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Title: Testing for variation in animal preference for Jesup tall fescue hays with wild-type, novel, or no fungal endophyte

Author
item Fisher, Dwight
item Burns, Joseph

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/12/2008
Publication Date: 9/23/2008
Citation: Fisher, D.S., Burns, J.C. 2008. Testing for variation in animal preference for Jesup tall fescue hays with wild-type, novel, or no fungal endophyte. Crop Science. 48:2026-2032.

Interpretive Summary: Tall fescue is the principal cool-season forage grass in the humid areas of the USA and is especially prominent in the transition zone between cool-temperate regions and subtropical areas. However, there is a fungus that lives within the fescue (an endophyte) that can result in improved growth and stand persistence for the fescue but also results in decreased animal performance in animals fed the forage because it produces toxic alkaloids causing losses of over 500 million dollars a year. An improved cultivar named Jesup is currently available with a nontoxic endophyte marketed as “MaxQ’. This cultivar combined with this nontoxic fungal endophyte has shown improved agronomic performance and warrants further evaluation as a feed for ruminants. A USDA-ARS scientist from the Piedmont Conservation Research Unit in Watkinsville, GA teamed with a USDA-ARS Scientist from the Plant Science Research Unit in Raleigh, NC to test for variation in animal preference for 2 cuts of three hays made from Jesup tall fescue that varied in endophyte status. Two of the hays had no endophyte, two hays contained the nontoxic endophyte, and the other two hays contained a wild-type endophyte that produces toxic alkaloids associated with fescue toxicosis. We tested for preference using goats, sheep, and cattle. Animals preferred the first cut hay with the greater nutritive value over the second cut hays. Endophyte status was not a factor in the preferences of the 3 animal species. This means that it is unlikely that animals will preferentially select improved fescues and avoid plants with toxic endophytes. This information is important in renovating the approximately 30 million acres of fescue in the USA. Renovation to eliminate the fescues with toxic fungal endophytes is more likely to be successful since it does not appear that animals will detect and over graze the newer cultivars while volunteer plants with toxic endophytes reestablish.

Technical Abstract: Tall fescue (Festuca arundinacea Schreb.) is an important source of forage for herbivores across the North/South transition zone but a fungal endophyte can result in decreased animal performance in response to alkaloids. Removing the endophyte can reduce agronomic performance. An improved cultivar (Jesup) with a novel (nontoxic) endophyte (trade mark “MaxQ’) has improved agronomic performance and warrants evaluation hays fed to ruminants. Persistence may be related to both agronomic traits and to animal feeding preferences based on endophyte status. We tested for variation in animal preference for 2 cuts of three hays made from Jesup tall fescue that varied in endophyte status. Two hays had no endophyte, two hays contained the novel endophyte, and the other two hays contained a wild-type endophyte that produces alkaloids associated with fescue toxicosis. We tested for preference using goats (Capra hircus), sheep (Ovis aries), and cattle (Bos taurus). All possible pairs were tested and compared using traditional analysis of variance as well as multidimensional scaling to estimate the number of criteria that animals were using to separate the hays. Multidimensional scaling of the animal preferences indicated that 2 dimensions were being used to rank the hays. The first dimension was related strongly to variation in maturity in all three animal species. The second dimension used to separate the hays was not correlated with any of the measured variables. In addition, endophyte status was not a factor in the preferences expressed by the 3 animal species. It appears that no effective feedback mechanism exists that would result in a preference against an endophyte infected fescue when paired with a fescue without the endophyte or with a novel endophyte without alkaloids.