Understanding Passive Verse Active Immunity

Posted by Tomlyn on Dec 14th 2016

Adequate immunity in calves is critical to ensure continued growth and development. Understanding the two types of immunity and ways to support both promotes thriftiness in herds large or small.

Active immunity is that derived primarily from vaccination. It is the introduction of an antigen (usually a bacteria) through an injection to stimulate the calf’s immune system to produce antibodies. Vaccination with specific disease-causing organisms promotes the production of adequate levels of protection within the calf’s immune system, supporting health when the animal is challenged by these organisms in nature. Think of the antibody as a “key” fitting into the “lock” of the disease-causing agent. Once the key is in the lock, the bug is inactivated. Active immunity can also be derived from natural exposure to organisms as the calf grows and develops.

To bolster active immunity, make sure the vaccines being used are protective against diseases common to your area. Make sure vaccines are stored properly and administered appropriately. The response to a vaccine depends on proper administration into animals that are healthy and free of excessive stress. Humane handling and care of your animals during the vaccination process will support a strong response to the vaccine.

Passive immunity is that derived from the delivery of pre-formed antibodies into the calf and provide short-term protection. Ingestion of colostrum (“first milk”) from the dam by the calf within the first 12 hours of life represent classic passive immunity. The colostral immunoglobulins (antibodies) can only be absorbed by the calf during these first 12 hours of life. After that, the ability of the calf to absorb these large molecules is no longer possible and the calf must then rely on its own immunity (and future active immunity). Failure of passive transfer (or failure to receive adequate colostrum) significantly compromises the survivability of the calf. The calf is dependent on this immune protection for the first two weeks of life.

To ensure adequate passive immunity is received, make sure the dam has been appropriately vaccinated prior to delivery of the calf. It is these vaccinations (active immunity) that produce antibodies that will ultimately be transferred through the colostrum to the calf. Make sure her udder and teat confirmation are satisfactory to allow the calf to nurse adequately. The cow’s body condition should be satisfactory to produce good quality colostrum and moving forward, milk. Make sure the calf has nursed aggressively within the first 12 hours of life. If there are any doubts, consider administration of a commercial colostrum product, or frozen colostrum from a dairy, through tube feeding during this period. 

Another form of passive transfer now available to support a calf’s immunity is through egg proteins. Chickens are now being custom vaccinated to specific disease-causing organisms important to the health of calves. The antibodies produced are concentrated in the yolks of the egg and can be processed and packaged in powder form. These bird antibodies do not react with the cow antibodies and provide additional immune support for the calf. Tomlyn’s EPIC line of products utilize this technology in the three products for the calf: one for the newborn, one for scouring calves, and one for those calves needing additional electrolyte support. While not a replacement for adequate passive transfer, the EPIC products provide additional support and “fill in the gaps” where additional immune boosting is needed.