An invisible nemesis: How to identify biofilm build-up and why you should be looking

After each feeding, calf raisers rally to the same dreaded task – washing nipples, bottles, and buckets. Even if you use an automatic feeder, you need to clean the lines and hoses regularly. After a job well done, calf feeding equipment may appear clean, but depending on cleaning protocol, there may be a hidden danger right in plain sight – an invisible sticky layer known as biofilm.

Milk residues that aren’t completely removed from surfaces are the beginning of biofilm – this is why experts recommend specific cleaning temperatures (not too hot or too cold) and techniques (like brushing all surfaces) to avoid getting these fats, proteins and carbohydrates stuck on in the first place.

Once these particles are stuck onto your feeding equipment, bacteria find and adhere to them, secreting a protective substance that prevents them from being removed by cleaning products or vigorous scrubbing. These protective substances stick together and form what is called a matrix.

Once established, these matrices can become a feeding and breeding ground for even more bacteria. The late Dr. Sam Leadley and Penn State have great analogies and liken the structure of biofilm to an apartment development or fort, respectively, that bacteria continue to attach and build onto, and which even more milk residues stick to.

Biofilm can accumulate on many types of surfaces, and the longer it goes undetected, the harder it is to remove. In the early stages, it’s difficult to detect by sight or feel, but a sticky film may develop and eventually it will have some texture or a yellow-ish hue.

The worst part is that every time you use your feeding equipment, both parts of the matrix and bacteria can escape the biofilm and contaminate what your calves are drinking – whether it’s colostrum, milk, milk replacer, or water.

Along with your feeding equipment, another place to watch for biofilm is your bucket milker – raw milk is full of nutrients and contains bacteria, which make it a prime location for build-up. This is particularly of concern for colostrum collection. According to Dr. Leadley, high colostrum bacteria counts may be the cause of persistent scours in calves under three weeks of age.

Preweaned calves repeatedly exposed to low levels of this sloughed bacteria from biofilms in their milk or milk replacer can also have ongoing issues with scours. And as Dr. Dave Renaud commented at the recent Dairy at Guelph Research Day, diarrhea is the gateway disease. It’s not uncommon to see preweaned calves with scours need treatment for respiratory illnesses, too.

Your vet is a great resource and can help you assess your calf treatment records, troubleshoot your cleaning process, and monitor for bacteria counts. Ask if they’re signed up for the portal on where they can access protocols and templates for cleaning and disinfecting, and other helpful topics.