Animal health matters: A new look at colostrum monitoring

Russ Daly Special to the Farm Forum
Farm Forum

When I mention, “baby calf health,” what word comes to mind? I bet many of you would say “colostrum.” Dairy and beef producers have had the importance of colostrum drilled into their minds for a long time, and rightfully so.

Calves and other farm animals are born without a full tank of antibodies in their systems. Their mothers’ placenta doesn’t allow for antibodies to pass from the mother’s bloodstream to the fetus. Until the newborn calf can begin making these on their own (weeks or months later), they’re completely dependent upon getting that dose of antibody-rich colostrum in their first hours of life.

Antibodies are remarkable and critical components of the immune system. They’re made by certain white blood cells and are exquisitely specific for the germ against which they were made. They’re one of the quickest ways for the body to combat disease-causing germs. They latch onto bacteria and viruses, tagging the germs for removal by other immune system cells or blocking them from unleashing their harmful effects.

Since newborn calves don’t come pre-loaded with these antibodies, mother nature has devised an extraordinary workaround. Antibodies from the cow are selectively pumped into the udder and into colostrum, which becomes a concentrated source of those disease-preventing molecules. Good colostrum is a rich mixture of all the antibodies resulting from the cow’s lifetime exposure to farmyard germs and vaccines (as well as other potent nutritional and immunity factors).

While we understand colostrum’s importance for early-life disease prevention, we’re also finding longer-term benefits. First-lactation milk production, reproductive performance, and weight gains in the feedlot are all better in animals that received sufficient colostrum as babies. This is probably due to better prevention of inapparent disease that silently robs the animal’s health and production.

Fortunately, we don’t have to guess whether we’re doing a good job of ensuring our calves get adequate colostrum. A blood sample taken from a young (less than a week old) calf can be tested at the lab for antibody levels, indicating how much was absorbed into the calf’s system from colostrum. This, however, isn’t very handy as it needs to be done at a laboratory. Total serum protein, which can be measured on the farm or in the vet clinic with a refractometer, is a very good proxy for antibody levels.

Dairy and beef producers have been familiar with the cutoff point for serum protein levels separating a calf that obtained “sufficient” colostrum from one that did not. That point, based on past research, is 5.2 grams per deciliter (g/dL). That’s not to say that every calf below the line is doomed, nor that every calf above the line is home free; health and disease are influenced by factors besides colostrum, too. Serum protein is best used as a general guideline for overall colostrum management, rather than as a prognosis for an individual calf.

That cutoff has served us well, but as more research accumulates, we’ve come to realize it’s a pretty blunt tool. Most significantly, we’ve found that calves with serum proteins significantly higher than the cutoff have even lower illness rates compared to ones just over the cutoff. In addition, dairy and beef producers have been doing a better job with colostrum management, making the former cutoff level less useful. As an example, a beef herd we did a project with a couple years ago showed an average of 6.3 g/dL in their calves.

The result of these observations and research is the development of a new set of guidelines by dairy calf experts. Instead of just one cutoff, the new guidelines for passive transfer are broken into poor (less than 5.1 g/dL), fair (5.1 – 6.1 g/dL), good (5.8 – 6.2 g/dL) and excellent (over 6.2 g/dL) serum protein levels. Dairies and beef operations should shoot for having 40% of their calves in the “excellent” group and less than 10% in the “poor” group.

Monitoring calves for their absorption of colostral antibodies is a great tool for investigating health problems in dairy, as well as beef operations. When problems are identified, operators can work with their veterinarians to modify the quantity, quality and timing of colostrum delivery in their calves.