Interpretation Guidance

The test is able to rapidly and reliably demonstrate the level of antibodies (IgG) present in calves. Using a novel lancet, blood samples can be collected by any competent person.

The IgG level indicates whether the calf has received sufficient, high quality colostrum in the correct time frame. This is critical as calves which did not absorb enough colostrum are at higher risk of infectious disease and tend not to perform as well throughout their life. This is known as failure of passive transfer or partial passive transfer. As the animal moves over 10 days of age, it is likely that other factors will also influence the level of IgG present, however, despite this, data to date has shown that that future performance and the level of IgG are significantly correlated in animals up to 42 days of age.

During test development, calf IgG status was determined using the test. Subsequent daily liveweight gain and antibiotic usage data was then monitored. The following guidelines for interpretation of test results have been established on the basis of the available data to date:

Age range Red Amber Green
2 – 14 days <10 mg/ml 10-15 mg/ml >15 mg/ml
15 to 42 days <7.5 mg/ml 7.5 – 12.5 mg/ml >12.5 mg/ml
 Age Range
2 – 14 days15 to 42 days
RED <10 mg/ml <7.5 mg/ml
ORANGE 10-15 mg/ml 7.5 – 12.5 mg/ml
GREEN >15 mg/ml >12.5 mg/ml

Data from animals between 14 and 42 days of age showed that animals of adequate IgG status (amber and green range) as compared to inadequate (red range) demonstrated improved daily liveweight gains of up to 11% and up to a 46% reduction in antibiotic use (mg/PCU).


The ultimate goal should always be to obtain ‘green status’. Animals of optimum IgG status will perform better both in the short and long term which is critical for welfare, sustainability and profitability.


Animals of ‘Amber Status’ are considered adequate however they are bordering an unacceptably low IgG reading. The higher the IgG reading, the better the subsequent performance. Work in partnership with your vet, to improve upon this and enhance welfare and productivity.


Animals of ‘Red status’ require an immediate intervention in partnership with your vet to investigate and rectify. Animals in the red range have been shown to achieve reduced daily liveweight gains (up to 11%) and up to a 46% increase in antibiotic use (mg/PCU).

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