64: How DON Mycotoxin Slows the Rumen and Erodes Dairy Performance

Ruminate This | Agrarian Solutions

Ruminate This | Agrarian Solutions
64: How DON Mycotoxin Slows the Rumen and Erodes Dairy Performance
Jan 12, 2026 Season 2 Episode 64
Scott Zehr

In this episode of Ruminate This, Scott Zehr is joined by Dr. Larry Roth (VP of Nutrition, Agrarian Solutions) for a discussion about DON (deoxynivalenol/vomitoxin)—one of the most common and most misunderstood mycotoxins in dairy rations.

Rather than causing an obvious crash every time, DON often works like a “pause button” on rumen microbes. It doesn’t necessarily kill bacteria, it slows microbial function and disrupts fermentation, reducing the cow’s ability to convert the TMR into energy and microbial protein. The result can be a quiet, cascading problem: lower feed efficiency, reduced intake, erratic manure, and performance erosion that shows up long after the damage begins.

Scott and Larry discuss how DON can:

  • Disrupt rumen microbial balance by interfering with protein synthesis and slowing fermentation
  • Push undigested nutrients “down the river” into the hindgut, leading to undesired hindgut fermentation
  • Create signs that look like acidosis, when the real issue may be hindgut acidosis driven by poor rumen breakdown
  • Weaken gut barrier integrity, increasing permeability and contributing to leaky gut
  • Trigger immune activation and force nutrient reallocation, pulling glucose and energy away from milk and reproduction to support inflammation control
  • Compound other stressors, making DON a major player in stacked inflammation 

They also discuss why the same DON ppm level can hit two herds very differently, and why ongoing mycotoxin testing can help connect the dots before a slow decline turns into a full-blown crisis.

If you’ve ever wondered, “Is this really rumen acidosis… or something else?” This episode will change how you diagnose digestive, immune, and performance problems in high-producing dairy cows.

🎧 Listen now on Apple Podcasts, Spotify or your favorite podcast platform 

💬 Have thoughts or a story to share? Email podcast@agrsol.com.

🔗 Stay informed: Get expert livestock nutrition insights, cutting-edge research, and updates on future episodes by subscribing here: agrariansolutions.com/podcast

Social Links:
YouTube:  https://www.youtube.com/@RuminateThis
YouTube Page:  https://www.youtube.com/@agrariansolutions5557
LinkedIn:  https://www.linkedin.com/company/agrarian-solutions/
Facebook Page: https://www.facebook.com/AgrarianSolutions
Instagram Page:  https://www.instagram.com/agrariansolutions/
Website: https://agrariansolutions.com/

Got a Question or want free Mycotoxin Testing? Send us a Message!!

Episode Artwork 64: How DON Mycotoxin Slows the Rumen and Erodes Dairy Performance 33:58 Episode Artwork 63: Best of Ruminate This: The Dairy Nutrition Conversations That Still Matter 17:23 Episode Artwork 62: Why Culture Builds Better Calves 24:01 Episode Artwork 61: Mycotoxins & Subtle Stress: Why Cows Look Fine but Performance Drifts 22:37 Episode Artwork 59: Nine Months of Pain All Because Testing Came Too Late 26:39 Episode Artwork 58: The Truth About Calcium Carbonate in Dairy Nutrition 28:04 Episode Artwork 57: The True Cost of Staying the Same on Your Dairy 33:57 Episode Artwork 56: Shaping the Future of Transition Cow Health 39:37 Episode Artwork 55: Best practices for disbudding 27:34 Episode Artwork 54: The next generation of transition cow care 51:10 Episode Artwork 53: Silage inoculates: what they do and don't do 29:27 Episode Artwork 52: Corn Silage Secrets: Stop Shrink, Boost Quality 53:11 Episode Artwork 51: Optimizing Transition Cow Health to Boost Fertility and Milk Production 21:23 Episode Artwork 50: Drone Technology for Accurate Silage and Feedstuff Inventory 19:26 Episode Artwork 49: Mycotoxins, Inflammation, or Something Else? 14:30 Episode Artwork 48: Fishing for Feedback: Its Role in Building Strong Teams and Culture 42:41 Episode Artwork 47: Invest in Yourself: The Power of YDLI 23:24 Episode Artwork 46: How to Make High-Quality Haylage from Grass, Alfalfa, and Winter Annuals 42:26 Episode Artwork 45: Mycotoxins on the Rise: Tips to Protect your Livestock 25:06 Episode Artwork 44: Rising Fumonisin Threat: What You Need to Know 17:27 Episode Artwork 43: Strong Starts, Strong Futures: Mastering Colostrum Management 40:25 Episode Artwork 42: Boost Calf Health by Strengthening Farm Teamwork 30:38 Episode Artwork 41: Optimizing Calf Health: Managing Mycotoxins in Pre-Weaned Diets 28:42 Episode Artwork 40: The challenges and rewards of working with family in business 42:47 Episode Artwork 39: How LivOx Boosts Gut Health, Liver Function, and Milk Production in Dairy Cows 32:52