Before Foaling: What Shapes Colostrum Quality

Colostrum quality starts long before foaling

Foaling season is a long game. Nearly eleven months of careful planning and management all lead up to one short window that matters more than most people realize.

The first hours after a foal is born.

That window determines how well the foal absorbs colostrum, the mare’s first milk, and with it the antibodies the foal depends on to get started. While a lot of attention goes to the foal once it hits the ground, research and veterinary experience continue to point back to the same place.

It starts with the mare.

What is really happening inside the broodmare

Foals are born without circulating antibodies. Unlike humans and some other mammals, they do not receive immune protection across the placenta during pregnancy. Instead, newborn foals rely entirely on colostrum to acquire immunoglobulins, especially IgG, during the first hours of life¹.

The foal’s gut is only able to absorb these antibodies for a limited time. Most absorption happens within the first 12 to 24 hours after birth². Once that window closes, the opportunity for passive immune transfer is largely gone.

Because of this, colostrum quality matters just as much as timing.

What many owners do not realize is that colostrum quality is influenced well before foaling. The mare’s immune system, digestive health, and overall management during late gestation all play a role in what ends up in that first milk³.

Why the mare’s gut matters for colostrum

A large portion of the immune system is connected to the gastrointestinal tract. The gut is not just responsible for digestion. It is also a major site of immune activity, influencing antibody production and immune signaling⁴.

When a broodmare’s digestive system is supported and stable, her immune system is better positioned to function normally during the final stages of pregnancy. That normal immune function is what allows antibodies to concentrate in colostrum as foaling approaches.

Late gestation is also a time when many mares experience changes in routine. Breeding farms, stall time, handling, diet adjustments, and reduced turnout are common. These changes can influence gut rhythm and microbial balance⁵.

Supporting digestive consistency during this period helps the mare stay steady through those transitions.

What research shows about probiotics and colostrum

Researchers have evaluated yeast-based probiotic supplementation, including strains such as Saccharomyces boulardii, during late gestation to better understand how maternal gut support influences colostrum quality and passive immune transfer in offspring.

Peer-reviewed studies involving probiotic yeast supplementation during late gestation have reported measurable increases in colostrum immunoglobulin concentrations. In one study, colostral IgG levels increased by 14.5 percent, alongside a 21.86 percent increase in serum IgG concentrations in nursing offspring⁶.

These findings reinforce the connection between the maternal gut microbiome and normal immune transfer during early life, highlighting the role digestive support plays during the final trimester of pregnancy.

Why broodmares benefit from consistency late in pregnancy

As foaling approaches, the mare is doing a lot of work behind the scenes. Her body is supporting fetal growth while also preparing for lactation and immune transfer.

Management changes are often unavoidable during this time, but digestive consistency matters. Fluctuations in diet, environment, or stress levels can influence gut rhythm and immune efficiency.

From a veterinary perspective, supporting the mare before foaling is often easier than reacting after something is missed. Once the foal is born, there is very little time to correct gaps in colostrum quality.

The preparation has already happened.

Practical ways to support broodmares

Supporting broodmares does not require complicated programs. Small, consistent steps make a difference.

• Maintain steady forage access and avoid abrupt feed changes
• Keep routines consistent whenever possible
• Manage stress from housing or handling changes
• Work closely with your veterinarian on vaccination and deworming schedules
• Pay attention to digestive consistency, appetite, and attitude

These basics support the systems that influence colostrum production long before foaling day arrives.

Where probiotics fit in the broader approach

Gut support matters year-round. Keeping mares on daily probiotic pellets as part of their regular nutrition helps maintain normal digestive balance through seasonal changes, breeding preparation, pregnancy, and foaling. That consistency supports overall stability rather than reacting to change once it occurs.

During late gestation, consistency becomes even more important as demands on the mare increase and management routines shift. Probiotics are designed to support normal gut balance, which in turn supports normal immune function during periods of routine stress and transition. They are not a replacement for veterinary care or proper nutrition, but a foundational part of maintaining digestive stability when needs are heightened.

~Breeding and Foaling Season Must-Haves~

From supporting your mares to caring for your newborn foals, preparation makes all the difference.

Probiotic Pellets for Broodmares

Used as part of a daily nutrition program, Probiotic Pellets support your mare through every stage - breeding, foaling, and nursing. 

Foal Kit

The FullBucket Foal Kit is a complete early-life support system designed for the first week of a foal’s life.  The kit contains:
• 1 tube of FullBucket Foal Kick Start Paste for Day 1
• 6 tubes of FullBucket Foal Probiotic Paste for Days 2 through 7
• 1 set of foal indicator strips
• 1 foal information cards

Breeding and foaling season move quickly, but the foundation for a healthy start is built long before your foals hit the ground. Consistent management, steady nutrition, and daily digestive support help your mare and foal through every stage.