Fescue toxicity testing John Benner Matt Booher

From the Extension publication: “Making the Most of Fescue in Virginia”

Endophyte Infection Levels in the Shenandoah Valley Test locations: June 2013 2013: Tested 26 pastures in Rockingham, Augusta, & Rockbridge Collectively, the farms sampled represent about 10,000 animals

Sample collection: 20 fescue tillers, cut at soil junction, retain bottom 4” for testing, damp paper towel Store & ship frozen (dry ice, overnight $100-$200) Testing: Agronostics Lab, Watkinsville GA ELISA: $60/sample (quantity break) Also sell ELISA kits

Results 65% of pastures were 100% infected Lowest infection rate (1 pasture) was 50%

Seasonal Ergot Alkaloid Production in Shenandoah Valley Pastures

5 Sample Locations Tracked 9 pastures Continuously grazed Timberville, Rockingham County Tracked 9 pastures Continuously grazed Rotationally grazed Clipped/bushogged Summer stockpiled/hay Harrisonburg, Rockingham County Elkton, Rockingham County Weyers Cave, Augusta County Tracked 11 treatments (9 pastures) over the growing season. Various grazing management treatments were implicated, for the most part there was replication among farms. Raphine, Rockbridge County

Sampling Fresh pasture: STORE AND SHIP FROZEN Hay: AS-IS Sampled only fescue Avoided high-N areas around manure Watch out for ryegrasses! To mimic animals’ diets Observed selective grazing prior to sampling each time Whole plant through early-head, undergrowth only after that Grab-sampled to mimic animal bite Fresh pasture: STORE AND SHIP FROZEN Hay: AS-IS COST: $15/sample to freeze dry and grind $30/sample to test (20 or more) Agrinostics Lab. Toxicity testing looked at only fescue in order to provide a baseline for potential toxicity in fescue monoculture situations. For nutritive testing, looking at the grass component without legumes give a baseline to work off of. A farmer can look at this information and say, “yeah I have some fields that are nearly all fescue – its probably similar to what they found” or “I have about 20% clover in this pasture, I’m probably a couple points higher in energy and significantly less toxic than what they found.” We also tried to mimic animals selection of forage. For example, through early heading in June when seed heads and stalks were still relatively green animals seemed to consume the whole plant (upper photo) – so we sampled accordingly. From July on, when seed stems and heads dried up and turned brown, animals seemed to put their heads to the ground and focus on undergrowth. This does influence our results, but I think it gives us a chance at a truer picture of what animals are actually seeing.

Average Seasonal Alkaloid Content of 9 Shenandoah Valley Pastures This is the average alkoloid content of all pastures in the study over the course of the season. Alkaloid levels rose quickly after spring greenup and stayed high throughout the season. There are many factors influencing endophyte growth and toxin production but one thing we saw consistently was that alkaloid production mirrored the growth of the plant. On this graph you can see a little bit of a spike early around mid-may as fescue was starting to show a seedhead, the drop we recorded immediately after that was likely due to dilution as plants began to mature and stemmy growth diluted out the alkaloids. Again we say a little drop in late-summer when rainfall was very low, follwed by a spike in fall once we got rain and growth resumed. N=6 N=6 N=9 ~500 ppb: threshold for toxicosis?

Average Seasonal Alkaloid Content of 9 Shenandoah Valley Pastures This is the average alkoloid content of all pastures in the study over the course of the season. Alkaloid levels rose quickly after spring greenup and stayed high throughout the season. There are many factors influencing endophyte growth and toxin production but one thing we saw consistently was that alkaloid production mirrored the growth of the plant. On this graph you can see a little bit of a spike early around mid-may as fescue was starting to show a seedhead, the drop we recorded immediately after that was likely due to dilution as plants began to mature and stemmy growth diluted out the alkaloids. Again we say a little drop in late-summer when rainfall was very low, follwed by a spike in fall once we got rain and growth resumed.

Total Ergot Alkaloids by Plant Development Stage

Demonstration of Principles Spring-applied N Early-heading Dilution by stemmy growth Fall-applied N Summer slump Vegetative regrowth Winter dormancy

Summary: What have we learned from a season of testing alkaloids? We have the potential for alkaloid levels far above the threshold There can be large differences between farms Seasonal fluctuations mirror plant growth Management that results in better pasture can increase toxicity Vigorously growing plants Nitrogen fertilizer