Transfer of passive immunity in calves: Ensuring calf health and profitability

Calves rely heavily on colostrum for immunity. Successful transfer of passive immunity is crucial. Evaluating and improving immune transfer can reduce deaths and the number of days calves are sick, enhancing overall herd performance and profitability.

for decorative purposes only, a pictorial depiction of the article.
Image explaining calf morbidity and mortality rate and how to calculate it for a group of calves.

Calves are the future of the herd, and everything that happens during the development phase can have long-term effects on their productive life and herd profitability. Calf immunity heavily relies on the transfer of immunoglobulins from colostrum within 24 hours after birth, as there is minimal transfer of immunoglobulins from the dam to the calf during gestation. Ensuring successful colostrum management is crucial for achieving adequate transfer of passive immunity (TPI).

Colostrum Management

The success of colostrum feeding management depends on the amount fed, the quality of the colostrum and the timing, also known as the three Q's: Quantity, Quality and Quickness of feeding colostrum. Michigan State University  Extension recommends feeding 10% of the body weight of high-quality colostrum, which consists of colostrum harvested hygienically and with high concentrations of immunoglobulins 50 g/L IgG's (Brix ≥22) within six hours after birth.

An additional suggestion to improve your colostrum management is the implementation of a second feeding of 2-4 quarts of colostrum 6-12 hours after the first feeding. Here you can find more information on how to evaluate your colostrum and tips on harvesting, storing and thawing colostrum to optimize immunoglobulin absorption.

Impact of failure of passive immune transfer

Failure to transfer immunoglobulins to the calf through colostrum feeding, also known as failure of passive immune transfer (FPT), is a significant concern for dairy producers as it is associated with increased calf morbidity (number of animals that get sick) and mortality (number of animals that die), as well as poor growth. It’s considered FTP when a calf has serum IgG concentration lower than 10g/L.  

Successful transfer of passive immunity reduces mortality in the pre and postweaning phase and improves rates of gain and age at first calving. Benefits from colostrum may be attributed to protective immunoglobulins as well as high levels of nutrients and bioactive compounds that stimulate growth and development, according to Godden et al., 2019.

A national study conducted in 2013 showed that approximately 13% of dairy calves in the United States still have FPT. Although a considerable number, it shows significant progress in colostrum management compared to a previous national study in 1993, which reported 41% of calves in the U.S. having FPT.

Interestingly, calf morbidity rates have changed little since 1993, which tells us that improvement in colostrum management aiming at individual calves achieving serum IgG >10 g/L reduces the risk of animals dying from disease but not the chance of getting sick. A study conducted by Heinrichs & Heinrichs in 2011 observed that calves experiencing more illness and treatments during the first days of life had lower milk, protein and fat production during their first lactation and throughout their lifetime. These findings suggest that reducing pre-weaning morbidity rates can lead to long-term productive cows. 

Based on Lombard and colleague’s study, passive immunity should be evaluated both on calf- and herd-level to maximize calf health, reduce use of antibiotic and minimize future performance losses.  

Table 1. Target percentages of calves in each transfer of passive immunity category, IgG concentration, total protein, and equivalent Brix values


Serum IgG


Total protein


Equivalent Brix


Herd goal

(% calves)










~ 30





~ 20

Poor (Failure)





Source: Lombard et al. (2020)

Instead of using a cutoff point of ≥ 10 g/L to determine success of passive immune transfer on an individual level, the new goal is to have at least 40% of calves in a herd with serum IgG concentrations ≥ 25.0 g/L, and less than 10% with concentrations below 10 g/L. These new goals are driven by research demonstrating that higher serum IgG concentrations than traditionally recommended in dairy calves lead to improved health, increased disease protection and, ultimately, lower morbidity rates.

Evaluating 4,489 calf records from a commercial dairy farm in Michigan, Crannell and Abuelo compared the risks of morbidity, mortality and growth until weaning across the four categories of TPI proposed by Lombard and colleagues. The results revealed that calves with poor TPI had a higher risk of experiencing diarrhea, pneumonia and mortality when compared to those with excellent TPI. Likewise, recent research conducted in 2023 in Germany found that calves displaying an elevated TPI exhibited reduced susceptibility to pneumonia and decreased overall morbidity. Additionally, these calves demonstrated lower mortality rates in the preweaning phase.

Evaluating transfer of passive immunity

Measuring TPI is essential to identify Failure of Passive Immunoglobulin Transfer (FPT) and audit farm colostrum management based on herd-level TPI.

If calves fail to receive sufficient immunoglobulins through colostrum feeding within the first 24 hours of life, it can be attributed to various factors such as colostrum of poor quality, the inadequate volume of colostrum provided or other circumstances like high bacterial contamination that hinders proper absorption. Also, delayed colostrum administration can result in insufficient absorption of immunoglobulins.

It's important to understand that because many factors affect an individual calf's ability to ingest and absorb IgG, not every calf will achieve serum IgG concentrations above a critical threshold. Thus, it is expected that at least a small percentage of calves will have a failure of passive transfer even when an optimal colostrum management program is in place. As mentioned in the previous section, we want to maximize the number of animals with excellent TPI and minimize animals with FPT. 

Best practices for TPI evaluation

Keep a regular check on calves: To implement the new serum IgG recommendation, farmers should routinely check enough newborn calves within 2 to 7 days of age. This will help determine the percentage of calves falling into different serum IgG concentration categories.

Sampling strategies for different herd sizes: On smaller farms, sample each heifer calf individually. For larger farms, consider sampling every heifer or choose specific days of the week to sample all calves aged 2- 7 days.

Evaluating the program: It's a good idea to set a regular time for program evaluation. Monthly evaluation works well for most farms, while larger farms may prefer weekly evaluations.

Farm audits: Alternatively, to a continuous evaluation, audits can be performed once or twice a year. To do that, sampling at least 14 animals on the evaluation day or a small herd until 14 animals are evaluated can be a good strategy.

Importance of evaluating FPT in your farm

  • Allows monitoring and assessing passive immunity transfer's effectiveness in your herd.
  • Helps identify potential issues or gaps in colostrum management practices.
  • Enables timely intervention and adjustments to improve passive immunity transfer rates.
  • Facilitates informed decision-making for breeding and culling strategies based on the data trends.
  • Provides valuable information for veterinarians and consultants to offer targeted advice and support.

A helpful spreadsheet is available through MSU Extension to use when collecting data at your farm.

Transfer of passive in calves evaluation tool

Evaluating immunoglobulin passive transfer is crucial for dairy farmers to ensure herd health and long-term profitability. By implementing effective colostrum management practices and evaluating TPI using indirect measurements, farmers can identify cases of FPT and take necessary actions to mitigate its impact. Understanding the link between TPI and calf health, growth, and long-term productivity can guide farmers in optimizing their calf management practices. Continual research and monitoring of TPI in dairy operations will contribute to the overall success and sustainability of the dairy industry.

For additional information or to discuss how to implement a program to monitor the transfer of passive immune or colostrum management on your farm, please do not hesitate to contact Michigan State University Extension / Dairy Team personnel.

This article was written as part of a collaborative program of Michigan State University Extension and the Cornell Cooperative Extension SWNY Dairy, livestock and field crops program.

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