Orexin gene expression analysis in two Nigerian indigenous and exotic chickens using quantitative polymerase chain reaction (qPCR)

Abstract

This study investigated orexin gene expression patterns in two Nigerian indigenous chicken ecotypes (Fulani and Yoruba) compared to the exotic Cobb-500 breed using quantitative polymerase chain reaction (qPCR) technology. A total of 135 birds (45 per breed) were reared for four weeks, after which liver tissue samples were collected for RNA extraction and analysis. The orexin gene serves as a crucial regulator of appetite, energy balance, and stress responses in poultry, making it an important molecular marker for understanding breed-specific physiological adaptations. RNA was extracted using the Zymo RNA mini prep kit, followed by cDNA synthesis and qPCR analysis using Luna® Universal qPCR Mastermix. The TATA box binding protein served as the housekeeping gene for normalization. Gene expression was quantified using the 2-ΔΔCT method (Livak method) to determine fold changes between breeds. Results revealed significant inter-breed variations in orexin expression levels (P < 0.05). The Fulani ecotype demonstrated the highest expression (1.37-fold), followed by Cobb-500 broilers (0.35-fold), while Yoruba ecotype chickens showed the lowest expression (0.02-fold). Melt curve analysis confirmed primer specificity and amplification consistency across all samples. These findings suggest that elevated orexin expression in Fulani chickens may reflect superior physiological adaptability and energy regulation capabilities, supporting their resilience in variable environmental conditions. The differential expression patterns highlight orexin's potential as a molecular marker for selective breeding programs aimed at improving indigenous chicken productivity while maintaining genetic diversity and environmental adaptability in Nigerian poultry systems.