What to Feed Your Mare Before, During and After Pregnancy 

A veterinarian’s practical guide to fertility, gestation and lactation 

Breeding a mare is never “just” about timing, semen quality, or ultrasound checks. One of the most overlooked (and most fixable) pieces is whether your mare’s diet and body condition match what her body needs at each stage. Research consistently links body condition and key nutrient balance with reproductive efficiency and healthy pregnancy outcomes. (Henneke et al., 1984; Morley & Murray, 2014) 

A mare’s nutritional requirements do not change overnight, but they do follow a clear biological pattern.

These are the three main periods: 

Each phase places different demands on energy, protein, and micronutrient supply. 

The good news: you don’t need an exotic feeding program to support mare fertility. You need a consistent routine that gets the basics right: 

Below is a practical, science-based feeding guide you can use day-to-day, whether you’re trying to get your mare in foal, keep her safely pregnant, or support milk production while keeping her healthy for re-breeding (Robles et al., 2021; NRC, 2007). 

Body Condition Score: the cornerstone of fertility  

Before you change feeds or add supplements: score your mare’s body condition (BCS). 

Studies show mares in better body condition generally conceive in fewer cycles and have better reproductive efficiency than mares that are too thin. (Henneke et al., 1984; Morley & Murray, 2014) 

Aim for BCS 5–6 (on the 1–9 scale) 

Too thin (BCS < 5): 

Too heavy (BCS > 6): 

Practical take-away: 
If your mare sits outside BCS 5–6, small hormonal and metabolic shifts can quietly undermine fertility long before breeding management becomes the problem (Morley & Murray, 2014; Vetcchi et al., 2010). 

Build your mare’s ration from forage 

For every mare (and horse), forage is the foundation. Nutrient requirements shift across reproduction, but gut physiology doesn’t: consistent forage intake supports hindgut function and reduces risk of colic (Hallebeek, 2024).  

How much forage? 

A practical starting point is 1.5–2.0% of body weight/day as forage (dry matter basis), then adjust based on condition, forage quality, and stage (Hallebeek, 2024).  

Example for a 500 kg horse:  

Feeding your mare before pregnancy: lay the foundation (fertility phase) 

Fertility isn’t only about ovulation timing. The mare’s body needs the right baseline to support: 

What matters most here 

Fertility is shaped by slow, highly regulated biological processes. Egg cells mature over time, hormones need to be balanced, and antioxidant defences must be established well before conception occurs.  

This is why targeted nutritional support should begin early.  

That’s why, as a veterinarian, I often recommend starting a prenatal supplement, like Fresh & Fertile, that is designed to support fertility at least three months before you plan to breed.  

Fresh & Fertile includes ingredients like folic acid,  that: 

This approach mirrors human prenatal care, where nutrients like active folates are also recommended before pregnancy because they support the very earliest stages of development (Geerinckx, 2024).   

Feeding the Mare During Pregnancy: Supporting Two Lives  

Once your mare is pregnant, her nutrition needs change, but not all at once! A common myth is that she needs a lot more feed for the whole pregnancy. In reality, her needs stay fairly steady early on and only rise noticeably in the final months. 

Months 1-4: Maintenance level 

During the first four months of pregnancy, the mare’s energy requirement is only minimally higher than that of a non-pregnant mare. 

Foetal growth is limited at this stage, and most mares can remain on a maintenance-type ration consisting of: 

Add more only if needed: 
If BCS starts dropping, increase nutrient density first (better forage, balanced concentrates, or a ration balancer) rather than just “more grain” (Cronje & Lategan, 2007). 

Months 5-7: Subtle changes 

Nutritional demands begin to gradually increase. The increase is still moderate, but biologically relevant. 

What changes during this period? 

Energy needs therefore start to rise modestly, but in most cases it is sufficient to: 

Months 8-9 to 11: The last trimester 

The last months of pregnancy are when your mare’s nutrition matters most. This is when the foal grows fastest and puts on a large part of its birth weight. To support that growth, your mare especially needs enough high-quality protein and the right balance of vitamins and minerals. Many people think she mainly needs a lot more energy, but energy needs only rise a little compared to the jump in key nutrients (Cronje & Lategan, 2007).  

The final trimester is when nutritional demands rise sharply:

 
As the foal grows, your mare’s stomach capacity decreases. She physically cannot consume large volumes of forage in the final months. 

This makes it crucial to:

Grow & Glow fits this need perfectly: 

Adjust the feed like this (for a 500 kg mare): 

Feeding your Mare After Foaling: Managing Peak Demand  

After foaling, your mare has two big jobs at once: recovering from birth and making milk. This is the most nutritionally demanding stage of the whole cycle. 

If her diet doesn’t keep up, you’ll often see: 

Lactating mares typically need 2–3% of their body weight per day in total feed.  

For a 500 kg mare, this roughly means 11,500–14,500 extra kcal per day. This is about the same energy as ~35–45 minutes of steady galloping per day. Even mares that start this period in good condition may lose a little weight, and that’s often normal. But if a mare begins lactation below a BCS of 5, she’s much more likely to struggle to regain condition, which can delay rebreeding and reduce conception rates. (Cronje & Lategan, 2007) 

Adjust the feed like this (for a 500 kg mare): 

Around the fourth month of lactation, milk production and energy demands gradually decline, allowing feeding levels to be gradually lowered again. 

Conclusion  

Feeding a broodmare doesn’t need to be complicated, but it does need to be planned by stage. The biggest wins come from a few practical habits done consistently: 

Before breeding (8–12 weeks out) 

Start with good-quality forage. If your hay is low in protein, add alfalfa to improve protein quality. Cover vitamins and minerals daily with Este Balancer (developed by Dr. Sara Torfs). Begin a prenatal vitamin like Fresh & Fertile early so nutritional support is in place before conception. 

Early–mid pregnancy (months 1–8) 

Keep the plan steady: forage + Este Balancer. Only make changes if her condition starts to drop. Continue Fresh & Fertile until 3rd month into pregnancy. 

Late pregnancy (months 9–11)