Unlike whole milk, colostrum contains many important substances for calf health such as immunoglobulins (antibodies), energy, cytokines, growth factors, and increased levels of vitamins and minerals. In addition, colostrum has a higher fat and protein content than whole milk.
The first feed of colostrum should be at least three litres (approx. 8.5% of birth bodyweight) and should be fed within the first two hours of birth. This provides the calf with immunity to disease before pathogenic organisms can become established in the calf’s gut.
The ability of the calf to absorb IgG is highest immediately after birth and this absorptive ability completely ceases 24 hours after birth. Therefore, the earlier a calf is fed after birth, the greater the level of IgG absorption.