Date of Graduation


Document Type


Degree Type



Davis College of Agriculture, Natural Resources and Design


Animal and Nutritional Sciences

Committee Chair

John Killefer.


Myostatin, belonging to the TGF-beta family, negatively regulates skeletal muscle growth. The current study was conducted to assess the efficacy of in ovo administration of exogenous myostatin antagonist (MA) to enhance skeletal muscle growth and improve feed efficiency of broilers.;Growth hormone secretion is under the control of a pair of hypothalamic factors, growth hormone releasing hormone and somatostatin. The growth hormone secretagogue receptor (GHSR) and its endogenous ligand represent a novel third mechanism regulating the release of growth hormone. Early chicken embryonic development, prior to day 14, has been proposed to be independent of GH. However, recent evidence shows that peripheral GH secretion has paracrine/autocrine functions during embryonic development. In the current study, we used the reverse-transcriptase polymerase chain reaction to determine the expression pattern of the GHSR during embryonic development and the effects of in ovo recombinant human (rh) IGF-I administration on its expression pattern.;Administration of the recently identified ligand of the growth hormone secretagoue receptor (GHSR) has been found to increase feed intake and fat deposition. During growth and aging, the myostatin knockout mouse has been shown to have a significant reduction in fat accumulation. In this study, we used RT-PCR to investigate the relationship between ghrelin and myostatin expression. Ghrelin expression was significantly reduced in the heart (P < 0.05) and showed a trend for reduced expression in the pectoralis muscle (P = 0.07) in myostatin knockout mice. However, ghrelin expression was not different in the brain, heart and liver between the control and myostatin knockout mice. These data indicate loss of myostatin may act by down regulating the expression of ghrelin to reduce the accumulation of fat in the myostatin knockout mouse. Additionally, these data are consistent with an autocrine/paracrine role for ghrelin, in the peripheral tissues, in metabolic regulation and nutrient partitioning. (Abstract shortened by UMI.).