For producers growing fescue, toxic or harmful endophyte infections can be a common issue. In a University of Missouri Forage and Livestock Town Hall, retired University of Georgia professor and Agrinostics Ltd. representative Nick Hill covered the basics of why, how and when to test endophyte levels.
The main reason to test for endophyte infections is to understand the impact it may have on production.
“There is an inverse relationship between infection rate of the endophyte and animal performance,” Hill said.
While having a low frequency of endophytes may not be an immediate cause for concern, high levels can have a dramatic impact on production. In stocker steers, there is generally about .1 pound per day reduction for every 10% of endophyte in fescue pastures, Hill said.
“Calving and conception rates can be affected and with horses it could be all sorts of issues,” Hill said. “The bottom line is you get a reduction in animal performance.”
While some issues may be mitigated through the use of supplements, Hill reminds producers supplements do not overcome the root problem.
Because all pastures are not equally infected, testing endophyte levels can help producers make management decisions.
“A study I did back in 1984 found that 95% of pastures are infected with 60% or more of endophyte frequency and the highest proportion was between 80% and 100%,” Hill said. “The reason for this is that endophyte is doing things for the plant. It gives the plant a competitive advantage, so pastures have a tendency to go from a low infection rate to a high infection rate over time.”
When creating a farm plan for endophyte management through killing off fescue and reseeding, Hill recommends considering infection rates, productivity potential of pastures, pasture conditions, pasture utility and pasture acreage.
Any pasture with an infection rate of 40% or more can be a candidate for renovation through reseeding, Hill said. Pastures with high productivity potential or in poor condition should be prioritized, but producers should also consider how the pasture is used to determine which fields to treat.
“We have found bigger pastures are easier to renovate than smaller pastures,” Hill said. “The size of the pasture and the ease of operation in terms of reseeding and getting that pasture back into a nontoxic situation."
How to test
There are several methods available for producers to test for endophytes, each with their own advantages and disadvantages.
Microscope tests are inexpensive because they are conducted in state-run laboratories with subsidized labor costs, Hill said. However, microscope tests are dependent on technicians, which can lead to technician fatigue and long waits for results.
“The big detriment to this is there’s not permanent record,” Hill said. “If theres an argument that needs to be made, if things weren’t done correctly or there’s misrepresentation of a seed lot or field condition, there’s no way to go back and check.”
Molecular DNA tests can detect specific endophytes - meaning it can determine the difference between toxic and nontoxic endophytes, Hill said. These tests can also be conducted more rapidly than microscope tests and produce a permanent record for producers. Because of the high initial capital investment required for this type of testing, it is not a standard method across the country. These tests also have lab dependent methods and require highly trained technicians.
The final method is the immunoblot test developed by Agrinostics Ltd. These tests are simple to use and have rapid turn around times, Hill said. They also have a low capital investment, use a uniform lab method and produce a permanent record.
“The one big detriment is that it cannot differentiate between toxic and nontoxic endophytes,” Hill said. “In order to do that, we have to perform a separate test.”
When to test
Knowing the correct time of year to collect samples is important when looking to fully understand pasture infection rates.
Producers wanting to know absolute values of endophytes in their pasture should refrain from collecting samples in February, March or April.
“If you want to know relative values between one pasture and another, its probably still okay to sample at this time,” Hill said. “Just know that the values that you get are going to underestimate the amount of endophytes you get in your pasture.”
This drop in apparent endophyte levels is caused by endophytes moving to the reproductive tissues of fescue plants. This occurs while these tissues are still below the soil surface, making it difficult to get accurate samples.
“If we wanted to sample at this point in time, we would actually have to dig the plants up and send in some of the roots system,” Hill said. “That gets really tedious and I wouldn’t suggest it. It’s easier to just wait.”
Testing by seed companies
“Seed companies have to go through some extra hoops to provide you with information so that you can be confident if you buy novel endophyte tall fescue its truly what it says it is,” Hill said.
Claims of endophyte content are not required unless a seed is “endophyte-free” and labeling requirements are state regulated, Hill said.
“The important thing to note is there is no federal regulation for the labeling of Novel Endophyte technology, or these new, nontoxic endophytes that are in these tall fescue varieties,” Hill said.
To provide customers with more information, many seed companies work with Agrinostics Ltd. to get a clear understanding of the endophyte levels in their seed lots. Producers looking for products proven to contain nontoxic endophytes can look for the Alliance for Grassland Renewal logo on seed bags.
“Along with the logo will be this qualifying statement: This seed lot has been tested and determined to contain at least 70% novel endophyte and no more than 5% off-type or toxic endophyte,” Hill said. “I can tell you that the vast majority of seed lots are 95% infected and have 0% off-types. Seed companies are doing a really great job of quality control in their seed.”