Colostrum and Calves

When a calf is born, it does not have any immune system of its own. The very first milk that the cow makes is called colostrum. It contains the entire immune system that the calf needs. As the calf nurses in the first few hours of life, that immunity contained in the colostrum (first milk) is absorbed from the calf’s stomach directly into its bloodstream, establishing the calf’s immunity.

A calf relies on the antibodies received through its mother’s colostrum until the calf is able to develop its own immune system. The calf will begin to develop an immune system for itself at 4-8 weeks of age.

When a calf does not get colostrum (what we call “passive immunity” – because the body gets the antibodies directly without actually making any for itself), it will most likely die, or at the very least, be a very sickly calf (what is called a “poor doer”).

How soon and much colostrum does a calf need?
An average calf should receive 2 pints (1/2 gallon) of colostrum within the first six hours, and another 2 pints before the calf is 12 hours old. Colostrum will be present in the udder for the first 2 days after birth, then it transitions over approximately 5 days to pure milk.

Frozen colostrum

Dairy cows will produce more colostrum than a single calf can consume. This is a prime time to milk the cow and save colostrum in the freezer for any calf that may need colostrum in the future. Powdered commercial colostrum is available for purchase if there is no access to fresh or frozen colostrum.

Why would a calf need colostrum? Many time when a cow gives birth to twins, she will accept one and abandon the other. That calf will need to be fostered. It must receive colostrum within those first 12 hours of life.

Thawing the colostrum must be done carefully. If it is overheated, or boiled, the protein structure can be damaged and render the antibodies ineffective. Thawing slowly over a double-boiler is a good choice.

Freezing is an important thing to think about. a large chunk is more difficult and will take longer to thaw than a flat frozen bag of colostrum.

Be sure the colostrum is at body temperature. Too hot can cause burns. Too cold can cause the calf to lose body temperature, which isn’t well regulated in the first few hours of birth.

If the calf is healthy and has simply been abandoned or something has happened to the cow, it should do fine after the immune system is established with a good source of colostrum.

If the calf is over 12 hours old, it may need a plasma transfusion to acquire the antibodies it requires to be a healthy calf.

After the calf begins nursing, it will need to be fed every 8-12 hours. In the past it has been recommended to feed an orphan calf one bottle (1/2 gallon) every 12 hours; however, more recent studies have shown it can be beneficial to feed a calf until it is full. Repeat every 8-12 hours. This calf (Frank) drank 6 pints of milk at 24 hours of age. He continues to drink as much as he wants twice daily with supplementation in the middle of the day if he is hungry.

A few things need to be observed routinely. Urine output is very important to be sure the calf is staying hydrated. Diarrhea can quickly cause death because of electrolyte imbalances.

Frank (the calf pictured here) was abandoned by his mom because he was a twin. He was brought to me within a few hours of his birth. He received two bottles of colostrum within 24 hours of his assumed birth. He was found in a pasture, so we can’t be sure of his exact time of birth.

He is currently 5 days old and doing well. He is switching between nursing his foster mom (a Jersey 4-H show cow) and taking a bottle. Once he is older and stronger, he will nurse the cow exclusively.

I will keep you updated as to his progress!


  1. This is the most unique post I’ve seen on WP. What great information. It does make me chuckle that I had no idea that humans also make colostrum for weeks after giving birth. Amazing, amazing stuff. The difference between life and death for a calf. Wow


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