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ARS Home » Midwest Area » Lexington, Kentucky » Forage-animal Production Research » Research » Research Project #442960

Research Project: The Roles of Forage and Phytochemicals at the Plant-Microbe-Animal Nexus for Sustainable Ruminant

Location: Forage-animal Production Research

Project Number: 5042-32630-004-000-D
Project Type: In-House Appropriated

Start Date: Aug 30, 2022
End Date: Aug 29, 2027

Objective 1: Determine how secondary metabolites influence positive and negative changes in grazing livestock physiology; and how biological and genetic factors influence the incidence of fescue toxicosis and develop strategies to reduce impacts. Sub-objective 1.A: Investigate the interaction of serotonin and ergot alkaloid exposure to determine if serotonin can compete with EA at the receptor level. Sub-objective 1.B: Determination of the optimum dose of L-DOPA, and the use of L-DOPA to mitigate the decrease of feed intake provoked by EA. Sub-objective 1.C: Determine the effect of leucine, glucose, and acetate infusion on mTOR pathway activation in muscle and adipose tissue, determine infusion rates of leucine, glucose, and acetate required to achieve submaximal and maximal activation of mTOR and downstream proteins in muscle and adipose tissue, determine the effects of fescue-derived alkaloids on muscle and adipose mTOR activation. Sub-objective 1.D: Use remote sensing technology to generate a phenotype of ergot alkaloid exposure that can be used to characterize genetic tolerance to these toxins. Objective 2: Effects of clover isoflavones on development, finishing and meat quality in fescue-based pastures. Sub-objective 2.A: To determine the effect of isoflavone supplementation via red clover during post-weaning management on nutrient utilization and performance of grazing and confinement-finished lambs. Sub-objective 2.B: Examine the effect of isoflavone supplementation during post-weaning management on carcass traits, muscle proteome, and meat quality of grazing and confinement-finished lambs. Sub-objective 2.C: Evaluate the impact of dietary isoflavone supplementation on the rates of antimicrobial resistance (AMR). Objective 3: Identify the impacts of environmental and nutritional adaptation on development and develop strategies to improve reproductive and growth performance. Sub-objective 3.A: Investigate the impacts of pre-weaning nutritional management on microbial development, health and performance of beef calves and lambs. Sub-objective 3.B: Investigate the role of adaptation to grazing system and environment on rumen microbial communities, nutrient utilization, reproductive, and growth performance in first calf beef heifers. Sub-objective 3.C: Determine how ergot alkaloid exposure, grazing system, and environment influence calf microbial development, health, and performance. Sub-objective 3.D: Evaluation of the form of supplemental selenium to ameliorate fescue toxicosis in lactating beef cows consuming toxic E+ TF (TF). Sub-objective 3.E: Manipulation of the form of supplemental selenium (Se) to increase fertility in beef cattle.

Forages are a key component to many livestock production operations. There are numerous bioactive compounds in forages that are consumed by grazing animals. Some of these compounds benefit the pasture at the expense of the grazer. Others have beneficial effects in the plant as well as the animal, but their efficacy may be limited to certain production settings. The overall goal of this project plan is to study bioactive compounds consumed during grazing at the microbial and animal levels to improve productivity and sustainability of forage-based enterprises. Ergot alkaloids (EA) are mycotoxins frequently found in pasture grasses and are credited with imparting persistence that makes tall fescue (TF) grass very sustainable. Unfortunately, EA also cause fescue toxicosis, an ergotism syndrome with significant negative impacts on animal productivity and welfare that is not completely understood. Conversely, isoflavones are legume-derived secondary metabolites that have been shown to have antimicrobial activity, growth promotion potential, and the ability to mitigate negative effects of EA. Isoflavones are phytoestrogens and their potential influences on livestock reproduction and on muscle development and composition are of interest. How phytochemicals integrate into livestock management practices is also important. Exposure of naïve livestock during gestation or grazing to EA and isoflavones, phytochemical influences on development and production, and interactions with mineral supplements are not clearly defined. These unknowns will be studied at the animal and gut microbial levels, in stocker steer, cow-calf and small ruminant models. They will be evaluated at genetic, genomic, cellular, tissue, and whole animal aspects. The research results will be both an improved mechanistic understanding of pasture-based phytochemicals and transferable technologies that minimize negative and maximize positive attributes. As pasture forages and their secondary metabolites continue to be optimized, researchers will have better tools to offer livestock producers allowing them to produce more with less.