The Physics of Meat Tenderness and Why Genetic Testing Matters

Why Is Some Meat Tender and Some Tough?

We've all experienced the difference: one steak is fork-tender and buttery, the next is chewy and dry. The difference isn’t luck — it’s science, both physics and biology working hand-in-hand, and it starts long before the meat hits your plate.

Meat tenderness is influenced by several factors:

• Muscle fiber structure (Dexter cattle like ours, are known for having smaller, shorter muscle fibers)

• Connective tissue density

• Fat distribution (marbling, juiciness)

• Animal age and stress levels (injury and stress causes small scar tissue adhesions on muscle fibers called "plaques")

• How the meat is aged post-harvest

• Most importantly: GENETICS

Let’s break it down.

🧪 Muscle Fibers, Connective Tissue & Tenderness

Muscles are made of bundles of muscle fibers surrounded by connective tissue (collagen and elastin). Tough cuts (like brisket or round) come from muscles that do more work, building more connective tissue, and likewise, more scar tissue plaques. Tender cuts (like ribeye or tenderloin) come from less-used muscles.

But here’s where genetics comes in: certain breeds and individual animals naturally develop more tender muscle fibers or lower-density connective tissue — even in the same cut.

🧬 The Genetic Markers for Tenderness

Thanks to modern science, we can now test cattle and swine for genetic markers linked to tenderness. Key genes include:

• Calpastatin (CAST) – regulates enzymes that break down muscle post-mortem. Lower CAST = more tender meat.

• Calpain (CAPN) – helps degrade muscle fibers after harvest. Specific CAPN variants are strongly associated with tender meat.

• Leptin, DGAT1, SCD – influence marbling, flavor, and fat quality, all contributing to juiciness and perceived tenderness.

At Dos Lobos Ranch, we genetically test our Dexter cattle herd and our Kunekune pig herd for the species-specific CAST, CAPN, and Leptin markers, selecting for proven tenderness, marbling potential, and high eating quality. The result? Beef and pork that’s not just grass-finished and pasture-raised — it’s consistently delicious.

🔬 The Physics of Tender Meat

After harvest, meat goes through rigor mortis, and enzymes begin breaking down tough muscle proteins. This is why aging is important — it allows enzymes to naturally tenderize the meat over time.  However, if the individual animal does not carry the right genes to allow this process to happen, then you're swimming against the current.

This is why strategically raising both the breed and individual animals with favorable genetic enzyme activity (like those with optimal CAPN and CAST variants) tenderize faster and more thoroughly, improving both texture and flavor without the need for artificial methods.

Neogen Genetic Labs has put together a scale to score beef (and likewise, pork) based on the bite-force required (measured in "N" = Newtons); this scale is rated on a 1 to 10 with 1 being very tough meat with maximum bite-force needed to shear through it, and 10 with far less effort to chew through it.  Each genetic score has a bite-force score that correlates with it, graphed out below.  The lower the score (negative number) represents the decrease in shearing force of your teeth to shred a bite of meat.

Each of those scores means a percentage increase or decrease of force needed to chew a bite of meat.  For example, to go from a 6 to a 7 means a huge jump in 17% less force required to chew the meat, and 7 to a 10 means a 48% decrease in the bite force needed to chew through the meat!  To go from a 4 to a 5 means a 33% decrease in the force required!  

This is why we chase the right genetics in our animals so that we can deliver a consistently tender and enjoyable product, because nothing says success better than a returned customer!  On the flip side, nothing says failure more than a customer who said they had the toughest, worst meat ever.  Data matters, testing matters, and genetics play the biggest role!

🌿 Why It Matters for Grass-Finished & Pasture-Raised Meat

Tenderness is especially important in grass-finished beef and pasture-raised pork, which tends to have leaner profiles. With less fat acting as a buffer, muscle structure and genetics become even more critical to ensuring that customers get an enjoyable eating experience and get the full value of what they're paying for.

By using genetic selection alongside regenerative grazing and low-stress handling, we ensure our Dexter beef and Kunekune pork is:

✅ Nutrient-dense
✅ Full of natural CLA and Omega-3s
✅ Sustainably raised
✅ AND tender, every time

🧠 Better Genetics = Better Beef and Pork

At Dos Lobos Ranch, we’re not guessing. We’re breeding for excellence with data-backed decisions. Our Dexter cattle and Kunekune pigs are DNA tested, both are slow-grown for quality and nutrient density, and our pastures are managed holistically to support soil health and animal wellbeing.

Breaking it down further to the individual animals in our own herds, they must meet a certain "scoring" criteria on their genetic test for tenderness. 

Our standard starts at a score of "6" which we have benchmarked on two steers so far who both scored 6's.  Tenderloins and roasts have been fork-tender, melt in your mouth, best beef ever.  Ribeyes and New York strips have been a slightly more tough cut, but still a very good choice-grade cut.  Any animal that scores below a "6" gets turned into ground beef or sausage.  Anything above that is just gravy and proudly posted for sale!

As to breeding towards consistency, all of our brood females in our Dexter cattle herd are 6's, 7's, or 9's, and our herd bull, Elvis, is a 9.  The result?  Breeding to Elvis will always get us 6's, 7's, 9's, and 10's when breeding those individuals to him, without going too in-depth into how that works (that's another post for another day).  For our Kunekune pig herd, our two boars, Chumbawomba and Kaitoa both scored 7's, while our three females scored 9's, and 10's.  This means all piglets from these individuals will always give us 6's, 7's, and 9's.

That means when you buy from us, you’re getting premium meat backed by science — not mystery.

🥩 Ready to Taste the Difference?

Explore our selection of pasture-raised, genetically tested Dexter beef and Kunekune pork — raised with integrity, science, and a whole lot of love.

👉 Shop Dexter Beef Now

Blog post curated with the help of ChatGPT with input from our on-staff Biologist and Dos Lobos Ranch owner (Heather). :)