Evaluation and comparison of colostrum replacers using a digital Brix refractometer

Citation

Livingston SE, Swanhall A, Tibbs A, and Sullivan KE. 2025. Evaluation and comparison of colostrum replacers using a digital Brix refractometer. In Treiber K, Brooks M, D’amato-Anderson J, Nylander J, Eds. Proceedings of the Sixteenth Conference on Zoo and Wildlife Nutrition, AZA Nutrition Advisory Group, Oklahoma City, OK.

Abstract

While it is preferred to keep neonatal mammals with their dam for rearing, there are instances where newborn animals need to be hand-raised or assist-raised. If an animal does not receive colostrum from its mother, a quality colostrum replacer needs to be used in order to facilitate passive transfer of immunity. A number of colostrum replacers exist for livestock (primarily bovine based), six of which were purchased for testing. Ten grams of each colostrum replacer was prepared based on the product instructions and mixed on a Corning PC-620 Laboratory Stirrer/Hot Plate for 5 minutes at 550 rpm and then tested with an Atago 3810 (PAL-1) Digital Pocket Refractometer, 0-53% Brix. Three bags of each product were purchased and tested in triplicate (n=9).

Brix refractometers are reported to be a valuable tool for evaluating the quality of colostrum (Bielmann et al. 2010; Quigley et al. 2013; Bartier et al. 2015). There are some variations in published cut offs for Brix values as estimates of immunoglobulin G (IgG) content of colostrum.  Quigley et al. (2010) reported values of 21% as estimates of >50 g/L IgG while Bartier et al. (2015) reported 23% as an estimate of IgG content >80 g/L. Gamsjäger et al. (2023) noted that colostrum with a Brix value between 24 and 30 should provide IgG values between 100 and 150 g/L.

Based on the above values, four of the six tested products would provide IgG values between 100 and 150 g/L. Two of the products averaged Brix values below 21% which would indicate IgG values below 50 IgG g/L which is below the recommended IgG level of 75-100 g/L reported by Sockett et al. (2023). Information on the IgG content of colostrum replacers is important when developing protocols and lists of products to use when hand- or assist-raising neonatal mammals. A Brix refractometer can be a useful tool to assess whether a colostrum replacer will provide the desired quality level.

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