Passive immune transfer in dairy calves

By Isaac Haagen

You will have undoubtedly noticed that I am a new contributor to the University of Minnesota Dairy Connection column. I was recently hired at the University of Minnesota as an assistant professor of dairy production and Extension specialist.

I grew up on a dairy farm in Pennsylvania and received my Ph.D. at Penn State University researching the genetics of dairy calf health. I am extremely excited about this new role and to be working alongside producers and stakeholders in Minnesota and the Upper Midwest.

I like to think of calves and heifers as the foundation of the dairy herd because these animals will eventually replace animals in the milking herd. As such, keeping these animals healthy is often a top concern. However, calves are born without an active immune system and rely on immunoglobulins found in colostrum for passive immunity. Measuring transfer of passive immunity is one of the rst steps a producer can take to ensure their calf program is setting animals up for a healthy start. On farms, refractometers can be used to measure serum total protein and percent Brix because these measurements are highly correlated with the serum immunoglobulins of the calf. However, if you are using a refractometer on your farm, be sure to know what yours is measuring because refractometers are calibrated for either serum total protein or percent Brix.

Researchers at Penn State and the University of Minnesota studied transfer of passive immunity in Holstein calves on organic dairy farms. Brad Heins and I were included in this research group. This was quite a unique dataset as we had more than 7,000 female calves with producerrecorded serum total protein measurements in DairyComp.

One of the areas we were most interested in exploring was the relationship between calf serum total protein and heifer stayability. Stayability represented animals that did not die on-farm and were not culled from the operation; therefore, stayability represented an animal’s ability to remain in the herd. Calves were split into quartiles, or four equal-sized groups, based on their recorded serum total protein concentration. We then looked at the percentage of calves that remained in the herds at 1 year of age within each group. Table 1 shows these proportions.

Calves with the lowest concentrations of serum total protein had the lowest proportion remaining in the herds at 1 year of age: 67%. This was 4 percentage points fewer calves than calves in the highest serum total protein group. This demonstrated that serum total protein measured on-farm by producers is associated with an animal’s ability to remain in the herd. Despite high levels of transfer of passive immunity within these herds, a large proportion of calves left the farms before 1 year of age. This was likely a result of these herds aggressively removing diseased calves.

Table 1:

Stayability by serum total protein group

The group of researchers in this study were mostly geneticists, so we also wanted to determine if serum total protein was heritable and could potentially be used for genetic selection. We found that serum total protein measured in calves was heritable at about 8%. This heritability is similar to health traits that are currently part of national genetic evaluations. Whether serum total protein is ever included in national genetic evaluations is unknown, but demonstrating that we can make genetic progress is an important rst step.

Finally, the timeless adage, “If you don’t measure it, you can’t manage it,” holds true for passive transfer of immunity. In fact, research shows that producers who measure serum total protein have greater transfer of passive immunity. If

Dana Adams, adam1744@umn.edu 320-204-2968

Joe Armstrong armst225@umn.edu 612.624.3610

Luciano Caixeta lcaixeta@umn.edu 612-625-3130

Gerard Cramer gcramer@umn.edu 612-625-8184

Marcia Endres miendres@umn.edu 612-624-5391

Joleen Hadrich jhadrich@umn.edu 612-626-5620

Les Hansen hanse009@umn.edu 612-624-2277 you measure transfer of passive immunity on your farm, keep a record of results for benchmarking. Further, if you use herd management software, like PCDART or DairyComp 305, I encourage you to create an event just for serum total protein or percent Brix. This is a convenient location to store measurements because results can be related to animal health and performance at later dates.

As I settle into Minnesota, I look forward to meeting and working with the producers and stakeholders across the state. Please feel free to contact me at any point.

Brad Heins hein0106@umn.edu 320-589-1711

Nathan Hulinsky huli0013@umn.edu 320-203-6104

Kevin Janni kjanni@umn.edu 612-625-3108

Karen Johnson ande9495@umn.edu 320-484-4334

Emily Krekelberg krek0033@umn.edu 507-280-2863

Claire LaCanne lacanne@umn.edu 507-332-6109

Brenda Miller nels4220@umn.edu 320-732-4435

Erin Royster royster@umn.edu

Isaac Salfer ijsalfer@umn.edu 320-296-1357

Jim Salfer salfe001@umn.edu 320-203-6093

Mike Schutz mschutz@umn.edu 612-624-1205

Emma Severns sever575@umn.edu 507-934-7828

Melissa Wison mlw@umn.edu 612-625-4276

Isaac Haagen hagge041@umn.edu 612-624-7455