What’s Happening #06 – Colostrum & Refrigeration
Today’s What’s Happening tells the story behind a photo that was taken on a dairy farm not too far from Green Bay, Wisconsin in the U.S. a few years ago. Green Bay is famous as the home of the Green Bay Packers American football team. Let’s go see “The Pack”!
The nipple bottles all contain colostrum. Also, we have some silage sample, probably for forage analysis, a bottle of antibiotic along with a needle, and I think, someone’s lunch. Yikes.
So, what’s happening? Let’s leave the biosecurity issues of storing human food along with animal feed and improper antibiotic storage alone for today, although the idea of storing my lunch along with corn silage reminds me of some fermented foods I’ve eaten in the past.
Actually, I want to focus on the bottles of colostrum in the fridge and the risk of bacterial contamination.
This is a situation I see on farms in many places around the world. The issue is that the refrigerator really isn’t a great place to store colostrum.
Here is a PowerPoint slide I use when I talk about colostrum management. The slide show results of a study conducted at the University of Minnesota and published about 20 years ago. The researchers collected colostrum from fresh cows and then stored samples at room temperature or in the refrigerator for 1, 2, or 4 days. They measured the total plate count, which measures the total number of bacteria in a milliliter of the colostrum. The graph on the right shows the times of storage on the X-axis and the total plate count in CFU, or colony forming units, per milliliter on the Y-axis. At collection or zero hours, the pooled samples had 100,000 bacteria per milliliter. This is the maximum we want in colostrum, so already this colostrum would be considered not great from a microbiological standpoint.
At 24 hours, the samples in the fridge had increased from 100 thousand to over 500 thousand. At this point, these samples are too contaminated to feed calves. The pH had declined also, as a result of fermentation by bacteria. The number of bacteria in the sample stored at room temperature was 18 million per milliliter. I couldn’t fit that on the graph, so it looks something like this. Wow. This is terribly contaminated and completely unfit to feed.
By 48 hours, or 2 days of storage, the samples had about 1 and 4 million bacteria per milliliter depending on the storage. Both had lower pH, and the number of bacteria represent the amount of fermentation going on in the colostrum. Keep in mind that the words “fermentation” and “colostrum” generally shouldn’t go together. In any case, neither of these are appropriate to feed newborn calves. Ditto the samples at 4 days.
The bottom line here is that, by 24 hours, the microbiological quality of the colostrum was such that none of the colostrum should be fed. Without some kind of intervention, refrigerating colostrum more than one day is not a good idea.
Here are a few references if you’d like to take a “deeper dive” into the topic of colostrum storage. Feel free to stop the video and scan the QR code to go directly to each.
Long ago, we didn’t know as much as we know today about refrigerating colostrum. Calf Note #13, which I wrote back in 1997, says that it’s OK to store colostrum for a week. Not so. One day and no more. It’s a case of changing our minds when we learn new information.
Calf Note number 215 gets it right. Of course, this one was written more recently – in 2020 – and we know more about the topic today. This Note suggests that a fridge can be used for 1 day to store colostrum. Otherwise, it should be frozen.
Other publications offer different recommendations for how long we can store colostrum. A quick review of these three articles suggests these recommendations range from 1 day to 1 week. Don’t believe those recommendations for more than 1 day.
Remember, calves crave clean colostrum!
Trust me on this one. Use the refrigerator for no more than one day unless you are pasteurizing or using a preservative such as potassium sorbate. That’s a topic for another episode! Generally, colostrum should be in one of two places – in the calf or in the freezer. Well, that’s it for today. Thanks for watching and see you next time!
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