Understanding Passive Transfer of Immunity
A newborn calf’s immune system is like a blank slate. Calves must rely on a process called passive transfer of immunity to gain early immunity through immunoglobulins (IgG). This happens through the absorption of antibodies through the intestine into the bloodstream from colostrum, either maternal colostrum or a dried colostrum replacement product.
Getting this right isn’t just good practice—it’s essential for the calf’s survival, health, and long-term performance.
Why Passive Transfer of Immunity Matters
Passive transfer of immunity sets the tone for the calf’s immune development- overall health, growth and future productivity are dependant on calves receiving immunoglobulins.
The goal is simple: deliver enough high-quality IgG at the right time—and the clock starts ticking the moment the calf is born.
The First 12 Hours: A Critical Window
IgG absorption opportunity peaks in the first few hours of life, rapidly decreasing with time. This gives calf caretakers an urgent window to ensure calves receive the immunity they need.
Our recommended approach:
200 grams of IgG delivered within the first 1 to 3 hours after birth.
An additional 100 grams of IgG delivered within 12 hours of birth.
This two-step strategy maximizes antibody absorption during the calf’s most receptive period and supports a strong foundation for health and resilience.
Not all maternal colostrum is created equal. That’s why it’s important to test every batch.
Use a Brix refractometer to measure quality quickly and easily on-farm. A Brix reading of 22% or higher is generally accepted as a threshold for high-quality maternal colostrum, indicating sufficient IgG concentration.
If maternal colostrum reads below this level—or if it’s contaminated or the sufficent amount is unavailable—have a high-quality colostrum replacer ready to fill the gap and hit your IgG targets.
Supporting Passive Transfer of Immunity with IMMUNOLIFE | 200
At Truvital Animal Health, we believe early immunity is a foundation for lifetime performance.
IMMUNOLIFE | 200 is one of those tools. Designed to provide calves with 200g of IgG per dose, it’s formulated to support successful passive transfer of immunity when high-quality maternal colostrum isn’t available. A full sachet of IMMUNOLIFE | 200 providing 200g of IgG should be fed at birth, preferably within 2 hours of life, and an additional 100g of IgG (half a sachet) should be provided 6-8 hours after the first feeding. These recommendations will provide calves with an optimal start in life. Read more about IMMUNOLIFE | 200 here.