MMN May 2024 – Colostrum Beyond Antibodies: What is New?

Project: Identifying critical control points for colostrum contamination and Mycoplasma bovis prevalence in first milking colostrum from Scottish dairy herds.

When colostrum quality is discussed, it is tempting to think that story has been told. What more is there to know than 10 to 12% of bodyweight of colostrum measuring >22% Brix within the first 6 to 8 hours of life? The short answer is lots – the story is more nuanced. A collaborative Hannah Dairy Research Foundation funded project looked further into colostrum quality on Scottish dairy farms last year. Researchers looked at the bacterial contamination of colostrum at specific critical control points throughout the colostrum harvesting, storing and feeding processes.

Why is a bit of bacteria important? Excessive bacterial contamination does several things to interfere with the transfer of passive immunity in the calf’s gut. Bacteria:

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 calf’s gut lining, meaning it can no longer absorb antibodies.

4. Can cause disease in their own right – for example Johne’s, Salmonella, E. coli.

Coliform bacteria are particularly responsible for interfering with the transfer of antibodies across the calf’s gut lining. Coliforms are a group of bacteria associated with the environment and faecal contamination. Dirty colostrum puts calves at risk of failure of transfer of passive immunity (FTPI). FTPI puts calves at risk of scours, pneumonia, death, reduced daily liveweight gains and reduced productive performance. What we do to these calves in the window of opportunity in the first 24 hours of life has a huge impact on the future of that calf during the early days and way beyond. Let’s get it right. Let’s make it clean!

A secondary aim of the study was to estimate the prevalence of Mycoplasma bovis in first milking colostrum. Many dairy farmers will recognise the challenges M.bovis infection on farm can bring.

So what did the researchers find? The noticeable trend is that whilst colostrum starts off clean at harvesting, it progressively gets more contaminated as it passes through storage to the point of feeding. The maximum count in the Feeder sample was 295 million total bacteria count (TBC) CFU/ml (see table 1) and around 70% of Feeder samples failed colostrum cleanliness thresholds for total bacterial and total coliform counts (TCC), as seen in tables 1 and 2 below.

 

Simple messaging around cleaning of equipment – hot water, detergent and physically scrubbing to remove colostrum scum from buckets and bottles. Sorry – a quick swish with cold water doesn’t cut it here! Check equipment for perishing – cracks that bacteria can hide in. Does your colostrum harvesting equipment or cluster get cleaned effectively with the normal parlour wash cycle? What could you do to improve the quality of cleaning?

As the colostrum passes through more buckets the dirtier it gets – 100% of samples failed the threshold for coliforms by storage bucket 3. Looking at your colostrum process and streamlining it to minimise transfers and containers will reduce opportunity for contamination, ultimately making the colostrum you feed to the calf cleaner.

The study looked at detailed information regarding on farm colostrum management protocols to establish risk factors for colostrum cleanliness. Interestingly, an association between colostrum cleanliness and the size of container colostrum was stored in was found. This leads to a discussion about the cleanability of equipment used around colostrum harvesting. Getting into hard-to-reach places like handles of bottles, or small containers with tight corners is a challenge. These simply won’t be cleaned to a high enough standard.

Finally, a low prevalence of M.bovis was found in first milking colostrum – 1.3%. This is the first time the prevalence has been established in a Scottish dairy calf population. Whilst this might be surprising to read for those of you who struggle with the disease, it is in line with other work in this area carried out in Belgium, with a prevalence of 1.9%. The impact of this finding is that when considering M.bovis management a multifactorial approach is best. Simply implementing colostrum pasteurisation will help but cannot be considered a silver bullet. Look at ways this bug can spread from calf to calf via fomites or aerosol spread. Consult your farm vet who knows your business well and can offer bespoke advice – there is not a one size fits all approach to controlling M bovis.

We gratefully acknowledge the following authors for this article:

Katie Denholm, University of Glasgow katie.denholm@glasgow.ac.uk

Ali Haggerty, University of Glasgow/Stewartry Veterinary Centre alexandra.haggerty@glasgow.ac.uk