How to evaluate the quality of colostrum for calves

As calves have the peculiarity to be born without immunoglobulins (antibodies), they are particularly vulnerable to pathogens during their first days of life.

Immunity is only acquired 3 to 5 weeks after birth, therefore additional protection is needed in this transition phase. This extra protection is brought by the mother through her colostrum, which contains huge quantities of antibodies.

The quality of colostrum can be highly variable from one mother to another (depending on age, breed, condition, length of dry period, etc.), therefore it is important to systematically check its quality.

Colostrum contains huge quantities of antibodies, which are needed by the calf due to its lack of innate immunity

A “good” colostrum has a concentration of antibodies (or immunoglobulins G, IgG) greater than 75 g/l

Various tools are available to evaluate the quality of colostrum. They are all based on the strong correlation between colostrum density and antibody content.

The colostrometer is a simple and cheap tool that immediately gives an approximate value of the antibody concentration. It generally comprises a graduated column containing a densimeter.

To use it, just suck colostrum into the graduating column and look at the colour associated to the densimeter result:

Green if the concentration is greater than 100 g/l
Yellow between 50 and 100 g/l
Red below 50 g/l

The advantages of the colostrometer are its low price and its ease of use. 

Nevertheless, it has major disadvantages: 

it is very fragile and it gives results which vary according to the temperature of colostrum.

As a consequence, it is not the best method to assess colostrum quality.

The Brix-scale refractometer is used to measure the Brix value of a solution. Initially intended to indicate the sugar content of a solution, this scale has been adapted for on-farm use.

A refractometer offers significant advantages over a colostrometer:

• instrument accuracy is not affected by sample temperature,
• it can be used to assess total protein in calf serum and
• it is considerably more durable.

A Brix value of 22% is equivalent to 50 grams/litre of IgG, which is where the yellow (i.e. acceptable quality) zone begins on the colostrometer.