Reducing the bacterial load - colostrum collection and storage

When talking about colostrum, there are things we can control and things we can’t.

My preference is to not spend too much time or energy worrying about what we can’t control, and focus on stacking the odds in our favour for the things we can.

And there are still plenty of things we can control that we could do a whole lot better than we currently do.

Despite our best efforts (repeat after me: clean cups, clean teats, clean buckets), it’s impossible to collect colostrum in a completely sterile manner.

This means some level of microbial contamination is pretty much guaranteed. When colostrum is fed within two hours of collection, this is unlikely to be an issue. However, excess colostrum is commonly stored on-farm for future use.

As bacteria can rapidly multiply — with numbers as much as doubling every 20 minutes at 20°C — how we choose to store our colostrum can play an important role in its quality.

I have seen colostrum stored in everything from specially-designed bags in chest freezers to 44 gallon drums left out in the sun.

What works for you will depend on your operation, but what follows is a few mainstays of colostrum storage that almost everyone can take on board.

Cleanliness is key

Contaminated colostrum can actually be a source of infection for newborn calves.

It can also inhibit their ability to absorb the important immunoglobulins they require from colostrum within the first 24 hours of life.

Talk about a double whammy!

Good colostrum hygiene begins by milking cows as soon as possible after calving, pre-stripping to remove any sealants and washing contaminated teats thoroughly before drying with paper towel.

Putting clean cups on clean cows and collecting colostrum into clean test buckets (ideally stainless steel) should be a normal part of your colostrum collection routine.

Keep lids on buckets whenever possible.

None of the following points can make dirty colostrum clean again, so the most important step to get right in the whole process is this first one.

Not all colostrum is created equal

Colostrum quality is highly variable and influenced by numerous factors — age, breed, vaccination status, volume, time until milking and leakage prior to calving can all impact antibody concentrations.

Antibody (most importantly, immunoglobulin G or IgG) concentration can be measured indirectly using a Brix refractometer, and a level of ‘quality’ assigned (22 per cent or above is good).

Good and poor quality colostrum shouldn’t be pooled — don't shandy the Moet with Passion Pop!

Blood in fresh colostrum can artificially enhance a Brix quality reading and support bacterial growth, so avoid using bloody colostrum where possible.

Prioritise using and storing your good quality colostrum first.

Storage matters

Short-term storage of colostrum should include refrigeration at 4°C.

Chilled colostrum has a shelf-life of two days before quality deteriorates below acceptable thresholds.

Potassium sorbate is a cheap salt solution used commonly in the food industry as a preservative. It inhibits bacterial and yeast growth, extending shelf-life.

Colostrum with potassium sorbate added can be kept refrigerated for up to seven days.

Freezing can offer a longer-term storage option for some farms, and extend colostrum shelf-life by six to 12 months.

Colostrum should be frozen as soon as possible after collection, in appropriately-sized containers for future use.

Oversized containers will not defrost evenly and risk elevated bacterial loads during the defrosting process.

Thawing should be done in a 50°C water-bath, NEVER in a microwave or you’ll destroy the immunoglobulins.

If storing colostrum, get into the habit of recording date of collection, Brix quality and if potassium sorbate has been added.

Treatment options

Heat treatment may be of benefit for some farms where specific diseases (such as salmonella or mycoplasma) are of concern.

Talk to your vet before you go investing in any equipment, though. UV treatment is not currently considered an effective method for reducing pathogen loads and significantly reduces colostral IgG levels.

Note that traditional high-temperature pasteurisation of colostrum is not an option for newborn calves. It inactivates the immunoglobulins in colostrum and completely defeats the point behind trying to get it into them so quickly.

Monitor and review

Total plate and coliform counts provide a quick, relatively inexpensive and measurable way of determining the bacterial load in a colostrum, milk or water sample using cultures.

Many vet clinics can now help you assess the pathogen levels of what you’re feeding your calves by performing these tests in-house.

Contact your regular vet for more information.

Investigate industry calf-rearing benchmarks, ask yourself regularly where you might improve your current system and know when to seek advice should you need it.

Calf-rearing can be hugely rewarding but also poses many challenges — so stack the odds in your favour where you can.

Lucy Collins is completing her Dairy Residency with The University of Melbourne. She works as a dairy veterinarian for Apiam Animal Health, and on her partner’s dairy farm in south-west Victoria. She is a 2021 Nuffield Scholar supported by Gardiner Dairy Foundation.