Submitted to: Book Chapter
Publication Type: Book / chapter
Publication Acceptance Date: 8/20/2004
Publication Date: 2/15/2005
Citation: Stuedemann, J.A., Seman, D.H. 2005. Integrating genetics, environment, and management to minimize animal toxicoses. Book Chapter. Interpretive Summary: Tall fescue is a valuable pasture grass that is grown on over 49 million acres primarily in the east and southern parts of the U. S. It is estimated that it is grazed by over 8.5 million beef cows and 700,000 horses. Its contribution to agricultural production and environmental quality is dependant upon the mutualistic relationship between a fungus or endophyte that lives inside the plant and the plant itself. The fungus gives the plant hardiness that enables it to survive in environments that it would ordinarily die in. Unfortunately, the wild-type endophyte or fungus that is present in over 80 percent of the tall fescue pastures in the U. S. also results in animal health problems that cost producers over 600 million dollars annually. The purpose of this paper is to evaluate and summarize literature dealing with opportunities for eliminating, reducing or minimizing the effects of the endophyte on animal production. This interpretive review was compiled by researchers at the J. Phil Campbell Sr., Natural Resource Conservation Center, Watkinsville, GA. In spite of a recent major breakthrough that involves insertion of nontoxic endophyte strains into various varieties of fescue, there are still many pasture and animal management options, as well as dietary additives and supplements, that have value in reducing the impact of wild-type endophyte infested tall fescue on animal production. However, none appear to have universal application. This information can be used by producers, consultants and the Cooperative Extension Service to better design management options that improve productivity of animals grazed on tall fescue.
Technical Abstract: Since the discovery of the wild-type endophyte and the accumulation of evidence associating its presence in tall fescue with reduced animal productivity, much research has been devoted to developing methods aimed at reducing the impact of endophyte-infested tall fescue on animal production. Our objective was to summarize this body of research. We briefly assessed the impact of the endophyte on animal performance and production. We have summarized opportunities for eliminating, reducing, or minimizing negative effects on animal production by pasture and/or animal management. These opportunities include reseeding with endophyte-free fescues, or fescues containing non-ergot alkaloid producing endophytes, dilution with other grasses or legumes, differential stocking rate, differential forage mass available, stockpiling of forage, and mechanical management of the pasture such as mowing. We reviewed the impact of a host of feed treatments and dietary additives on the symptoms of fescue toxicosis. The role of pharmacologic agents and the potential for immunologic protection have been included. Lastly, we have coupled the role of producer expectations with management time and expertise in making decisions to minimize the effects of fescue toxicosis.