Achieving early and adequate intake of high quality colostrum is the single most important management factor determining calf health. While feeding 3 to 4 quarts of clean, high quality maternal colostrum within a few hours of birth remains the gold standard, farms can experience periods when an adequate supply of high quality fresh or stored maternal colostrum is not available, or producers may discard colostrum from cows testing positive to such pathogens as Mycobacterium avium ssp. Paratuberculosis(Johne's disease agent). Under such circumstances, feeding a colostrum supplement (CS) or colostrum replacement (CR) product offers a simple, consistent and convenient means of delivering necessary immunoglobulins (Ig) and nutrients to newborn calves while reducing the risk of pathogen exposure.
Colostrum supplements versus colostrum replacements
Colostrum supplements, costing $9 to $18 per dose, are designed to provide protective Ig to calves by supplementing poor quality maternal colostrum (colostral IgG < 50 g/L). Most CS provide 25 to 60 g of IgG per dose. Feeding one dose of a CS alone will not provide a sufficient mass of IgG to prevent failure of passive transfer (FPT; Serum IgG < 10 mg/mL). By comparison, CR products, costing $25 to $40 per dose, are designed to be fed instead of maternal colostrum. They must provide a minimum of 100 g of IgG per dose.
Manufacturing and licensing
Immunoglobulins in commercial CS and CR products are derived either from spray-dried bovine colostrum or bovine serum. Some products are licensed through the USDA Center for Veterinary Biological Products (CVB) while others are not. CVB-licensed products must contain IgG from bovine colostrum collected from Grade A dairies, are processed using accepted protocols, and undergo regular purity, potency, and efficacy testing. Samples from every lot are tested at a central USDA laboratory and annual site inspections are conducted. Non CVB-licensed CR or CS products may contain colostrum- or serum-derived globulin proteins, are not legally able to claim to be used for prevention of FPT, and fall under Association of American Feed Control Officials guidelines. Manufacturers of non-CVB licensed products will conduct internal quality control testing, but testing details will be at the manufacturer's discretion.
Evaluating the performance of colostrum replacement products
Achieving adequate serum IgG concentrations (≥ 10 mg/mL) will be primarily determined by the dose of IgG (g) fed and the efficiency of IgG absorption into the calf's circulation. A dose of 150 to 200 g of IgG must be fed to consistently achieve acceptable passive transfer rates. While most CR products provide 100 to 130 g IgG per dose, some newer products now provide a larger mass of IgG per dose or provide label directions that suggest feeding increased masses of IgG. Studies have demonstrated that several commercially available CR products, when fed at a high enough dose (150-200 g IgG) within a few hours after birth, can provide acceptable-to-very good serum IgG concentrations in calves (Goal: ≥ 90% of calves with serum IgG ≥ 10 mg/ml). However, not all products have proven to be equally efficacious. Producers are encouraged to select products that have undergone independent evaluation of efficacy in controlled field studies. The product manufacturer can be contacted to provide information on whether efficacy studies have been completed and to provide study results. Alternately, a review of CS and CR study results conducted before spring, 2013 is reported in the 5th edition of the textbook Large Animal Internal Medicine (2014).
Monitoring passive transfer rates when feeding CR or CS products
Measuring serum total protein (STP) concentrations by refractometer offers a rapid and inexpensive method to monitor the colostrum program. For calves fed either maternal colostrum or a colostrum-derived CR product, a STP test cutpoint of 5.0 or 5.2 g/dL most accurately predicts adequacy (a serum IgG value of 10 mg/mL). However, for serum-derived CS or CR products, the relationship between STP and serum IgG in calves varies widely among products (between 4.2 and 5.4 g/dL), depending on the source, level of inclusion, and/or degree of absorption of non-Ig proteins. Given this variation in predicted STP cutpoints, producers using serum-derived CR products should use refractometry to monitor the effectiveness of the CR feeding program only if studies are available describing the relationship between STP and serum IgG for the specific CR product in use on the farm. If such studies are not available, then the herd veterinarian should periodically submit frozen serum samples for direct serum IgG analysis using laboratory methods such as radial immunodiffusion or enzyme-linked immunosorbent assay.
High quality CS and CR products offer a consistent and convenient source of Ig for newborn calves for when clean, high quality maternal colostrum is not available, plus may be a useful management tool to help break the transmission cycle of some infectious diseases (e.g. Johne's disease). When fed a large enough dose (150 to 200 g IgG) of a high quality CR product within a few hours after birth, calves can achieve at least equal passive transfer levels and health outcomes as compared to feeding 3-4 quarts of high quality fresh maternal colostrum. Given the significant differences in performance among various products, producers are encouraged to select CR or CS products that have demonstrated efficacy in independently conducted controlled field studies.