Article
How to reduce bacterial contamination of colostrum
Testing and feeding good-quality colostrum is essential. However, many farmers overlook the risk of bacterial contamination of colostrum during storage and handling.
Colostrum quality depends on its antibody (IgG) concentration. Good-quality colostrum contains at least 50g/L of IgG, as measured by a refractometer or within the green zone on a colostrometer.
If bacterial contamination of the colostrum occurs before being fed to the calf, it can have a negative effect on IgG absorption. This failure to transfer passive immunity means the dam cannot pass on vital protection to the calf. Even when you harvest and test good-quality colostrum, poor handling can quickly render it ineffective.
Calves absorb IgG from the colostrum through specific sites along the intestinal tract called enterocyte receptors.
When bacteria are present, in contaminated colostrum, they compete with IgG molecules for these receptors. In turn the binding of the IgG within the intestinal lumen is restricted, and damage to the enterocyte brush border can occur. Overall, initiating the acceleration of gut closure and reducing the calf’s ability to achieve successful passive transfer.
In Ireland, a study showed that 56% of colostrum samples exceeded the standard bacterial count thresholds. In New Zealand, around 90% of pooled colostrum samples showed high contamination levels. (Denholm et al 2017 and McAloon et al 2016)
What counts as contamination?
A total bacterial count (TBC) of (>100,000 CFU/ml) or a bacterial contamination count of (>10,000 CFU/ml) total coliform count (TCC) is deemed to be over the bacterial count thresholds and may have a negative effect on IgG absorption. (Godden et al 2019).
Identifying critical control points for colostrum contamination
A study in Scotland was conducted to identify specific colostrum management risk factors. Eleven dairy farms across Dumfries and Galloway submitted 478 colostrum samples for analysis. Samples were taken from three areas, divided into 152 samples per area sampled;
• Direct from cow – teat after teat preparation from milking
• Collection bucket and storage bucket
• Calf feeder
Farmers also completed questionnaires on their colostrum harvesting and feeding practices.
The study highlighted that the more times the colostrum was handled, the higher the risk of bacterial contamination. For some farms the bacterial counts had tripled by the time the colostrum was fed to the calf.
This directly correlated with the size of the feeder. Samples taken from larger feeders were found to have lower TBC and TCC counts. This indicated that the feeders were potentially easier to clean.
In contrast, farms using two or more buckets before feeding saw higher bacterial counts.
How can I reduce bacterial contamination of colostrum on my farm?
The key factors to take away from the Scottish trial work (Haggerty 2025) are;
• Feeder utensil hygiene
• Identifying pitfalls in colostrum storage and handling
• Create a streamlined approach to colostrum storage and handling
Feeding and storage utensils
Identify how easy your feeding buckets/bottles are to clean.
Within the study (Haggerty 2025), it was found that feeding utensils with a larger surface area had a lower TBC and TCC compared to smaller feeding utensils. Highlighting the potential ease of cleaning a larger surface area with a brush, for example, bottles that can hold over 3 litres compared to smaller bottles that can hold 2 litres.
• Avoid re-usable colostrum tube bags, unless a strict cleaning protocol can be followed.
• Ensure a cleaning protocol is in place
• Thoroughly clean feeding utensils after every use
• Use hot water, a brush and chemical detergent to break down the fatty residue from the colostrum
• Store the utensils in a clean, dry environment
• Discuss with all members of the team the cleaning protocol
Reduce the number of containers
The Scottish study (Haggarty et al 2025) showed that using only one bucket and one feeder to feed the calf reduced the amount of bacterial growth in the colostrum, compared to farms that used up to three storage buckets before feeding to the calf.
• Streamline the number of buckets used to store the colostrum before feeding
• Ensure every storage container of bag is spotless before adding colostrum
• Identify potential pitfalls in your colostrum storage and handling methods
• Storing colostrum at an ambient temperature can allow bacteria to multiply every 20 minutes
• Ensure colostrum is refrigerated or frozen quickly after harvest, instead of being stored at an ambient temperature in buckets
Other factors to consider
• The number of people handling the colostrum can also have a negative effect on the bacterial counts in colostrum. Where possible, designate one member of the team to handle and store colostrum
• When harvesting the colostrum, flush and clean the milk pipes to the collection bucket before each use.
• When cleaning the freshly calved cows’ teats, ideally use a fresh pair of gloves and ensure the teats are dry before applying the milking unit
• If the cow is milked on the robot, be mindful of the time the milk could be left at an ambient temperature in the collection bucket before being fed to the calf – note. Likely to be classed as transition milk at this stage
Leave a Reply