It is common knowledge that colostrum or ‘first’ milk produced by dams in the first few days postpartum is critical to the health and vitality of newborn calves. Providing sufficient amounts of high-quality colostrum is one of the primary factors in preventing newborn calf diseases and reducing economic losses. Understanding the various components of colostrum and its important functions can help producers utilize best management strategies to maximize benefits from this essential nutrient.
Colostrum contains over ninety compounds that fight against pathogens and establish immune response (immunoglobulins, lactoferrin, lactoperoxidase); provide nutrients (lactose, lipids, protein); and stimulate growth and generation of nerves, cartilage, bone, and muscle (essential fatty acids, minerals). Compared to mature bovine milk, colostrum contains higher total solids (27.6% vs. 12.3%), higher protein (14.9% vs. 2.8%), and slightly higher fat (6.7% vs. 4.4%) (Christiansen, 2010). The quality and quantity of colostrum produced is affected by breed type, cow age, and nutritional status of the dam. Dairy cows typically produce more colostrum than beef cows, and mature cows produce more than heifers. Feeding energy-deficient diets can significantly reduce colostrum yield. In addition, factors such as temperature stress, dystocia or calving difficulty, and lack of mothering (licking the calf dry after birth) can reduce the ability of the newborn to absorb immunoglobulins in colostrum.
One of the most important functions of colostrum is to deliver immunoglobulins that transfer passive immunity to the calf and enable it to fight off infections for the first three-to-five weeks of life. This is accomplished by absorption of antibodies through the wall of the newborn’s small intestine. For maximum transfer of antibodies, the newborn must receive colostrum soon after birth. Antibody transfer becomes more limiting over the first 24 hours after birth as permeability of the newborn gut is reduced and the concentration of immunoglobulins in colostrum decreases (Figure 1).
Figure 1. Effect of age of calf on the percent absorption of immunoglobulin through the calf intestine.*
*Adopted from Arthington et al., 2008.
The principal colostral immunoglobulin is “IgG,” which is commonly measured in the serum of the calf after birth to determine successful transfer of passive immunity. If transfer does not occur, calves are considered to have “FTP”, or “Failure of Passive Transfer,” which is highly correlated to illnesses such as diarrhea and other more serious diseases, such as colisepticemia, caused by absorption of certain serotypes of E. coli. Generally, calves with serum IgG concentrations of less than 10 g/L are thought to be at higher risk of disease. Calves with severely low concentrations of immunoglobulins typically die within days.
Since some dams do not produce an adequate amount of colostrum, it may be collected from other cows. To ensure that adequate levels of IgG are available, calves should receive 100 to 300 grams of immunoglobulin within the first 12 hours after birth. Because the quality of colostrum is highly variable, it is difficult to recommend an exact amount of colostrum that must be fed in order to provide maximum antibody response. General recommendations are to feed 5-6% of the calf’s body weight within the first 6 hours of birth, and the same amount again at 12 hours. For a 90-pound calf, this amount would be approximately 2.5 quarts of colostrum per feeding. Actual antibody content of colostrum can be determined by using an instrument called a Colostrometer™. Results can be used to determine whether or not the colostrum is acceptable to feed. It is important to collect a clean sample and cool it to approximately 70⁰F prior to taking a reading in order to obtain accurate results.
An ideal source of colostrum would be a healthy older cow from within the same herd. It is important to ensure that colostrum does not contain contaminants, such as blood, mastitis, and bacteria. Colostrum should not be fed from cows that are infected with Johne’s disease. If possible, colostrum should be collected within 24 hours of calving and fed fresh. Alternatively, it can be frozen in one or two quart zip-top freezer bags or freezer-safe containers and used later. Correct thawing is important to prevent the proteins in colostrum from being denatured. Because microwaves often heat unevenly, the recommended method of thawing is to place the frozen bag or container of colostrum in warm water (110⁰ F) and stir every five minutes. The colostrum should be warmed to 104 to 110⁰ F.
It is important to note that a variety of colostrum supplements and replacements are commercially available if quality colostrum is limited. Both supplements and replacements are made from dried bovine colostrum or serum; however, colostrum supplements provide <100 g of IgG/dose and are formulated to be fed in conjunction with natural colostrum, while colostrum replacements contain more immunoglobulins (>100 g of IgG/dose) and also contain digestible proteins, vitamins, and minerals. Multiple researchers have reported acceptable levels of serum immunoglobulins in calves fed various replacer products; however, producers should carefully research products and choose one that has been proven to provide adequate immunity.
Management factors that enhance the development of passive immunity in the calf include proper prepartum nutrition and early assistance with heifers or cows experiencing calving difficulty. Calves born to first-calf heifers that have insufficient colostrum production or those too weak to nurse naturally should be provided with appropriate amounts of colostrum via tube or bottle feeding. Taking the time to ensure that colostrum needs are met can increase calf vigor and survivability and reduce losses from calf deaths.
To continue your colostrum conversation, contact Janna Kincheloe, SDSU Extension Research Associate II.