2011 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.
Palatability trials using a diverse array of tall fescue lines and cattle have been concluded after three years of data collection. Six new tall fescue populations having softer leaves have been developed. Three locations of a 24-entry tall fescue variety trial were seeded that include 12 new novel endophyte lines. A bioinformatics approach was used to identify the orthologs of the mapped red clover genes in the sequenced Medicago truncatula genome. A comparative genetic map between the two species has been constructed. A model was developed and validated to induce fescue toxicosis using a fescue seed extract and shown to produce similar toxicosis symptoms to traditional seed feeding. Experiments are underway to use the fescue seed extract model to study energy metabolism. The large scale extraction protocol efficiency and partial purification of the ergot alkaloids in infected tall fescue seed have been increased. It is now possible to extract 300-350 pounds to ground seed and do a partial purification of this ethanol extract with hexane and chloroform in a large column. A second year of enzyme analyses was completed to determine the effect of endophyte infection on soil function. Earthworm populations indicated movement of earthworms away from locations in which fescue was planted in preference to weedy buffer strips. The effects of the novel endophytes on plant diversity and production have been found to be less than those of the common toxic strain, but are still different from endophyte-free tall fescue alone. A drought stress experiment was conducted using another clone pair [endophyte infected (E+) and endophyte free (E-)] of tall fescue. Differences in the recovery of tillers, metabolites accumulation, and gene expression between E+ and E- plants from water deficit stress were investigated. A field-collected baculovirus shown to infect armyworms, Mythimna unipuncta (Haworth), was not more infective when caterpillars fed on smooth-edged grass blades compared with those feeding on standard spiny-edged grass blades. Microarray evaluation of the effect of fescue toxicosis on (a) liver and (b) Longissimus dorsi muscle mRNA expression profiles of growing beef cattle after 36 days of grazing endophyte-infected tall fescue was completed. Protocols for VGLUT protein extraction from non-brain tissues were developed. The effects of E+ vs E- fescue seed were tested in pregnant mares, with biological endpoints of vasoconstriction of the palmar artery vs uterine artery, as well as changes in hormone levels. Because of greater than expected variability both within and between mares, extra blocks of mares were added to the experiment. Twelve weanling horses were assigned to either an endophyte positive group (n=6), or a control group (n=6). Treatment did not affect daily gain, feed intake or growth hormone but the insulin response to feeding was decreased by treatment. This agreement is monitored by submission of an annual report, meetings with UK officials/scientists, and close collaborations between unit and UK scientists.