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)          


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Appendix G - Considerations for preparing formula with single-step spray-dry milk replacer powders for wild mammals, including Esbilac®


Some wildlife rehabilitators saw good results with juvenile wild mammals that were fed formula made with Esbilac® powder in 2009. Others reported serious problems. This describes many of the tips used by rehabilitators who reported successful results with single-step spray-dry milk powders, including Esbilac®. They used their previously effective ‘recipes’ for formula for the wildlife species being fed. Recipes should approximate similar ratios of total solids:fat:protein found in mother’s milk for the species and provide minimal digestible Kcals. Check nutrient and calorie calculations at www.ewildagain.org.

The tests, analyses and confirmations are still in process. While there are still questions and unknowns about the ‘new’ Esbilac® powder and its use, these tips appear to help resolve solubility issues for Esbilac® powder. These mixing ideas are also helpful for other single-step spray-milk formulas, such as Zoologic® 33/40 and GME®. These are some DRAFT tips for wildlife rehabilitators who are wondering about using milk powders for the rapidly approaching wildlife baby season. To date, rehabilitators following these tips have reported positive results.


1.Store unopened milk replacer powders in a cool place. Consider purchasing in cooler seasons.

2.  Store opened milk replacer powders in refrigerator or freezer. Minimize air left in bags.

3.  Examine for rancidity. If the formula has an odd color or odor, or if animals refuse, don’t use it.

4.  Turn can over several times before each measurement to ensure even distribution and to reduce compaction.

5.  Plan ahead! Estimate the amount needed for a full day – and make that amount. An immersion (stick) blender is useful when making more than a cup. Do not allow formula to foam!

6.  Weigh the milk replacer powder rather than measuring (scooping) volume to increase accuracy and consistency.

7.  Add fats to adjust caloric and nutrient content if needed for the species or due to composition of the milk replacer powder, which can be influenced by the product composition or lot number. Typical Nutritional Analyses with additional information is available for some milk replacer products by lot number at www.ewildagain.org.

a.      Mixing tips if using liquid fats (i.e., heavy whipping cream).

o        Measure milk replacer powder accurately. Do not compress powder.

o        Add half of the water to powder. Use very hot water (about 175ºF).

o        Stir thoroughly for at least a minute to make into a smooth thick liquid. Add remaining hot water. Stir.

o        Add small amount of heavy whipping cream as per nutritional needs. Stir.

b.      OR -- Mixing suggestions if using powdered fats (i.e., MultiMilk® or UltraBoost).

o        Accurately measure milk replacer powder and fat powder. Do not pack. Mix powders together.

o        Add half of the water to the combined powders. Use very hot water (about 175ºF).

o        Stir thoroughly for at least a minute to make into a smooth thick liquid.

o        Add remaining hot water. Stir. 

8.  Place the cooled formula in refrigerator to ‘rest’ for minimum 4 hours, preferably 8 hours. Do NOT use formula immediately after mixing! PetAg says to use the mixed formula within one day. 

9.  Stir lightly and remove amount needed from container. Warm only the amount needed for feeding. Stir again before use. Follow normal feeding practices. Note: Since MultiMilk® contains lard, formula including MultiMilk® should be heated so that the lard becomes liquid (109ºF) – and then allowed to cool to temperature normally used for feeding (e.g., body temperature of the species).

Freezing for storage: Some rehabilitators make formula and allow it to rest in the refrigerator for 8 hours according to the description above. They then freeze small amounts, such as in ice cube trays, until solid. The frozen cubes are placed in freezer-proof plastic bags or containers and sealed securely. Food scientists suggest frozen milk products should be used within 6 weeks. The thawed formula should be stirred well before using. The formula is then warmed and used in a normal manner. While this method is very convenient, a few rehabilitators have reported that some juvenile wild mammals have developed soft stool when fed formula that was frozen.

Considering adding probiotics or yogurt: There are many benefits of adding probiotics to formula fed to juvenile mammals, such as helping to improve digestion, increasing availability of nutrients, increasing good bacteria and decreasing ‘bad’ bacteria and reducing gastrointestinal inflammation. More information on these benefits, products, and uses are described in “Quick Tips about using Probiotics with Wildlife in Rehabilitation” at www.ewildagain.org. 

Rehabilitators have reported positive results from adding a small amount of probiotics to formula at two feedings per day. They used probiotics with live cultures or plain organic yogurt with live cultures (full or low fat yogurts are preferred over the fat-free varieties). They avoided products with sugar and/or sweeteners, as well as artificial flavoring or coloring.

Some rehabilitators who stirred in a tiny amount of probiotics or yogurt in to the partially cooled formula which resulted in probiotics being included in every feeding believed that some juvenile wild mammals, especially the very young, developed an imbalance of microflora and subsequent gastrointestinal difficulties. They strongly recommended providing probiotics only twice a day to reduce the problem and potential risks. Other rehabilitators believed that the adding probiotics when the formula was prepared and having them in every feeding was beneficial. Research is continuing to determine the effectiveness and factors that influence results, including species and age of animal, type of probiotics (powder, gel, liquid, yogurt, etc.), brand, type and amount of bacteria, frequency of administration and so forth.

If gastrointestinal problems occur, first consider common causes, such as overfeeding formula (i.e., amount, frequency), endoparasites (e.g., coccidia, giardia), introduction of a new food, overfeeding solids, and amount or type of supplements added to formula (e.g., fat, probiotics, yogurt). This may include performing one or two fecal cultures to check for parasites. Consider switching to a different package of milk replacer powder in case the first milk powder had spoiled. If the problem continues, explore whether it could be the milk replacer powder. Communicate with fellow rehabilitators. Check with milk replacer manufacturer.

Current updates on milk replacers, feeding practices, and information on gastrointestinal conditions in wildlife are available at www.ewildagain.


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