Location: Forage-animal Production Research2012 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:
The first year of a 2-yr grazing experiment indicated that suppressing emergence of seed heads in toxic endophyte-infected tall fescue pasture can increase steer weight gains and reduce the severity of toxicosis with both light and moderate grazing intensities. The fescue toxicosis model developed last year was used to study energy metabolism and absorption of volatile fatty acids. Accompanying this were studies to develop and evaluate techniques to assess fasting heat production so these could be applied using the fescue model. Cyclooxygenase IV (COX IV) and glucocorticoid receptor (GR) antibodies were validated, COX IV was found elevated in livers of fescue toxicosis steers, and GR was found expressed by liver tissue and Madin-Darby bovine kidney (MDBK) cells, and vasicular glutamate transporter 2 (VGLUT2) extraction protocols were tested and refined. Methods for measuring osteocalcin and bone alkaline phosphatase were validated and samples obtained in the previous study were analyzed. Partial purification of extracts using pilot plant scale columns was not successful. Liquid/liquid exchange with 4L bottles was successful but required more physical labor. Field performance of new novel endophyte tall fescue populations was measured in three variety trials across Kentucky in 2011-2012. Use of livestock-safe endophytes and soft-textured, non-spiny fescue cultivars for improved livestock performance did not increase vulnerability of the grasses to damage from insect pests. Pseudostem samples of tall fescue clone pair (E+ and E-) that were harvested from drought stress experiments were analyzed for different metabolites such as neutral sugars, amino acids, and loline alkaloids. Gene expression studies were also completed using multiplex Illumina messenger ribonucleic acid (mRNA) sequencing. The strong correlations between the near infrared spectroscopy (NIRS) scans and the actual diet composition show good promise for using NIRS to predict the grass diet composition of grazing horses. More than 300 red clover genes were mapped with known genetic locations to the medicago (M.) truncatula genome. The data revealed broad regions of conservation and also identified numerous chromosomal rearrangements between the two genomes. Work is continuing to illustrate the alignment using Medicago genome version 3.5. Limited research evaluating the impacts of steroidal implants in cattle grazing fescue suggests that increases in average daily gain are possible, but that the response to implants may depend on forage availability as influenced by stocking rate. The influence of various strategies have been quantified that can be incorporated into fescue-based systems to add substantial live weight to stocker cattle produced in the upper transition zone. Lactation data show that consumption of ergot alkaloids during the dry period increases milk production in the ensuing lactation. Soil tests suggest that replacement of tall fescue infected with the common toxic strain of fungal endophyte with the more animal 'friendly' novel endophytes will have ecological consequences that require consideration and further exploration in order to understand the likely environmental effects of widespread deployment of novel endophyte symbioses.