Location: Forage-animal Production Research2010 Annual Report
1a. Objectives (from AD-416)
Objective 1. Improve persistence, productivity, and quality of forage grasses and legumes for use in the transition zone of the Eastern and Midwestern U.S. Objective 2: Identify the biotic components and mechanisms of the animal-plant interface impacting grazing animal health and production. Objective 3: Improve animal and forage productivity of forage-based systems through optimization of grazing and preconditioning management protocols.
1b. Approach (from AD-416)
Forage systems provide low cost feed, conserve soil and water resources, and mitigate man’s impact on the environment. Limited basic biological information exists on how plant and/or fungal metabolites affect forage plant quality, persistence, and production. Even less information exists on the cross-talk mechanism between tall fescue (the predominant forage of the transition zone) and its endophyte or about the impact that forage and/or fungal metabolites have on pasture ecosystems. Additionally, 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. Thus, to increase the sustainability of forage-based animal 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 Specific Cooperative Agreement (SCA), through the development and utilization of cutting-edge technologies, real world testing, and technology transfer, proposes to help decipher the complex interactions within the animal-plant-environment interface in order to improve forage production and persistence as well as forage-animal health, performance, and forage intake and utilization. Research is focused on the utilization and production of the predominant forage (tall fescue) of the transition zone and its alternatives and/or companion species. To accomplish the objectives of this SCA, a number of differing methodologies including molecular and chemical investigations of animal tissue and cellular function, nutrient flux experiments in cattle, classical animal nutrition studies, doppler ultrasonography, molecular and chemical investigations of plant/fungal metabolites and physiological function, pasture ecological studies, forage breeding and applied grazing trials, will be utilized.
3. Progress Report
Four grazing trials have been completed to study the preference of beef cattle for a diverse array of tall fescue and other forage grasses. Cattle showed preference for the festulolium entries over most other entries, but for each grazing period they discriminated among the choices. The preferences were not always consistent over the four grazing periods. Forage samples from all four grazing periods have been analyzed for forage quality by Near-Infrared Spectroscopy (NIRS). A test of nonpregnant mares was expanded upon to determine time of onset of vasoconstriction after first seed feeding. Because of greater than expected variability in pregnant mares, those studies will be repeated to increase the number of animals in the study. Analysis of arthropods from tall fescue pastures with modified alkaloid profiles showed that removing livestock-active toxins will not provoke pest outbreaks. A field-collected baculovirus shown to infect armyworms will be used to study compatibility of modified grasses with biocontrol. During the last year, tests have focused primarily on developing an NIRS technique to determine horse diet composition from manure. Strong correlations have been developed between known composition samples and NIRS predictions. A second comprehensive digital image library has been developed and analyzed for percent cover using ERDAS software. The image library has been validated based on measurements from the Pasture Evaluation Program. Dry conditions precluded establishment of bermudagrass so an additional corn grazing treatment was implemented. This addition constituted evaluation of two population densities of corn. Steer growth and forage characteristics were measured. Comparative genomics and species-specific tools are being used to develop the genome infrastructure in red clover (Trifolium pratense), a short-lived perennial diploid species with a small genome (~440 Mb). The objective is to construct a comparative genetic map between Medicago (M.) truncatula and red clover based on cross-legume orthologous markers so that the genomic information of Medicago can be used for red clover improvement. In field sampling of E+ swards have been done on vegetative and reproductive plants during the spring growth period. Alkaloid levels on first harvest plants and regrowth harvests have been determined. Significant amounts of ergovaline + ergovaline remained after 4 to 8 weeks in these experiments indicating that pregnant mares should not graze killed forage for at least 10 weeks after treatment. In addition vascular sap was sampled to determine sugar content with sequential harvesting. Mares have foaled and weanlings will be available to begin the study evaluating the effect of endophyte infected tall fescue (E+TF) on growing horses. An initial study using denaturing gradient gel electrophoresis suggests that the gastrointestinal ecosystem of the foal is established rapidly after birth. This agreement is monitored by submission of an annual report, meetings with UK officials/scientists, and close collaborations between unit and UK scientists.