One of the most nutritionally demanding phases of life
for a horse is lactation.

It can be argued that a lactating mare needs as much nutritional support as a top performing equine athlete under intense training. During this time, the mare is busy producing as much milk as she can for her foal, while also preparing her body for another pregnancy, and, eventually, supporting a new, gestating foal.

The first consideration with your lactating mare is that you will want to maintain her in a minimum body condition score (BCS) of 5. Anything less than a 5 on the Henneke Body Condition Scoring System can lead to poor milk performance during lactation. Additionally, research has shown mares under a BCS of 5 have difficulty getting pregnant and even maintaining their follow-on pregnancies post-foaling. In fact, the ideal body condition score for pregnant mares is 6.5 up to 7.

One of the reasons for keeping broodmares in a heavier BCS is they tend to lose condition after foaling. There are many factors that contribute to this loss, with the major one being milk production. Furthermore, a mare’s daily nutrient requirements from late gestation to the day after foaling changes dramatically. According to the National Research Council, an average sized (1100 lb) mare’s nutritional requirements from late gestation to early lactation (first 30 days) increases to (per day):

  • Energy requirements from 2,140 to 3,170 Calories
  • Crude Protein from 1.97 to 3.38 pounds
  • Calcium 36 to 59 grams
  • Phosphorus 26.3 to 38.3 grams

Mares will not only draw on the nutrients provided in the diet, but also their body reserves to produce enough milk to feed their foals. The mare’s “first milk,” the milk produced in the first 24 hours after foaling, is called colostrum. This sticky and yellow colored milk is critical for the foal as it is heavily laced with immunoglobulins. These immunoglobulins provide foals with their ever-important immunity for the first few weeks of their life against illness and disease until their own immune systems fully mature. Thus, this is why it is always critical that foals nurse within their first few hours following birth.

Mares will continually produce milk until a foal is weaned. However, peak milk production is during the first 30 days after foaling, with an average of 27 pounds of milk produced per day. This will decrease as foals nurse less and transition themselves to solids of forage and concentrate (creep feeding). For the months following, a mare will produce on average:

  • Second month (days 31-60) 26 lb milk per day
  • Third month (days 61-90) 25 lb milk per day
  • Fourth month (days 91-120) 24 lb milk per day
  • After the fifth month (>150 days) 20 lb of milk per day until weaning

Mare’s milk is highly nutritious for a young foal. It is full of fat, protein, carbohydrates, vitamins and minerals. Over the weeks post-foaling, studies have shown that the nutritional quality of the mare’s milk does decrease. Thus, it is important to ensure our young foals are receiving adequate nutrition and has led to the common practice of introducing creep feed, such as Foal Foundation™.

To learn more about introducing creep feeding, you can read our Nutrition for the Suckling Foal article. Briefly, within a few weeks of birth, foals will mimic their mother’s behavior and begin to sample forage and even her concentrate feed. Creep feed is specially formulated to meet a foal’s nutritional needs and is often kept out of reach of a mare by use of a “creep feeder.” This ensures foals are eating the nutritionally dense feed and not the mare.

To meet the challenges of supporting a lactating mare, our Feeding the Lactating Broodmare article details some important considerations. To summarize, any feeding plan for a lactating broodmare should:

  • Always start with high quality forage.
  • Use a concentrate specifically designed for a lactating broodmare to ensure she is receiving adequate support. For example, we suggest Essential K® or Growth for mares being fed predominantly grass hays. Alternatively, we suggest Alfa Essentials® or Alfa Growth® for forages greater than 50% legume.
  • Be properly balanced to meet any possible deficiencies, such as amino acid imbalance (lysine most important), have the proper calcium to phosphorus ratio, as well as fortified with copper and zinc, amongst other nutrients.

Finally, it is important to remember to slowly make changes to the mare’s diet post-foaling. While her nutritional demands change dramatically, her diet needs to be changed slowly like any other horse. Thus, it is another reason it is recommended broodmares are kept in higher body condition, so their reserves can supplement any short-term nutritional deficiencies.

If you have any questions or concerns about what you are feeding your broodmare or foal, please reach out to us directly so we can assist in developing and personalizing a feeding plan.
 
 

Chris J. Mortensen, Ph.D.