How To Feed a Thin Mare After Weaning

By Dr Duncan Houston

By the time a foal is weaned, some mares look like they have given everything they had to the job. Their topline has dropped, ribs are easier to feel, hips look sharper, and the big shiny lactating broodmare from a few months ago suddenly looks tired and light.

This is common, especially in high-milking mares, mares on average forage, older mares, mares that were only just holding condition before foaling, or mares that have already been rebred. But common does not mean it should be ignored.

The goal after weaning is not to “dry her off” by starving her. The goal is to safely reduce lactation stimulus, monitor the udder, rebuild body condition, restore nutrient reserves, and prepare the mare for the next stage, whether that is pregnancy, another breeding season, or recovery.

Quick Answer

A thin mare at weaning should be fed to regain body condition, not aggressively restricted to stop milk production. Merck Veterinary Manual states that broodmares should generally be maintained around body condition score 5 to 6, and that there is no scientific evidence supporting withholding feed to decrease or stop milk production. (Merck Veterinary Manual)

For a lean mare, prioritise high-quality forage, a balanced broodmare concentrate or ration balancer, gradual calorie increases, and careful monitoring of the udder for mastitis. Feed changes should be gradual, and fat sources such as rice bran, flaxseed, vegetable oil, or high-fat feeds can help if forage and concentrate alone are not restoring condition. (University of Minnesota Extension)

Why Mares Get Thin During Lactation

Lactation is one of the most demanding stages of a broodmare’s life. She is not just maintaining herself. She is producing milk that contains energy, protein, calcium, phosphorus, and other nutrients for a rapidly growing foal.

University of Kentucky notes that a 1,200 to 1,300 pound mare may produce about 40 pounds of milk per day in early lactation, and lactating mares may consume more than 30 pounds of hay daily. It also notes that loss of body condition during lactation means nutrient intake is not sufficient and the diet should be changed. (Equine Programs)

Merck’s lactating mare nutrient table shows how dramatic the change can be. For a 500 kg mare, estimated energy needs rise from 16.7 Mcal per day at maintenance to 31.7 Mcal per day in the first month of lactation, with large increases in crude protein, lysine, calcium, and phosphorus. (Merck Veterinary Manual)

That is why thin mares at weaning are not just “a bit light.” They may be depleted of calories, muscle, and mineral reserves. The post-weaning period is the chance to rebuild before the next nutritional demand hits.

What Body Condition Score Should a Mare Have at Weaning?

The practical target for most broodmares is a body condition score of 5 to 6 out of 9.

A mare at BCS 5 has ribs that are not visually obvious but can be felt. A mare at BCS 6 has a little more cover, which can be helpful for mares that predictably lose condition during lactation.

University of Kentucky recommends that mares foal at a BCS of at least 5 and maintain that condition. It also states that if a mare is thin at weaning, she needs enough concentrate to increase her BCS to at least 5. (Equine Programs)

BCS 4 or Lower

This mare is too thin.

You may see ribs, a sharper spine, poor topline, prominent hips, or a tucked-up appearance.

What to do: increase nutritional support, check for underlying causes, and involve your vet or equine nutritionist. This mare needs a structured recovery plan.

BCS 5

This is usually acceptable.

The mare has enough cover to support normal recovery and future breeding, assuming she is otherwise healthy.

What to do: maintain or gently improve condition depending on her next reproductive plan.

BCS 6

This is often a useful target for mares that lose weight easily during lactation.

What to do: maintain carefully without letting her become overweight.

BCS 7 or Higher

This mare is carrying excess condition.

What to do: do not crash diet, but reduce unnecessary calories and focus on forage, minerals, and safe exercise.

The Big Myth: Should You Cut Feed to Dry Up the Mare?

This is where broodmare advice gets messy.

Some owners reduce feed at weaning because they believe it will stop milk production faster. In a mare in good condition, a short-term reduction in concentrates may be used as part of a drying-off routine. But for a thin mare, aggressive feed restriction is the wrong reflex.

Merck states there is no scientific evidence supporting the practice of withholding feed to decrease or stop milk production. It also states that mares should be maintaining or gaining weight to optimise reproductive success in the next breeding season. (Merck Veterinary Manual)

The main driver stopping milk production is the removal of nursing stimulus. Once the foal is no longer suckling, milk production naturally declines.

The practical rule is simple: do not punish a thin mare nutritionally just because she is drying off.

Should You Milk the Mare After Weaning?

Usually, no.

Routine milking can keep stimulating the udder and may prolong milk production. It can also increase handling stress and, if done roughly or unhygienically, create more problems than it solves.

However, this is different from treating mastitis. If the mare develops mastitis, your vet may recommend controlled milking, anti-inflammatories, antibiotics, culture, cold hosing, or other treatment. Merck describes mastitis in mares as marked, painful swelling of the affected gland, often with abnormal secretion, fever, listlessness, stiffness, and possible abscessation if not treated promptly. (Merck Veterinary Manual)

So the rule is:

Do not milk a normal drying-off mare just to empty her udder. Do call your vet if the udder is painful, hot, swollen, abnormal, or the mare is unwell.

What Should You Feed a Thin Mare After Weaning?

The foundation is simple: forage first, then balanced nutrients, then extra calories if needed.

1. Start With High-Quality Forage

Forage should be the base of the recovery diet.

Options include:

• Good pasture

• High-quality grass hay

• Alfalfa or lucerne hay

• Alfalfa-grass mix

• Hay cubes or pellets if chewing is an issue

• Beet pulp where appropriate

University of Minnesota recommends giving underweight horses as much forage as possible, then moving to higher-quality hay such as alfalfa or immature grass hay if normal hay is not enough. (University of Minnesota Extension)

For mares, this matters because gut health still comes first. You can add calories, but you do not want to rebuild condition by dumping starch into a stressed hindgut.

2. Use a Broodmare Concentrate if She Needs Calories

If the mare is thin, forage alone may not be enough.

A broodmare concentrate can help provide:

• Energy

• Protein

• Lysine

• Calcium

• Phosphorus

• Copper

• Zinc

• Vitamins

• Trace minerals

University of Kentucky recommends a concentrate formulated for mares and foals when concentrate is needed, and notes that early lactation concentrate intake commonly ranges from 5 to 12 pounds per day depending on mare size and diet. Intake usually decreases as the mare approaches weaning, but a thin mare at weaning still needs enough nutrition to restore condition. (Equine Programs)

3. Use a Ration Balancer if Calories Are Adequate

If the mare is not very thin but the forage may be short on minerals or protein, a ration balancer can be useful.

This is especially helpful when:

• The mare holds weight easily

• She is on good pasture

• She is eating alfalfa or mixed hay

• She does not need much concentrate

• You still need copper, zinc, selenium, amino acids, and vitamins covered

A ration balancer is not a weight-gain miracle. It is a nutrient-balancing tool.

4. Add Fat if Weight Gain Stalls

Fat can be useful when a mare needs more calories without large grain meals.

Useful options may include:

• Stabilised rice bran

• Flaxseed

• Vegetable oil

• Commercial high-fat feeds

• Dried granular fat products

University of Minnesota lists rice bran, flaxseed, vegetable oil, and dried granular fats as high-fat options for underweight horses when extra calories are needed. (University of Minnesota Extension)

Merck notes that edible oils and fats can increase energy density, but they should be introduced slowly. Horses may tolerate around 10% fat in the total daily ration if introduced gradually and given 3 to 4 weeks to adapt. (Merck Veterinary Manual)

This is the bit owners often miss. Fat is useful, but do not tip half a bottle of oil into the feed and act surprised when the mare produces shiny diarrhoea. The hindgut has opinions.

5. Protect Protein and Minerals

A thin mare does not just need calories. She needs the right building blocks to rebuild muscle and replenish reserves.

Important nutrients include:

• Quality protein

• Lysine

• Calcium

• Phosphorus

• Copper

• Zinc

• Selenium

• Vitamin E

• Salt

Merck notes that soybean meal can be a palatable, high-quality protein supplement when protein requirements are high, including during lactation. (Merck Veterinary Manual)

Do not build a diet around calories alone. A mare can gain fat and still be poorly nourished.

Feeding Timeline After Weaning

Week 1 to 2: Do Not Make Dramatic Changes

The foal is removed, the udder is drying off, and the mare is adjusting.

Focus on:

• Keeping forage steady

• Avoiding sudden feed changes

• Monitoring udder swelling

• Watching appetite and manure

• Checking behaviour and stress

• Recording body condition

If the mare is thin, do not slash feed just because the foal is gone.

Weeks 3 to 6: Start Rebuilding Condition

By this point, milk production should be reducing and more nutrients can go back into the mare.

Focus on:

• Increasing calories if needed

• Improving forage quality

• Adding or adjusting broodmare concentrate

• Considering fat supplementation

• Checking teeth if intake is poor

• Monitoring weight and topline

Weeks 7 to 12: Prepare for the Next Stage

This is the reconditioning phase.

Focus on:

• Getting BCS back to at least 5

• Maintaining steady weight gain

• Checking pregnancy status if rebred

• Reviewing minerals

• Planning winter feeding if relevant

• Preparing for the next breeding season

University of Kentucky specifically describes the post-weaning period as an opportunity to replenish body stores before fetal development demands become greater again, especially if the mare has already been rebred. (Equine Programs)

Severity and Risk Framework

Low Risk: Slightly Light but Bright

The mare is BCS 5 or close to it, eating well, bright, sound, and has a normal udder.

What to do: maintain good forage, balance minerals, and monitor condition every 2 to 4 weeks.

Medium Risk: Noticeably Thin but Stable

The mare is BCS 4 to 4.5, has lost topline, but is eating, drinking, passing manure normally, and has no udder pain or illness.

What to do: increase nutritional support, improve forage, add appropriate concentrate, and track weight gain. A vet or nutritionist review is sensible.

High Risk: Thin, Poor Appetite, or Not Gaining

The mare is BCS 4 or lower, not gaining after diet changes, losing more weight, eating poorly, older, dentally compromised, heavily parasitised, or already pregnant again.

What to do: veterinary assessment is needed. Do not keep adding feed without finding out why she is not responding.

Critical Risk: Sick Mare or Mastitis Signs

The mare has a hot, swollen, painful udder, fever, abnormal milk, depression, colic signs, diarrhoea, laminitis signs, or rapid weight loss.

What to do: call your vet promptly. This is no longer just a feeding issue.

What Else Can Cause a Mare To Be Thin at Weaning?

Do not assume every thin lactating mare is only underfed.

Important rule-outs include:

Poor Forage Quality

Hay can look fine and still be low in calories, protein, or minerals. Testing is the only way to know properly.

Dental Disease

Sharp enamel points, missing teeth, wave mouth, painful chewing, or quidding can reduce forage intake, especially in older mares.

Parasites

A mare with parasite burden may lose condition despite adequate feed.

Herd Competition

Some mares are quietly bullied off hay or hard feed. This is especially common in group-fed broodmares.

Chronic Pain

Arthritis, hoof pain, back pain, or chronic lameness can reduce appetite and condition.

Gastric Ulcers

Poor appetite, weight loss, irritability, and dull coat can sometimes be linked with ulcers, especially after stress, transport, or management changes.

Pregnancy Demands

If the mare has been rebred, she may already be entering mid-gestation around weaning. That changes the recovery plan.

Disease

Chronic infection, liver disease, kidney disease, inflammatory bowel disease, or other systemic illness can cause poor condition.

The clinical clue is response. A mare that eats well and gains steadily was probably short on calories. A mare that does not respond needs investigation.

When Is This an Emergency?

Nutrition is usually managed over weeks, but some signs need urgent veterinary attention.

Call your vet if:

• The mare stops eating

• She has colic signs

• She has diarrhoea

• She has fever

• She is dull or depressed

• The udder is hot, hard, swollen, or painful

• Milk or discharge is bloody, clumpy, yellow, foul, or abnormal

• She walks stiffly or stands with hind legs apart because of udder pain

• She is rapidly losing weight

• She shows signs of laminitis

• She is dehydrated

• She is weak or unstable

• She is not improving despite increased feed

Merck notes that mastitis can cause painful gland swelling, abnormal secretion, fever, listlessness, stiffness, and can progress to abscessation or hardening of the gland without prompt treatment. (Merck Veterinary Manual)

What Should You Do Next?

1. Body Condition Score the Mare

Use your hands, not just your eyes. Winter coats and broodmare bellies are professional liars.

Score the ribs, neck, withers, shoulder, loin, tailhead, and hips.

2. Record Her Weight or Girth

Use a scale if available. If not, use a weight tape consistently.

Track:

• Body condition score

• Weight tape estimate

• Photos from side, front, and behind

• Feed amounts by weight, not scoops

• Udder changes

• Appetite and manure

3. Review the Current Diet

Write down:

• Type and amount of hay

• Pasture access

• Concentrate type and weight

• Balancer or supplement

• Salt access

• Water intake

• Feeding frequency

• Herd competition

A “scoop” is not a nutrition plan. Weigh the feed.

4. Increase Forage First

Give as much safe, high-quality forage as she can use.

If normal hay is not enough, consider alfalfa, alfalfa-grass mix, hay cubes, or a better-quality forage source.

5. Add Balanced Calories

If forage alone is not working, use a suitable broodmare or performance feed, depending on the mare’s reproductive status and veterinary advice.

6. Add Fat Gradually if Needed

Use fat sources slowly and carefully. Merck notes that horses need several weeks to adapt to higher-fat diets. (Merck Veterinary Manual)

7. Do Not Forget Minerals

If the mare is on hay and only a small amount of concentrate, she may not be getting enough trace minerals. A ration balancer may be needed.

8. Monitor the Udder

Check daily for heat, pain, severe swelling, abnormal discharge, fever, or stiffness.

9. Check the Foal Separately

The weaned foal now needs its own nutrition plan. University of Minnesota recommends using a properly formulated concentrate for the growth stage and feeding only enough to support the desired growth rate and moderate body condition. (University of Minnesota Extension)

10. Recheck in 2 to 4 Weeks

If the mare is not gaining, do not just keep increasing feed blindly. Check teeth, parasites, pain, disease, pregnancy status, and actual feed intake.

Common Mistakes Owners Make

Cutting Feed Hard in a Thin Mare

This is the big one. A thin mare needs recovery nutrition, not a punishment diet.

Thinking the Udder Must Be Emptied

Routine milking can stimulate ongoing production. Monitor the udder, but do not keep emptying it unless your vet has advised this for a medical reason.

Feeding by Volume Instead of Weight

One scoop of pellets, one scoop of oats, and one scoop of beet pulp are not the same. Weigh feed.

Adding Oil Too Fast

Fat is useful, but it needs to be introduced gradually. Too much too soon can cause loose manure and poor acceptance.

Forgetting Teeth and Parasites

A mare that cannot chew well or is carrying parasites may not gain properly no matter how good the diet looks on paper.

Ignoring Herd Bullying

Some mares are not poor doers. They are just losing the dinner fight.

Forgetting the Foal

The mare’s diet and the weanling’s diet are now separate plans. The foal still needs controlled growth, good protein, minerals, and safe forage.

Prevention: How To Avoid a Thin Mare at Weaning Next Time

The best fix is to avoid letting the mare get too lean in the first place.

A better broodmare system includes:

• Foaling mares at BCS 5 to 6

• Identifying mares that are heavy milkers

• Increasing nutrition early in lactation, not after weight loss is obvious

• Feeding enough high-quality forage

• Using broodmare concentrate when needed

• Separating thin mares at feeding time

• Checking teeth before breeding or foaling season

• Monitoring parasites

• Tracking BCS monthly

• Testing hay where possible

• Planning for winter before pasture drops

• Rechecking diet after foaling, at peak lactation, and before weaning

University of Kentucky suggests that mares that lose condition during lactation may need to foal next year with a larger buffer, such as foaling at BCS 6 if they previously foaled at BCS 5 and ended lactation at BCS 4. (Equine Programs)

That is practical broodmare management. Learn the mare’s pattern, then feed ahead of the problem next season.

FAQ

Should I reduce a mare’s feed after weaning to stop milk?

Not aggressively, especially if she is thin. The main driver reducing milk production is removal of the foal’s nursing stimulus. Merck states there is no scientific evidence supporting withholding feed to decrease or stop milk production. (Merck Veterinary Manual)

What body condition score should a mare be at weaning?

Most mares should be around BCS 5 to 6. If she is below 5, she needs a recovery plan. If she is 4 or lower, involve your vet or equine nutritionist.

What is the best feed for a thin mare after weaning?

Start with high-quality forage, then add a balanced broodmare concentrate or ration balancer depending on her needs. If she still needs more calories, fat sources such as rice bran, flaxseed, vegetable oil, or high-fat commercial feeds may help when introduced gradually. (University of Minnesota Extension)

How quickly should a thin mare gain weight?

Weight gain should be steady, not rushed. Recheck every 2 to 4 weeks. If she is not gaining despite improved forage and balanced calories, look for dental disease, parasites, pain, pregnancy demands, herd competition, or illness.

When should I worry about the udder after weaning?

Call your vet if the udder is hot, hard, painful, very swollen, leaking abnormal fluid, or the mare has fever, stiffness, depression, or reduced appetite. These signs can indicate mastitis. (Merck Veterinary Manual)

Final Thoughts

A lean mare at weaning needs rebuilding, not rough handling or sudden feed restriction.

The best approach is calm and practical: remove the nursing stimulus, monitor the udder, feed high-quality forage, balance minerals and protein, add calories where needed, and track condition over the next several weeks.

The mistake is treating drying off as the only goal. The bigger goal is recovery. A mare that finishes lactation thin needs help restoring body condition before winter, pregnancy demands, or the next breeding season arrives.

She has done the hard work. Now the feeding plan needs to do its job.

---

If your mare is thin after weaning, losing condition during lactation, or showing udder swelling after the foal is removed, ASK A VET™ can help you work through the urgency, feeding changes, and when veterinary care is needed.