What is it?

Colostrum or “first milk” is produced in the initial secretions of the mammary gland following the birth of offspring. Colostrum is most commonly distinguished from whole milk because it contains high concentrations of immunoglobulins (Ig), otherwise known as antibodies. Antibodies are proteins which function to identify and destroy disease-causing pathogens in livestock. Colostrum is also a vital source of growth factors and nutritional elements such as protein, fat, milk sugar, vitamins and minerals.

Why is Colostrum Important?

Transfer of maternal antibodies across the placenta to the fetus does not occur during pregnancy in cattle. For this reason, calves are born with limited resistance to disease. Colostrum is important because it provides calves with passive immunity until their immune systems are developed and able to actively produce antibodies in response to infection or immunization.

The main classes of antibodies present within colostrum are IgG, IgM and IgA. Each antibody differs in structure as well as responsibility. IgG, colostrum’s most predominant antibody, functions to identify and demolish pathogens found within the bloodstream as well as other parts of the body. IgM recognizes and destroys bacteria solely entering the blood. IgA acts by fastening to membranes that line various organs, such as the intestine, and prevents pathogens from attaching and causing disease.

Research indicates that calves obtaining sufficient levels of antibodies from colostrum are less susceptible to sickness and death caused by common infectious diseases including septicemia, diarrhea and respiratory illness. Since colostrum is rich in nutrients it is also a superior source of energy, protein, vitamins and minerals. Calves utilize fat and lactose from colostrum to instigate heat production and maintain a constant body temperature. Vitamins and minerals are also important to initiate metabolism and possibly assist in the development of the digestive system. Non-nutritive components of colostrum such as growth factors aid to develop and mature the digestive system.

Factors Influencing the Success of Colostrum Feeding

The success of passive transfer of immunity via colostrum to new-born calves is mainly dependent on three factors: quality of colostrum, quantity of colostrum and timing. Colostrum quality is directly linked to it’s concentration of antibodies. Quality is always greatest the first-milking post-calving. Second or later milkings of colostrum contain significantly lower Ig concentrations because Ig transfer from the bloodstream of the dam into the mammary gland typically stops by the time of calving. For this same reason, cow’s leaking milk pre-partum may have considerably reduced colostrum Ig concentrations. Antibody concentration of colostrum is also a function of breed type and lactation number. Beef cows typically have higher Ig concentrations in colostrum than dairy cows. Additionally, older cows generally produce elevated concentrations of antibodies compared to first-calf heifers since they have been exposed to a greater number of pathogens in their lifetime.A critical mass of 100 to 200 grams of Ig must be ingested and absorbed by the new-born calf to attain passive immunity. Accordingly, calves should consume a minimum of 2 litres of colostrum within their first hour of life followed by an additional 2 liters over the next 6 to 12 hours. Timing of colostrum intake is critical because the intestines ability to absorb antibodies declines as the calf ages. Intestinal absorption progressively lessens after 12 hours of age and complete gut closure typically results after 24 hours.

Natural suckling to accomplish passive transfer of immunity from dam to calf can be relied on in beef cattle unless some condition exists that is likely to decrease the success of this process. If vigorous active nursing has not started within 2-3 hours of life, every effort should be made to supplement new-born calves with the best source of colostrum via bottle or tube feeding.

Alternative Sources of Colostrum for the Beef Calf

It is best to have colostrum on hand from your own herd if possible, since using colostrum from other herds raises biosecurity issues as well as differences in antibody concentrations. It is important to know the operation and their health management strategies before using their colostrum. Colostrum replacement products are available in the event that colostrum can not be collected quickly. Regardless of which product you are feeding, it is important to remember that colostrum replacer must deliver at least 100 grams of IgG for absorption to the new born calf.

Storing Colostrum

Colostrum that is not fed within 2 hours of collection should be refrigerated to control bacterial growth. Refrigeration at 4 degrees C in plastic containers maintains the viability of antibodies and other components of colostrum for up to 7 days. For long term preservation, colostrum can be frozen for up to one year with little nutrient loss. The best method for storing colostrum in the freezer is in 2 litre stackable, plastic containers or freezer bags (be sure to double bag). Thaw colostrum slowly in warm water (38 degrees C) to preserve quality. Rapid thaw can damage and reduce the efficacy of colostral antibodies. Colostrum can also be thawed in a microwave set on low power. Microwave for short periods of time and constantly pour off thawed portions.

ever pool together colostrum from different cows. This practice, once believed to minimize the effect of low Ig colostrum and increase volume available to calves, has a negative effect on the acquisition of immunity. It also increases the likelihood of disease transmission to calves because multiple cows are represented in a single feeding.


Besser, T.E. and Gay, C.C. 1994. The importance of colostrum to the health of the neonatal calf. Vet Clin Food Anim. 10: 107-117

Blomquist, N. 2008. The importance of colostrum for calves – frequently asked questions

Kopp, J. 2007. Colostrum and milk replacers: Cattle production for women seminar

Lang, G. 2008. Factsheet: Colostrum for the dairy calf

McGuirk, S.M. and Collins, M. 2004. Managing the production, storage, and delivery of colostrum. Vet Clin Food Anim. 20: 593-603

Petrie, L. 1984. Maximizing the absorption of colostral immunoglobulins in the newborn dairy calf. The Veterinary Record. 114: 157-163

Prepared by
Kristen Bouchard
Animal Nutritionist
Manitoba Agriculture, Food and Rural Initiatives