Colostrum management: An important part of mitigating disease in dairy calves

By Dr. Cynthia Miltenburg on behalf of the Ontario Animal Health Network

The importance of colostrum for newborn calves cannot be underestimated. There have been countless studies, articles, and presentations on the integral role it plays in calf development, yet there remain challenges to ensure we meet our targets in a way that provides calves with optimal protection without additional risk of disease.

Colostrum is the only source of early immunity for calves because immune protection cannot be transmitted across the placenta. When colostrum is provided from the dam to her own calf, it provides targeted protection for the pathogens in that herd. In addition to providing essential immune active substances, colostrum is rich in fat and protein and is the calf’s first source of nourishment.

Firstly, an appropriate colostrum program involves feeding calves three to four litres (depending on breed and size) promptly after birth. Ideally this should occur within the first hour, but no later than six hours, after birth. The quality of colostrum, which refers to having a high concentration of immunoglobulins AND a low concentration of bacteria, is also important. Lower immunoglobulin concentration can be associated with younger dams, a short dry period, or cows who have suffered from illness, heat stress, or leaking prior to calving. Colostrum can easily be tested on farm to verify its quality with a Brix refractometer. Guidelines recommend feeding colostrum that measures ≥ 22 per cent. Finally, it’s important to collect and feed colostrum in a hygienic manner which includes collecting from a clean udder prepped as for milking, and utilizing properly cleaned and disinfected buckets, bottles, nipples, and feeding tubes to avoid bacterial contamination during harvest or delivery.

While the feeding of colostrum can provide targeted protection against disease, there are also some diseases in the cow herd that can be transmitted to the calf through the colostrum if they are present in the adult cows. This makes colostrum delivery a risk factor for infecting the calf. Some pathogens that can be shed directly into colostrum and passed to the calf include Mycobacterium avium paratuberculosis (MAP), the causative agent of Johne’s Disease, Salmonella Dublin (SD), and bovine leukemia virus (BLV). These pathogens and others such as E. coli or other Salmonella species may also contaminate colostrum from manure and the environment. While producers are undertaking efforts to reduce these diseases in their herd, refining their colostrum delivery program is an important part of the long-term plan. In addition to the risk of transmitting disease, the presence of pathogens in colostrum can interfere with the absorption of colostral antibodies.

Pasteurization is an established method to reduce microorganisms and reduce bacterial contamination of milk. Pasteurization of colostrum is a more sensitive procedure because we need to preserve the antibodies while also reducing pathogen load. Over the last decade, important research has been conducted on how to best achieve this. What we have learned is that the protocol used is critical to avoid ruining the colostrum. On average, the bacterial load can be reduced without reducing immunoglobulin concentrations by heating bovine colostrum to 60°C for 30 to 60 minutes. Given this difference in protocol from pasteurizing milk, it may be more appropriate to call the colostrum heat-treated rather than pasteurized.

In general, when utilizing a protocol as above, feeding heat-treated colostrum compared to untreated does not affect the immunoglobulin concentration in the serum of calves – most studies show no difference or a slight increase in immunoglobulin concentration in the serum of calves fed heat-treated colostrum. This means that we can still count on calves absorbing the immunoglobulin and receiving adequate immune protection. However, it’s important to note as already mentioned, there are many factors that can affect absorption including volume fed and time of first feeding. These elements of the program remain critical, regardless of whether colostrum is heat-treated or not.

Collectively, studies have shown other calf health and growth benefits including a higher average daily gain, lower prevalence of pneumonia and diarrhea, and lower mortality among calves fed heat-treated colostrum and pasteurized milk compared to calves fed untreated colostrum and milk, even after accounting for successful immunity transfer.

The technology to heat-treat individual colostrum feedings on-farm has improved, making it more practical. Some studies have examined heat treating and feeding individual colostrum from each dam, whereas others use pooled first colostrum from multiple dams that may or may not include the dam of the calf receiving it. From a disease transmission perspective, there are benefits to using single source colostrum and research has shown that absorption may occur differently between these two scenarios. However, from a practical perspective, when colostrum has to be harvested, heated for 30 to 60 minutes and cooled down before feeding, it extends the time to feeding a calf. Therefore, most farms that undertake feeding heat-treated colostrum feed colostrum from a previous dam that calved.

Even with these advances, there are some farms where heat-treating may not be an option. However, changes can still be made to reduce risk of transmitting diseases such as MAP, BLV, and SD from mature cows to calves. As previously mentioned, preparing the udder for milking is important to avoid contamination from manure that may contain these pathogens. Pooling untreated colostrum is not advised, and calves should receive colostrum only from a dam of known negative disease status. Herds can use an annual screening program for MAP or BLV to identify healthy, low risk dams. Colostrum from positive or ill cows should be discarded. For other diseases such as E. coli, rotavirus, and coronavirus that cause calf diarrhea, vaccination of the adult cows during the dry period can maximize the amount of antibodies calves receive against these pathogens in the colostrum.

Since the detection of highly pathogenic avian influenza (HPAI) in lactating dairy cattle in the U.S., there has been much discussion on the safety of feeding untreated colostrum or milk to calves. This is an emerging disease in dairy cattle and there is still a great deal to learn about the transmission risk to cattle, including calves. Dairy cattle with HPAI have been found to have high levels of virus in their milk. Abnormal milk or colostrum (flakes, clots, or gross alteration in appearance) and milk or colostrum from sick or treated cows should always be discarded and not fed to calves. The current recommendation from the Food and Drug Administration in the U.S is that colostrum or milk fed to calves be pasteurized to kill harmful bacteria or viruses, such as influenza, before feeding.

Different herds will have different disease challenges – the herd veterinarian is best positioned to identify the practices that will protect calves and can be feasibly instituted by the herd considering the pathogens of greatest concern, supply of calves, and tools available. These decisions will not only protect calf health in early life, the but the future longevity of the herd.

References available upon request.

The Bovine Ontario Animal Health Network is a group of veterinarians and specialists working in government, university research and laboratory, and in beef, dairy, and veal practice who meet regularly to monitor and discuss disease trends in Ontario. Our goals are to facilitate coordinated preparedness, early detection, and response to animal health and welfare in Ontario. For our recent reports or more information visit