WildAgain Wildlife Rehabilitation, Inc.

(Excerpted from: Manufacturing Changes for Esbilac^® Powder Affect Wildlife Rehabilitators. 2010.

 Allan M. Casey, III and Shirley J. Casey, WildAgain Wildlife Rehabilitation, Inc., Evergreen, CO)          

or the Short Report (PDF 1.5 MB).

Question 5 - Is product stability or rancidity an issue? Answer: Inconsistent.

In October, 2009, WildAgain reported that rehabilitators were asking if the juvenile wild mammals may have become ill because of possible spoilage of the Esbilac® powder due to high temperatures during transport or storage. PetAg responded that their tests showed that Esbilac® powder was not rancid when it left their facility, and that people would notice a strong odor when opening a package with a rancid product. Most rehabilitators with animals that became ill did not report noticing a strong odor in the Esbilac® powder. A few rehabilitators who noticed a rancid odor returned the packages to PetAg.

About the same time that rehabilitators were trying to identify possible problems with the ‘new’ Esbilac® powder, reports of rancidity were emerging about KMR® powder, another PetAg milk replacer, formulated for orphaned kittens. Some wildlife rehabilitators used KMR® with other wildlife species, such as cottontail rabbits and raccoons. PetAg placed a statement about rancidity on its website and its president conducted media interviews. KMR® powder is high in unsaturated fats and has no preservatives. PetAg stated that, while the KMR® met specifications and was suitable for use when it left PetAg facilities, the powders are highly perishable and may develop problems when exposed to high heat in transport and storage. Summaries of and links to these statements are included in Appendix F below.

Rancidity tests

Esbilac® powder also contains unsaturated fats that are highly perishable. Since the product contains no preservatives, rancidity could easily develop if the Esbilac® powder was exposed to high temperatures during transportation and storage, especially during heat of the summer. It can also spoil if not properly handled by the consumer.

Since it seemed that rancidity could be a problem, Midwest Laboratories tested Esbilac® powder from several old and new lots for rancidity. Some of the tests were performed on cans from which animals became ill after eating formula made with that specific Esbilac® powder. The test results reported back to WildAgain did not indicate elevated levels of rancidity with the ‘old’ Esbilac® powder, but did indicate elevated levels for the ‘new’ Esbilac® powder in 2 out of 6 lots tested (33%). See Appendix F below for a complete discussion of these tests and results.

One container of the ‘new’ Esbilac® powder showed a very high level of rancidity. There had been no unusual odor or color when that can of Esbilac® was first opened for a few minutes to remove some powder. When the container was removed from the freezer and reopened several weeks later, the powder had a strong odor. A sample was immediately sent to Midwest Laboratories and confirmed that it was indeed extremely rancid (peroxide value of 67), even though it had been kept in the freezer after it was opened.

This finding suggests that it is important to examine the color and odor of any milk replacer powder each and every time that the package is opened, even if it has been stored in a cool place, such as a freezer. It should be noted that not every rancid product has a strong odor.

Rancidity could have been a possible cause of the gastrointestinal and other health problems seen in these wild orphans fed formula made with Esbilac® (and KMR®) powders.  However, the test results provided to WildAgain of samples of Esbilac® powder that were fed to wild orphans that became ill were negative for elevated levels of rancidity. That said, rancidity could be a risk for any milk powders, particularly for those that do not contain preservative, such as Esbilac® powder.

Appendix F - Rancidity Issues with Esbilac® powder and KMR® powder

PetAg’s Esbilac® and KMR® powdered milk replacer products contain unsaturated fats that are highly perishable. Since these products contain no preservatives, rancidity could easily develop if the products have been exposed to high temperatures during transportation and storage, especially during the heat of the summer. They can also spoil if not properly handled by the consumer.

While a consumer’s detection of an off-odor or strong odor is a strong indication of the presence of rancidity (the oxidation of fats), a more scientific way is to measure the peroxide value of the product. Peroxide Value (PV) is the most widely used indicator of fat oxidation.  A peroxide value is required only for USDA certified edible animal fats, such as tallow or lard. However, the feed industry also uses PV to assess the stability or rancidity of fats used as feed ingredients, by measuring lipid peroxides and hydroperoxides formed during the initial stages of oxidation.  Values are reported as meq of peroxide per kg of fat. 

Figure F-1. Esbilac® powder - peroxide value test results..

Esbilac® test results

PV tests were conducted by Midwest Laboratories on eight Esbilac® powder samples (2 of the 'old' multi-step dry lots and 6 of the 'new' single-step spray dry lots). The results, as shown in the chart below, indicate the PV tests relative to the standards for the maximum level for edible vegetable and animal fats as established by the Codex Alimentarius Commission (Food and Agricultural Organization of the U.N. and the World Health Organization).

As shown in Figure F-1, neither of the samples of the ‘old’ Esbilac® powder exceeded the maximum standard value for PV. However, one third of the samples for the ‘new’ Esbilac® powder did exceed the maximum value, with one lot sample exceeding it significantly.

KMR® and rancidity

About the same time that rehabilitators were trying to identify possible problems with the ‘new’ Esbilac® powder, reports of rancidity were emerging about KMR® powder, another PetAg milk replacer, used to make formula for orphaned kittens. 

PetAg placed a statement on its website  (http://petag.com/news_detail.asp?RegID=15) that said:

“High heat stresses these types of products [KMR® and Esbilac®]. These high heat conditions may occur in transit, in warehouses, in in-store storage, in your automobile, or in your house. PetAg, Inc. tests all of these products before leaving its warehouse to assure that they meet specifications and are suitable for use. Changes occurring after leaving the PetAg warehouse can only be noted by the consumer.

BEFORE using KMR or Esbilac Powders you should always: Examine it visually for any off colors. If the color is extremely yellow, please call. Sniff to determine if the product smells right to you (milk replacement powders should have a bland, somewhat milky aroma). If the aroma is strong, smells old or smells like something other than milk, please call. Reconstitute the product in water and look at and sniff it again. If it does not mix well, it looks or smells different from what you are expecting, there may be a problem so please call.

If the animal you are feeding is hesitant to take the formula or develops diarrhea, please call. It may or may not be a problem with the formula but either way we would like to know so that we may be able to help you with pointers for feeding your newborn or send replacement product if necessary.” 

An interview with Darlene Frudakis, the PetAg President, conducted by 575magazine.com, an online news service, in December, 2009 confirmed that there had been some spoilage with a few packages of KMR® powder. She said that PetAg had recently changed their manufacturing process in order to reduce the problems that could occur as a result of exposure to heat. While she did not describe the change in the interview, communication with PetAg confirms that they started producing KMR® powder in the summer of 2009 with the same single step dry method at the manufacturing facility where they are manufacturing the Esbilac® powder.

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