One more colostrum study

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There have been a lot of studies regarding colostrum in dairy calves. By now, everyone knows that quantity, quality and timeliness of delivery are critically important for proper absorption of immunoglobulins into the calf’s bloodstream and that adequate transfer is needed for optimal calf health and growth.

Until recently, most experts described the level of IgG or total protein in the calf’s blood as adequate or as a failure of passive transfer. For example, a total protein value of somewhere between 5 and 5.5 was considered adequate, depending on whose standard one was following. In 2020, the recommendations were changed and categories of excellent, good, fair and poor were created. Excellent means a total protein value of greater or equal to 6.2, good means 5.8-6.1, fair means 5.1-5.7 and poor is below 5.1. In addition, a herd standard was created. We now expect more than 40% of calves in a herd to test excellent, 30% to test good, no more than 20% to test fair and less than 10% to test poor. It turns out that, with calf antibodies, more is better. However, do we know that calves with excellent passive transfer do better than good, or that good do better than fair and fair better than poor?

A recent study (Sutter, et. al. JDS 2023) looked at exactly these questions. For the study, researchers assessed 3,434 Holstein calves from a farm in Germany. Total-protein assessment found 4.8% of the calves in the poor category, 29.5% in the fair category, 28.3% in the good category and 37.4% excellent category. Calf health was evaluated for the first 90 days of life and showed 28% percent of the calves had at least one case of pneumonia, 6.3% had diarrhea and 0.9% had a naval infection. Overall, 32.6% of calves had one disease and 2.5% had multiple diseases.

Combining the health data with the total protein results showed that the level of antibody did affect the incidence of disease and death. For example, calves with a poor level of total protein had a greater hazard risk for pneumonia (2), overall morbidity (1.99) and mortality (2.47) than calves in the excellent category. The hazard risk is just the relative risk of developing a disease compared to another animal. For example, a hazard risk of 2 means that the animal is twice as likely to be affected as the other animal. Calves with good and fair total protein levels had significantly greater hazard risk for pneumonia (good 1.35, fair 1.41) and for overall morbidity (good 1.26, fair 1.32) compared to calves with excellent total protein levels.

Calves born with calving assistance had lower total proteins than unassisted calves. Calves from cows with three or more lactations had lower total protein levels than calves from heifers or lactation-two cows. The employee providing calving assistance and neonatal care also significantly affected the total protein levels.

There was also a relationship between average daily gain during the first 60 days of life and total protein status. Calves with excellent and good levels had an ADG of .90 kilograms per day and .92 kilograms per day, respectively. The ADG of calves with fair levels was .89 kilograms per day and of calves with poor levels was .86 kilograms per day.

The study did not show a strong relationship between incidence of diarrhea and total proteins. However, this may have been due to a relatively low number of cases of diarrhea reported.

This study supports the validity of the new passive immunity classification scheme based on four categories. It shows that total protein testing should not be a pass-fail test but instead should have categories of success. Higher levels of antibodies in blood of baby calves means less disease, especially pneumonia in the first 90 days, less overall morbidity and reduced death rates. Thus, farmers can be confident that achieving the standards for levels in those four categories will reduce the levels of disease and death on their farms. Excellent really is better than good when it comes to passive transfer in dairy calves.

Bennett is one of four dairy veterinarians at Northern Valley Dairy Production Medicine Center in Plainview, Minnesota. He also consults on dairy farms in other states. He and his wife, Pam, have four children. Jim can be reached at bennettnvac@gmail.com with comments or questions.

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