Feeding For Breeding: Nutritional Strategies For Mares, Foals, And Stallions

A well-balanced diet is crucial to supporting optimal fertility, pregnancy, lactation and development of healthy youngstock. Each stage of the breeding cycle presents unique nutritional demands, from ensuring the broodmare has adequate nutritional reserves, supporting a stallion’s reproductive performance and crucially, supporting a foal’s early growth and development.

FEEDING THE BROODMARE: TACKLING TRIMESTERS

The nutritional needs of a broodmare change significantly throughout pregnancy and lactation. Proper management during these phases supports foetal development, milk production, and the mare’s long-term health.

Preparing for Conception...

• To improve the chances of conception in mares with a body fat score (BFS) below 5 (on the 9-point scale), it’s essential to increase their energy intake. This helps support their reproductive health and ability to get in foal. However, for mares with a BFS of 5 or above, there is no need to increase their energy intake prior to conception, as excess weight provides no benefit. Ideally, broodmares should maintain a BFS between 5 and 6 to optimise fertility and overall health. Avoid allowing mares to become obese, as this can lead to complications.
• Ensuring your mare has a good source of Omega 3 fatty acids in her diet can increase the likelihood of a successful pregnancy. Omega 3’s support fertility and conception by supporting the production of hormone-like substances that play a key role in reproductive health. Adding an appropriate level of omega-3s can be a valuable part of your broodmare’s nutrition.
• Vitamin E can positively influence fertility in broodmares by supporting reproductive health. As a powerful antioxidant, it helps protect cells from oxidative stress, which can be particularly beneficial for reproductive tissues. Including sufficient levels of Vitamin E in your broodmare’s diet may enhance fertility and improve the chances of a successful pregnancy.
• For broodmares, the quality of protein in their diet is just as important—if not more—than the total amount they consume. Providing high-quality protein helps support the hormones needed for healthy follicle growth. Studies show that mares on a quality protein diet tend to ovulate 2-3 weeks earlier compared to those on lower-quality protein diets.

TOP TIP: When looking for quality protein sources on a feed label, look out for ingredients such as pea flakes, soya, and alfalfa (lucerne).

EARLY PREGNANCY

During early pregnancy, a mare’s energy (calorie) requirements do not increase significantly above maintenance levels. Therefore, the mare can largely be fed as though she isn’t pregnant at all. However, providing a high-quality, balanced diet is always recommended as this will support successful placental development and prepares the mare for the energy demands of late pregnancy and lactation.

Did you know?
The foetus undergoes minimal growth during the first seven months of pregnancy, with the majority of its development occurring in the final trimester. Growth isn’t steady throughout the gestation period, so there’s no need to start ‘feeding for two’ as soon as your mare becomes pregnant. During the early stages, her nutritional needs remain similar to her maintenance diet.

• Forage: As with any horse, forage should form the basis of the broodmare’s diet. High-quality pasture or hay/haylage should always be supplied at a minimum intake of 1.5-2% of the mare’s body weight per day.
• Protein: Broodmares require at least 10-12% quality protein to support the growth of the placenta and amniotic tissues surrounding the foetus. Quality protein sources will supply essential amino acids that must be provided by the diet.
• Body Fat Score (BFS): Mares should be maintained at a BFS of 5-6 on a 9-point scale. Both underweight and overweight mares may struggle to conceive. Once pregnant, avoiding excess weight gain can reduce the risk of complications whilst foaling, whereas avoiding weight loss is crucial to ensuring the mare maintains a healthy body fat score during lactation. There is often no need to ‘feed for two’ during early pregnancy and avoiding this can reduce the risk of obesity and any associated health risks.

TOP TIP: Familiarise yourself with Body Fat Scoring. Regularly body fat scoring your mare whilst she is pregnant will help you to feel if her weight maintenance is on track, or whether adjustments need to be made prior to late pregnancy/lactation. Whilst gravity will inevitably cause some ‘drooping’ of the abdomen and can pull the skin tighter over the ribs, this is perfectly normal, so it is important to familiarise yourself with other areas of fat deposition.

THE LAST TRIMESTER

Approximately 60-65% of foetal growth occurs in the last trimester, from the 7^th month onwards, necessitating up to a 30% increase in the mare’s energy requirement. It is at this time that we recommend introducing a ‘specific’ stud diet, that supplies additional trace minerals such as copper and zinc, which are vital for building liver stores in the foal.

• Protein: Crude protein requirement increases to 12-14%. It is important to consider not only the quantity of the protein, but the quality of the protein also.
• Energy: A gradual increase in concentrate feeds may be necessary to meet rising energy demands. As per above, it is important not to increase calorie (energy) excessively prior to foaling, as an overweight broodmare is at an increased risk of complications when foaling. In addition, overweight mares are more likely to produce heavier, faster growing foals (increasing the risk of development issues).
• Essential Fatty Acids (EFAs): One of the advantages of feeding Omega 3 fatty acids has been found to be improved colostrum quality. Good colostrum quality is defined as having a high concentration of immunoglobulins, also known as antibodies, that help the new-born foal to fight infection until their own immune systems are developed and functional. Research has found that mares supplemented with Omega 3 fatty acids produced richer colostrum, which in turn could assist with providing young foals with a more established immune system.
• Vitamin E - Vitamin E also has the potential to improve the passive transfer of antibodies through colostrum. Supplementing mares with additional vitamin E at a rate of 2500iu per day during the last four weeks of pregnancy has been shown to increase levels of the key immunoglobulins of the mare’s milk in the first three days after birth, as well as increasing her serum levels of vitamin E. The same effect was seen in the foals, having elevated serum Vitamin E and immunoglobulin levels.
• Vitamins and minerals: Proper calcium-to-phosphorus balance (ideally 2:1) is essential for foetal skeletal development. The recommended feeding rates of a fully fortified breeding feed or balancer should be utilised to ensure vitamin and mineral requirements are met, as mineral deficiencies in the mare have been linked to developmental orthopaedic diseases in their foals. The foetus itself will store iron, copper, zinc and manganese in the liver, ready for use during the first month of life. The micro mineral content of milk is naturally low, therefore storage during the last few months of gestation is essential to provide an adequate supply for development during the rapid growth period following birth. Compensatory feeding of the mare post-partum will not correct for earlier shortfalls.
• Appetite and feed retention: During the latter stages of pregnancy, it is common to see a reduction in appetite. A reduction of 10-30% is normal. Typically, appetite ranges from 2-3% of bodyweight, so for a 500kg mare we would expect her to eat 10-15kg per day. When appetite is restricted, this could lower to 7-11kg per day. Along with appetite, food retention in the digestive system can decrease by 30% meaning less time for digestion and so poorer uptake of nutrients.

TOP TIP: Using fibre sources with a higher level of digestibility, such as soaked sugar beet pulp and alfalfa can be of help.

Lactation

The first three months of lactation place the highest nutritional demands on the mare. Milk production can exceed 3% of the mare’s body weight per day, requiring increased calorie and nutrient intake.

• Energy: Digestible energy (DE) needs can rise by 50-70%.
• Protein: The mare’s diet should contain at least 14-16% crude protein. Milk is 20-25% protein, and mares can produce up to 2-4% of their body weight in milk each day (approximately 20 litres for a 500kg horse) and so providing quality protein as well as meeting energy requirements is also essential. One study found that protein restriction in mares during lactation led to reduced foal growth rates after 90 days when compared to those that did not have any restriction. Not only did the quantity of protein lead to reduced milk production, but quality protein also had an impact on lactation and foal growth rates.
• Calcium & Phosphorus: From the third trimester of pregnancy to the first month of lactation, Calcium and Phosphorous requirements increase by 64% and 46% respectively. Avoid supplementing calcium and phosphorus exclusively as other mineral requirements are also increased. Increased intake of a suitable feed or supplementing with a feed balancer will typically provide for the increased requirements.
• Water: Lactating mares require significantly more water (up to 75 litres per day) to support milk production. Monitoring water intake and always ensuring fresh, clean water is available is vital. During warm weather, offering soaked mashes and adding 1-2 tablespoons of salt to daily feeds can help to stimulate the natural thirst response and support optimum hydration status.

Feeding the Foal

Proper nutrition during early growth sets the foundation for sound development and future performance. Foals have distinct dietary needs that evolve rapidly from birth through to weaning.

Neonatal Nutrition (0-3 Months)

Colostrum intake within the first 12-24 hours is critical for the mare to pass on immunoglobulins to the foal, also known as passive transfer of immunity. As discussed previously, mares supplemented with omega-3 fatty acids and Vitamin E in the last 4 weeks of pregnancy were found to have colostrum with higher immunoglobulin scores. Milk provides all essential nutrients initially, but foals begin nibbling on solid feed within a few weeks.

• Energy – The foal’s digestive system is not properly developed until they are approximately 3 months old, and so the mare's milk is almost solely responsible for the foal's energy intake. Though foals may nibble at grass, or the mares concentrate feed, the hindgut is still largely developing until 6 months of age.
• Minerals: Even at 3 months old, foals will still be relying on the mare’s milk to provide 30-50% of their nutrients, with calcium, copper, phosphorous and zinc being the more critical minerals required to support the growth of young horses. Calcium requirements for lactating mares is at its highest level during the early stages of lactation, and insufficient calcium intakes increase the chances of bone demineralisation. Milk is also naturally low in copper and zinc, which is required for cartilage development. Adequate intake of copper in mares is associated with a significant reduction in physitis (inflammation of growth plates) and number of cartilage lesions for their foals. Foals from mares that did not receive properly balanced rations had higher physitis scores and more cartilage lesions. If the mare has had an appropriate balanced ration during late pregnancy, the foal will have built up adequate stores of trace minerals in the liver prior to birth.
• Creep Feeds – A foal will begin picking at their mum’s feed from a very young age, but creep feeds can be introduced from approximately 90 days old, if required. Offering a creep feed will help to supplement the foal's nutrition as the mare's milk becomes less nutritious, as well as reducing stress around weaning. Typically, these creep feeds are stud balancer rations, which keep the energy (calorie) intake to a minimum, whilst supplying important nutrients required for their continued growth and development. For those who do require additional calories, tailored stud feeds can then be added in reduced quantities to support weight maintenance.

Reducing the risk of Development Issues

Developmental orthopaedic disease (DOD) is the term given to describe abnormal growth conditions in young horses. Factors such as an imbalanced ration and excess growth are well researched, and implementing management strategies can help to maintain the risk of these issues occurring:

• Reduce energy intake – limit access to lush pasture if necessary and offer lower calorie forage sources to maintain fibre intake.
• Consider weaning if appropriate.
• Reduce starch intake. Stud feeds that are high in starch have been linked to DODs, so selecting stud feeds that have a greater reliance on fibre and oil as a calorie source is recommended.
• Offer small, frequent meals to reduce glycaemic response after feeding.
• Ensure a fully balanced diet is being supplied - over supply of energy combined with an inadequate supply of minerals will increase risk of development issues.
• Regularly body fat score to avoid obesity and 'fits and starts,' changes to growth patterns.
• If the mare requires condition, lift the bowl out of the foal's reach using door buckets if necessary.

Weanling to Yearling (4-12 Months)

Weaning can be a stressful period that necessitates a carefully managed diet transition. Once weaned, the foal is completely dependent on forage and supplemental feeding provided by their owner. How the weanling is fed following weaning often depends greatly on what is expected of it in the following months. A weanling that is destined for the sales ring later in the year, for example, would be managed much more intensely than one that is being raised as a performance prospect, where maximal growth and condition are not as imperative at such an early age. Regardless of their eventual use, the primary goal of feeding all weanlings is the same steady and even growth.

• Forage First - As with any horse, forage should continue to provide the majority of the young horse's calorie intake, and so providing access to ad-lib, quality forage is usually recommended.

• Concentrate Feeds - The weanling should ideally be already accustomed to a concentrate feed, such as a stud balancer, which will not only help to maintain nutritional intakes but also help to reduce stress once separated from their dams.

• Quality Protein - The requirement for lysine has been reinforced by research over the years. In one study, weanlings fed a diet with sufficient protein but insufficient lysine had slower growth rates than their peers who were fed diets containing adequate levels of lysine. Quality protein sources that provide essential amino acids such as lysine include soya, alfalfa (lucerne) and pea flakes.

• Digestive Support – As weaning can be a stressful time for youngstock, providing additional digestive support can be of great benefit. Weanlings are known for being at an increased risk of developing gastric ulcers. Furthermore, the shift from milk to feed and forage can increase the risk of hindgut disturbances. Supplementing with buffering agents or pre and probiotics can all help to support a normal digestive tract throughout this period of change.

TOP TIP: If possible, wean foals in small groups and introduce solid feed beforehand to help ease the transition. This can help to reduce both stress levels and reduce the risk of digestive upsets.

BODY FAT SCORING THE FOAL

• Foals store fat differently to the mature horse. They carry very little body fat, with most of their mass being muscle tissue. They also have different areas and degrees of fat deposition.
• Foals should have a crease down their back. Fat is laid down behind the withers and shoulder first, it then moves back and down along the ribcage. It is important to note that ribs may be visible even in the well-conditioned foal.
• Yearlings should be scored using the criteria for mature horses.

TOP TIP: It is important to get hands on when fat scoring your foal, as the fluffy coat can often be deceptive.

Feeding the Stallion

A breeding stallion’s diet must support sperm production, libido, and overall health. While their basic nutritional needs are similar to other adult horses during maintenance, breeding activity increases energy demands. Furthermore, maintaining a calm and trainable temperament can be a challenge, so selecting concentrate feeds to reduce excitable behaviours where possible is key.

• Energy Intake - It is important to ensure a breeding stallion stays at an ideal weight all year round. A stallion’s calorie intake can vary hugely from animal to animal, and whilst some stallions will lose condition throughout the breeding season, others can stay on the heavier side. In addition, some stallions will be more naturally active than others, and once an ideal weight has been achieved, every attempt should be made to keep it.

• Obesity in stallions can cause many issues such as predisposition to laminitis, insulin resistance and lameness issues (particularly of the hind legs, which is reflective of the strain placed on them during breeding). Regularly fat scoring throughout the season will again help to identify changes in fat deposition, much sooner than may be detectable by the naked eye.

• Concentrate Feeding – As with any horse, the stallion’s calorie requirements can vary on several factors. Their age, number of coverings, breed and even temperament can all play a role. Stallions who become stressed or ‘highly strung,’ can lose a lot of weight very quickly, whereas those with a laid-back temperament might maintain their weight solely on forage alone. For these types, a stud balancer that supplies sufficient intake of vitamins and minerals, quality protein and antioxidants can be sufficient. For those with higher calorie requirements, the source of energy can play a large role in both adding to or reducing excitable or anxious behaviours. Reducing the intake of starch and increasing the use of digestible fibre sources and oil will help to support a calm and trainable temperament without compromising on body fat score.

• Antioxidants - Stallion fertility can also benefit from specific supplementation of natural vitamin E. Both libido and sperm quality have been linked with vitamin E. Supplementary feeding of vitamin E during the covering season is recommended for all stallions, particularly those with fertility related concerns such as low sperm motility. Research into vitamin E supplementation has found that supplementation with a natural source of vitamin E can increase total sperm output, concentration, and motility in other species as well as a reduction in DNA fragmentation, where the DNA in sperm cells breaks.

• Essential Fatty Acids - Omega 3 and Omega 6 fatty acids are key fatty acids contained in semen. Fatty acids contribute towards sperm motility, sensitivity to cold shock, and fertilisation capacity. Research has shown that supplementing stallions with omega 3 fatty acids can increase total motility, progressive motility and rapid motility of sperm. Research also showed that supplemented horses had almost double the concentration of sperm and sperm motility in frozen-thawed sperm was better. Omega 3 fatty acid supplementation can also promote coat shine, which is an extra bonus for stallion showings.

Conclusion

Feeding for breeding requires careful consideration of each horse’s stage in the reproductive cycle. A well-balanced diet that meets the unique needs of broodmares, foals, and stallions ensures optimal fertility, healthy foal development, and overall breeding success. Incorporating scientifically supported feeding strategies helps maximise reproductive efficiency while promoting long-term equine health.