2007 Annual Report 1a.Objectives (from AD-416) The objective of this cooperative research project is to determine the physiologic, genomic, and proteomic responses of beef cattle exposed to tall fescue toxicants (i.e., ergot alkaloids) under conditions of controlled and natural environmental temperature changes. 1b.Approach (from AD-416) Most studies of fescue toxicosis are conducted under short-term, controlled or long-term, field situations. Each approach has unique problems that reduce the ability to derive meaningful results needed to develop realistic solutions for improving animal tolerance to toxic tall fescue. This cooperative research project will combine the two approaches to provide more adequately determine and describe the physiologic, genomic and proteomic response of beef cattle to toxic tall fescue. Beef cattle will be heat stressed in environmental chambers located at the Brody Environmental Center at the University of Missouri (Dr. Don Spiers, Cooperator) to establish baseline responses to induced stress. Core body temperature as well as both blood samples and liver biopsies will be taken to measure physiologic, genomic, and proteomic responses to stress prior to being exposed to tall fescue toxicants naturally via grazing of toxic tall fescue pastures. Cattle will then be exposed to either non toxic tall fescue or toxic tall fescue for 2 to 3 months (determined by pasture availability). During the grazing period, routine blood sampling, core body temperatures, and body weights will be taken to assess physiologic response to toxic tall fescue and naturally induced environmental stressors (e.g., heat). Environmental parameters will be recorded as covariates in analysis. Following the grazing period, cattle will return to the environmental chambers for a second round of heat stress. Animals will be provided either non toxic tall fescue seed or toxic tall fescue seed while in the chambers. Assessment of responses will be done in a similar manner to that stated for the first environmental chamber challenge. Following removal from the chambers during this second expose, cattle will be euthanitized and tissues collected from various locations (including but not limited to: brain, skeletal muscle, fat beds, liver, pituitary glands, gastrointestinal tract, and cardiovascular system) to assess physiologic, genomic and proteomic responses to toxic tall fescue. Further, these tissues will be analyzed for ergot alkaloid residues in order to identify and characterize the disposition of these compounds in the animal’s body. Information collected during the conduct of this cooperative agreement will be equally shared among the cooperators and be used to model animal responses to stress and toxic tall fescue. 3.Progress Report This report serves to document research conducted under a Specific Cooperative Agreement between ARS and the University of Missouri. Additional details of research can be found in the report for the in-house project 6440-21310-001-00D, "Enhance Forage-Based Livestock Production Systems." Cattle consuming toxic tall fescue are predisposed to heat during the warmer months of the grazing season. Research was undertaken to determine the physiologic, genomic, and proteomic responses of beef cattle exposed to tall fescue toxicants and heat stress. Year 1 treatments (toxic endophyte-infected tall fescue vs endophyte-free tall fescue) have been applied and tissue collected after euthanasia for vascular response, alkaloid, genomic ,and proteomic analysis. Vascular response was assessed via the in vitro lateral saphenous vein bioassay developed and validated in the Forage-Animal Production Research Unit. Veins from previously exposed animals to alkaloids during grazing of toxic endophyte-infected tall fescue were less responsive to ergovaline exposure in vitro than those veins from animals consuming endophyte-free tall fescue. Alkaloid, genomic, and proteomic profiling are planned for the coming fiscal year. Research Leader meets with the collaborator in a face to face meeting 2 times/year to discuss the progress of the meeting and further, participates in data collection and paper writing. Also, exchanges phone calls and emails on a regular basis concerning the project.