DON'T PUT A FREEZE, FOR TOO LONG, ON YOUR COLOSTRUM

Colostrum is one of the most important meals for a newborn calf. Its administration is required to be appropriately timed in the right volume and quality to facilitate transfer of passive immunity (TPI). Colostrum includes nutrients required by the newborn calf in addition to the immunological aspects that are highly emphasized in colostrum management i.e. immunoglobulin G (IgG), which confers TPI to newborn calves. Furthermore, immunoglobulin M (IgM) in colostrum can help to mitigate pathogen colonization on mucosal surfaces and in the blood stream, and insulin can influence intestinal maturation by stimulating insulin receptors.

Many farms are constantly managing colostrum storage to help ensure the proper supply and administration to their calves. Saving excess colostrum can be a great way to ensure that adequate supplies are available when production is low or when you have an excess when supply is good. Longer term storage is often facilitated through freezing. Historically, it was commonly accepted and promoted that colostrum could be stored in a non-frost-free freezer for up to a year.

A couple of things to digest here. A “frost-free” freezer is one that cycles temperatures to avoid accumulation of ice within the unit. This temperature cycling means that the contents within the freezer also experience different temperatures. With colostrum, there are a couple of concerns with fluctuating temperatures. The first is that if there is any bacteria contamination in the colostrum this could potentially grow during these cycles. The second is there are functional proteins within the colostrum (i.e. immunoglobulin G) that we want to preserve. Therefore, we want to use freezers that do not go through these cycles. The freezer temperature should be -20°C (-4°F).

When preserving colostrum here are some key things to capture or monitor. On the label include cow identification number and date of collection. Furthermore, if your farm is measuring colostrum quality with a Brix, include the number on the label.

When thawing, use a hot water bath of 40°C (104°F). Warmer temperatures >60°C (140 °F) should not be used as this can denature the proteins in the colostrum. Repeated freeze-thaw cycles can denature IgG so only one thaw is advised.

A recent paper from Cornell University (JDS Communications, 2025, 6:406-410) evaluated colostrum samples stored at -20°C for up to a year. They compared the fresh samples that had never been frozen, to samples frozen for different times over the course of a year. They analyzed the colostrum for Brix%, IgG, IgA, IgM, insulin, and total plate count (TPC).

Over the year of freezer storage there was no difference in IgM, IgA, or TPC. However, over time IgG, coliform, insulin, and Brix% decreased. After 32 weeks (8 months) IgG decreased by ~8 % compared to the fresh colostrum.

From these results it’s now recommended to use colostrum within 8 months of storage in a freezer, though it may not mean you cannot use the colostrum that has been stored per se. You could still use this for a second feeding and not a first feeding to ensure that there is the appropriate amount of IgG to have more success of TPI.

When considering the lower Brix% I would encourage the use of this at the time of colostrum collection and not worry about measuring this after it’s been frozen. The Brix % would be important to include on the label and still can provide information about the quality of the colostrum that has been stored up until 8 months of storage. Because Brix% decreases over time, but up until 8 months IgG doesn’t go down, it would still be safe to use this as a quality measure on farm at the time of collection.

The study conducted at Cornell did use high quality colostrum, so more information is needed on a range of qualities over time. However, this is important information to incorporate into colostrum management systems. Make sure to check the date on when colostrum was collected and make sure to use the oldest stuff first to ensure the best quality for your calves. Will you be adding a “Best By” date on your colostrum?

— Sarah Morrison

morrison@whminer.com