Date of Award
Master of Science
Osteoporosis is a serious problem in the laying hen industry due to welfare issues and economic losses related to bone fractures. Nutrition, exercise, and genetics are all important factors in bone fracture susceptibility. The main objective of this body of research was to better understand genetic influences on bone integrity by comparing gene expression profiles from the bone marrow of chickens expressing phenotypic differences for a number of bone characteristics. Layer and broiler chickens were utilized for this experiment because significant differences in bone density and strength have been documented between them. The expression profiles of specific functional candidate genes as well as the global expression profiles of genes included on the Fred Hutchinson Cancer Research Center Chicken 13K array were assessed. Significant differences in the mRNA abundance of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), osteoprotegerin (OPG), and transforming growth factor-[Beta]2 (TGF[Beta]2) were found at 15 weeks of age using quantitative real-time PCR (qPCR), with higher levels of mRNA in broilers. On the microarray, 53 and 85 features, at 15 and 60 weeks, respectively, were considered differentially expressed (p [less than or equal to]0.05 and q [less than or equal to]0.25). At least 9 of the 53 features differentially expressed at 15 weeks correspond to the GAPDH gene. In addition, a significant difference in fibronectin mRNA abundance at 15 weeks was validated using qPCR, with higher levels of mRNA in broilers. Phenotypic data collected on layer and broiler lines showed significantly higher body weight, bone mineral density (BMD), bone mineral content (BMC), and bone breaking force in broilers across all ages. All together this data indicates that genes important in bone metabolism are differentially expressed in the bone marrow of layer and broiler chickens and these expression differences can be associated with biological differences observed between these two lines of chickens. Further investigation of genes differentially expressed between layer and broiler lines will aid in understanding the genetic differences in regulation of bone integrity in chickens.
Anna Kathleen Bennett
Bennett, Anna Kathleen, "Differential gene expression in the bone marrow of layer and broiler chickens: relevance to bone integrity traits" (2006). Retrospective Theses and Dissertations. 19359.