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What is Colostrum?

Colostrum is the name of the special milk produced by a mare that is a foal's first meal after it is born. Although it comes from the mare's udder and is rich in nutrients, colostrum is much more than "just milk". Colostrum is also a source of important antibodies (called immunoglobulins) and other factors that help protect the foal from serious (or even fatal) infections picked up from other horses or the foal's environment.

Newborn foals are born with no immunity to disease. So by drinking colostrum, the foal receives immediate (but temporary) protection from its mother until it is old enough to receive vaccination and for its own immune system to take over. The process of acquiring protection in this way is called passive transfer of immunity, because the antibodies and other immune factors are passively transferred from the mother to the foal when the foal drinks the colostrum.

Colostrum is produced in the mare's udder during the final 2-4 weeks of pregnancy but is only present for about 12-24 hours after a mare foals. It is vital that foals nurse soon after birth so that they consume the antibody-rich colostrum, and not the "regular” mare’s milk that eventually replaces the colostrum after the first 24 hours or so.

What does colostrum looks like

Colostrum looks quite different to the milk that a mare normally produces. Colostrum is thicker than regular milk and has a yellowish colour.  Like regular milk, it contains carbohydrates, fats, proteins and vitamins and minerals, but at different levels, to ensure that the newborn foal is well nourished immediately after birth.

Another way that colostrum is different to regular milk is that it contains concentrated levels of antibodies  from the mare's body. These antibodies are special proteins that can help protect the foal against common infections like pneumonia, navel ill and septicaemia (blood poisoning). Colostrum also contains important hormones, growth factors, enzymes and other proteins plus white blood cells that play important roles in providing immunity and protecting the foal.

Is colostrum all a foal needs?

Although colostrum is vital to help protect a foal during its early life, it doesn't provide total protection. So it's important to remember other aspects of foal and broodmare management – including good hygiene in the stall or barn – and other strategies to prevent disease, such as vaccination of all animals and regular worming.