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What is a Purebred Mini Jersey?

You may have read on some breeder’s websites that Mini Jerseys can not be “Purebred.” That’s not only misleading, it’s 100% FALSE.  The biological definition of Purebred genetics is simple, offspring resulting from breeding many generations from a single recognized breed.  This is the way to produce offspring that would carry the same phenotype as the parents.  Um, okay, but what exactly is a phenotype?  It’s the expression of a particular trait, for example, skin color, height, behavior, etc., according to the individual’s genetic makeup and environment.  It’s all those things you think of when you think of a Jersey as compared to another breed, things like black rimmed eyes in dished faces with white ringed black noses and large oval ears set to the side of the head.  What all that means is if you want to produce Purebred Mini Jerseys you have to breed with Purebred Mini Jerseys.

​​Many of the “Mini Jerseys” available today aren’t really Mini Jerseys at all.  They are the result of crossbreeding Dexter and other small cattle breeds with Jerseys to reduce their stature.  Those cattle very simply aren’t Purebred.  To learn more about breeding back to purity after crossbreeding visit this page.

You’ll want to take a careful look at the source when you hear the claim that Purebred Mini Jerseys aren’t possible.  It’s very likely you will see pink skin pigment on the nose and around the eyes, brindle pattern coats or predominantly white broken coats, telltale signs of crossbreeding in their herd since these aren’t typical Jersey traits.  Do their little cows look like Jerseys at all?  If unsure of how to tell a Purebred Mini Jersey from a crossbred Jersey you’ll want to read this article.

It’s time to breed pure Jersey genetic traits back into our Mini Jersey cows.

Pink pigment
Dexter Jersey cow
Brindle coat

Can Mini Jerseys be Purebred?  Of Course!  To be a Mini the cattle must be 42″ or less.  That’s quantifiable.  We can take height measurements at 3 years of age to confirm stature.  We can also measure the amount of Jersey genetics in our Mini Jerseys by testing their DNA against the 4,214 A.I. bulls in the Jersey reference group (April 2021).  This test is called Breed Based Representation (BBR) and gives a percentage.  Mini Jerseys are derived from Jerseys, either by smaller heritage Jersey bloodlines, Jersey crosses, or breeding a Jersey to a Mini Jersey.  All these situations include Jersey bloodlines so offspring can be tested for BBR percentage.

​The key to improvement is testing our cows for a baseline BBR and identifying the Mini Jersey bulls that carry the highest percent of Jersey DNA and meet stature requirements for Mini.  PMJS has identified several Mini Jersey bulls that are producing calves with high BBR.  We want to help you improve upon your family cow or herd so the offspring you produce are more valuable.

Purebred Jerseys

Don’t buy into the idea that Mini Jerseys didn’t start as a pure breed and therefore can’t be.  Its a fact that the foundation of Mini Jerseys wasn’t pure so “Foundation Pure” is a misnomer.  But, there’s a growing number of Purebred Mini Jerseys that have done the DNA testing and have a BBR of 100.  There are many, MANY more that are in the range over 90% and can produce Purebred calves with the right mating.

​As a Member you can be mentored, if you wish, and get advice for breeding.  As Purebred Mini Jersey Society grows, and more Mini cows and bulls are proven to carry pure Jersey genetics, you will have access to the expanding database.  You can also have your Purebred Mini Jerseys and breeding stock recorded, increasing their value to others looking for miniaturized Jerseys.  

Our registration requirements ensure our Registered Mini Jerseys are backed by DNA proof for purity, parental verification and genetic traits.  

Purebred Mini Jersey Society is here to help support breeders seeking to produce Mini Jerseys with  pure Jersey genetics, leading to consistent appearance, dairy traits and performance.

Lorinda Barnes, PMJS President

About the Author

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Lorinda Barnes, PMJS President, North Woods Homestead, ID has written 7 posts.

Lorinda and her husband, Lance, own North Woods Homestead, in Idaho. Wanting to know where their food was coming from, they bought two bred Jersey cows in 2012 and dreamt of Spring calves and fresh Raw Milk for their family. The dream expanded into a passion for pure little Jerseys. Lorinda and her family homestead on 60 acres in the northern Rocky Mountains. They produce grass hay for their growing herd of Purebred Mini Jerseys. She’s a Master Gardener, cans their harvest, breeds rare Salmon Faverolles chickens and of course, makes lots of dairy products. Lorinda is the Fundraising Chairperson on the Board of Directors for the non-profit, National Ladies Homestead Gathering. She’s the founder of PMJS and a leading voice in utilizing genomics and DNA for breeding Purebred Mini Jerseys.

2 thoughts on “What is a Purebred Mini Jersey?

  1. Hello, I have two mini’s that are registable.they came with papers.I purchased another Jersey that has all the traits and actually looks truer to breed type than the two with papers.Do you know a good source /lab where I could get a DNA test for my heifer?

    1. PMJS doesn’t automatically recognize registration papers from other registries because we have requirements that need to be met, such as parentage verificationa by DNA matching. We do accept AJCA papers.

      It sounds like your new Jersey is likely more Jersey than your “Mini Jerseys”. This is very common and you’re in the right place to work with the genetics you have to improve the future generations. You’ll want to set up a free account with the American Jersey Cattle Association, register all your cows (oldest to youngest) using the generic sire and dam codes, and order the 94k LD (Low Density SNP CHiP) Genomics test found under the Services tab at That test includes the Jersey BBR test and will tell you how much Jersey DNA your cows have. To learn more:

      If you want help, that’s what we’re here for! You can contact any PMJS Advisory Board Member, Lifetime Member, or email

      Lorinda Barnes, PMJS President

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