Nutrition plays a big role in the success of the broodmare and, therefore, the success of a breeding program. This article will address how to feed mares from conception through weaning to ensure the health of the mare, as well as to support proper development of her foal.

Pleasantly Plump

While there are many causes of poor reproductive performance, one of the biggest and most cost-effective methods for achieving success in the breeding shed is making sure mares enter the breeding season in good body condition.

Mares that are moderately fleshy, or even fat, can be expected to cycle earlier in the year, have fewer cycles per conception, have a higher pregnancy rate, and maintain pregnancy more easily than thin mares.

A mare in "fleshy" body condition will have a level or slight crease down her back and a good layer of fat covering her neck, ribs and hips. In general, if you can see her ribs, she is too thin.

The blame for many management and genetic problems has been wrongly placed on broodmares who are fat (see "Myth Defying" sidebar). To the contrary, mares need ample body fat stores to support reproductive processes, as well as milk production. Thin or "ribby" mares will not have the body reserves to support a growing fetus and, as a result, have much more difficulty conceiving. In addition, thin mares may not produce adequate milk, which ultimately affects the growth of her foal.

Allowing your mare's girlish figure to become pleasantly plump is perfectly acceptable, and even necessary to ensure her success as a broodmare. However, gross obesity should be avoided due to the increased risk of laminitis and other conditions related to insulin resistance. Excessive weight also aggravates arthritis and extreme obesity may even decrease milk production.

A Bun in the Oven

Unless she has a foal by her side, early pregnancy places relatively little demand on the mare. For the first eight months after conception, fetal growth proceeds at only 2 to 4 ounces per day. Nonetheless, the diet of a mare in early gestation is still critical.

Accumulating evidence in other species indicates that early nutrition of the fetus in utero may have an effect on the development of health problems much later in life. For example, researchers have speculated that the foods consumed by our own mothers while pregnant could predispose us to diabetes, Alzheimer's disease and cancer. Although this concept has received little attention in the horse, it demonstrates the importance of meeting the broodmare's requirements in early gestation, even if they are relatively low compared to the other stages of her production cycle.

Feeding a high quality grass hay (eg, coastal bermudagrass, timothy, orchardgrass) or alfalfa-grass mix hay is sufficient to meet most of the energy and protein requirements of a mare in early gestation (see Table 1). Some portion of the 8-month early gestation period may coincide with adequate pasture, which can be used in place of hay.

For mares in good body condition, and for those who do not have a foal by their side, grain supplementation may not be necessary. For mares that are thin, early gestation is the best time to put extra body condition on a mare to prepare her for the demands of late pregnancy and lactation.

A vitamin-mineral supplement is recommended if: 1) no grain is being fed; 2) less than 5 pounds of a fortified commercial grain mix is being fed; or 3) hay or pasture quality is questionable.

The Countdown is On!

When the mare enters her 9th month of gestation, the growth of the fetus accelerates to over a pound a day. In fact, during the last 90 days of gestation, the foal will gain 60% of its weight at birth. To support this rapid fetal growth, the mare's diet must be adjusted to provide more calories and protein. In addition, fetal uptake of minerals is greatest during the last three months of gestation. Therefore, adequate provision of calcium, phosphorus and trace minerals, such as copper and zinc, are critical.

Similar to early pregnancy, the mare should be fed a good quality forage (Table 1). Typically, the last three months of gestation coincides with poor pasture productivity in early-foaling mares (January - March), whereas good quality pasture may be a more viable option for mares who foal later (April - June).

The decision to add grain supplementation should be based on the mare's body condition. Easy-keepers may not need grain, particularly if forage quality is good, whereas other mares will need the calories grain provides. Commercial grain mixes should be selected based on the forage being fed (Table 1).

While the mare's requirements in late gestation can often be met by forage alone, there are several advantages to including a small amount of grain in her diet. The rapid growth of the foal in utero tends to compress the mare's digestive tract, thereby reducing her digestive capacity. Including some grain in her ration will supply the additional nutrients she needs while reducing the amount of bulky hay she has to consume. In addition, almost all mares will need grain to support milk production during lactation. Accustoming her to grain feeding during late gestation may help to prevent digestive upset when larger amounts of grain are added to the diet after foaling.

Because minerals are extremely critical during late pregnancy, a suitable vitamin-mineral supplement is recommended if no grain is being fed or if the mare is consuming less than 5 pounds of a fortified commercial grain mix per day. If you are feeding a grass hay or a hay of questionable quality, a supplement that provides additional protein, as well as vitamins and minerals should be used.

Happy, Happy Birthday!

Finally, the day you've been waiting for! The foal has arrived and appears strong, straight and healthy. Although you may be dreaming of the foal winning the World or the Kentucky Derby, the mare is enjoying her last bit of quiet time before the real work begins.

Broodmares produce 2% to 3% of their body weight per day as milk. As a result, her nutrient requirements increase dramatically and her diet must be adjusted to contain more calories, protein, vitamins, and minerals. Underfeeding a lactating mare will lower milk production (and subsequently foal growth).

In addition to using the nutrients in her diet, the mare will also pull nutrients from her own body reserves and put them into milk for her foal. While some loss of body condition can be expected, significant weight loss can lower milk production and may prevent her from getting back into foal when re-bred. Therefore, mares should enter lactation in fleshy body condition and reasonable attempts should be made to prevent excessive weight loss. In some cases, early weaning may be necessary to keep the mare from losing too much weight, as well as to support a healthy rate of growth in the foal.

Meeting the higher requirements of lactation almost always requires grain supplementation. A commercial grain mix that has been formulated for lactating mares (or growing foals) should be selected (Table 1). The increase in grain should take place over 7 to 14 days to avoid digestive upset, particularly if the mare did not receive grain during gestation. In addition, each meal of grain should be limited to less than 5 pounds. If your mare needs more grain than this to maintain good body condition, split the daily ration into several, smaller meals. If your mare is an easy keeper, capable of getting by on less than 5 pounds of grain per day, you should provide her with an additional protein-vitamin-mineral supplement.

Once again, good quality forage is essential for maintaining gut health and helping to meet the mare's nutrient requirements (Table 1). Alfalfa, perennial peanut, and alfalfa-grass mix hays are very useful in helping to meet the higher requirements of lactating mares. Use of such high quality hays also helps to reduce the amount of grain needed, which may help prevent colic and laminitis associated with feeding large amounts of grain. Lactation often overlaps with spring pasture, which can also provide a significant source of nutrition for the mare. Whichever forage you choose, make sure that your mare receives at least 1.5% of her body weight per day as forage or free-choice grazing of good pasture.

After the first 3 months of lactation, the mare's nutrient requirements begin to decline as her milk becomes more dilute and the foal starts to sample solid feeds. If mares are in good body condition, the amount of grain can be cut back at this time.

One or two weeks before weaning, you should decrease or even eliminate grain feeding of the mare. This practice will decrease milk production, and thereby udder distention, which will help reduce the mare's discomfort from an un-milked udder after weaning. Reducing milk production in the days leading up to weaning also encourages foals to seek out more solid feeds to meet their nutrient requirements. Once the foal is weaned, the mare can be managed as a mare in early pregnancy once again.

Conclusions
Broodmares often lead a modest life, however, they should be hailed as saints for all of their efforts. Keeping the mare healthy and productive is of utmost importance if your goal is to have strong, healthy foals. Proper nutrition plays a key role in maintaining the health and productivity of broodmares. In providing an adequate diet, we must remember that broodmares are often eating for two and, if she continues to be bred year after year, there are times when she's even eating for three. Mares should be provided with good quality hay or access to green pasture throughout the year. As her requirements increase in late gestation and during lactation, appropriate grain mixes and supplements should be chosen to support foal development and milk production. Ultimately, if you take proper care of your mares, she will pay you back with winning foals.