Colostrum
Colostrum, or “first milk,” is the initial secretion produced by the cow’s mammary gland after calving. It is distinct from whole milk due to its extremely high concentration of immunoglobulins (IgG, IgM, IgA)—specialized antibodies that identify and destroy disease-causing organisms.
Colostrum also provides:
- Essential nutrients: protein, fat, lactose, vitamins, minerals
- Energy for thermoregulation
- Growth factors that support early digestive system development
Why Colostrum Matters
Unlike some species, cattle do not transfer maternal antibodies across the placenta, meaning calves are born with virtually no disease resistance.
Colostrum delivers passive immunity until the calf’s own immune system becomes functional.
Colostrum delivers passive immunity until the calf’s own immune system becomes functional.
Roles of Major Antibodies
- IgG: Primary antibody; provides systemic protection throughout the body
- IgM: Early defense against bacteria entering the bloodstream
- IgA: Protects mucosal surfaces (e.g., gut lining) by preventing pathogen attachment
Adequate absorption of colostral antibodies reduces illness and death from:
- Septicemia
- Scours (diarrhea)
- Respiratory disease
Key Factors for Successful Passive Transfer
Passive immunity depends on colostrum quality, quantity, and timing.
1. Quality
High-quality colostrum contains a high concentration of antibodies.
- Best quality: First milking after calving
- Each subsequent milking contains significantly lower Ig concentrations
- Risk factors for low-quality colostrum:
- Pre-calving milk leakage
- First-calf heifers
- Dairy breeds (lower Ig levels than beef breeds)
2. Quantity
A newborn calf must absorb 100–200 g of IgG to achieve adequate immunity.
- Feed 2 litres within the first hour, followed by another 2 litres within 6–12 hours
3. Timing
Antibody absorption declines rapidly with age:
- Reduced absorption after 12 hours
- Gut closure occurs by 24 hours, after which antibodies cannot be absorbed
Assisted Feeding
Natural suckling is usually sufficient in beef cattle.
Intervene if the calf has not nursed within 2–3 hours, using bottle or tube feeding with high-quality colostrum.
Intervene if the calf has not nursed within 2–3 hours, using bottle or tube feeding with high-quality colostrum.
Alternative Colostrum Sources
If dam colostrum is not available:
- Use herd-sourced colostrum when possible (better herd immunity match, lower biosecurity risk)
- Only use outside-herd colostrum if the donor herd’s health status is known
- Colostrum replacers are acceptable substitutes but must provide ≥100 g IgG per feeding
Storing Colostrum
Proper handling prevents bacterial growth and preserves antibody effectiveness.
Refrigeration
- Store at 4°C for up to 7 days
Freezing
- Freeze for up to 1 year with minimal nutrient loss
- Best stored in 2‑litre containers or double-bagged freezer bags
Thawing
- Thaw slowly in warm water (38°C)
- Avoid rapid heating, which destroys antibodies
- Low-power microwave thawing can be used carefully in short intervals while mixing
Important
Never mix colostrum from multiple cows.
Pooling reduces immune quality and increases the risk of disease transfer.
Pooling reduces immune quality and increases the risk of disease transfer.