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What is the Zinc Sulphate Turbidity Test?

The cornerstone for success in any calf rearing enterprise starts with having an effective colostrum management practice in place.

This essentially revolves around four key aspects in colostrum feeding: quantity fed, quickly, quality and hygiene of feeding utensils.

Monitor colostrum management programme

However, College of Agriculture, Food and Rural Enterprise (CAFRE) dairying technologist Dr Alastair Boyle stated: “it is always important to check if colostrum feeding management is working in practice”.

A calf, which has had a ‘successful passive transfer of immunity’, essentially consumes sufficient immunoglobulins, (IgG’s), from colostrum. Subsequently, these IgGs are then absorbed across the gut into the bloodstream.

Alternatively, failure passive transfer of immunity, occurs when a calf fails to absorb an adequate quantity of IgGs.  In practice, failure of passive transfer can occur for a number of reasons.

For example, poor timing of colostrum feeding post-calving, or not enough quantity consumed. In calves where failure passive transfer is identified as a problem, this can lead to increased veterinary treatments and increased mortality, along with reduced daily live weight-gains, (DLWGs), and also reduced milk yields when lactation commences.

It is, therefore,  important to monitor the colostrum management programme over the rearing period, both to identify if calves are achieving sufficient immunity and to rectify any management issues quickly.

Zinc Sulphate Turbidity Test

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One indirect measurement used to monitor the passive transfer of IgG via colostrum, is the Zinc Sulphate Turbidity Test.  This test involves a veterinary practitioner blood sampling calves at 2-7-days-old, with samples then sent off for laboratory analysis.

The results from this test can provide valuable information on calf health status in terms of immunity, particularly where health problems/issues have been identified.

A result above 20 units for the zinc sulphate turbidity test indicates adequate passive transfer of immunity.

In order to evaluate the effectiveness of colostrum management feeding protocols at CAFRE, a total of 53 calves were blood sampled by veterinary practitioners from Firmount Veterinary Clinic, during the 2018 winter period.


Samples were sent to the Agri-Food and Biosciences Institute (AFBI) Stormont for zinc sulphate turbidity testing.

As highlighted in Figure 1, the majority of calves had adequate colostrum absorption. These results suggest colostrum management protocols in place at CAFRE are good and working in practice.

Assessing the effectiveness of colostrum management protocols is an important aspect of calf rearing. Results from testing should be reviewed and monitored in conjunction with your private veterinary practitioner over the calf rearing period.


This is just one of the topics that will be discussed during the series of Calf 2020 webinars starting at 8.00pm on Thursday, November 19th.

For further details on the upcoming webinars, please go to the events section of the CAFRE website:

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