Broodmare Nutrition During Pregnancy and Lactation

By: Dr Rosie Alcorn BVSc PG Cert VPS Cert AVP MRCVS

As we head into the stud season, foals are beginning to hit the ground and many of our Thoroughbreds are in the thick of the season. Broodmare nutrition is always an important topic, but one of the most critical periods is after foaling, when the mare must support both herself and her new offspring. Nutrition also plays a key role in supporting fertility when covering mares again during the same season, as well as in promoting long-term health in the foal.

So, how do dietary requirements change throughout pregnancy and lactation, and what can we do to best support our mares?

Nutrition in Early Pregnancy: Maintaining Body Condition and Fertility

During early pregnancy, the mare’s nutritional needs are similar to those of an adult horse at maintenance. Good-quality forage should be sufficient to maintain body condition score (BCS).

Supplementation with a balancer is recommended to ensure the mare and the developing foetus receive adequate vitamins and minerals that may not be supplied by forage alone.

Maintaining an appropriate BCS - ideally 5 to 6 out of 9 - during this stage is important, as both under- and over-conditioning can negatively impact fertility and embryonic development.

Nurture contains long chain omega 3 (DHA) to support mares who are in foal, mares in postpartum recovery and foal development and behaviours. The concentrated nuggets are easy to chew and digest as well as being steam extruded for maximum nutrient absorption.

Late Pregnancy Feeding (Final Three Months): Supporting Rapid Foetal Growth

In the final three months of pregnancy, nutritional demands increase significantly. Requirements rise for:

• Protein

• Energy

• Macro-minerals such as calcium and phosphorus

• Micro-minerals such as copper and zinc

• Vitamins

Approximately 60–70 per cent of foetal growth occurs during this period. The foal can grow by as much as 0.4 to 0.5 kg per day in late gestation, making this the most nutritionally demanding phase of pregnancy.

Care must be taken with starch levels in pregnant broodmares. Research has shown that mares fed high-starch diets are more likely to produce foals predisposed to developmental orthopaedic disease (DOD). For this reason, fibre- and oil-based energy sources are preferable to high-starch concentrates, allowing energy demands to be met while supporting healthy skeletal development.

Lactation Nutrition: Meeting the High Energy Demands of Milk Production

Lactation is the most nutritionally demanding stage of the reproductive cycle.

During this period:

• Energy requirements can increase to up to twice maintenance levels

• The mare will typically consume 2–3 per cent of her bodyweight in feed per day

At this stage, we are effectively feeding both the mare and her foal.

If the mare is underfed during lactation:

• Milk production will decrease

• The mare will lose body condition

• Fertility may be compromised

Milk production peaks early in lactation and gradually declines over time. By the fifth month, less than 30 per cent of the foal’s energy requirements are supplied by the mare’s milk.

As lactation progresses, levels of key bone-building minerals - including calcium, phosphorus, magnesium, zinc and copper - decline in the milk. These minerals are critical for proper skeletal development in the growing foal.

Providing a well-formulated concentrate designed specifically for broodmares helps maintain adequate mineral intake, supports milk quality and preserves mare condition, all of which are essential for successful rebreeding.

Supporting the Foal’s Gut Health: The Importance of the Microbiome

Increasing research suggests that young foals with a diverse and well-established gut microbiome may be less likely to suffer from orthopaedic and respiratory issues later in life.

While evidence regarding direct supplementation of pre- and probiotics in young foals remains mixed, one of the most effective ways to support early microbiome development is through the mare herself.

In the early stages of life, the foal’s primary nutritional source is milk. Therefore, supporting the mare’s gut health and overall dietary balance provides the best foundation for establishing microbiome diversity in the foal.

A forage-based diet, controlled starch intake and well-balanced micronutrition in the mare all contribute to creating an optimal start for the developing foal.

Correct nutritional management throughout pregnancy and lactation protects the health and longevity of the mare while setting the foal up for optimal growth, soundness and long-term performance.