During the development of the calf in the dam’s body, maternal antibodies cannot be passed on to the foetus via the placenta in ruminants. Thus the calf is born without antibody protection and is unable to form antibodies of its own for several weeks.
The transport of antibodies (immunoglobulins) from blood serum to the mammary gland begins several weeks before parturition, reaching a peak before calving and are passed on after birth in the colostrum to the calf. These antibodies are of vital importance providing passive immunity to the newborn calf that does not have a fully developed immune system and is vulnerable to infection and disease from the environment.
The extent of passive immunity is decided in the first few hours of the calf’s life and the reasons for this are as follows:
- The largest number of antibodies is secreted in the first milk and the immunoglobulin content of subsequent milkings decreases rapidly. The second milking only has 50% of the antibody content of the first milk and on the third day after birth the composition is almost that of normal milk.
- The highest concentration of antibodies in the colostrum is immediately after calving and unnecessary delays in milking the cow thereafter will result in lower concentrations e.g. +/- 20% reduction in milking six hours after calving.
- The highly permeable gut lining allows for maximum antibody uptake through the calf’s intestinal cell walls at birth (100%) and begins to close after birth (50% after six hours and 33% after eight hours). Although the intestinal wall does not absorb any antibodies 24 hours after birth, feeding colostrum will still have a beneficial effect in the intestines.
In addition to providing antibodies which are vital to help protect the newborn calf, colostrum also contains high levels of protein, energy, lactose, vitamins and minerals, making it a concentrated nutritious feed.
The immunoglobulin content of colostral milk depends on a number of external factors such as; breed, immune status of the dam, parity, environmental temperature, length of the dry period, dry cow nutrition, quantity produced, mastitis, processing and storage.
There are three methods for assessing the Immunoglobulin-G (IgG) quality of colostrum on farm:
- Colostrometer – colour coded scale distinguishing between three classes of IgG
- Refractometer – measures total serum blood protein (highly correlated to IgG levels)
- BRIX Refractometer – measures solids content (closely correlated to IgG concentration)
High quality colostrum is indicated by 50mg/ml or more of IgG using the Colostrometer. Typically, the total volume of colostrum required is 10% of birth weight and varies between 2 to 4 litres per calf for the first feed. Colostrum should provide a minimum of 200 g of IgG per calf within the first 6 to 8 hours of birth e.g. feeding 4 litres of colostrum with a quality of 50mg/ml provides 200g of IgG to the calf in that feed. Evaluating your colostrum quality is the difference between success and failure of passive immunity to the newborn calf.
Not only does the highly permeable gut lining allow for maximum antibody uptake in the first 24 hours, it has the disadvantage that other molecules can pass into the bloodstream such as pathogens and toxins. Colostrum should be harvested from healthy cows once the udder has been sanitised and collected, stored and fed in clean/disinfected vessels/equipment to prevent contamination. If colostrum is not fed straight away, it should be frozen or cooled as quickly as possible to prevent bacterial contamination. Frozen colostrum should be thawed slowly using a warm water bath as overheating can destroy antibody effectiveness.
The following principles of colostrum management should be considered:
- Quality: the target is > 50g IgG/L of colostrum
- Quantity: four to six litres within the first 24 hours following birth
- 150 – 200g of IgG intake
- Quickly:
- Milk dam and feed calf within 1 to 2 hours after calving with a maximum delay of 6 hours
- Quite Clean:
- Bacterial count < 100 000 cfu/ml
- Faecal coliforms < 10 000 cfu/ml
- Quantify:
- 10 g/L Serum IgG
- 5.1 g/dL Serum Total Protein 8.1% Serum Brix
- Geiger et al. (2020)
Usually, maternal colostrum is an adequate source of protection and nutrition for the newborn calf, however, there are instances when this is not possible e.g. poor quality, inadequate quantity produced, presence of disease (Johne’s) and an alternative such as a colostrum supplement or replacer needs to be considered.
Fresh Start® Premium Calf Colostrum is a complementary, easy to mix feedstuff for new-born calves designed to complement or replace maternal colostrum.
Benefits include:
- Effective, convenient, and consistent supply of IgG in each feed
- Enhances poor or moderate quality colostrum
- Balanced colostrum supplement with essential protein and energy from easily digestible sources
- Proportion of colostrum from natural freeze-dried sources, helping reduce potential competition from other non-colostrum sources
- Product scanning of colostrum proteins ensures levels that are of high standards.
- Supports establishment of a healthy immune system
- Pro-Zest Formulation: soluble ingredients, enriched with digestible fats, natural anti-oxidants and prebiotics
- Certified EBL, IBR and Johne’s free.
For further information on colostrum testing or management on your farm, contact your territory manager.