top of page # Too many, too few? How do I know?

NOTE: How to Use This Information – The math in this article will provide an exact number, such as 5.3 or 5.5 feedings/day. Typical examples are calculated in the squirrel and opossum cases discussed below. However, that is not the complete answer. The correct number is actually a range of feedings/day, as in these two examples, a range of 5 to 6 feedings to consider. This range suggests that for this example that 7 or more feedings/day is likely excessive, and 4 or less feedings/day is likely insufficient to provide adequate calories (kcals). Even the suggested range of 5 to 6 feedings, in these examples, has to be regularly adjusted based on (1.) the animal’s reaction to the level of formula fed in a 24-hour period (healthy stool, appropriately hungry at each feeding, etc.) and (2.) expected growth and development rates (weight gain, fur development, alertness and activity level, social interactions, etc.). Stated another way, the calculations are a guide and starting point, requiring adjustments as circumstances warrant.

Lots of conflicting information

A common question facing wildlife rehabilitators is estimating how many feedings of a substitute milk formula per day will result in a healthy, growing and thriving animal. Sources ranging from scientific research papers and publications to more informal social media postings provide various suggestions. Unfortunately, many of these sources provide widely varying instruction, little consensus, and very sparse references, which prompts a questionable level of confidence in the information.

Will the accompanying paper give me a starting point?

Yes. Fortunately, with a few pieces of basic information that the rehabilitator should have at hand, and some simple math, an estimate of number of feedings can be estimated fairly easily as described in the paper briefly described below and linked to this page. [Very Important Note: For readers not interested in the detailed math discussed in the paper, the examples in Part 3 of the paper provide an easier way (aka shortcut) to arrive at the estimate for feedings per day.]

As a quick preview, Part 1 of the paper presents the mathematical equations used to calculate an estimate for feedings per day. Part 2 discusses the derivation of a critical variable in the equation that has been empirically derived specific to young wild animals in rehabilitation. Lastly, Part 3 presents several specific examples to illustrate the straightforward use of the equations.

It all starts with knowing the quantity of kcals required per day

That’s actually the easiest part. A long-established scientific equation provides the answer for all eutherians (placental mammals) and marsupials. The equation and math are described in the accompanying paper, which results in the following table: Can I use this table to estimate feedings per day?

Sure. All you need to know is the kcal content (per cc) of the formula you are feeding, and the volume (cc’s) of formula you feed at each feeding.

First, to know the kcal content of the formula, simply use WildAgain’s Wildlife Formula Calculator to provide the kcals/cc of your selected formula recipe.

Second, you probably already know the cc’s you feed at each feeding.

Third and lastly, do the simple math as illustrated in a few of the following examples included in the paper and shown below:  (The component of the equations above shown as (.925) is a formula utilization factor derived from WildAgain’s testing of substitute powdered milk products, formula preparation methods and solubility tests.)

So that’s all I need to know?

Yes and no, as is discussed in the paper. The math will in fact calculate a number or a range of feedings per day, as shown in the examples above. But that number needs to be viewed as an estimate, and reasonably adjusted for other factors. These would include how the animal is digesting the formula (processing through the stomach, stool quality and amount, appropriately hungry for next feeding, etc.). Monitor the animal’s progression through its overall development and weight gain; any observed changes in behavior or medical condition; the rehabilitator’s own experience; etc. At a minimum, the calculation should help confirm that the number of feedings you are providing is ‘ballpark’ correct, or perhaps falls enough outside the suggested range that your current feeding regimen may be over or under feeding and in need of adjustment.

Take a look and see what you think!! Click here for the longer, in-depth paper (PDF).

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