Date of Graduation

12-2021

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Animal Science (PhD)

Degree Level

Graduate

Department

Animal Science

Advisor/Mentor

Huang, Yan

Committee Member

Maxwell, Charles V.

Second Committee Member

Zhao, Jiangchao

Third Committee Member

Baum, Jamie I.

Keywords

Breeds; Crude protein level; Gene expression; Meat quality; RNA-seq; Western-blot

Abstract

In order to improve the meat quality of livestock, intrinsic and extrinsic factors that impact meat quality have been studied for a long time to optimize production quality. Nutrition, breed, and environment are the three most common factors to improve meat quality and muscle growth. The objective of this thesis is to perform a horizontal comparison of the effects of crude protein levels, breeds, and topsoil on the growth performance, muscle development, and meat quality of livestock, and also a longitudinal analysis using RNA-seq, RT-qPCR, and Western-blot to investigate the changes in genes and proteins related to muscle growth, and intramuscular fat deposition of livestock. Chapter II evaluated the effects of crude protein levels on the growth performance, meat quality, and genes expression of finishing lambs. For nine weeks, the lambs were assigned randomly to low-protein (LP; 8% crude protein) and high-protein (HP; 13% crude protein) diets. The results showed that a high-protein level diet promoted the growth performance of finishing lambs; however, the low-protein diet benefited the meat color of lambs. Chapter III evaluated the impact of breeds on the growth performance, meat quality, RNA-seq, and gene expression of pigs. Large Black pigs and Cross-bred commercial pigs were used to evaluate the differences, and they were fed with a common diet. The results showed that the Large Black pigs had more intramuscular fat content, and the Cross-bred commercial pigs had better growth performance. The genotype differences between these two groups of pigs may result in the meat quality and growth performance variance. Chapter IV evaluated the effects of topsoil on muscle growth, lipid droplet area, and gene and protein expression of piglets. A Total of 180 piglets were separately assigned to the No soil, Antibacterial soil, and Normal soil group (each group, n=60), and were fed ad libitum with typical antibiotic-free corn-soybean meal diets until day-31. These data suggest that early exposure to topsoil regulates muscle fiber growth, modulates the expression pattern related to myogenesis, muscle fiber type, intramuscular fat metabolism, and increases the phosphorylation of mTOR and AMPK pathways.

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