.

In our reviews, the ME shown is either the number supplied by the manufacturer (which could be by calculation or by feeding trial), or one that we calculated using Modified Atwater. We ran into some cases where the manufacturer didn’t have a clue how to calculate the ME, and others where our calculations were much more accurate than theirs. We provide the numbers in which we have the most confidence. For raw food diets, we provide both Modified Atwater and plain-old Atwater numbers.

Ross Becker – 1999

What’s Age Got To Do With It

Activity isn’t everything. Age plays a big part. Those were the findings of two studies by Dr. Mark D. Finke in 1991 and 1994. At the time, Dr. Finke was at the ALPO Pet Center in Allentown, PA. Now he works for PETsMART, handling all petfood-related issues.

The first study was conducted with Beagles, Siberian Huskies, and Labrador Retrievers. All were kennel dogs. The second test was done with 19 unspayed, adult female Beagles, over a 60-week period. These also were kennel dogs, with a high activity level..

Detailed measurements were taken of caloric intake, and of urine and feces, to determine the energy requirements of each dog. The data were analyzed using regression analysis, a statistical method, and a formula was generated which gives a result consistent with the data.

Dr. Finke found that as dogs age from 1 to 7 years, their energy requirements drop by 24%. That’s similar to the 20% to 25% drop in adult human energy requirements from age 19 to 51 years.

Weather plays an important part, too. A house dog can have a 10% to 15% variation in calorie needs between summer and winter. Outdoor dogs will have an even bigger variation. Arctic breeds, with well-insulated coats, will have a smaller variation based on weather.

Adjustment will also be necessary if your dog is extremely active, or not very active. These figures are based on dogs who, for the most part, were quite active in their kennel runs.

Individual variations also will mean up to 10% difference in calorie requirements from these numbers.

How Many Calories Does Your Dog Need? How To Use The Calorie Chart

The first chart, “How Many Calories Does Your Dog Need?” gives you an estimate of how many calories your dog needs per day. It’s based on a standard formula used in the pet food industry (ME=K x Metabolic body size). Themetabolic body size is the weight, in kilograms, to the 0.67 power.) The formula is a bit complicated to calculate, so we’ve done it for you. All you have to do is look up your dog’s weight, and estimate his activity level, to find the estimated number of calories per day your dog needs.The shaded columns are a good starting point for typical dogs.

Traditionally, the industry has used activity K figures of 132 for inactive, 145 for active, 200 for very active, and 300 for endurance/performance/sled dogs. These numbers are now considered to be about 30% too high for most dogs, with 99 to 110 typical of the average house dog. Since dog food companies base the feeding recommendations on the bag on the old numbers, those feeding recommendations are about 30% too high. (One exception is the Eukanuba line, which has made the adjustment on the bag.)

To accommodate all types of dogs, we’ve provided a wide variety of activity levels. Choose the one you think is best. If you want to be safe, err on the lower side. The gray columns are starting points for three different typical activity levels. You’ll also note that the latest research has shown that working sled dogs use a huge amount of energy – vastly different from what was previously thought.

All of the estimates are based on how much energy your dog uses, and that’s the part that’s impossible to pinpoint. One dog may get the same amount of exercise as another, but use up a different amount of energy. So, use this table as a starting point only. Adjust the number of calories based on your dog’s needs, and weigh your dog every few weeks to see the result of any changes in diet.

These numbers are for ADULT DOGS only. You can adjust for different lifestages and situations like this:

Growing puppies, weaning to 11 weeks:  k=375 (1.875 x 200 column)
3-4 months Pre-Adolescent puppies K=350 (1.75 x 200 column)
5-7 months Adolescent puppies K= 225 (1.125 x 200 column)
8-12 months Teenage K=160
12 months = Adult level
Large breeds – back off 10% to 15% (65 lbs or bigger)
Pregnant, late in pregnancy                Calories x 1.5
Nursing mothers                                    Calories x 3
Prolonged physical work                      Calories x 2 or 4
Living in cold or extremely hot weather Go up 1 column in heat if panting a lot, 2 columns in cold weather

Remember, the objective is weight maintenance. Weigh your dog monthly and keep track of gain  or loss. (If you can lift your dog, you can get on the scale with your dog and subtract your weight. Otherwise, make a date to take your dog to a pet store or vet clinic that has a scale. Record the weight on your calendar.) Weight measurement is important, especially if you’re changing the diet. Don’t trust your eye – it’s very difficult to discern changes.

To calculate how much to feed, take the number of calories per day from the chart, and divide by the ME per cup listed for your dog food. Feed that many cups per day. Deduct some if you add treats, canned food, table scraps or home cooked mix-ins. We recommend feeding at least twice a day, so remember to divide the amount in two. Don’t forget to adjust the amount you feed for changing weather conditions and changing daily activity levels.

For weight loss or weight gain, use the numbers for the weight you’d like your dog to achieve.

Ross Becker

Thanks to Dr. Dan Carey of The Iams Company for the update on K figures.