Department of Animal Science
First Advisor
Dustin Yates
Date of this Version
5-2022
Abstract
The objective of our first study was to determine how administering anti-inflammatory dexamethasone and ω-3 polyunsaturated fatty acid (PUFA)-rich fish oil affects growth efficiency and body composition in heat-stressed finishing lambs. Commercial wethers were randomly assigned to be fed under heat stress (35°-40℃) or thermoneutral (19℃, n = 10) conditions for 30 d, and controls were pair-fed to eliminate differential feed intake. Heat-stressed wethers were randomly assigned to receive clinical-dose dexamethasone IM injections every 72 h, twice daily fish oil capsule oral boluses, or placebos. Heat stress decreased (P < 0.05) growth and efficiency, but dexamethasone and fish oil supplementation recovered these performance measures. Heat stress also decreased (P < 0.05) predictive body composition metrics that were at least partially improved by administration of dexamethasone and fish oil. Proximate analyses of muscles showed that heat stress decreased (P < 0.05) percentage of protein and increased (P < 0.05) percentage of intramuscular fat, neither of which was improved by dexamethasone or fish oil. Immunohistochemistry revealed that heat stress decreased (P < 0.05) myoblast differentiation and muscle fiber size, but anti-inflammatory supplementation recovered differentiation only. Plasma IGF-1 concentrations were not different among groups throughout the study. These findings demonstrate how heat stress-induced inflammation contributes to impaired growth, efficiency, and body composition observed in heat-stressed feeder lambs. However, targeting inflammation with dexamethasone or fish oil recovers many of these deficits.
The Cooperative Extension Service, created in 1914, facilitates interaction and communication between academics and the general public related to agriculture and public health. Agricultural extension services benefit producers of agricultural products and inform the research programs at land-grant universities. Extension methodology follows a general pattern that directs the flow of information, regardless of the discipline. This chapter describes the creative processes for written extension materials and digital media materials using a recently created NebGuide and an extension podcast as respective illustrations of the methodology in practice. Extension programming and content delivery via a broader range of modes will better ensure effective communication and assist extension professionals in reaching wider and more diverse audiences.
Advisor: Dustin Yates
Comments
A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Animal Science, Under the Supervision of Professor Dustin T. Yates. Lincoln, Nebraska: May, 2022
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