What's in My Milk?

There's a lot of discussion in society today about our food supply and agriculture in general. One of the most common discussions is about dairy cows and our milk supply. There are many misconceptions that go around about dairy cows, especially about what exactly is in our milk. Specifically about hormones, antibiotics, and other foreign substances that we don't want to ingest.

Our milk supply in the United States is extremely safe and very healthy! Let's start by talking about what's NOT in our milk:


You will never, ever, ever drink milk that contains antibiotics. Literally never. It's not even a remote possibility. How, you ask? Some cows receive antibiotics, right? How do they stay out of our milk? Let's look at a scenario really quick: 

Say you own a dairy farm and are currently milking a herd of 250 Holsteins. You have 2 cows that come down with mastitis, which is an infection of the mammary gland. You call your vet out to check out your cows and the vet prescribes amoxicillin to treat the infection. You will then put a leg band on your cows receiving antibiotics, or give them some other physical identification. These 2 cows will also be milked last in the herd. When it comes milking time, you'll milk your 248 cows not receiving antibiotics, then bring in your treated cows. You'll unhook the milk line from the tank and milk your treated cows into a dump bucket. Their milk will then be properly discarded of. After milking those 2 cows, you'll sanitize your milking equipment and start the process over during the next milking period. No antibiotics go into the holding tank! You will continue to do this during treatment and then after treatment for the withdrawal time of the medication- that is, for how long it takes for milk to be rid of the antibiotic residues. This can range anywhere from 2-8 days. When the truck comes to pick up your milk, they will take a sample of it to test for the presence of antibiotic residue. Milk trucks typically go to multiple farms at a time, so all the different farms milk gets mixed into the tanker truck. If the sample from your farm comes back positive, you have just contaminated an entire tanker truck of milk. Congratulations, you now have to pay for the entire truck of milk that was supposed to be delivered to the processing plant, but now has to be dumped out because you contaminated it.

There is a financial incentive for farmers to not contaminate milk with antibiotics, but furthermore, there is a duty that they feel compelled to uphold- to provide a safe food supply for our communities.

This sweet girl's milk contains exactly ZERO antibiotics!


Exogenous hormones are hormones that are given to dairy cows that they do not produce themselves. "Wait, are you saying that there actually are hormones in our milk???" Well, actually, yes. There are hormones in your milk - endogenous hormones that the cows naturally produce themselves. This includes estrogen, oxytocin, and bovine somatotropin (growth hormone). These hormones are produced by various glands throughout the cow's body and essentially help the cow to continue living. And yes, they get in the milk. But the good thing is that everything you eat contains hormones that are produced by the animal or plant. Yes, even plants produce hormones. You know that coffee that you drink to get your day going? It contains up to 20 micrograms of phytoestrogens per 100 grams. Good news - that is a miniscule amount. More good news - hormones from other animals and plants aren't exactly useful by your body! 

Take a look at the graphic below:

Which estrogen molecule will fit in the human estrogen receptor? Human estrogen! So, don't worry about those endogenous hormones - they're harmless and if you didn't know about them, well, hey, you've already been ingesting them for however many years now and you're alive to tell the tale!

The majority of your milk that you buy in the store, however, comes with a label that states something to the effect of: "This milk is from cows not treated with rBST. The Food and Drug Administration has determined that there is no significant difference between rBST treated and non-rBST treated cows." rBST is recombinant bovine somatotropin. It is a molecule that is synthesized to act like bovine somatotropin that the cows naturally produced. It was approved by the FDA for administration to dairy cows to increase milk production. It is completely safe to give to cows and there are no health concerns to humans drinking milk from cows that have been given rBST. However, the majority of producers in the United States do not give their cows rBST, hence the fact that most of the jugs of milk you see in stores contain that label. It has not really shown to be economically feasible or increase milk production all that much.

This cutie, who happens to share my birthday, doesn't get any exogenous hormones! She naturally produces a lot of milk.


There's more than a few things wrong with this image. First of all, any blood or pus that is exiting a cow's teat is a sign of a major case of mastitis. In order to ensure that all cows are healthy and have functioning teats, milkers will "strip" the teats prior to hooking up the milking machine to the claw. This means that the milkers will squeeze a couple squirts of milk out of each teat to make sure everything is healthy and working properly and to stimulate the cow's body to let the milk out. If there is any sign of infection, that cow is NOT milked into the holding tank. Therefore, even if the cow is sick, no pus or blood even enters your milk supply. 

Now, I'm not going to lie - teats get dirty sometimes. Most dairy cows, especially in the South, are bedded on sand. It stays clean and cool and the cows love it. When they lay down, however, sand or other bedding can (and will) get on the teats. Before cows are hooked up to the milk machine, and after they are stripped, they go through a cleaning process that involves dipping each teat in a hydrogen peroxide solution and wiping them off to clean off any dirt or debris and to kill any pathogens that may be on them. 

Secondly, there are many filters in the pipes that travel from the milk machine to the holding tank. They trap anything that may have made it into the milk to ensure that there is absolutely no debris. This, combined with pasteurization, which kills any bacteria or other harmful organisms, ensure that we have clean, high quality, healthy milk for everyone to drink!

Lastly, when milk comes out of the cow, it is white. Like really white. As white as it is when you buy it. Milk is not artificially whitened, despite what some rumors may say!

These girls live on grass. There might be dirt on their teats. It will be cleaned off before they're milked! They also produce naturally very white milk.
 So there's a quick (although lengthy) rundown of what's not in your milk! As you can probably tell, agriculture and animal production is an extremely complicated, regulated process. So complicated, even, that some groups fill in what they don't understand with lies and misinformation! Agriculture awareness and literacy is so important today, and I really hope that this has helped shed some light on what goes on in milk production!

This little girl is living in a cozy hutch to keep her healthy and safe!

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