Location: Forage-animal Production Research2010 Annual Report
1a. Objectives (from AD-416)
The long-term goal of this project is to improve competitiveness and sustainability of forage-based animal enterprises in the transition zone between the subtropical south and temperate north of the eastern half of the United States. Over the next 5 years the Forage-Animal Production Research Unit (FAPRU) and collaborators will focus on the following objectives: Objective 1: Improve forage-animal health, performance, and forage intake and utilization. Subobjective 1.A. Develop and validate analytical methodologies for profiling ergot alkaloids produced by toxic endophyte-infected (TE) tall fescue (TF), and resulting metabolites following consumption and metabolism by animals. Subobjective 1.B. Identify the biotic components and mechanisms of the animal-plant interface impacting grazing animal health and production. Subobjective 1.C. Enhance nutrient utilization through an improved understanding and manipulation of microorganisms of the rumen. Objective 2: Improve animal and forage productivity of forage-based systems through optimization of grazing and preconditioning management protocols. Subobjective 2.A. Evaluate animal performance on novel endophyte-infected TF pastures. Subobjective 2.B. Develop a preconditioning program to reduce morbidity and mortality in feeder calves that have been backgrounded on TE TF.
1b. Approach (from AD-416)
Forage systems provide low-cost feed, conserve soil and water resources, and mitigate man’s impact on the environment. However, basic biological information is limited on how plant metabolites affect animal performance and health beyond the production level. Fundamental information concerning how these production level effects are elicited has only recently become a focus. As such, the available information for predicting animal performance in response to plant nutrients under varying environmental, genetic, physiological status, and management conditions is of limited use. Even more problematic is the poor understanding of the effects of plant nutraceuticals and anti-quality factors on nutrient intake, metabolism and assimilation for product, health maintenance, or work by the animal. To increase the sustainability of forage-based enterprises, it is essential that a better understanding be developed of the fundamental biological processes underlying the interactions between the animal, plant, and environment. This project, through the development and utilization of cutting-edge technologies and real world testing, proposes to decipher the complex interactions within the animal-plant interface in order to accomplish the following two objectives: 1) improve forage-animal health, performance, and forage intake and utilization; and 2) improve animal and forage productivity of forage-based systems through optimization of grazing and preconditioning management protocols. These objectives will be focused on the predominant forage (tall fescue) of the transition zone and its alternatives. Accomplishing these objectives will improve sustainability of forage-based enterprises through more reliable predictions on the impacts of management and environment on animal health and performance.
3. Progress Report
Development of an ultra-performance liquid chromatographic separation protocol for seven ergot alkaloids has been completed. Determined that recovery by cattle from vascular dysfunction following consumption of toxic tall fescue is not accomplished over a short period of time, thus requiring adequate withdrawal times prior to shipping to feedlots. From the vascular recovery data it was recommended that cattle grazing toxic tall fescue should be transported to feedyards in early spring or fall to avoid high ambient temperatures that can lead to excessive heat stress (exacerbated by the ergot alkaloids in toxic tall fescue) and a greater risk of high morbidity and mortality. Determined the presence of and involvement of a 5-hydroxytrptamine 2A (serotonin) receptor in the contractile properties of a bovine lateral saphenous vein bioassay to ergot alkaloids commonly found in endophyte-infected (toxic) tall fescue and the ergot of rye. Developed and validated a ruminal artery and vein bioassay for the study of ergot alkaloid effects on gastrointestinal blood flow. As with the lateral saphenous vein, it was demonstrated that the ergopeptines are more effective at causing vasoconstriction of the ruminal artery and vein than the simpler ergot alkaloid, lysergic acid. Additional information is available in the Annual Reports for the Congressionally mandated Specific Cooperative Agreements (6440-32630-001-06S, Continuation of Improved Forage Livestock Production Systems; 6440-32630-001-03S, Improved Forage Livestock Production) that is partially funded by this research project. Likewise, relevant information is available in the sister project (6440-21000-001-00D, Forage Systems for Sustainable Animal Production in the Mid-South) to this research project.
1. Evaluation of an Ethanol Extract of Tall Fescue Seed for Induction of Fescue Toxicosis in Holstein Steers. Tall fescue toxicosis caused by ergot alkaloids produced by the endophyte Neotyphodium coenophialum results in health and production issues in animals grazing the infected fescue, resulting in negative economic effects for producers. The decrease in productivity caused by fescue toxicosis has been estimated to cost United States producers more than $600 million per year. Most research examining the effects of fescue alkaloids on animal performance uses ground seed added to a basal diet to mimic grazing infected pasture. As one of the symptoms of fescue toxicosis is a reduction in feed intake, alteration of alkaloid intake level can occur using this methodology. A more precise method may be to dose animals with an extract containing the alkaloids found in toxic fescue. As such, University of Kentucky and ARS scientists located in Lexington, Kentucky, measured physiological indicators of fescue toxicosis following ruminal dosing of Holstein steers with an ethanol extract and showed that the ethanol extract of tall fescue seed can induce the symptoms of fescue toxicosis. Animals exhibited reduced intake, lowered heart rates, increased core temperatures, in addition to other symptoms. This research demonstrates the validity of an extract model for further research in the field of fescue toxicosis. This model should provide a more precise and repeatable method for inducing fescue toxicosis and subsequent nutritional and physiological studies on the mechanisms of the intoxication.
5. Significant Activities that Support Special Target Populations
Continue a research project with University of Kentucky (Project #6440-32630-001-10N) and Berea College faculty (Project #6440-32630-001-11N) aimed at understanding the effects of tall fescue (especially endophyte-infected) on meat goat production. This project will provide much needed data for the meat goat industry, a rapidly growing industry well suited to small acreage farms, but also provides a learning opportunity for a number of first generation college students from the Appalachian region of eastern Kentucky. Conducting a research project with Kentucky State University faculty on the microbial ecology of the goat rumen. This project provides much needed data for meat goat production, a growing industry suited to small farms and culturally important to Arabic-, African-, and Mexican-Americans and provides unique education opportunities at a traditionally minority-serving institution. Collaborated on a Capacity Building grant application with Kentucky State University, a minority serving institution.