Most of the time, we veterinarians, being scientists, are careful to make recommendations that do not imply certainty.
    For example, we might say using a particular vaccine is a good idea or that a particular management practice has been shown to be helpful. We are not trying to be wishy-washy; science just works that way. Certainty is rare in biology. However, sometimes the evidence is so overwhelming that we might say, “You need to do this.”
    The other day, while reading an article about feeding a second dose of colostrum (Cullens & Abuelo) in Hoard’s Dairyman, I had a you-need-to-do-this moment.
    The article was about a study comparing calves fed one meal of colostrum with calves fed a second meal a few hours later.    
    The study was done on a large dairy in Michigan and included over 4,000 calves. It was published in a peer reviewed journal named Animals in 2021. What caught my eye in the article was that calves receiving a second dose of colostrum 5-6 hours after the initial meal gained 0.24 pounds more per day through weaning and produced 2,165 pounds more milk in their first lactation than calves receiving one 3-liter meal at birth. That is around $400 more gross income in first lactation milk sales for feeding 3 liters of free colostrum. It is also highly likely, based on studies of calf growth rates and later milk production, that this production effect carries over into future lactations. That is a remarkable return on investment. So yes, if you are not feeding an additional dose of colostrum at the next feeding now, you need to do this.
    There were other benefits too. Calves getting an additional dose were two times less likely to get respiratory disease, three times less likely to get diarrhea and 2.3 times less likely to get any disease before weaning. Mortality was not lower for calves getting three doses, but the overall mortality before weaning was very low (1.6%), so it is likely that excellent calf management may have prevented any effects on mortality.
    What are the reasons for better performance? Some may be due to less failure of passive transfer in calves fed two meals (9.4% failure for two meals versus 22% failure for one meal), but this is not the whole picture. The authors speculate that other bioactive compounds in colostrum may play a role.  
    In addition, a previous study showed the optimal range for total protein in calves was 6 to 8.5 and higher in Jerseys. In that study, FPT prevalence was very low, so FPT was not likely the cause of differences. Clearly, there are other reasons for better health and performance than just the prevalence of FPT.
    Here are some other findings from this study.
    Calves fed one feeding that developed diarrhea developed it on an average age of 2 weeks compared to an average of 4 weeks for calves supplemented with two meals. Calves that develop diarrhea in the first two weeks of life are often more difficult to cure than older calves, so this is an important finding.
    For calves developing respiratory disease, one meal fed calves were first diagnosed at 5 weeks versus a diagnosis at 10 weeks for the two meal fed calves. Because we know that pre-weaning growth is important to maximize future milk production, delaying the onset of respiratory disease until after weaning is likely also important.
    Calves were housed in individual pens in a barn until day No. 7 when most of them were moved to an automatic feeder barn. Some calves remained in individual pens and were fed with buckets. Calves in the auto feeder barn were 2.7 times more likely to be diagnosed with respiratory disease than the individual penned calves. This is interesting because the comparison was between groups of calves that were both housed in a building. This suggests that group housing, or sharing a nipple or waterer, likely is a significant risk factor for pneumonia, not just air quality.
    In contrast, group fed calves were only 1.3 times more likely to experience diarrhea than individually-housed calves. This may seem counterintuitive, but we have seen similar results on farms in our practice. Auto feeder barns typically result in a much greater prevalence of pneumonia but less so for diarrhea.
    Our practice has seen great results on farms that feed a second dose of colostrum. Such farms can achieve total serum proteins of over six in nearly all calves tested. That additional dose is clearly important, so if you are not doing it now, you need to do this.
    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.