how to calculate guaranteed analysis

What Is Guaranteed about the Guaranteed Analysis?

1. The guaranteed analysis is only required to provide information on four nutrients protein, fat, fiber, and moisture (water). Information on other nutrients can be included but is not required.
2. More importantly, the guaranteed analysis doesnt give us the actual percentages of these four nutrients in the food; instead, they are listed as minimum levels (for protein and fat) or maximum levels (for fiber and moisture). There can be a lot of variation between these minimum, or maximum, values and the actual amount of that nutrient in the food. Lets say the guaranteed analysis on your dogs dry food says 24% protein (minimum); it could be 24%, but it also might contain a larger percentage, say, 26% or 32%. To get more accurate information, call the manufacturer and ask for the average or typical nutrient percentages (or, even better, per 100 or 1000 kilocalories see below; note that 1 kilocalorie for pet food is equivalent to one human calorie).
3. Even if the guaranteed analysis gave exact percentages, rather than just minimums and maximums, these numbers dont help us to compare nutrients in pet foods because the guaranteed analysis numbers are on whats called an as-fed basis, meaning they include all the water in the diet, which varies widely between dry, canned, and other forms of pet foods. A slightly better way to compare pet foods is on a dry matter basis, which is the nutrient levels without including the water in the food. Pet foods vary widely in their water content; most canned food contains about 80% water and dry food is only about 10% water. That means that if youre comparing a dry food with a protein level of 33% from the guaranteed analysis to a canned food with a 8% protein level from the guaranteed analysis, the canned food seems much lower in protein. However, the protein levels are almost identical (at about 36%) when compared on a dry matter basis!

You can convert the as fed percentages from the guaranteed analysis to dry matter percentages fairly easily (see our Nutrition Math 101 post), but it still doesnt account for the lack of an exact value noted above or the issue of calories (see #4).

1. The best way to compare nutrients between pet foods is to compare them on a calorie basis. Instead of messing around with percentages whether dry matter or as fed nutritionists compare foods using grams of that nutrient per 100 or 1000 kilocalories. This is the most accurate comparison because it adjusts for the variable kilocalories (kcals) in pet foods. Dry cat foods, for example, can range from less than 300 kcals per cup to more than 600 kcals per cup! This not only affects the volume of food that the cat would eat (for a typical 10 pound cat, about 1 cup per day of the low kcal food and about 1/3 cup per day of the high kcal food), but also affects how much of other nutrients theyll ingest, such as protein, vitamins, and minerals. So, comparing nutrients per 100 or 1000 kcals is the best way to compare foods, but the guaranteed analysis isnt written in these terms.

So, if you want to compare nutrients in different pet foods most accurately, we recommend basing the comparison on grams per 100 or 1000 kcals. Our Petfoodology website has a calculator to help you make the conversions if the manufacturer cant give you this information.

1. Finally, even without all the other important limitations mentioned above, the guaranteed analysis relies on the manufacturers nutritional expertise and quality control measures. In the United States, if the manufacturer states that the diet has a minimum fat level of 4% or a minimum protein level of 50%, there is usually no one double-checking this information. In fact, we analyzed 90 canned cat foods that all stated they were nutritionally complete and balanced (which means they should have at least the minimum levels of all essential nutrients).* We measured just one nutrient (thiamine or vitamin B1) and found that 13% of the diets were below the Association of American Feed Control Officials (AAFCO) minimums for thiamine. While thiamine isnt part of the guaranteed analysis, it does emphasize the importance of selecting diets from manufacturers with strong nutritional expertise and rigorous quality control measures.

You probably didnt think there could be so many problems with just 4 simple numbers on a pet food label! However, I hope this illustrates that not much is guaranteed about the labels guaranteed analysis, and that its fairly useless as a way to compare pet foods or judge the nutrient levels of an individual food. Instead, we recommend asking our Questions You Should be Asking about your Pets Food to help you select a nutritious and high quality pet food. If your pet needs adjusted levels of certain nutrients, you should call the manufacturer to get average or typical values per 100 or 1000 kcals (and if they cant or wont give you that information, it should be a red flag). If your pet needs nutritional adjustments for medical issues, be sure to talk to your veterinarian about the best diet or, for more complicated situations, you can work with a Board Certified Veterinary Nutritionist (www.acvn.org).

*Markovich JE, Freeman LM, Heinze CR. Analysis of thiamine concentrations in commercial canned foods formulated for cats. J Am Vet Med Assoc 2014;244:175-179.

Dr. Freeman is a veterinary nutritionist and a professor at Cummings School of Veterinary Medicine at Tufts University. She is on the cutting-edge of science, with hundreds of articles in prestigious journals, speaking engagements at national and international conferences, and awards for her scientific achievements. However, she also is passionate about providing objective and accurate information on pet nutrition to veterinarians, pet owners, and other animal enthusiasts.

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Fur Your Consideration - Guaranteed Analysis

Guaranteed Analysis: What is it all about?

Whether youre considering selling your homemade pet treats or starting a new pet treat business, one of the first steps you may find yourself tasked with is determining what a guaranteed analysis is. Figuring out how to have a product tested and what information is pertinent can be intimidating the information in this post is intended to get you started in the right direction.

What is a Guaranteed Analysis?

Minimally, guaranteed analysis as dictated by the Association of American Feed Control Officials (AAFCO) Model Regulations for Pet Food and Specialty Pet Food, is comprised of the following required guarantees:

• Minimum percentage of crude protein
• Minimum percentage of crude fat
• Maximum percentage of crude fiber
• Maximum percentage of moisture

These guarantees must be listed before any other claims, such as ash content or vitamins/minerals, for a treat or diet. Other claims for substances that are recognized in the AAFCO Dog/Cat Nutrient Profiles should immediately follow the required guarantees. Nutrients that are not recognized in the AAFCO Dog/Cat Nutrient Profiles must indicate that they are not recognized as an essential nutrient by the species-appropriate AAFCO Nutrient Profile. If you arent sure where you can find information on the species-specific nutrient profiles, we recommend purchasing the AAFCO Official Publication where this information is readily available. Note that products not intended to contribute fat, fiber, or protein to a pets diet are not required to include these parameters.

How often should you test each product for Guaranteed Analysis?

New businesses also find themselves tasked with determining how to evaluate their product for these specific nutrients. There are several factors that can lead to varying final-product results, including, but not limited to:

• Batch-to-batch ingredient differences
• Processing environment changes
• Test method analytical variation
• Sampling variation

Maybe you have access to robust, accurate ingredient data, as well as sophisticated software that allows you to calculate a guaranteed analysis on a final product based on ingredient inclusion. It doesnt matter if the values come from calculation or testing. However, if the product is audited (analyzed) by a feed control official and does not corroborate the label claims, there could be serious implications for selling an inaccurately labeled product.

If you do not have access to an ingredient database or software to calculate the guaranteed analysis, analytical testing is likely the best route for you. Now the question is; Do I test my product once? Do I need to test it several times? Many times, testing a product once only provides a snapshot. Testing the same product several times from different batches is recommended to give a better picture of the potential batch-to-batch differences. Below is the data portion of an example report. This specific report is showing each result on an as-fed basis:

So you have the Guaranteed Analysis data, now what?

The most straightforward way of determining what to list as your guaranteed analysis is very simple. If you had multiple data points for each analyte from testing multiple batches of your product, you can:

• Locate the lowest number for protein round down to the next whole percentage
• Locate the lowest number for fat round down to the next whole percentage
• Locate the highest number for crude fiber round up to the next whole percentage
• Locate the highest number for moisture round up to the next whole percentage

We highly recommend reaching out to the governing bodies (many times the state department of agriculture) in each state the business would like to do business in, to ensure the respective requirements are met. AAFCO also has a list of state feed control officials that can assist with information required for sale of pet foods/commercial feeds in their state. It is pertinent that businesses comply with all federal and state regulations set for their product type(s).

Guaranteed analysis isnt the only data manufacturers should be thinking about when developing a pet treat or pet food. Look for next months blog where we will discuss nutrient testing and other testing considerations for pet foods and treats.

Connect with an expert.

The Author

Kari Nichols, Senior Project Manager - Pet Nutrition

Eurofins Nutrition Analysis Center (Des Moines, IA)

Nutritional Labeling

How do I calculate the Guaranteed Analysis in my pet treats?

All pet food labels require a guaranteed analysis on the label to advise the purchaser of the products nutrient content. At minimum, guarantees are required for minimum percentages of crude protein and crude fat, and maximum percentages of crude fiber and moisture. The only exception is for products that do not and are not intended to provide protein, fat or fiber (for example, vitamin and mineral supplements), in which case the product is exempt from guarantees for those components. In all cases, though, a moisture guarantee is required. Guarantees for other nutrients are normally voluntary, although additional guarantees may be required to support claims made on the label. For example, claims such as with calcium or high in vitamin E would require minimum calcium or vitamin E guarantees, respectively.

Unless the product is formulated through the use of sophisticated computer software with a complete and accurate database on nutrient content of all ingredients used in the product, the best means of determining appropriate guarantees is by laboratory analysis. A proximate analysis of the finished product includes testing for the four nutrient components mentioned above in addition to ash. Results are typically reported in percentages as fed (AF). If unsure as to the units reported, it is prudent to ask the laboratory for clarification.

Important to note is that a single analysis of a product may not provide sufficient data to determine reliable guarantees. Guarantees are declared as either minimums or maximums, meaning that if a feed control official obtained a sample of the product and tested it in his or her official state lab, the crude protein and crude fat must be NO LESS THAN the stated percentage on the label, while the crude fiber and moisture must be NO MORE THAN the label declaration. Each batch of finished product is going to vary in composition due to variation in ingredient composition, mixing rates, and amount of water driven off during the cooking process. Unfortunately, a single analytical value does not give any indication as to the expected batch-to-batch variation. As a result, the composition of the batch that was tested may be very different from the one the feed control official analyzes!

Failure to meet the guarantees may result in possible enforcement action against the product. It is prudent, then, to test multiple batches of each product. How many? In general, the more analyses conducted, the better one can estimate batch-to-batch variation and hence more reliably set guarantees. Understanding economic limitations of start-up companies, it is prudent to conduct at least two analyses of each variety to start. As more batches are produced and analyzed, more data may indicate the need to adjust the guarantees on the next label printing.

In the following example, four batches of product are tested and the results tabulated. The best means of determining appropriate guarantees from the data is by statistical analysis, calculating the average and standard deviation for each nutrient (these calculations can be done easily in MS Excel). Assuming the variation will have a normal distribution (i.e., it follows a bell curve), the average plus or minus two standard deviations will encompass approximately 95% of the population. In other words, based on this estimate of variation, by setting the minimums below the low end and maximums above the high end, 95% of the time the product will meet the guarantee.

Alternatively (and far less complicated), finding the lowest value among the crude protein and crude fat results, and then further rounding down from that value to the next whole percentage can be done to set the minimum guarantees. For crude fiber and moisture, the same can be done, except in those cases, the highest value is rounded up.

In the following example, if the manufacturer relied solely on data from the first batch to set guarantees, there likely would have been problems down the road. The first batch measured 25% crude protein. However, one of the subsequent batches was much lower at 23%. If that later batch happened to be analyzed by a state, the product would have been found deficient. The average crude protein was found to be 24.8%. Subtracting two standard deviations from the average is 22.25%. Thus, a prudent minimum crude protein guarantee for this product is 22%.

Example: Calculating guarantees from proximate analysis data

NOTE: Ash guarantee not required on pet food labeling, but is typically included in proximate analysis lab reports