The Last 85 Days

Arriving to pick up their newly pregnant mares, one of the first questions proud mare owners ask is “what should I feed my mare to produce the best possible colt? Unfortunately the answer is often forgotten by the time it becomes important.

The nutritional needs of the broodmare prior to the last quarter of pregnancy - the last 85 days - are basically the same as any other mare. A quality diet that keeps the mare in good flesh but not too fat. This is because during the first 255 days the fetus grows to only size of a 10 pound cat.

Over the next 85 days, however, the embryonic horse will put on about 80 pounds as it quadruples in size. This is when the nutritional needs of the broodmare become critical to the development of a big, strong, healthy foal.

Amazingly, Nature has designed the broodmare to accomplish this feat of rapid growth with the ingestion of an additional 925 kilocalories of energy. This amount of energy can be found in about an extra ¾ of a pound of oats or a couple of extra flakes of quality hay. Although this 6% increase is energy consumption is minimal, it is extremely important that the hot housed broodmare have the opportunity to fulfill her dietary energy needs for the growth of this fetus.

But this is not the end of the story

It is also important to monitor protein levels for the broodmare. Prior to the last quarter, the broodmare’s protein requirement is the same as any other horse her age doing the same amount of work. A mature horse grazing in the pasture can easily survive on a diet containing about 8-10% quality protein. The average mare eating 25 pounds a day is consuming about 2.5 lbs of protein a day.

During the last 85 days of pregnancy, the broodmare needs an extra ½ pound of crude digestible protein a day to build the body of her impending foal. Putting this 25% increase into perspective, it takes an extra 4+ lbs of oats a day to satisfy this need.

Thus the dilemma! Feeding enough pasture, hay or grain to supplement the protein requirement provides 8 times too much energy. The result: The mare gets fat

How could Mother Nature hand us such a problem?

Actually, she didn’t! Her system was designed to work in an environment where mares foaled in late spring and early summer. The last 85 days then occur sas the green grasses were sprouting. Early grasses generally have a higher protein and water content and are low in energy - the perfect feed for the last quarter. And besides, any additional calories serve to fatten the mare that was pulled down over the winter.

Under many of today’s management systems, this natural model has a hard time being played out. Mares are bred to foal earlier in the year. Most horse producers do not let their mares slim down during the winter. Consequently, feeding the extra feed during the last 85 days results in fat foaling mares.

But there are possible solutions to this problem. Not every solution will work for every mare or every management situation. As with all management decisions, individualized programs are the key to success.

Here are 3 possible solutions. Choose the one that is best for your mare and your situation.

1. Mares can be allowed to loose a little weight over the winter with the plan of regaining the weight during the last 85 days. This means that the mare should ideally not loose more than 100 pounds which will allow you to see the imprint of her last couple of ribs.

2. Feed a commercial feed supplement (like soybean oil meal or milk replacer) during the last 85 days that is designed to be high in protein. Therefore a small amount will satisfy the protein requirement without adding a lot of calories.

3. Subscribe to the theory that fat is healthy and beautiful. Believe that the extra fat will be valuable when the mare begins to produce large quantities of milk. Although this approach is not the most efficient and many believe it is not the healthiest for the mare and the foal, it is viable. It is boils down to "When is fat, too fat".

And now you know the rest of the story.

Copyright, 1999 Dr. Jim and Lynda McCall

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