Colostrum and calves seems like an old topic. Good-quality colostrum fed to calves shortly after birth leads to passive transfer of immunity. Have you heard this before? Of course – but the old book on colostrum may be getting a new chapter. Colostrum is now being looked at as not just a source of antibodies but as a source of many nutrients and immune components.

President / DAY 1 Technology, LLC
Hayes is a veterinary consultant with Day 1 Technology, based in Winona, Minnesota.

Why have researchers in the past focused on antibody levels in colostrum? Because antibody levels are simple to measure and easy to understand.

The typical calf is born with no circulating antibodies, and when colostrum is fed, these antibodies pass from the intestinal tract into the bloodstream, and after 24 hours of life, we can pull a blood sample and measure the transfer of maternal antibodies.

These research-based numbers can then relate successful passive transfer of antibodies to better health, improved growth and feed efficiency, and eventually, increased milk production. Is there a need to look at anything else? When there are research dollars available, the answer is “absolutely.”

I am sure you have heard that there is up to 40 percent failure of passive transfer in calves, but yet the death loss of pre-weaned calves is less than 10 percent. If passive transfer is not achieved, how are these calves surviving?

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Good management, pathogen control and proper nutrition are certainly part of the survival story, but there may be parts of the immune system we have ignored when we only talk about antibodies.

The immune system is a very complex (this is an understatement) topic, but we do know a few things. First, the immune system is capable of working without antibodies. This is the innate immune system at work. Second, the immune system uses energy to do its job.

This leads us to the first item in colostrum worth talking about: energy. There are two major sources of energy in colostrum and milk. These are lactose (sugar) and fat. Colostrum has excellent levels of fat and lowered levels of lactose.

This is probably for two reasons. Fat is more concentrated in energy, and lowered lactose levels will keep bacteria from growing on a ready source of energy. More energy for the calf and less energy for bacteria seems like a good combination for calves surviving.

Feeding colostrum to a newborn calf is good for the antibodies, but do not underestimate the power of the energy that comes with that feeding.

The next item being discussed in colostrum feeding are the non-antibody proteins. This is where current and future research will be focusing on colostrum. There are many such proteins. Some of these are:

• Cytokines such as interferon and Interleukin-6

• Growth factors such as IGF-1 and IGF-2

• Hormones such as insulin, cortisol, thyroxine and relaxin

What do all of these proteins do? It is hard to know all of the intricacies, but it is a good bet they are helping to prime the immune system for what the newborn calf will be seeing in the coming days, weeks and months. This priming of the immune system may be occurring with or without antibodies.

Another item to mention in relation to colostrum are the maternal white blood cells that are present. These cells can be absorbed by the newborn calf and start circulating in the bloodstream. This is all achieved when fresh colostrum is ingested by the newborn calf.

How do these active white blood cells interact with the newborn calf? Once again, it’s hard to know the full story, but there is no doubt some positive interaction of these cells on the newborn calf’s immune development or early disease protection system.

The final aspect of colostrum to discuss is simply the volume and liquid of the colostrum being fed that helps to hydrate and jump-start all the organs to start working.

The calf has been enjoying the past nine months flipping and turning in a very well-protected hot tub called the uterus.

Life has changed, and now the calf is on its own, and all the organs including the intestinal tract need to start working and nourishing the calf on its own without the cow to help.

The simple first feeding of colostrum will start the hydration process and get the liver and kidneys to start functioning. Seem simple? Yes, but only simple if colostrum is actually fed to the calf.

Colostrum research in the future will continue to discuss and detail antibody content and the importance of passive transfer, but we can look forward to learning more about how the “other” components in colostrum are valuable and may prove to be just as important as the antibody levels we have been talking about for such a long time.

It is exciting to see such new developments on the concept of colostrum feeding to calves. In the meantime, keep feeding colostrum for the antibodies, but rest assured that the other components found in that colostrum will be working as well. PD

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Stephen Hayes
DAY 1 Technology, LLC