Understanding EPDS

In his book, The Lion, the Witch, and the Wardrobe, CS Lewis uses an illustration of Santa Claus meeting up with the three children once they discover the magical kingdom of Narnia. Santa gives each one of the children a gift to assist them in staying safe while they’re in Narnia. Lucy is given a dagger and a special cordial that can heal the sick; Susan is given a bow and arrows and a special horn that will always bring help when blown; and Peter is given a sword. As Santa’s sleigh departs, he looks back and says, “Remember, children, these gifts are tools and not toys!”

Consider the theory behind the BLUP (Best Linear Unbiased Prediction) equation. If you’re like me, seeing something like this is like looking at a website coder’s computer screen. A feeling of awe overcomes you, and in that moment, you’ll trust absolutely anything you’re told.

What we are so often told is that EPDs or EBVs are a science that we need to use as cattle breeders to improve our genetics and, in effect, an animal’s productivity, a herd’s profitability, and a family’s prosperity.

Consider what using EPDs for the last 36 years in the US has done. In essence, Angus steers in US feedlots are $144 more profitable today than they were in 1980. Big win if you run a feedlot!

But Angus cows are $136 per year more expensive to run today than they were 36 years ago. Big loss if you run a cow/calf operation.

So, if you’re a cow/calf operator who sells weaned calves, you lose $136 so that someone else can make $144. Is this genetic improvement? Or is it just genetic change?

NOW, ARE EPDS SCIENCE?

In Science, if two laboratories do the same experiment with the same procedure and ingredients, they will always have the same outcome. e.g., If I hold my arm out holding an apple in Texas and my brother in South Africa does the same, and we let go of our apples, they fall to the ground. Every single time. That is Science.

If I sell a cow and calf to my neighbor, also a registered breeder, and at weaning, the calf is weighed and ratioed with my neighbor’s calves, his EPDs will reflect where he ranked in a contemporary group set up by my neighbor.

If the pair had remained on my side of the fence and been rationed with my calves, his EPDs would reflect where he ranked in a contemporary group set up by myself.

Let’s assume:

• My neighbor and I have very different herds in terms of quality and genetics.
• My neighbor doesn’t manipulate contemporary groups. I have manipulated contemporary groups to benefit outliers down to an art.
• My neighbor and I have the same grass, the same nutrition, and have had an identical season. We stock at the same rate, using the same herd sizes in each pasture. We use identical vaccinations and supplements given on the same days.
• We use the same scale with the same person reading the weights.

So naturally, there should be no difference in the calf’s EPDs -whether he was retained by me or sold to my neighbor in-dam? Correct? Wrong!

There is a 100% chance of these EPDs having different outcomes, and therefore EPDs are not Science.

I’ll argue that EPDs are an incomplete math equation.

The system makes some incredible assumptions.

1. That breeders all measure and weigh their cattle.
2. That breeders all measure and weigh their cattle accurately.
3. That everybody’s herd is equal. E.g., Having a ratio of 100 in herd A is equivalent to having a ratio of 100 in herd B.
4. That contemporary groups are honest and not manipulated.
5. None of these assumptions are true, and yet, we are provided a spread of numbers that we are encouraged to have faith in and are told that they are Science.

Even more concerning is that cattle are given values for traits that neither they nor their parents nor offspring have even been measured in. e.g., Ribeye Area and FAT. (A remarkably small percentage of cattle with REA and FAT EPDs are actually measured. But they still get EPDs. And if their calves are not measured, they’ll still get EPDs too).

Please try and follow this logic with me. When I was in high school, I didn’t play chess, but I played cricket and took history. If there were EPDs for me as a high school student other than direct measurements, like a batting average in cricket or an exam score for history, then I could have been given EPDs for batting and history. What EPDs claim to be allowed to do is to give scores for tests I hadn’t even taken. So even though I didn’t play chess, the formula would give me a chess score based on how I was at math and accounting, as it would claim that these two activities correlate. And then also work into my score the fact that I did sports. Chess and sports correlate negatively, so because I was good at sports and poor at math, my chess EPD would be low.

One generation later, my kids don’t play chess either, but because I had a poor chess EPD, even though I never played chess, they inherited my bad chess EPD and my wife’s poor EPD for chess (she did play chess, but at another school, so they don’t take her numbers into account at all).

Is it just me that finds this illogical?

The comment about my wife coming from a different school is what happens to cattle brought in from different countries. Decades of data and performance testing in New Zealand, for example, translates to nothing if it is exported to the US.

Forgive me for getting technical, but this is clearly not Science and certainly not a complete math equation. But it is a tool that can work if used in context and when backed by raw data and an understanding of the herd the animals come from.

If the breeder of the animal measures all the traits that are published as EPDs, has a well-managed herd with great data capturing and is honest with his scale, and doesn’t manipulate contemporary groups, then yes, the EPDs on his animals are a very useful tool. I’ll go as far as to say that one can incorporate these EPDs into your breeding decisions and give them significant weight, provided the phenotype and pedigree is sound and of high quality.

WHEN DO THEY BECOME A DANGEROUS TOY?

EPDs are an extremely dangerous toy when used out of the aforementioned context.

Using EPDs for marketing cattle for high premiums or publishing EPDs for traits that aren’t measured, or even worse, traits that can’t be measured, instead of understanding cattle for what they are and what their purpose is can be very dangerous. (Traits that can’t be measured like udder scores. You describe an udder score; you don’t measure it. And each score is described by a different person. Science is not described; it is measured).

Thankfully though, there is still a remnant of breeders who still breed cattle with common sense and caution. Who use EPDs for what they are and only trust them as much as they trust the cow or bull that produced them. These breeders are the saviors of the industry, who will have good feet and real tangible muscle and docility and softness when the industry realizes that things got out of hand.

We will be forced to turn to the conservative breeders when the “progressive” breeder’s tank runs out of gas.

If I end this here, my phone will erupt with calls and texts from my industry friends and colleagues. What about genomics, they’ll say? Genomics and GE-infused EPDs solve all of this.

That’s why I didn’t end there.

I could have if genomics was being used as intended by scientific discovery and in their pure unadulterated form. But they’ve been hijacked by promoters and associations.

The mapping of the bovine genome was a remarkable discovery and is real Science. This has enabled breeders to identify genes for color, horn status, genetic defects, etc. This is all amazing, and we should all be grateful for it.

Then we took it one step further; we started identifying genetic markers for the traits that we’re measuring and formulating into EPDs. By combining genomics and conventional EPDs, we developed GE-EPDs. It’s like the hybrid car, only more reliable, or so they say.

Doing a 50K or 75K SNP or genomic test on an unproven calf can improve the accuracy of its EPDs for up to the equivalent of it having 7-12 offspring. That is helpful indeed. Not a silver bullet, but better than what we had previously.

Again, it may just be me, but the issue I have with this is the process from where the gene is identified to where it becomes an actual number. So, one identifies the gene for marbling, and then it becomes a 0.27 marbling score when combined with the raw data (If we’re lucky enough to have any).

There is a magical bridge that transports that genetic marker into the EPD profile.

This is a remarkable claim if there ever was one. And remarkable claims require remarkable evidence. In the case of GE-EPDs, the evidence is not remarkable at all; it’s absent. The bridge is a bridge requiring a lot of faith.

Oh, but they’ll say, we’ve changed now from the two-step system to the onestep system. It’s a lot less complicated and saves a lot of time. It may be less complicated, but the bridge is still magical, mysterious, and imaginary unless they can demonstrate it to us in a remarkable way.

I would love for this to be true. And if it is demonstrated with remarkable evidence, I will become a true believer.

Up until now, fluctuations in individual EPDs, phenotypes that are antagonistic with their own EPDs, and the type of cattle which are produced using full faith in the GE-EPD system are evidence enough to me that this is a dangerous toy, one being used to manipulate unknowing investors into believing that their potential purchase is indeed, scientifically, the best at what it is in the free world.

Tom Lasater, founder of the Beefmaster breed, famously said: “Breeding cattle is simple. The difficult part is keeping it simple!”