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Why do foals need colostrum?

Quick facts

  • Colostrum, the mare’s first milk, provides foals the antibodies and nutrients they need to stay healthy.
  • You can monitor the antibody levels in a foals blood through tests.
  • If a foal doesn’t receive enough antibodies, they are more prone to disease. 

What is colostrum?

Colostrum is the first milk that a mare makes to feed her foal. 

Key to building an immune system

Colostrum is key to a newborn foal’s health and well-being. It provides the following elements:

  • Infection-fighting antibodies

  • Vitamins

  • Minerals

  • Energy

  • Protein

  • Fat

  • Acts as a laxative to help the foal pass their first stool

Foals are born with no infection-fighting antibodies in their blood. Therefore, foals must consume colostrum to receive the antibodies they need (passive transfer). The mare produces these antibodies to protect the foal from bacteria and viruses specific to their environment.

After three to six weeks of age, the foal will start making their own antibodies. Often, foals retain some protection from the mare until four to five months of age.

Monitoring colostrum intake

It’s important the foal begins nursing shortly after birth. Foals can only absorb the antibodies from the colostrum for a short time period. Each hour after birth the foal’s ability to absorb colostrum lessens.

You can monitor the amount of antibodies a foal receives using a Foal IgG SNAP test. This test measures the antibody level in the foal’s blood. The goal is to have antibody levels higher than 800 milligram per deciliter. Levels between 400 to 800 mg/dl is only a partial transfer of antibodies. Levels less than 400 mg/dl is a failure of transfer.

When should you perform this test?

Some breeders like to draw the blood at 12 hours. This way, if the test is low, they can supplement the foal's colostrum intake. But, this will overtreat some foals who just haven't had time to absorb the antibodies yet.

Others prefer to wait 18 to 24 hours to draw the blood. This way, there’s no chance that the foal's levels will go up. But if you discover that your foal is below the cut-off level, the steps to remedy the situation are more invasive and costly.

Failure of passive transfer

Failure of passive transfer isn't a disease, and has no clinical signs. These foals are at an increased risk of:

  • Pneumonia

  • Diarrhea

  • Infected joints

  • Infected umbilical cords

  • Other diseases

Contact your veterinarian if your foal has failure of passive transfer. Often a veterinarian will give a plasma transfusion.

Author: Jennifer Johnson, DVM, formerly with the University of Minnesota

Reviewed in 2021

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