Variability between lots

WildAgain Wildlife Rehabilitation, Inc.

Milk replacers for wildlife
Variability between lots

As can be seen in the analysis of results from Midwest Labs on the components of each product, there are considerable differences in the individual components (e.g., protein, fat, minerals). Where multiple lots have been tested, there are also considerable differences between different lots of the same product (see Esbilac®, KMR®, and Fox Valley® 32/40). These differences for each lot in components should be taken into account when preparing a formula to feed to wildlife in rehabilitation.

Additionally, during WildAgain's testing, significant differences in the physical characteristics of the products have been observed that can affect the performance of the product.

Weight differences

Figure 1. Weight of product comparison between Esbilac lots #0470E and K2409E.

For the various lots tested for Esbilac® and KMR®, significant weight differences were noted - both between lots and within an individual container due to the tendency of the powder to compact, especially for Esbilac® manufactured after late 2008.

The chart at right in Figure 1. shows the cumulative average weight of two separate lots of Esbilac® powder. The cans were opened and the large end (1 TBSP) of the red scoop (supplied with the product) was used to scoop and weigh the product. The scoops were taken from the very top of the can to the bottom of the can. Measurements from 45 scoops were recorded.

As can be seen, the average weight of the two different lots varies by .2 grams or about 3%. Additionally, the scoops at the top of the can were noticeably more light in weight than the average, by about 15%.

Additional examples of weight differences within various lots of a milk replacer product are available by clicking here.

Color and texture differences

Figure 2. Color and texture comparison between Esbilac lots #0470E and K2409E.

In addition to the weight differences described above for the two lots, significant differences were noted in the color and texture of the two lots. As can be seen in the photo at right in Figure 2, the color of the lots varies from a creamy white to a pale yellow. While this difference in and of itself is not necessarily of concern, it could indicate differences in product ingredients, product formulation or differences in the heat used to dry the product. Any of these differences could affect product performance.

Also, as shown in Figure 2, the texture of the product is different. Lot K2409E was somewhat finer in consistency, where lot 0470E had more of a tendency to clump and stick together.

Since companies are not required to mention process changes on their labels, changes in color and texture could be the first indication that a major processing change has occurred. While many have assumed that the ingredients on labels are accurate for each package, PetAg informed rehabilitators that they and other companies are allowed to use up old labels for up to 6 months after ingredient changes. Even if such a practice is allowed by law, WildAgain is disappointed that PetAg did not update the ingredients on the label to immediately inform customers of the product's contents.

There are also situations where changes in texture and color, especially when accompanied by an 'off-odor', may be signs that a milk replacer powder has spoiled. If there is any concern about product, the manufacturer should be contacted immediately.

This further emphasizes the importance of noting changes in the color and texture of milk replacer powders.