Research has shown that disease rates for preweaned calves range from 1 percent to 50 percent on farm. Mortality rates also fall in that same range. We also know that heifers that were challenged by disease before weaning often have poor growth, lower milk production and reproduction function, and subsequent health problems later in life.
Maximizing your adult cows’ immune status through good nutrition and a strong vaccination program is the first step toward improving the immune system of the calf. Once you have done that, getting adequate colostrum into the calf becomes key.
Window of opportunity
Because the newborn calf is born without or with very few antibodies, it is very susceptible to systemic infections. Calves lose the ability to absorb colostral antibodies within 24 hours of birth.
I view the calf’s ability to absorb these large protein molecules as if the intestinal tract is a long hallway, with windows that are large enough to allow the antibodies to pass through. Every hour after birth, these windows slowly close. When all of the windows are closed, the calf cannot absorb these protective antibodies anymore.
Newborn calves need 80 to 100 grams of immunoglobin mass to achieve adequate protection. However, when newborn calves are left to suckle cows, they often do not take in enough colostrum. In fact, studies have shown that more than 50 percent of these calves will not have adequate colostrum absorption.
Immediate feeding of high-quality colostrum by bottle or by feeding tube is the only way to ensure adequate colostrum intake and antibody transfer. I recommend 4 quarts of high-quality colostrum within two hours of birth (along with dipping the navel with 7-percent tincture of iodine) and an additional 2 quarts of colostrum at the next normal feeding.
Don’t pool colostrum
Colostrum should be collected from individual cows and never pooled. Once the colostrum has cooled to room temperature, use a colostrometer (or other colostrum-testing tool) to grade its quality. Only samples that test “green” should be used for the first two feedings. If you don’t have enough “green” colostrum for all calves, use the higher quality for heifers and lower quality (yellow or red) for bull calves. Colostrum can be frozen and saved for more than a year without a decrease in quality.
Strict sanitation must be observed while collecting and handling colostrum. Bottles and feeding tubes used to deliver the product must be cleaned after each use.
Two diseases can be transferred from the cow to the calf through colostrum. Bovine leucosis virus and Johne’s disease are both prevalent on many farms. I recommend testing cows at dry off for these two diseases. Colostrum from any cow that tests positive cannot be used in calves unless pasteurized at 140 degrees F for one hour. But pasteurization of colostrum is not easily done. And many times the process produces a thick, yogurt-like liquid that is difficult to feed calves and can clog pasteurizers.
Another option if you are short of high-quality colostrum is the use of colostrum substitutes. Several products are available. Be sure to examine the label for the globulin protein level per dose before using. I have seen products that range from 10 grams to 50 grams per dose. Remember, the calf needs 80 grams to 100 grams to reach protective levels.
You can monitor the immune levels of calves by testing total serum blood protein. Total serum blood protein has historically been used as a quick field test. Protein levels of 5 grams/dl are considered adequate transfer of colostrum. Care should be used to select calves that are not dehydrated, since those calves will give a false high reading. Protein levels are not 100 percent accurate, so periodic lab testing for antibody or IgG levels should be performed, also.
Jim Brett is a practicing veterinarian in