Calves are born into a world filled with bacteria, viruses, and parasites that can cause illness or even death in these young animals. For protection, the body develops an immune system.

“It’s an amazing system that is able to protect the calf on all fronts,” said Amelia Woolums, D.V.M., during the February Hoard’s Dairyman webinar.

While it is quite common for people to believe that a calf is immunodeficient or immunocompromised at birth, the veterinarian and professor at Mississippi State University said that is not really true. “It has a fully functioning immune system the day that it is born,” she said, “but there are factors that influence how well it will work.” Genetics, the dam’s health, housing conditions, and much more impact the development of immunity.

Although the calf’s immune system is functional at birth, Woolums pointed out that many functions are slower and weaker than they are in adult cattle. “It is naïve and immature,” she noted. “Colostrum is nature’s solution to this problem.”

She continued, “I love talking about vaccination, but I do not think you can overcome real problems with adequate colostrum intake through vaccination. Adequate colostrum intake is critical to calf health.”

Woolums said for a long time, the need to simply provide adequate colostrum was emphasized. A few years ago, new research showed that important health gains can be made if calves receive excellent-quality colostrum. Because of this, new colostrum recommendations were released as shown in the table that reflect varying levels of protection versus just one minimum cutoff.

“We used to use 5.2 g/dL of serum total solids as a cutoff for poor-quality colostrum. Now we are aiming for 6.2 g/dL serum total solids (a Brix reading of 9.4%) as the recommended cutoff for excellent passive transfer,” Woolums said. “There are important gains in health, less treatment for disease, and greater weight gain if we have more calves with excellent passive transfer.”

A National Animal Health Monitoring System (NAHMS) study sampled 1,623 heifers in 14 states. The results showed that about 40% of calves had either fair or poor blood antibody concentrations after colostrum feeding.

“We know that excellent transfer of passive immunity can improve health even more than adequate transfer,” Woolums said. “If aiming for excellent passive transfer, there is clearly room for improvement on many operations.”

To learn more about colostrum and vaccination in calves, watch the February Hoard’s Dairyman webinar, titled “Supporting calf immunity for health and growth.” The sponsor for this webinar was Hampel’s Calf-Tel.

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(c) Hoard's Dairyman Intel 2023
February 27, 2023
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