It’s not uncommon for Sam Leadley to observe people using colostrum supplements improperly. During farm visits, Leadley, a calf-care specialist with Attica Veterinary Associates in Attica, N.Y., has seen employees mix the powdered supplement directly into maternal colostrum, despite label directions that say to mix it with water. He’s also observed supplements being used as a complete replacement for fresh or frozen colostrum — another frowned-upon misuse.

If you want to get the most benefit from colostrum supplements and replacers, you need to use them properly. Use this Q&A format to help you do just that.

Q. What’s the difference between colostrum supplements and colostrum replacers?

Both colostrum supplements and replacers are designed to help calves achieve adequate immunity. However, these products are not interchangeable — as is often the case on farm — so, it’s important to distinguish between them.

Colostrum supplements generally contain between 30 and 60 grams of immunoglobulin G (IgG) per dose, says Jim Quigley, senior technical service director with Diamond V Mills in Cedar Rapids, Iowa. As such, they are only meant to boost the IgG content of poor-quality maternal colostrum, not replace it. Use them to help bring the level of IgG that the calf consumes as close as possible to 100 grams or more — the gold standard for adequate immune protection.

Supplements generally cost about $7 to $8 per dose, Quigley adds.

Colostrum replacers, on the other hand, cost $20 to $25 per dose because they contain a much higher level of antibodies — upward of 100 grams or more per dose, Leadley explains. They also contain vitamins and other nutrients found in colostrum.

Some of his clients use colostrum replacers to break a disease cycle, like Johne’s, Leadley says. Others use them in emergency situations when no fresh or frozen colostrum is available. Just remember, they are the ones you should use to replace maternal colostrum — not supplements.

Q. Is the timing of colostrum supplements and replacers important?

When it comes to feeding a colostrum supplement or replacer, time is still of the essence.

As a calf ages, she loses her ability to absorb antibodies from colostrum. That same situation holds true for colostrum supplements and replacers, Leadley says. So, feed them as soon as possible after birth — just as you would do with maternal colostrum.

Q. How well do calves absorb the antibodies in these products?

The first generation of colostrum supplements hit the market in the mid-80s. These products contained 25 to 45 grams of IgG per dose, Quigley says. The problem with these earlier products was that they were poorly absorbed. In fact, some of the earliest published studies done on colostrum supplements show apparent efficiency of absorption (AEA) rates as low as 5 percent. So, in a product containing 25 grams of IgG, the calf probably only absorbed about 1.25 grams of IgG -— hardly worth the cost or effort to feed it.

However, within the past 10 years, the absorption of antibodies from colostrum supplements has improved tremendously. Published studies now show absorption rates closer to 25 percent to 45 percent, Quigley says. While that may not seem very impressive, you have to remember that the absorption of antibodies from maternal colostrum is in that range, too.

Colostrum replacers, on the other hand, have only been on the market a few years. However, their track record is fairly impressive. The AEA of some of these products is similar to maternal colostrum. Others are quite a bit lower, Quigley says. It just depends on how they were processed.

Q. How do I measure the calf’s immune status after using these products?

Many producers and heifer growers like to know whether their calves received adequate passive transfer of immunity or not. A quick on-farm test or a refractometer helps them do that. You can use these same tools to measure the calf’s immune status after feeding a supplement or replacer.

An on-farm test manufactured by Midland BioProducts Corporation, (, measures IgG in either whole blood or blood serum. That test gives you a simple “yes” or “no” answer, meaning the calf did or did not receive enough antibodies. It’s similar to how a home pregnancy test works. This test is accurate regardless of whether you feed maternal colostrum, a colostrum supplement or a colostrum replacer, Quigley says.

A refractometer is another option, but it works a little different than the on-farm kits. This device measures the total protein level in the calf’s blood serum. A serum-protein level of 5.5 grams per deciliter or more is desirable. This indicates the calf received adequate antibody levels. However, be careful when using this device to measure the effectiveness of colostrum replacers, as it can give a false reading when you feed these products, particularly those derived from bovine serum. (Please see the “FOR MORE INFORMATION” box above.)

Q. How do I feed colostrum supplements and replacers?

Directions for feeding these products are found on the product label. But, as observed by both Leadley and Quigley, many people still fail to follow the manufacturer’s guidelines. Failure to do so can result in a lower level of antibody absorption, Leadley says.

And when it comes to powdered colostrum supplements, avoid the temptation to add them directly to maternal colostrum. You can disrupt the calf’s osmotic balance if you feed too many solids at one feeding and not enough liquid, Quigley says. Instead, wait 30 minutes after feeding maternal colostrum to feed the supplement.

Colostrum supplements and replacers have value when the quality of maternal colostrum is poor or none is available. Learn to use them properly to fill the void.

For more information:

A spreadsheet that shows the relationship between refracto-meter readings and plasma IgG levels for maternal colostrum and colostrum replacers is available at

Once there, click on “Calf Facts” and scroll down the alphabetical list of topics to “Refractometer Readings and IgG levels.”