The importance of colostrum management for dairy calves
The impact of excellent colostrum management practices for dairy calves can’t be underestimated. Research in dairy calves has shown that that different levels of cow colostrum intake had short term effects on immunity, growth, metabolism and endocrine status of calves1,2,3. Others have shown that good colostrum management for dairy calves also improves future lactational performance and longevity of dairy cows4,5,6,7. Calves need sufficient amounts of good quality cow colostrum for several reasons.
Good quality bovine colostrum contains sufficient levels of immunoglobulins
Bovine colostrum contains IgG, IgA and IgM. Because IgG is the most prevalent immunoglobulin in bovine colostrum and is easy to measure, the bovine colostrum IgG concentration is often measured, rather than the total bovine colostrum immunoglobulin concentration. It is generally accepted that good quality cow colostrum has an IgG concentration ≥50 mg/ mL
11. A practical method to measure colostrum quality of dairy cows is to use a colostrometer or Brix refractometer to check quality. Good quality cow colostrum should have a Brix reading of at least 22%, which correspondents roughly with 50 g/L of IgG or higher.
With the IgG level in colostrum being easy to measure, it has become an important parameter to measure the quality of cow colostrum. The benefits of good quality cow colostrum go beyond feeding the neonatal calf sufficient amounts of IgG.
Calves need immunoglobulins from cow colostrum for passive immunity
Cow colostrum provides dairy calves with maternal antibodies, including IgG, but also IGA and IgM8,9,10,11,12,13,14. Newborn dairy calves do no have immunological memory as they have not been exposed to pathogens. Next to this, the immune response of newborn calves is slow. Maternal antibodies from cow colostrum help protect dairy calves against pathogens during the critical early weeks of life.
During the first few hours of their lives, calves need energy from cow colostrum
Newborn dairy calves need energy from cow colostrum. At birth, body fat as a percentage of total bodyweight is less than 3%15 (see Figure 1). Part of the body fat of dairy calves is so-called brown fat, rich in mitochondria. Brown fat is crucial for survival of newborn dairy calves. Brown fat in dairy calves acts as a special heat-producing tissue by inducing non-shivering thermogenesis. Brown fat reserves are activated by cold conditions to keep neonatal calves warm. Brown fat is located around vital organs like the heart and kidneys. It is fueled by cow colostrum to kickstart this vital energy production. Depending on climate conditions, maintaining core body temperature can be challenging for a neonatal dairy calf. The energy level of cow colostrum is around 5.4 kJ ME/L, which is twice the amount of energy in milk. Calves can survive for up to 15 hours without being fed colostrum, but their fat reserves will be depleted rapidly if they do not consume colostrum during the first few hours following birth. Subsequently, their core body temperature will go down, and they will become lethargic and weak. Hypothermic dairy calves will lose their suckling reflex and stop drinking.
Bovine colostrum contains essential growth factors for dairy calves
Bovine colostrum contains several growth factors for dairy calves that are essential for gut integrity, growth and for development of the immune system. Insulin-like growth factors 1 and 2 (IGF-1 and 2) and transforming growth factors alpha and beta (TGF-α and TGF β) are the two most important growth factors for dairy calves. Bovine colostrum is the only source of these growth factors for newborn calves9,10 (see Figure 2).