Did You Know… Calves Are Born Without a Complete Immune System?

Dr. Erika Nagorske

Feb 17, 2022

While most species like humans and dogs develop an immune system in utero, calves are born without much of an immune system. Because of this, it’s important to know when you should supplement colostrum. 

Watch Dr. Erika Nagorske, a practicing veterinarian with Southwest Veterinary Services, FBN’s® official veterinary partner, in the video below to learn more about why colostrum matters, the differences between replacements and supplements, and how to choose the right one.

Watch Now: Expert Explains Why Colostrum Is Essential

Why Does Colostrum Matter?

Colostrum will provide calves with a functioning immune system for the first few weeks of life. Over time, they’ll develop their own. 

If they don’t get good quality colostrum, they won’t have a properly functioning immune system. 

Colostrum Requirements

A calf needs 150-200 grams of IgG (antibodies) for a good start to their immune system. These antibodies bind to antigens (bugs) and shut them down from infecting the calf

Usually 4 quarts of cow’s colostrum is enough to achieve this amount of IgGs. Depending on the quality of the cows colostrum, it may take more or less for calves to receive the correct amount of IgGs. 

When to Use a Colostrum Replacer or Supplement

There may be times when you need to use a replacer or supplement to ensure calves receive colostrum. This can happen when:

  • A cow is not producing enough colostrum

  • A cow gives birth to twins and doesn’t have enough colostrum

  • The calf is too weak to nurse or has dummy calf syndrome

  • A producer wants to ensure that a high quality calf has a great immune system

Differences Between Replacements and Supplements

It’s always important to read and follow label instructions to ensure that you are giving your calf the correct amount of replacement.

A replacer refers to a product that has a full replacement of at least 150g of IgG. A supplement refers to a product that only has part of the replacement, generally about 50-60g of IgG.

Additional Recommendations

A good example of a replacer is a product made by VetOne called Bovine IgG Replacer 115™ which is both cost effective and has 115 g of IgG. 

One bag of replacer will probably be sufficient if the calf has nursed the cow. If you really want to be sure the calf has enough total replacement, it’s recommended to use 1.5 to 2 bags of Bovine IgG Replacer 115™. 

Consider spreading out over time how much colostrum replacement you give the calf. Once you’ve given the calf the first bag, it’s recommended to wait at least 6-8 hours before giving them the other half of the second bag.  

[Many of these supplies can be purchased directly through the Animal Health section of FBN Direct and shipped straight to your farm.]

The above is provided for information purposes only and should not be used for the diagnosis or treatment of any condition. This information does not cover all possible variables, conditions, reactions, or risks relating to any topic, medication, or product and should not be considered complete. Certain products or medications may have risks and you should always consult your local veterinarian concerning the treatment of your animals.

Copyright © 2014 - 2021 Farmer's Business Network, Inc. All rights Reserved. The sprout logo, “Farmers Business Network”, “FBN”, “FBN Direct” are registered service marks of Farmer's Business Network, Inc. Feed products are offered by FBN Inputs, LLC and are only available where licensed.


Replacer 115 is a trademark of VetOne or its affiliates. All trademarks are the property of their respective owners.

Dr. Erika Nagorske

Feb 17, 2022

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