The Importance of Colostrum, Part 1

In this two-part horse-breeding series, learn about the importance of good quality colostrum and proper hygiene when foals are born.

From The American Quarter Horse Journal

Unlike other mammals, mares do not transfer antibodies to their foals via the placenta during gestation, but rather transmit them through colostrum, a yellowy substance in milk produced in limited quantity around the time of foaling. A foal that ingests its dam’s colostrum within the first 24 hours of life acquires the mare’s antibodies as protection against disease for the first four to eight weeks of life. But according to reproduction specialist Dr. Michelle LeBlanc, more factors come into play that could endanger your foal’s life.

Even if a foals stands and nurses within the first one or two hours of life, it still might be unable to ward off disease if the mare’s colostrum leaked out before foaling, is poor quality or if the foal was delivered into a bacteria-laden environment.

Colostrum Quality

In the final month of gestation, a mare concentrates antibodies in her milk, but she can only produce antibodies against disease and bacteria to which she has been exposed either through vaccination or environment. The mare’s age and breed also enter into the picture. Maiden mares might produce less colostrum - sometimes only one liter - but it is usually more concentrated with antibodies than the two liters typically produced by older mares. According to Dr. LeBlanc, a common mistake of mare owners is shipping a mare to a foaling facility within a week of her due date.

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“A mare will not have enough time to make antibodies (against) the bacteria in that environment if it is a different type of bacteria that what was in the environment from where she came,” Dr. LeBlanc says. “When the foal is born, if it encounters a bacteria for which his mother has not developed resistance, its immune system will not be equipped to fight it off. Dr. LeBlanc says moving a mare from a broodmare band to the foaling barn on the premises is not likely to cause problems, but she emphasized that the foaling barn must be clean. “It’s not only how much antibody that she makes, it’s also the amount of challenge from the environment,” she said. “If a mare foals in a dirty foaling stall, the first thing a foal does when it tries to stand is rub its face and mouth in manure. When it licks that manure off, bacteria enters the gastrointestinal tract.” Dr. LeBlanc developed and patented the “colostrometer,” a device used to measure the antibody content in mares’ first milk. Five milliliters of colostrum are deposited in a chamber of the colostrometer to measure the milk’s specific gravity. Specific gravity increases proportionately with the serum antibody level and the concentration of immunoglobulin G (IgG). “Mares over the age of 14 tend to have lower specific gravity and therefore, less antibody in the colostrum than younger mares,” Dr. LeBlanc says. “Not all of them, but a good portion of them. Those mares need to be tested as soon after foaling as possible. If they have problems, then hopefully there is colostrum in a colostrum bank available.” “Colostrum should be tested as soon as the mare foals, because once the foal sucks, the specific gravity of the colostrum drops very quickly,” she says, citing the study she conducted at the University of Florida College of Veterinary Medicine that found that normal foals typically consume 75 percent of a mare’s colostrum in the first eight hours they nurse - and all of it within the first 12 hours. Dr. LeBlanc says that although it might seem prudent to test colostrum before the mare foals (to allow time to obtain plasma or frozen colostrum and notify your veterinarian of potential problems), readings taken at this time are not an accurate predictor. “If you are concerned about an older mare, it might help,” she says. “In our study, we were very surprised that, from the beginning of the first-stage labor until the foal is delivered at the end of second-stage labor, the antibody level continued to concentrate. It might be borderline before foaling, but after foaling, it concentrates even more. Basically, what is happening is that the water is just leaving her bag.” Dr. LeBlanc is unsure why this happens, but she theorized that the effects of oxytocin, a hormone associated with foaling, somehow causes some of the milk’s water content to leave the udder.

One-Two-Three Rule

Remember the one-two-three rule after foaling: The foal should stand within one hour and nurse within two hours; and the mare should pass the placenta within three hours.

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“If the foal is not up and standing by two hours and actively sucking, you need to get colostrum into him,” Dr. LeBlanc says. “Milk the mare and put a stomach tube down the foal, which, in most cases the veterinarian would have to do, and get at least 500 milliliters in the foal.” She suggests feeding colostrum by stomach tube because in some cases, bottle feeding will not get adequate colostrum into the foal. “If the foal is weak, it is not going to suck, and the big thing is to get the colostrum in because what the gut absorbs in that first 18 hours is not specific for antibodies,” Dr. LeBlanc says. “Think of the gut as having an opening, and whatever gets in, gets in. If the foal is born and gets a mouth full of feces, he will absorbs all that bacteria, and as soon as the gut absorbs something - and we call those ‘somethings’ macromolecules, which are either bacteria or antibodies - it closes. On the other hand, if nothing gets in, the foal’s gut closes in 18 to 24 hours. So it is real important that they get colostrum in before they get bacteria in their mouths.” Look for Part 2 next week, when you can learn what to do should your foal have a failure of passive transfer.

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