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How to be absolutely certain the milk is 100% A2

written by

Marie Reedell

posted on

October 23, 2020

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It seems that there’s a lot of confusion and even misinformation out there about A2/A2 milk. I’m hoping to bring some light to the topic. How can you be absolutely certain the milk is 100% A2?

It’s NOT the breed of the cow. It’s NOT the fat content. It’s NOT whether it’s raw or homogenized. It’s NOT the nutritional content. It’s NOT what the cow is fed. It’s NOT how a cow lives.

The “A2” in A2/A2 milk refers to the type of beta-casein protein in the milk.


It’s that simple, and it’s absolutely objective. It’s not like Grade A and Grade B maple syrup, which is certainly subjective. 

The only way to tell if a cow produces 100% A2 milk is via a genetic test.


It’s a simple test done with a hair sample from a cow’s tail. You send it to a lab, and they send back the results. The test result tells you if the cow produces 100% A1, A1/A2, or 100% A2 milk. See some examples of what the test results look like below. 

It’s black and white. There is no wiggle room.

The farmer tests every cow to determine what type of milk it produces. Only cows that produce 100% A2 milk are in the milking herd.


You might be asking, why do cows produce different types of protein? And, why would I want to drink A2/A2 milk? Those are great questions!

You see, all other mammals - humans, goats, sheep, buffalo, whales, bears, pigs, platypuses, etc - produce 100% A2 milk. But...

A few thousand years ago in Europe, cows underwent a genetic mutation. This mutation made them produce a new type of beta-casein protein - A1. 


Genetic mutations generally happen under stress. Perhaps it was a switch to an unnatural feed (like leftover brewer’s grain) or a change in environment (cows living indoors or in cities) that prompted the mutation. We know a mutation happened but we may never know why.

Those European cows made their way to the United States. Now, basically all American milk is A1/A2 milk. On the other side of the world in Asia, cows were unaffected.

I’ve heard many stories about people from India or China coming to the United States and developing chronic digestive issues. When they switch to A2/A2 milk, the problems go away. 

Similarly, I’ve heard stories of children’s behavior improving when they switch to A2/A2 milk. Farmer Aaron himself had this experience. When his fourth child Hannah was a baby, she had terrible colic and had issues breastfeeding. Aaron’s wife Rebecca made her formula. When she switched to A2/A2 milk in the formula, Hannah was much happier. This is what inspired him to produce 100% A2 milk for others!

It seems that some people are intolerant to A1 beta-casein protein. It seems that 100% A2 milk may be more digestible. 


To be clear, this does not have to do with lactose intolerance. Lactose is milk sugar. It has to do with A1 protein intolerance. It seems that some bodies cannot digest it properly.

More research certainly needs to be done on the A1/A2 milk debate. I want to know more! For example, I’ve read that the A1 beta-casein protein may only be a problem when the milk is pasteurized…? 

If you’d like to learn more about A2/A2 milk, I suggest reading the book The Devil in the Milk.

Miller’s Bio Farm is proud to produce 100% A2 cow milk. We are also proud to be certified by the Pennsylvania Department of Agriculture for raw milk production.

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How to know if you can trust your raw milk farm

*Originally published on 1/13/26, Updated on 2/01/26.* I know how hard it is to find clean raw milk from a farm you can actually trust. You may have spent hours researching farms, reading reviews, asking questions in Facebook groups. Maybe you’ve even driven out to visit farms, met the farmers, looked at their operations. Or maybe you've been burned before by a farm that talked a good game but cut corners. Or maybe you're still searching for that one farm where you can feel completely confident giving their milk to your kids.So let me tell you what happened here in the last few weeks, because this story will show you exactly who we are, and more importantly, it might help you figure out what to look for in any farm you're considering trusting with your family's health. The first email It started the day after Christmas. A customer emailed in saying she wasn't feeling well after drinking our raw milk. Then, a day or two later, another email. Another customer, same story. The team got the details from them, the label color and the dates on the milk. My stomach dropped, it was my brother John's milk. Now here's what most farms would've done, and I'm being completely honest with you. They would've thought "it's only two people out of hundreds, it's January, it's flu season, the flu is spreading like wildfire right now, it's probably just that" and moved on with their day. Maybe they would've made a mental note to keep an ear out for more complaints, but that would've been it. I tried to tell myself the same thing that night. "It's probably nothing. It's flu season. These things happen." But I couldn't sleep. Because what if it wasn't nothing? What if there was even a small chance that something was wrong with our milk, and we did nothing about it? A tough decision I then contacted a DHIA to come out to test the milk. See, we'd already done our regular testing, the testing we do on every single batch that isn't even required by law. But those two emails kept replaying in my head. We needed to know for sure. We sent the milk samples to the state lab that day. Then came the hardest part, the waiting. If you've ever waited for medical test results, you know that feeling. Every hour feels like a day. You check your email or phone constantly. You play out every possible scenario in your head. And since we were now working with the state the test result didn't come back instantly, it took 2 weeks. The result that changed everything When the State inspector stopped in Thursday the 8th they confirmed the testing results."Positive for Campylobacter."  We’ve been doing this a long time. Through every season, every challenge, and every batch of milk, we’ve never had a positive Campylobacter test. That’s not luck, it’s the result of how seriously we take producing clean, safe raw milk. I sat there just processing it. The inspector then let John know that we couldn't use his milk until it was clean again. What happened next Immediately we'd pulled all of John's milk from going out the door. Then I started drafting an email, one that had to be sent to over 800 trusting customers. Every single family who had purchased milk from us and possibly John's farm in the affected timeframe. Some people thanked us for being proactive and honest. Some were understandably upset, and they had every right to be. A few were scared. I told a few to call or email back if they had concerns or if anyone in their family started feeling sick. Those were some of the hardest phone calls and emails I've ever answered. But every single one of those families deserved to hear it directly from us, not from a recall notice in the mail, a news station, or a post on social media. The State gets involved The State inspector put John's farm under official quarantine on 1/8. That means no milk leaves his farm until we get two consecutive clean tests, taken at least a week apart. 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Any farm can show you their clean barns and happy cows and tell you all the right things when you visit. But… you truly know who a farm really is by what they do when something goes wrong. Think about it. We could've ignored those two phone calls and convinced ourselves it was just the flu. We could've done the bare minimum, waited for the state's regular testing to maybe catch it, or maybe not. We could've quietly stopped using John's milk without telling anyone why. We could've sent out a vague email about "an abundance of caution" without admitting what actually happened. Instead, we: Took those two complaints seriously immediately, even when it would've been easier to dismiss them.Ordered extra testing on our own dime without being required to.Shut down production with John’s milk the moment we got a positive result.Emailed every potentially affected customer.Voluntarily reported to the state before they found it themselves. Are being completely transparent with you right now, even though it's embarrassing and painful and might make customers lose trust and go somewhere else.I'm not telling you this to pat ourselves on the back. I'm telling you this because this is what you should demand from any farm you're considering. Not perfection, no farm can guarantee perfection, and any farm that claims they can is lying. But you deserve a farm that will tell you the truth and do the right thing when problems happen. Questions you should ask ANY raw dairy farm:If you're shopping around for a raw milk source, here are the questions you should be asking:"Do you do any testing beyond what the state requires?"If they say no, that's not necessarily a dealbreaker. Plenty of farms only do state-required testing and produce perfectly safe milk. But if they say yes, ask them to explain exactly what they test for and how often. Farms that go the extra mile will be proud to tell you about it in detail."Can I see your most recent state inspection report?"By law, these are public records. A good farm will show you without hesitation. If they dodge this question or get defensive, walk away."How do you track which farm or batch milk comes from?"If they have multiple farms or multiple days of production, they need a tracking system. Our colored stickers might seem simple, but that simple system saved us in this situation. If they can't tell you how they'd trace a problem back to its source, that's a problem."Have you ever had to recall or stop production? What happened?"I wish I could tell you we've never had issues, but that would be dishonest. We had an issue a few years ago with RB51, a child was hospitalized from it. It was caused by the VACCINE strain of brucellosis. This is why we no longer allow cows in our herds who have been vaccinated for brucellosis. What matters is how farms handle those situations. 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Most cases resolve on their own.Q: How did this happen if you test every batch?A: That's exactly why we're investigating John’s cleaning protocols and farming standards. We're reviewing the timing of tests, storage protocols, everything. Once we know, we'll implement changes to help prevent something like this from happening again.Q: Will you use John’s farm’s milk in the future?A: If the milk is clean and the problem is resolved, yes we will. We will require two consecutive clean tests at least a week apart. And, we’ll need to identify and address the root cause. We won't rush this. Safety first, always.Q: Are you changing your safety protocols?A: We're reviewing everything right now. If we identify improvements we can make, we'll make them immediately across all farms. You can view our milk safety and protocols here: https://millersbiofarm.com/mil... The bottom lineWe believe raw milk should come from a place where questions are welcomed, testing is routine, and honesty isn’t conditional.  We believe in the benefits of raw milk and all its wonderful properties. Raw milk is honestly incredible for your body when you think about what's actually in it. It's a complete, living food packed with natural enzymes, vitamins, healthy fatty acids, and powerful immune-boosting compounds like immunoglobulins that work with your body exactly as nature intended. Raw milk keeps all those beneficial bacteria that are amazing for your digestion and gut health. You're getting natural antimicrobials and probiotics that actively support your immune system and help your body thrive. It's basically the difference between drinking something truly alive and nourishing versus something that's been processed into a pale imitation of real milk. When you drink raw milk, you're getting all the goodness that's meant to be there, nothing destroyed, nothing missing, just pure nutrition the way it was designed to fuel and protect your body. *UPDATE 2/01/26 John's herd has now had 2 negatives and the milk is safe to use again so we are integrating his milk back into our production again. I'd love to hear from you. Comment below to share your thoughts with our community (no account required). Or, contact us to keep it private 😊 References: https://www.cdc.gov/campylobac...