Your vet has just confirmed that your mare is pregnant, and you can’t wait for that healthy foal to arrive!

When should you be changing her feed? How much weight does she need to gain? What additional nutrients does she require to grow a healthy baby?

All these questions are important to consider when planning a nutritional program for your expecting mare.

How you feed a mare while she is pregnant not only affects growth and development in utero but can also have lifelong impacts on the foal. Your mare’s diet affects the foal’s bone and tendon health, neurological development, immune status and more.

If your broodmare’s diet is lacking in key nutrients, she can have a higher risk of complications during gestation and longer recovery after birth.

Carefully designing how youfeed and manage the mare while she is pregnant will give your foal the best start and support the health and longevity of the dam.

Feeding the Pregnant Mare

Planning the feeding program for your broodmare should start even before you begin breeding her.

Sound nutrition helps to support fertility and to build your mare’s nutrient reserves to meet the high demands of late gestation and early lactation.

If a mare’s diet is deficient in a key nutrient, she will tap into these bodily reserves to provide the foal with whatever is lacking.

But significant gaps in the diet cannot be compensated for and can lead to an increased risk of:

  • Loss of pregnancy
  • Retained placenta
  • Loss of skeletal strength in the mare
  • Weakness in the foal
  • Difficulty suckling
  • Bone, tendon and muscle disorders in the foal
  • White muscle disease in the foal
  • and more…
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What to Feed Pregnant Mares

Horses do best on a forage-based diet with plenty of fibre to support gut health. Hay alone will typically provide more than enough energy and protein during early gestation, depending on the quality of the forage.

Your mare will also need a supplemental source of vitamins and minerals to avoid common deficiencies in nutrients such as selenium, vitamin E, copper and calcium.

Later in pregnancy, your mare will require additional sources of protein and calories to keep up with the foal’s increasing requirements.

It is strongly recommended to submit a hay sample for analysis to determine whether free-choice access to forage is appropriate through all stages of gestation.

A hay analysis will also help you determine how much supplemental energy and protein is required to meet the needs of the gestating mare.

Example Diets for Gestating Mares

Below is an example diet for a mare that begins gestation at a body weight of 500 kg (1100 lb).

In these examples, the hay represents a typical moderate-quality mixed hay with 10% crude protein and 2 mcal / kg digestible energy on a dry matter basis.

Depending on the body condition of your mare, hay of this quality may need to be rationed during early gestation to avoid excessive weight gain.

For a personalized feeding program, submit your mare’s information online and our equine nutritionists can design a customized diet to best support the health of her and the foal.

Table 1. Sample diet for early, mid, and late gestation

Nutrient Early gestation
(1-6 months)
Mid-gestation
(7-8 months)
Late gestation
(9-11 months)
Feed
Hay Free-choice Free-choice Free-choice
Alfalfa
pellets
0.5 kg / 1 lb 0.5 kg / 1 lb
Roasted
soybeans
0.5 kg / 1 lb
Omneity
pellets
200 grams
(2 scoops)
200 grams
(2 scoops)
200 grams
(2 scoops)
Optimum
Digestive
Health
80 grams
(1 scoop)
80 grams
(1 scoop)
80 grams
(1 scoop)
w-3 oil 90 ml 150 ml
Salt 15 grams
(1 tbsp)
15 grams
(1 tbsp)
15 grams
(1 tbsp)
Nutrient Analysis1
Digestible Energy
(% of requirement)
119 111 103
Crude Protein
(% of requirement)
161 134 131
Lysine
(% of requirement)
172 144 148
NSC
(% of diet)
8.9 8.9 9.2
Fat
(% of diet)
2.8 3.7 4.9

1 National Research Council’s Nutrient Requirements of Horses (2007)

Each mare’s individual needs will differ depending on several factors including body condition, health concerns, breeding history and future breeding goals.

Consult with your veterinarian to ensure your mare is in good health through gestation.

Weight gain

Mares typically gain 12 to 16% of their initial body weight during pregnancy to support both the fetus and the placental tissues. [1] For example, a 1100 lb (500 kg) mare should gain 132 to 176 lb (60 to 80 kg) during gestation.

Mares should have a body condition score (BCS) of 5 to 6 on a 9-point scale during gestation.

Energy requirements increase significantly when lactation begins and some mares may lose weight during this period. For this reason, it is not advisable to have a mare below a BCS of 5 when she foals.

Additionally, mares in thin body condition (BCS < 5) are less likely to get pregnant. If rebreeding is a goal, keeping mares in good body condition is important. [2]

Nutrient Requirements

The nutrient requirements for pregnant mares laid out by the NRC (2007) are intended to provide sufficient nutrients for the mare and to support the developing fetus and placenta.

Most of a mare’s nutrient requirements do not increase significantly until the last trimester of gestation when 75% of fetal growth occurs.

During early pregnancy (< 5 months), most nutrient requirements are the same as a horse at maintenance.

Energy and protein requirements start to increase around month 5 of gestation (Table 2) and mineral requirements start to increase during month 7 (Table 3).

Vitamin E and A requirements increase as soon as a mare gets pregnant but do not change over the course of gestation (Table 3).

Table 2. Energy and protein requirements of a 500 kg (1100 lb) mare throughout gestation1

Month of gestation Digestible energy
(Mcal)
Crude protein
(grams)
< 5 16.7 630
5 17.1 685
6 17.4 704
7 17.9 729
8 18.5 759
9 19.2 797
10 20.2 841
11 21.4 893

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