Veterinarian View | September 2025

Rethinking Preconditioning Programs for Calves

contributed article by Dr. Vince Collison, Collison Embryo and Veterinary Services,

Rockwell City, Iowa

collisonembryoservices.com 

It is that time of year where we are starting to do preconditioning work on calves to prepare for weaning. Last month, I wrote an article about “Less is More” and feel that this can also apply to preconditioning as well.

For many producers, you are locked into certain vaccination requirements if you are trying to produce calves for the Iowa Green Tag or Gold Tag programs. But if you are not locked into a branded vaccination program, you can have some leeway to simplify your preconditioning program.

Evaluate Protocols

We have many more vaccine options available to us every year and I feel producers often feel they need to keep adding more vaccines to keep the calf health high. The problem I’ve seen is that you can give so much vaccine that you are just blitzing the immune system to the point where your calves are at higher risk of having reactions or poor responses due to receiving too many antigens at once.

I think the question we need to ask is, “What is the main problem I’m trying to prevent in my calves?” At weaning time, for most of us, it will be Bovine Respiratory Disease (BRD). Control for BRD can be as simple as a single injection of a 5-way viral vaccine combined with a Mannheimia haemolytica toxoid.

One other thing you will want to control is internal parasites. Parasite control at preconditioning can help reduce the suppressive effects of internal parasites and add substantial bloom to the calves by the time they are weaned and help the calf respond better to the vaccines that are given. This would be a basic program I would recommend for someone wanting to vaccinate 2 to 3 weeks prior to weaning.

Vaccination Protocols

At weaning we like to follow up with just a single injection of a 5-way viral vaccine. The main reason we like to booster the 5-way viral vaccine is for protection against BRSV. BRSV is more difficult to vaccinate against, and a booster will greatly improve the response to vaccine.

We have recommended this program to many and have had good results with it. By keeping it minimal, your calves will get what they need to prevent post-weaning BRD and keep vaccine stress to a minimum and response to vaccine antigens high.

Parasite Protocols

Along the lines of parasite control, it would be good to feed a coccidiostat during the first 3 to 4 weeks after weaning. Coccidia often will be associated with BRD outbreaks and control during this time is important for the prevention of BRD.

We will sometimes get some producer resistance to treating for internal parasites prior to weaning, since the cows are not also getting treated at the same time and calves will still be on infested pasture for 2 to 3 more weeks. Our feeling is that the bloom up that calves will experience after parasite treatments will better prepare them for weaning as well as help to improve their response to the first round of vaccine.

Other Vaccine Considerations

We left out Clostridial vaccine in the preconditioning program listed to help reduce vaccine stress and to simplify the program for BRD prevention. Clostridial vaccines can really heat up calves and it has been shown that calves that receive 7-way Clostridial vaccine will lay around considerably more over the next 2 to 3 days than the calves that didn’t receive the 7-way vaccine.

I’ve had reports from some of our clients stating that they’ve really seen calves get setback after using a 7-way vaccine on their calves. Also, many calves have already had a Clostridial vaccination during the neonatal period or just prior to going to grass.

There are many other vaccines available for various respiratory diseases such as Corona virus, Mycoplasma bovis, and Histophilus somnus. These vaccines should be tailored to the individual herd’s needs and may or may not be needed. They can be more complicated to implement and take away from the simplicity of the program listed earlier. Often these vaccines will be better implemented prior to the preweaning program. It is important producers work closely with their herd veterinarian prior to weaning to develop a program that works the best for their herd.

Your nutrition, environment, and overall herd health are some of the many factors that can affect what you do for your herd and how well they respond. Advice from your herd veterinarian is the best way to help assess your program and determine what is best for your herd.

learn more www.collisonembryoservices.com 

Dr. Vince Collison is co-owner of Collison Embryo and Veterinary Services PAC

in Rockwell City, Iowa.