Location: Forage-animal Production Research2009 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
A key research methodology, liquid chromatographic separation and mass spectrum analysis of ergot alkaloids in vascular tissue, for this project has been accepted and validated by experts in the field with the recent acceptance for publication of a manuscript on this method by the Journal of Food and Agriculture. This method is now being expanded to other animal tissues and fluids for use in tracking alkaloid disposition and clearance within an intoxicated animal. Validation of a new in vitro vascular model (i.e., gut vessels) is nearing completion and is key to our understanding of how ergot alkaloids affect vascular flow to splanchnic tissues and subsequent nutrient utilization. Approximately 40 hyperammonia producing bacteria (HAB) have been isolated from the meat goat rumen environment and partially characterized. Further, we have demonstrated that Hops extracts were capable of inhibiting members of the HAB class via the active compound lupulone. Hops extracts were more effective at lower ruminal pH’s. The results support the idea that plant-based feed additives may be useful in modifying the ruminal environment for better efficiency. The grazing phase of the second year of a two-year grazing study designed to assess steer performance and physiological responses on endophyte free or infected (toxic wild type or novel endophyte) tall fescue has been completed. Data during year one indicated that steer on new endophyte free and a new novel endophyte infected (AR584-KYFA9301) varieties of tall fescue had higher average daily gains and lower rectal temperatures than endophyte infected (toxic wild type) Kentucky-31 tall fescue. Carrying capacity was similar between all varieties. Year-2 data is currently under review.
1. Modifying Rumen Fermentation with Plant Metabolites. A principle theory in rumen microbiology is that the activities of the rumen microbes can be optimized like any other fermentation. This concept has been applied in a number of ways, and antimicrobial feed additives are one of the most successful. Bacteria produce most commercially available antimicrobial feed additives (i.e. antibiotics), but plants also make antimicrobial compounds. Hops (Humulus lupulus L.) decreased ammonia production by mixed rumen bacteria and inhibited pure cultures of ruminal hyper ammonia producing bacteria. Hops extracts revealed that the active compound was ß-lupulone, and the mechanism of action was bioenergetic uncoupling of the cell membrane. Like many membrane-active antimicrobials, the activity was enhanced at low pH values. Results indicate that plant-based feed additives could be beneficial in improving ruminal efficiency through decreased ammonia production and may serve as alternatives to bacterial products in modifying the rumen ecology.
5. Significant Activities that Support Special Target Populations
Continuing a research project (pilot study for logistics purposes conducted last year; Non-Funded Cooperative Agreement has been submitted) with University of Kentucky and Berea College faculty aimed at understanding the effects of tall fescue (especially endophyte-infected) on meat goat production. This project is not only providing much needed data for the meat goat industry, a rapidly growing industry well suited to small acreage farms, but is also providing a learning opportunity for a number of first generation college students from the Appalachian region of eastern Kentucky. Continuing a research project with Kentucky State University faculty on the microbial ecology of the goat rumen. This project will not only provide much needed data for meat goat production, a growing industry suited to small farms and culturally important to Arabic-, African-, and Mexican-Americans but provides unique education opportunities at a traditionally minority-serving institution.
Aiken, G.E., Mc Clanahan, L.K., Kirch, B.H., Schrick, F.N. 2008. Performance and Physiology of Steers Following Grazing of Toxic Tall Fescue as Influenced by Feeding Soybean Hulls on Pasture and Post-Graze Steroid Implantation. Professional Animal Scientist. 2008. 24:392-398.