By Jyme Nichols, PhD, sponsored by Bluebonnet Feeds

When a woman is pregnant, the first recommendation a doctor makes is to begin prenatal vitamins. This advice holds true for horses as well. Pregnancy and lactation are the times of peak nutrient demand for any horse. Roughly speaking, when a mare is providing milk for her foal, her calorie and vitamin requirements have doubled, protein needs have tripled, and calcium, phosphorus, and amino acid requirements have quadrupled compared to what she needed when she was not carrying a baby.

Hay or pasture alone does not come close to meeting the nutritional needs of a mare in late pregnancy or while producing milk. Therefore, a fortified feed should be used to round out her needs, much like a prenatal vitamin does in women. A properly designed feed would provide elevated levels of amino acids (particularly lysine, methionine, and threonine), increased trace minerals (especially copper, zinc, and manganese in the proper ratios), and higher levels of vitamins (most importantly, vitamin E and Vitamin A).

healthy foal walking next to mare based on meeting the nutritional needs for mares
Photo courtesy of Buckskin Rowe Media

One of the best tools for preventing developmental orthopedic diseases (such as OCDs) is to provide proper calcium, phosphorus and trace minerals. The diet should contain at least twice as much calcium as phosphorus (calculate this using a combination of hay and grain together). It is safe to have up to 5 or 6 times more calcium than phosphorus in the diet, but total phosphorus should never be higher than total calcium. Trace minerals copper, zinc, and manganese are critical for proper development. They should be included in the diet at proper amounts and also proper ratios. The most bio-available (absorbable) form of these trace minerals is when they are attached to a specific amino acid. You can find the best forms by looking at the ingredient list and finding the words “copper lysine complex”, “zinc methionine complex”, and “manganese methionine complex”. These particular forms fall in the organic mineral category, but they are superior to other organic minerals because the amino acid acts like a VIP pass to get the copper, zinc, and manganese directly where it needs to go in the body for maximum effect.

Feeding large volumes of feed with high NSC (non-structural carbohydrate) content can cause fast growth rates and may lead to weaker bones, OCDs, epiphysitis, and other growth problems. For this reason, it is important to understand the NSC content (starch + sugar) of the feed you are using. Oats would be an example of a very high NSC feed that also does not provide correct mineral balances. Oats alone are not a good option for a growing horse. If you must feed oats be sure to cut them with things like beet pulp to reduce the total NSC content, and then add a diet balancer supplement on top to ensure proper calcium, phosphorus, copper, zinc, manganese, vitamin A, and vitamin E levels.

Bluebonnet Feeds recommends Intensify Growth & Development or Horseman’s Elite Mare & Foal for pregnant mares and growing babies. In terms of a diet balancer, for those wanting to mix their own ration, the best option is 101 Diet Balancer or Boost ‘Em by Stride Animal Health. These products can be purchased from or your local Bluebonnet Feeds dealer.


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