Hot Weather, Cool Cows: The Future of Slick Gene Holsteins

In this episode of The Select Sires Podcast, host Ethan Haywood chats with Mark Kerndt, Aggressive Reproductive Technologies (ART) program manager, to explore the powerful potential of the Slick gene in Holstein cattle. Learn how this naturally occurring genetic trait improves heat tolerance, reproduction, and productivity, especially in hot, humid climates. Mark explains how the gene is being advanced through Select Sires' ART program and what it means for the future of dairy genetics. Whether you're breeding for performance, resilience, or both, this conversation is full of insights for producers everywhere.

Transcript

Welcome to The Select Sires Podcast, talking Your Success, Our Passion. Starting in three, two, one.

Ethan Haywood

Hello, and welcome back to another episode of The Select Sires Podcast. I'm Ethan Haywood, and today joining me to talk about Slick cattle genetics is Mark Kerndt, ART Program Manager (ART®). Mark, thank you so much for taking the time to be here with us today. 

Mark Kerndt

Yeah, you're welcome, Ethan. 

Ethan Haywood

Mark, tell us what is the Select Sires ART program and what is your work involved there? 

Mark Kerndt

Sure. The ART Program is an internal female donor program for Select Sires. We've been started since 2008 and transfer about 15,000 IVF embryos a year into recipient herds and the idea of making about 40% of our bull lineup each year that is sampled is sourced through the ART program. 

Ethan Haywood

And the ART program gives us the ability to really focus on honing some very particular genetic topics. And Slick has been one of those genes that we have focused on in that female population as of the last few generations. Tell us what is the Slick gene and what does it mean for a Holstein cow physically if they are a Slick gene carrier? 

Mark Kerndt

Sure. Well, the Slick gene is just a natural mutation of the prolactin receptor in dairy cattle, and it's exhibited in beef cattle as well. The prolactin gene is involved in thermoregulation for the animal in milk production and reproduction. Like the Polled gene, the Slick gene is a dominant gene. Cattle carrying this gene will have a shorter, sleeker hair coat and just have the ability to tolerate hot, humid weather better, which of course results in better milk production and improved reproduction due to the better heat tolerance ability. This is backed up by research at UC Davis in California, University of Florida, and Puerto Rico. There's been research done and more recently at Mississippi State. But animals that have this gene will have a Slicker, shorter hair coat. That's visually what you'll see on this, but the big thing is just a better ability to stand hot humid weather. 

Ethan Haywood

And the ability to perform better, both production wise and reproductively, as well as some growth and health implications, potentially as well as interesting across the globe. And you have talked to producers and breeders from across the globe. Where do you see a lot of interest for Slick genetics, both domestically as well as internationally? 

Mark Kerndt

Yeah, the natural target audience or target market for Select Sires and this gene or this product line would be in areas closer to the equator. So that would be hot, humid climates or hot, humid environments. Maybe these cattle are outside on grazing markets as well. And that's certainly the producers that have been more interested in the Slick gene have been in the southern US or the other countries closer to the equator. And it makes a lot of sense, especially if these are animals that are out in the sun. And that's also precipitated some of our development where we try to combine the grazing traits along with the Slick gene as well. We just think that's a natural target market for us. 

Ethan Haywood

And so the way to move this gene throughout the Holstein breed in a productive way is to be able to use bulls that carry the Slick gene. And that's really where you and the ART program come in is trying to generate some diversity within that gene. You're used to working with some of the very highest ranking females within the market. And we've seen with the Polled gene, it can be difficult to maintain that high rank and work those other genes in. And it takes a lot of generations and a lot of selection. What did the process look like when you started saying, okay, we want to make high-ranking Slick males for the market? 

Mark Kerndt

Yeah, I think it's been quite exciting, the progress that we've seen at Select Sires in our Slick program. Basically, I can back up. As far as most of the dairy cattle, hosting dairy cattle in the U.S. would be concerned, the Slick gene was introduced into the United States through the University of Florida, naturally from the centipole breed, which is a Caribbean breed, and cross that with some Holstein cattle at the University of Florida. Then about 20 years ago, they first identified the first Holstein animal in the Holstein Association USA, and she happened to be an 7HO6417 O MAN daughter, by the way, that carried this Slick gene. So that goes back and then we purchased semen on a bull named Lone Ranger. It started in 2018. And we're into our fourth and fifth generations now of Slick breeding. And we've seen rapid improvements from those first Slick animals we have. And that just goes back to, like you mentioned, working with high females and high males. We didn't have the highest males obviously here when we had to deal with the Slick gene, but we had high females and good fundamentals of cattle breeding never go away. You breed the best of the best and we've used them on some very nice and very good Holsteins and we've gotten some Very Good Holstein Slick bulls as a result now.

Ethan Haywood

And it's really good that you mentioned that this is a natural occurring mutation that we've brought in through breeding. It was not through gene editing with the batch of genes that we're working with now. How do you go about verifying that the females or males within the program are carriers of the Slick gene? 

Mark Kerndt

Yeah, that's a good question. Genetic Visions has the sole exclusive rights to Slick gene testing. So animals that we think have Slick in the pedigree or know that we have Slick in the pedigree, we send those samples in through genetic divisions and we'll get confirmation that they are indeed either a heterozygous carrier or a homozygous carrier or don't carry the Slick gene at all. 

Ethan Haywood

And so as we look at our lineup and the female pool that you're working with, what bulls are we offering currently that have the Slick gene and what other benefits do those bulls have? They're not special just because of the Slick gene, are they? 

Mark Kerndt

No, that's a good point. You know, anytime when you do a specialty niche market, we've seen that in cold, the tremendous increase there, and we're going to see that in Slick as well. We know there are advantages to the Slick cattle that we just stated for heat tolerance and better milk production and reproduction. But if they're so genetically inferior for the other traits, then you don't really reap the economic benefits. And that's why we're excited about some of the bulls that we have at Select Sires. A bull named 9HO16849 ICE CUBE-S was really the first outlier in the Slick breed, so to say. He's a bull that's still +1,000 pounds of milk, even after a base change. He started out his marketing career as a NxGEN® bull and now is available across the globe in the GForce lineup. But he was heavily used as a mating sire, just an exciting bull all around, I think. And then his brother, named 9HO17089 INTHEFIRE-S, is another bull that fits what we talked about before, fitting the grazing market and the Slick market. He's a bull that checks the boxes for the grazing market being high components and lower stature and good on reproduction as well. But we've got other bulls, a 7HO16485 SUNDANCE son that will be released later this year named 9HO17743 GLOWSTICK-S that I think can also be looked at by some grazing markets as well. But then the young bulls, I think, 2026 will be the year that you'll start to see some real excitement on the Slick gene. We have bulls as high as 3384 GTPI, and several other Slick bulls as well. Some will be these grazing markets and some will just be bulls that check the boxes for, frankly, any kind of market around the globe. 

Ethan Haywood

And I know ICE CUBE has been a favorite of many of the sire analysts over the last year. I think his 7HO15085 PARFECT Dam, S-S-I Parfect Slick 2539-ET (EX-90-EX-MS), who's scored excellent and had a record of over 30,000 pounds of milk, is one of the more impressive cows that I've gotten to see on my travels in the last 12 months. So it's really cool to incorporate that gene into cow families that are rock solid to begin with. 

Mark Kerndt

Yeah, absolutely. And one of the questions I think that I always get asked on these Slick cattle, well, can they survive in cold weather? I don't have a research study to back that up but anecdotally the answer is absolutely yes all of our Slick animals in the ART program have been born in Wisconsin and they went on to either be a cow surviving in a freestall either in Wisconsin or there's one or a couple in northeast Iowa and a couple in southern Illinois actually so yes they do have the ability to seem to be able to tolerate colder weather as well. They will grow here. We just sent back a couple of Slick animals to a dairy in Southern Illinois this week. And the producer called me up and he said, now these don't look that short haired. And I told him, yeah, you're probably right. Right now, typically as these animals mature, certainly the bulls and then both on the cows, they tend to shed hair then, but they will grow hair when they're younger here. Certainly they have survived and, as you pointed out, ICE CUBE’s dam is probably the best Slick cow currently who has ever lived in the Holstein breed made over 30,000 pounds in this test and classified excellent points. 

Ethan Haywood

A really exciting cow family, and you've got a picture of some Slick young bulls and hutches in the middle of winter in Wisconsin with a foot of snow on top of the hutches, and they're happy as can be. So it's really interesting. The first time that we were on the road together, you were showing me some Slick donors, and the length of the switch hair in the winter was really the only difference we could see. As you've mentioned, producers say that that hair really thins out in the summer and they respond to their climate a little more adequately than other Holstein cattle. As we go forward, Mark, what do you think the future of the Slick within the Holstein breed looks like? I know that now there are some changes where you'll be able to see that information more readily and testing will continue and the impact on the population will continue. What other changes do you anticipate that there being within the Holstein breed in relation to Slick? 

Mark Kerndt

Well, I think it would just be interesting to see the adoption of this gene into the mainstream population, the early adopters of this type of pedigree or this Slick gene, they're going to be looking for obviously some different cow families because in breeding, anytime you have a novel gene in the early days of the evolution of that gene, and especially when you have a dominant so-called cow family, like ICE CUBE, is going to dominate the best pedigrees for the Slick gene. So the only way around that is to get that gene out into the natural population. And I think you'll see that more and more. As you get bulls that are good on certain traits here, and if heat tolerance is an issue for your dairy, and a bull can transmit enough milk or enough fat or enough protein and be good on some of these health traits as well, I'm thinking as a producer, yeah, that heat tolerance is something I might want to breed into some of my Holsteins in my herd. And as you get that gene used more in the population, and it gets out there, not only in North America, but across the world, that's when you start to see some real excitement, I think. It's just another step in the evolution of the breed of the Holstein cattle. 

Ethan Haywood

A very impactful step that will be really interesting to see over the next few generations. We're turning over generations with such efficiency that it is a very bright future for carriers of the Slick gene in the future. So thank you so much for your time today, Mark. It's very exciting to see new and shiny things coming out of the Select Sires Art Program and the impact that they'll have on the Holstein breed. 

Mark Kerndt

You're welcome, man. 

Ethan Haywood

Thank you again for tuning in to The Select Sires Podcast, and we'll talk to you next time.