Colostrum and dairy calves. It's a tale that's as old as time, but it still needs banging according to a new project conducted by the Hannah Dairy Research Foundation.

The project looked beyond the message of antibodies and colostrum with assistance of researchers at Glasgow Vet School and the SRUC and support from farmers and vets from Stewartry Vets and Galloway Vets, in SW Scotland, looked at colostrum cleanliness through the harvesting, storing, and feeding processes on farm.

Why is dirty colostrum bad?

Calves are born without any antibodies and rely on the transfer of colostral antibodies to provide passive immunity. This passive immunity provides protection from disease in the first few weeks of life. Excessive bacteria in colostrum, especially coliform bacteria (associated commonly with faecal contamination), do several things to the antibodies in colostrum, and in the calf’s gut, to interfere with the transfer of passive immunity:

1. block the uptake of antibodies across the calf’s gut.

2. break the antibody molecule so it is no longer functional.

3. cause damage to the gut lining, increasing rate of gut closure.

4. can cause disease in their own right – Johne’s, Salmonella, E. coli and Mycoplasma bovis.

Dirty colostrum puts calves at risk of failure of transfer of passive immunity (FTPI). FTPI puts calves at risk of scours, pneumonia, reduced daily liveweight gains and death. Calfhood disease can massively impact the efficiency and effectiveness of any dairy business.

The accepted industry threshold for total bacteria counts (TBC) is 100,000 Colony Forming Units (CFU)/ml and the accepted industry threshold for total coliform counts (TCC) is 10,000 CFU/ml.

More than 500 colostrum samples were taken from 11 farms in SW Scotland from defined critical control points from harvesting through to feeding to examine the cleanliness of colostrum.

Samples were collected:

1. Directly from the teat after teat prep before harvest

2. From the dump bucket

3. From any other subsequent storage buckets

4. From the calf feeder at the point of feeding.

From the recent Scottish research project, it was found that 8% of samples taken directly from the teat exceeded the acceptable threshold for total bacterial counts (TBC) compared with 71 % of first milking colostrum samples taken from feeders at point of feeding (stomach tubes or bottles) – showing that colostrum became increasingly ‘dirty’ as it moved through the process from harvesting to storage and feeding.

Mean bacterial count for the feeder samples was 14m CFU/ml with the range between 0 CFU/ml and 295m CFU/ml. This would suggest that it is possible to feed clean colostrum, but also that many calves are getting a veritable bacterial soup of 3-4 litres of highly contaminated colostrum.

In addition, as the number of storage buckets used in the colostrum management process on study farms increased, so did the percentage of samples failing both TBC and TCC thresholds. In all, 50% and 54% of samples from the first storage bucket failed TBC and TCC thresholds respectively. This increased to 78% to 100% of samples failing bacterial thresholds from subsequent storage buckets.

Results of this study show just how dirty colostrum can become. There is vast opportunity for contamination throughout the colostrum management process from harvest to feeding of the calf. It is important on farm to think about cleanliness of feeding equipment and storage buckets. Detergents should be used first in the cleaning process to help breakdown and remove colostrum/milk scum; then disinfection.

Look out for worn, roughened stomach tubes, teat ends, bottles or storage buckets that may harbour bacteria and are difficult to clean effectively. Also pay attention to how you are storing any spare colostrum. Streamlining the process to minimise the number of buckets the colostrum is transferred to between harvesting and feeding may help.

A second part of this study looked at the prevalence of M.bovis in first milking colostrum samples. The prevalence was found to be 1.3%. This low prevalence of M.bovis DNA in samples, does not mean that colostrum should be ignored when considering on farm control strategies for this crippling disease. However, strategies should include a holistic look, with veterinary input, at fomite spread (e.g. teats, feeders, calf rears hands and clothing) as well as aerosol spread (e.g. shed ventilation and group sizing) to touch on a few to maximise overall effectiveness.