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GME® Milk Replacer - Test Results and Observations - Rancidity Detected



Rigorous discussions are occurring about milk replacer powders fed to wild mammal young as rehabilitators work to better understand various milk powders, results achieved, and how to prevent or reduce problems that appeared related to formulas in 2019. As a result, they are taking a closer look at several milk replacer powders used with wild mammals in rehabilitation, including Goats’ Milk Esbilac® (GME®).


In previous years, some wildlife rehabilitators have used GME® for wild mammal babies that they believe will benefit from a milk powder described as ‘for sensitive digestion’, such as neonate squirrels and young opossums. In September, 2019, PetAg® (the manufacturer) recommended using GME® during the time the company was in the process of changing the size of an ingredient in Esbilac® (PetAg® said they determined that a size change of an ingredient [Dicalcium phosphate] seemed to have adversely affected wildlife, though not puppies for which the powder was made). Following that announcement, PetAg replaced some containers of Esbilac® being fed to young wild mammals with GME®.


Some of the factors that rehabilitators discuss about GME® are similar to other discussions. One factor, however, is different and sometimes difficult to recognize before other problems develop and become harder to overcome. That problem showing up with some GME® is rancidity. Before discussing rancidity, the following provides a summary of the basic nutritional component testing and analysis for over a dozen individual lots of GME® spanning over ten years.



Comparing to Species Milks


Wildlife rehabilitators are becoming more aware of the importance of feeding a formula similar to the nutritional composition of the species in order to facilitate growth, development, health and ultimate survival. A key early consideration is how milk replacer powders used in the formula match the nutritional composition analysis for the species being fed. Like some other milk replacers, the GME® label says it has 33% protein and 40% fat. Review of published scientific studies of wild mammal milks suggest a milk replacer powder with 33% protein and 40% fat is rather different from many wild mammal milks. As result, rehabilitators are considering if and how to adjust the recipe to create a formula that more closely matches the species milk and, in with some species, are adjusting by the stage of lactation (e.g., opossums). Click here for more information on the different wild mammal milk compositions and shows how they vary by solids, protein, fats, kcals, and so forth.  


Rather than preparing a formula with just a single milk powder and water, some rehabilitators are considering GME® as one of several possible ingredients that could be blended with other milk replacer powders (from different manufacturers and product lines), in combination with additional items to get closer to the species milks (e.g., a supplemental fat) to produce a formula close to the species milk. Reconstitution and rehydration research shows that blending ingredients may require some adjustments to preparation methods, but that is another topic (coming soon).



Adherence to Label Guarantees


Another consideration discussed is the extent to which the GME® adheres to the guarantee minimum values on the label. Independent test results of 13 cans of GME® showed variations from the expected values – and lower from guaranteed nutrition analysis for both protein and fat content. The various charts show how the different nutritional components have changed over time. They also compare average values for the 2008-2018 time period to more recent lots manufactured in 2019.

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While nutrient levels vary between lots, independent lab tests show GME® powder testing low when compared to the label as well as some wild mammal requirements. Low protein levels can impair growth and development, and affect overall health. Low fat levels mean less essential energy for the animal to grow and function (e.g., thermoregulate, maintain normal activity). 


With fat levels testing below the guaranteed minimum values, it is not unexpected that the kcals would also be lower than expected. 

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Those low levels of proteins, fats and kcals certainly affect the animal’s growth, development, activity and overall health. More information on the consequences of feeding formula that is low in those nutrients is available by clicking on the three components in the previous sentence. Again, blending GME® with another milk powder that has a higher level of those nutrients could possibly help mitigate such deficiencies if it is carefully selected and prepared for effective utilization.



Calcium and Phosphorus Amounts


Amounts of calcium and phosphorus are other considerations. Rehabilitators know that calcium and phosphorus are two critical dietary minerals required by the body, especially for growing animals. The recently conducted independent lab tests showed that GME® has had a pattern of low concentrations of calcium and phosphorus (as compared to all of the other powdered milk replacers tested) even though critical calcium/phosphorus ratios remained within the 1:1 and 1:2 range. The lower concentrations (amounts) of Ca and P can cause a variety of serious health conditions, especially related to growth, development, and musculoskeletal problems – even if the Ca/P ratio is within an acceptable range. More information on calcium, phosphorus and the ratio of Ca/P is available by clicking on the three components just mentioned in this sentence.

Calcium Phosphorus Charts GME Milk Repla

Again, ‘blending’ GME® with other milk powders and fat sources may increase the mineral amounts and balance the nutrients needed for the species being fed the formula. This is a method that might mitigate the low levels of calcium and phosphorus. ﷯


While some rehabilitators have wondered about raising calcium and phosphorus levels with nutritional supplements, it is very difficult to select the correct types and forms of minerals - and then calculate and prepare such micro amounts to achieve the appropriate levels and balance. Even small problems with the minerals or calculations can pose far more risk to the young wild mammals’ health than people may have considered – and can cause serious health conditions, including fatalities.

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Potential Rancidity


Some rehabilitators are extremely concerned about the results of rancidity tests of some GME® made in 2018-19. Those cans of GME® were obtained from different distributors, including three shipped directly from PetAg® to the rehabilitator. Tests of GME® powder from six different lots of GME® conducted at the independent lab revealed rancidity. While that was 6 out of 6 cans tested, it does not suggest all GME® powders are rancid. It has, however, increased rehabilitator concern about the risk of possibly feeding formula made with milk powder that has shown a recent pattern of rancidity. More information on rancidity, recognizing it, testing and consequences of feeding rancid food is available by clicking here.


Some rehabilitators have reviewed cases of wild mammal babies fed formula made GME® in 2018-19. They reported that some wild mammals fed formula made with GME® were reluctant to eat, or vomited or regurgitated during feeding. When some of those young mammals were continued to be fed formula made with that GME®, rehabilitators reported seeing cases of bloat, diarrhea, overall discomfort, poor weight gain, dehydration, malnutrition and even more severe outcomes. It should be noted if an animal was gavaged (i.e., tube fed), the animal could not have shown a reluctance to eat. So while the rehabilitator would not have been able to seen reluctance to eat, they may have seen other health problems, including gastrointestinal disturbances and slow weight gain. While such health conditions can be caused by many different factors, they certainly can occur from eating rancid food, including formula.


While consuming a couple meals of a rancid product may cause minor gastrointestinal disorders in a healthy adult, longer consumption of even a smaller amount (such as in blending with another milk powder) can cause serious health problems, including severe and irreversible organ damage and fatalities. Some rehabilitators are concerned with the difficulty of knowing if a can of GME® might be rancid and the challenges of identifying health problems in early stages. More information on health effects of rancidity are by clicking here.

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While the effects of relativity lower nutrient values discussed previously may be mitigated by blending with some other ingredients, the effects of rancid products cannot be blended away or mitigated. While consuming a couple meals of a rancid product may cause minor gastrointestinal disorders, consumption over a longer period can cause serious health problems, including organ damage and fatalities. While the GME® powders certainly may be fresh and not rancid, rehabilitators are now concerned about not previously realizing that any particular GME® powder might have been rancid until revealed by the recent independent lab test results. 



Decision to Make Formula with GME® 


The decision of which milk replacer and formula to use is up to the wildlife rehabilitator. Some rehabilitators who used GME® to make formula for young wild mammals have reported previous positive results and plan to continue using it. As they would with any formula, they will monitor the animal's health and make changes should concerns develop. 


Others concerned with the possible safety issues of the GME® are choosing to not feed it until they are more confident that it is not rancid. They want to make sure the young wild mammals grow well and are healthy when fed formula made with it. More extensive documentation of the results of wildlife rehabilitators feeding GME®, as well as more data from the test results from the independent lab will help with future decisions. WildAgain plans to continue arranging for the independent lab tests of a variety of milk powders and post those results when available. In the meanwhile, sharing information with fellow rehabilitators about the results of using GME® and discussing details of the mammals’ growth and health can help identify positive outcomes as well as possible concerns. 



Based on the information above, some rehabilitators have asked why PetAg®, the manufacturer of GME®, recommended GME® for young wildlife in September, 2019. PetAg® seemed to be genuinely trying to help by recommending GME® as a nutritionally acceptable and digestible milk powder alternative to make into formula for wild mammal babies. They likely assumed that since the nutritional values on the label of GME® were comparable to Esbilac® that it would acceptable for wild mammal babies. Also, they would have assumed GME® powders to be fresh and certainly free of rancidity.

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