A Spring Break from Toxic Fescue Makes All the Difference!

My family has been raising cattle on the Virginia line, due north of Raleigh, NC, for 50 years, where we spent most of our childhood summers.  I grew up thinking that it was a miserable life for a cow in NC compared to cows I was around out west in Northern Arizona where we lived during the rest of the year.  It always puzzled me as it seemed there was little to eat out there, but the cows looked very healthy and thrifty, while in NC, there was always a lot of really good-looking grass, but the cows looked terrible.  I assumed that the problem was because of the heat and humidity that we are all so aware of each summer, and that our genetics were just sorry.  As it turns out, that great looking KY31 tall fescue is toxic and causes impaired blood flow, which makes cattle slow to shed their hair coats and have trouble regulating their body temperature to cope with the heat.  The syndrome is known as Fescue Toxicosis.

Today, after being a professor at NC State for 30 years and spending much of my energy working on the fescue toxicosis problem, toxic fescue is still the dominant forage related problem in our area. Even for me knowing all I do, it was very hard for me psychologically to load up the sprayer with glyphosate and kill really good looking grass.  About 6 years ago we finally set out to convert the front half of our farm to novel endophyte tall fescue, which has the advantages of toxic fescue without the toxins.  We have fields in various stages of the transition with most of the acres we have killed still in annuals, primarily oats and ryegrass in the cool season, and sudangrass or pearl millet during summer. 

The cattle shown in the photo are our bred heifers and coming three year olds that just weaned their first calves, and they are grazing an old stand of KY31 tall fescue on a very hot June 29, 2020.  These cattle don’t look like your typical cattle grazing infected tall fescue in summer, but why?  Is it because these cattle get a lot of feed?  No, they have been on forage only since March 1.  Is it because they are getting some kind of feed additive that cures the problem?  No, these cattle are on a very standard mineral supplement.   These heifers got a break from fescue toxins by grazing ryegrass during the time of year when fescue is making seedheads and is really toxic.  The stand of fescue in the photo was cut for hay which we know helps reduce toxin levels.  Also, the vegetative regrowth following spring hay cutting is less toxic.  Finally, putting the heifers on non-toxic forage for the months of March, April and May also allows them to shed their hair coats normally, adapt metabolically to the heat and to gain some body condition. 

There is research from the University of Arkansas that showed that converting only 25% of the toxic tall fescue to novel endophyte tall fescue dramatically improved breeding rate in spring calving cows.  Unfortunately, there are no studies with the same strategy for fall calving cows, and in our area most farmers, including us, calve in the fall.  Fescue is not as hard on fall calving cows as it is on spring calving cows, and that is why many use fall calving.  However, my observations at home confirm the value of the “toxin spring break”, even with fall calving. 

You might have a tolerable breeding rate with fall calving, but there are still many fescue-related problems plaguing the cows.  Being able to give developing heifers and young cows a break from the fescue toxins during the spring works wonders for the rest of their lives.  If you have never seen your cattle when they have had a significant break from fescue toxins you would not believe the difference.  If you have a mostly tall fescue base and would love to get more out of your cattle, start by killing a field of old KY31 and plant it to annuals.  Then, talk to your advisor and develop a plan to convert as much of your fescue acreage to novel endophyte tall fescue as is practical.

~ Matt Poore, NC State Professor and President of the Alliance for Grassland Renewal

The Alliance for Grassland Renewal is a national organization focused on enhancing the appropriate adoption of novel endophyte tall fescue technology through education, incentives, self-regulation and promotion.  For more resources or to learn more about the Alliance for Grassland Renewal, go to www.grasslandrenewal.org