A British study examining the effects of different feeding strategies on pregnant mares and their foals suggests that a ration balancer may enhance colostrum quality and improve passive immunity transfer.

Related: Newborn Foal Care: Essential Steps for a Healthy Start

Colostrum, a mare’s first milk, is essential for a newborn foal’s health, providing both vital nutrients and immune system support. Broodmare managers and veterinarians strive to ensure foals receive the highest quality colostrum possible. Previous research in livestock species has shown that supplementing specific vitamins and minerals can improve colostrum composition. Could the same hold true for horses?

Related: Preparing for Foaling: the High-Risk Mare

A study by scientists in the United Kingdom and published in the Journal of Equine Veterinary Science explored this question. Researchers from the University of Cambridge and the University of Liverpool analyzed two groups of pregnant mares on a single breeding farm. Before foaling, all mares followed a forage-based diet. In late pregnancy, one group received a custom grain mix formulated on the farm based on body condition, while the other group was supplemented with a commercial ration balancer.

What Is a Ration Balancer?

Ration balancers are designed for horses that maintain body condition well on forage and do not require the extra calories of a commercial grain mix. These balancers provide essential vitamins, minerals, and amino acids, ensuring horses receive balanced nutrition even when consuming less than the recommended amount of a commercial grain mix.

Related: Understanding Neonatal Brain Oxygen Deprivation in Foals: Causes and Risks

Study Findings

The peer-reviewed study found that mares receiving the ration balancer produced colostrum of higher quality, as measured using an optical sugar refractometer, compared to those fed the grain mix. Additionally, foals born to mares supplemented with the ration balancer had a significantly lower incidence of failure of passive transfer (FPT) — a condition where foals do not absorb enough immunoglobulin G (IgG) antibodies from colostrum, which is crucial for immune protection in early life.

Study Limitations

While the findings are promising, researchers acknowledged several limitations:

• Mares were fed free choice from shared feeders, making individual intake difficult to measure.
• Group assignments were based on field placement rather than random selection, as entire fields were fed together.
• Because the grain mix was custom-made in batches on the farm, nutrient levels could not be precisely compared to those in the ration balancer.

Despite these challenges, the study provides valuable insights into the potential benefits of ration balancers for broodmares. For more details, read the full study in the Journal of Equine Veterinary Science.

Related: Deciding Whether to Breed Your Mare

Related: A Guide to Your Mare’s Smooth and Successful Foaling Experience

Thanks to The Paulick Report for this information.

Photo: Alamy/Pat & Chuck Blackley