Date of Award:

5-2020

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Animal, Dairy, and Veterinary Sciences

Advisor/Chair:

Kara Thornton-Kurth

Co-Advisor/Chair:

Abby Benninghoff

Third Advisor:

Charles Carpenter

Abstract

For producers in more temperate areas, such as the Intermountain West, poor nutrition during the second trimester of gestation is common due to seasonal changes in forage and nutrient availability. The majority of muscle fibers are formed and adipogenesis is initiated in the second trimester, making it a critical time for skeletal muscle and adipose development in beef cattle. However, the extent to which these changes persist in the offspring postnatally is unknown. In this study, maternal nutrition was restricted during the second trimester in order to analyze the effects of maternal nutrient restriction on offspring skeletal muscle growth. Offspring were monitored throughout production postnatally and skeletal muscle samples were taken at weaning, the beginning of the feedlot phase,and at harvest.We investigated whether calves from cows restricted in the second trimester had a different expression of microRNA (miRNA) or messengerRNA (mRNA) known to be downstream targets of those miRNA. We also analyzed mRNA expression of myosin heavy chain (MHC) isoforms to determine whether maternal nutrition in the second trimester impacts muscle fiber type. There were no changes observed in mRNA or MHC expression between the two different treatments at either time point. Differences in expression of several miRNAs important in development of adipose and skeletal muscle were observed between the treatment groups. The findings of this research indicate that maternal nutrition during the second trimester of gestation alters miRNA expression in the skeletal muscle. However, more research is needed to determine exactly how these miRNA impact growth of skeletal muscle postnatally.

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