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 2 - Has the weight of Esbilac^® changed? Answer: Yes.

Figure 2. Esbilac® powder - Change in component values when reconstituted 1:2.

WildAgain weighed the ‘new’ Esbilac® powder made with the single-step spray-dry process. The weight of one tablespoon (the large end of the red scoop supplied in the can) of the ‘new’ Esbilac® powder is almost 10% less from 2008 and 12% less from 5 years earlier, as shown in the yellow shaded area of the table at right (Figure 2). This results in similar and significant reductions in the component values of a 1:2 formula and the amount of energy (kcals) contained in the formula.

The test results show the weight of the Esbilac® powder per a given volume has changed over the last five years, resulting in noticeable declines in all component values. There are double-digit percentage declines between component values of a new lot the ‘new’ Esbilac® (late 2009) compared with the ‘old’ Esbilac® (manufactured in 2004), except for protein which only declined 3%. Also, the energy value of the product has also significantly changed over the last 5 years (Figure 2).

The chart in Figure 3 shows how the kcals now differ from both the labeling on the Esbilac® can as well as from the prior ‘old’ Esbilac®. Figure 3 also shows kcals calculated using two different conventions.

Figure 3. Esbilac® powder - Calculated kcals when reconstituted 1:2.

The numbers on the left half are calculated by the modified Atwater calculation used by most pet food manufacturers. This convention assumes that pet food is only about 90% digestible and reduces calorie value of protein, fat and carbohydrates accordingly. PetAg uses this modified Atwater calculation for calculating kcals. The numbers on the right half of the chart follow the standard Atwater calculation for human foods. Some argue that a milk replacer should follow the standard Atwater calculation. As such both calculations are presented.

Question 3 - Has the uniform density of the product changed, and is it subject to compaction?  Answer: Yes.

Rehabilitators reported a noticeable difference in the texture of the product. They reported that the powder seemed lighter but also had a more “fluffy” feel at the top of the canon initial opening. They also reported that the powder at the bottom of the can seemed more dense and compact. They were concerned that scooping at the bottom of the can might yield a higher weight of product than a scoop from the top of the can. By phone, PetAg replied that it would be helpful to turn the can over before scooping to reduce compaction. However the label was not updated, so no such instructions were included or noted.

Figure 4. Esbilac® powder - measuring from top of can to bottom without frequent redistributing.	Figure 5. Esbilac® powder - measuring from top of can to bottom with frequent redistributing.

WildAgain set up trials to investigate whether there was more compaction of the Esbilac® powder at the bottom half of the can. The methodology used for this test is included in Appendix C below. The test confirmed that there is a noticeable difference in the measurements taken from the top of the can than the bottom of the can.  While the mean difference of weights from the top to the bottom of the can was approximately 6%, the range of weights varied by 1 gram or 18%. Figure 4 shows a trend of an increasing weight toward the bottom half of the can as measured by the curve of the cumulative average. The second test involved turning over the can twice after each fifth scoop to redistribute the product and determine whether this would result in scoops more uniform in weight throughout the can. The result, as shown in the Figure 5, while showing similar variability per individual scoops, did reveal a more uniform trend throughout the entire can.

The same tests conducted using a newly-purchased and previously-unopened can of Esbilac® powder made with the previous multi-step process (Lot J1186E) are shown in Appendix C below. Those tests showed that powder to be more evenly distributed in the can. Thus, it appears that the powder made with the single-step spray-dry compacts more in the can than the Esbilac® powder made with the multi-step dry method. Further research would need to be conducted to determine if or how compaction might affect powder composition or nutrients, such as densities of minerals or fines (finely crushed particles).

In sum, WildAgain tests confirm that the ‘new’ Esbilac® powder does compact more than the previous version of the product.

Appendix C - Weight Measurement and Compaction Test Methodology

The equipment used for the weight of the product test included the following:

-          -  Esbilac® powder and red scoop from Esbilac® can

-          -  Digital gram scale (precision in tenths of grams) and a kitchen knife

Test Methodology

Figure C-1. Esbilac® powder - Mean difference of weight - top half of can versus bottom.

The tests were designed to determine the average weight of 1 tablespoon (large end of the red scoop) of the 'new' Esbilac® powder, and determine if measurements taken in the top half of the can were lighter in weight than those same measurements taken from the bottom half of the can. Two series of tests were performed, both involving a 12 oz. can of the 'new' Esbilac® powder as well as a can of the 'old' Esbilac® powder. The first test involved measuring and recording the weight of each scoop, starting from the top of the can and proceeding until the can was empty. The second test involved the same procedure, except that after every fifth scoop, the can was covered and the product redistributed within the can. The back edge of a kitchen knife was used to level off the powder in each scoop prior to weighing. Gross weights of each scoop (scoop plus powder) were made and recorded. Net weights were then calculated by subtracting the weight of the scoop.

The results when measuring the 'new' Esbilac® powder are shown in Figures C-1 and C-2. The results do confirm that the product does seem to be subject to uneven compacting, as measurements were lighter in weight when taken from the top of a freshly opened can.

The chart in Figure C-1 shows the mean difference of weights from the top to the bottom of the can was approximately +/- 6%, the range of weights varied by 1 gram or 18%.

Figure C-2. Esbilac® powder - Uniformity of weight density - 'old' versus 'new' product lots.

The chart in Figure C-2 shows the relative difference observed in the test when comparing the 'new' Esbilac® powder with the old version. It demonstrates the average weight of the product has decreased almost 10% from 6.2 grams to 5.6 grams per tablespoon. It also demonstrates that the 'old' Esbilac® powder has a more uniform density and is not subject to compaction in the can, yielding more consistent and accurate end-user measurements.

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