Date of Graduation


Document Type


Degree Name

Doctor of Philosophy in Poultry Science (PhD)

Degree Level



Poultry Science


Sami Dridi

Committee Member

Charles F. Rosenkrans

Second Committee Member

Walter Bottje

Third Committee Member

Annie Donoghue

Fourth Committee Member

Geraldine Huff

Fifth Committee Member

F. Dustan Clark


Biological sciences, Dicer, HSPA9, Orexin, Poultry, Stress


Poultry production plays an important role in the food supply and security for billions of people. Poultry meat is considered the most efficient, nutritious source of protein, without religious taboos, and is relatively inexpensive. However, the poultry industry is facing substantial challenges. The global environmental temperature has experienced dramatic changes in the last few years. Modern broilers are not well adapted to environmental challenges (heat and cold stress), which have resulted in heavy economic loss in the poultry industry worldwide. In addition, the use of feed restriction regimens in management of breeders as well as the transportation of young chicks could induce additional metabolic disorders. Although seminal managerial thermo-conditioning, nutritional, and genetic efforts have been applied to partially alleviate these negative effects, poultry productivity still declines due to the adverse effects of these stressors and limited fundamental knowledge. There is, therefore, a critical need for mechanistic understanding of poultry response to these stressors which may help for the subsequent development of potential mechanism-based strategies to improve bird well-being, and thereby enhance poultry productivity and sustainability.

The present study aimed to identify new molecular signatures that are involved in environmental and nutritional stress responses in poultry. We found that chronic mild cold conditioning (CMCC) improves growth performance in young chicks via modulation of Adenosine mono phosphate- activated protein kinase (AMPK) and mechanistic target of rapamycin (mTOR) pathways. In addition, we identified heat shock protein A9 (HSPA9) or glucose regulated protein (GRP75), orexin (ORX) and its related receptors (ORXR1 and 2), and Dicer 1 as new molecular markers involved in stress response in poultry. HSPA9/GRP75 was identified to be expressed differently in various tissues of Jungle fowl and quail, as well as avian cell lines and was affected by heat stress. Orexin and its related receptors are altered by heat and oxidative stress in avian muscle both in vivo and in vitro. The ribonuclease type III, Dicer 1 which plays a key role in microRNA biogenesis, is regulated by nutritional stress (feed deprivation) in quail and chicken livers, and in immortalized chicken embryo liver (CEL-im) and neuroblastoma (SH-SY5Y) cell lines.