Pearl Snaps

Stories of a cowgirl living life by her own lights

Fescue toxicity issues in Texas?


by Jesse Bussard

I received an intriguing email from a Facebook friend this week. This friend serves as an operations manager for an order buying company in southeastern Texas. Due to the drought induced shortage of cattle in their state in order to fill their cattle orders they’ve been purchasing cattle from some Southeastern states. Upon arrival these cattle were process and place on bermudagrass/annual ryegrass pastures with access to concentrates until they were ready for shipment to the feedyard.

Example of rough appearance of fescue cattle

As expected some of these cattle due to the stresses of weaning and hauling develop some health problems that must be treated. Interestingly, though some of these cattle seemed to be exhibiting other symptoms, have a rough appearance, and are not responding well to vaccinations or treatments. What could the problem be he asked? He’d heard of tall fescue and the potential toxicosis that can occur with cattle grazing this forage, but he wasn’t really sure if this is what the issue could be. After further communication we determined that these cattle were indeed suffering from the residual effects of fescue toxicosis.

If you’re unfamiliar with fescue toxicity or it’s symptoms, see this blog post I previously wrote giving a basic overview.

If you don’t feel like going to the blog post here’s a quick and dirty Fescue Toxicosis 101:

  • Tall fescue contains an endophyte (fungus) which affects palatability and inhibits cellulose digestion through production of alkaloids (toxins).  This buildup of alkaloids leads to a syndrome known as fescue toxicosis in both cattle and horses.
  • Fescue toxicosis causes hormonal imbalances and constriction of blood flow to peripheral tissues that restrict the cattle’s ability to dissipate core body heat.  Because of this, calf weight gain can be decreased, especially in warm, humid climates.  Many of the hormones reduced are related to reproduction and lactation and can lead to lower calving rates, milk yields, and weaning weights for cattle producers.  There are also concerns of alkaloid carryover in the feedyard.

Usually these symptoms are most common in the heat of the summer when cattle are grazing toxic endophyte-infected  tall fescue. However, it has been shown thru previous research both in the lab and in the field that these ergot alkaloids that cause the toxicosis symptoms can bioaccumulate in cardiovascular and fat tissues. Researchers speculate that these alkaloids may continue to negatively affect blood flow and thermal regulation for an extended period after cattle are removed from toxic tall fescue pastures. There is even speculation that ergot alkaloids may possibly be metabolized from fat tissue and cause residual toxicity symptoms after cattle are no longer consuming toxic forage. With all this being said, these are still just speculation and need to be scientifically proven before we can say for a fact this is what is occurring.

You might be wondering why this cattleman contacted me of all people and how I know so much about this topic. Well this is kind of my thing. This is basically what my graduate research has focused on in the past 2 years I’ve been studying at the University of Kentucky.

So what can this cattlemen do to cope with these fescue cattle? First off, he’s going to have to give these cattle a little extra TLC. You must understand that an animal suffering from fescue toxicosis is already severely stressed. Their blood vessels are constricted and they cannot properly regulate body temperature. This leads to a whole host of other issues and ultimately decreased animal performance. Throw in the stress of hauling, weaning, and Texas heat and these calves are really getting what I call the triple whammy.

No wonder vaccinations or antibiotics aren’t effective. It’s a known fact that animals under stress have a weakened immune response. For a vaccination to be effective the animal’s immune system must be functioning normally so that an adequate immune response can be launched to the introduced antibodies. With a downed immune system, this will never happen.

The best thing for these cattle is to isolate them from the rest of the herd, give them a week or so to adjust, and then process the calves with vaccinations, etc. This will give their bodies time to adjust and for the alkaloids to dissipate from their system.

I plan on staying in touch with my friend to find out how these cattle are faring in the next 2-3 weeks. I’ll let you know how it works out. I’m hoping with a little extra care they pull through alright.

3 thoughts on “Fescue toxicity issues in Texas?

  1. Endophyte-infected tall fescue is one of the worst things we have going in the southeast! I know that there are new varieties of fescue will “friendly endophytes,” if only we could get those better established around here!

  2. Novel endophyte (E-) tall fescue varieties definitely are the way to go. You’re right about the possible issues with establishment. I think the biggest challenge is making that all preexisting E+ tall fescue is eliminated before novel varieties are planted. KY 31 is an aggressive and challenging plant to eliminate and even with spraying some seeds are always left in the seedbank. Upon successful stand establishment of novel endophyte E- tall fescue, the next challenge is to manage the grass properly. Many times cattlemen think that they can graze novel endophyte fescues just as they previously had KY 31 when this just isn’t the case. Unlike KY 31, the cattle will graze novel endophyte harder, so a higher degree of grazing management must be maintained to ensure stands are not overgrazed and stressed.

  3. Pingback: My Thesis and Tall Fescue 101 « Pearl Snaps' Ponderings

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