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How Nutritious Is Your Mare's Colostrum?By Kentucky Equine Research Staff · March 30, 2015

A mare’s colostrum or first milk is the most important meal your foal will likely ever have. Isn’t all colostrum created equally, though? Simple answer: no.

Good-quality colostrum contains more than 60 g of immunoglobulins per liter of fluid. The first liter of colostrum produced by the mare carries the highest amounts of immunoglobulins. If the foal fails to consume colostrum in the first 6-8 hours after birth, levels of immunoglobulins in colostrum decrease, even if the mare has remained unmilked.

But how can you reliably gauge colostrum quality?

“There are several ways to determine whether a mare’s colostrum contains enough immunoglobulins to protect her newborn foal against disease until his or her own immune system is fully functional at approximately 8–11 weeks of age,” shares Kathleen Crandell, Ph.D., Kentucky Equine Research nutritionist.

The appearance of the colostrum can provide a subjective means of assessing colostrum quality. The first milk should be thick, sticky, and golden or yellow. Watery or opaque colostrum usually signals potential problems, says Crandell.

Tests are a quick and easy way to objectively assess colostrum quality. One of the more popular objective measurements of colostrum quality is a handheld refractometer.

“Collect a couple of drops of colostrum from the mare’s udder, after cleaning it, before the foal nurses for the first time, and place it on the glass plate of the refractometer to measure the specific gravity or density of the colostrum,” advises Crandell. “The specific gravity essentially indicates how many immunoglobulins are in the milk. If the specific gravity is more than 1.06, it is high-quality colostrum.”

Although there are steps you can take to maximize your mare’s colostrum quality prior to parturition, experts advise being prepared for any colostrum emergency by having access to an alternate source of colostrum or immunoglobulins. Examples include frozen colostrum from a bank or intravenous administration of plasma.