In ‘Transcriptomic and epigenomic network analysis reveals chicken physiological reactions against heat stress’, one of 19 chapters in the book ‘Transcriptome Profiling: Progress and Prospects’, researchers from Wageningen UR (together with researchers from other universities and research institutions) present the results of a study that focused on the general physiological reactions to heat stress in muscle and heart tissues of chickens.
Relatively little is known about the underlying biological mechanisms behind the effects of heat stress in livestock. Given that global warming is expected to result in larger temperature fluctuations by which heat stress may become an important stressor for animals, affecting both health and productivity, understanding the biology and molecular mechanisms of heat stress is pivotal for the development of novel approaches for breeding and management strategies.
Comparing different datasets
The objective of the researchers was to investigate the adaptivity of chickens by studying the biological mechanisms underlying the response to increased temperature in chickens adapted to and not-adapted to high daytime temperatures in two tissues differing in metabolic activity (muscle and heart). Consequently, they compared the results of three highly different experiments. Two experiments studied the transcriptome profiles of heart and muscle tissues of two different mature chicken populations using heat stress adapted and non-adapted chickens, and one experiment studied the epigenome changes of heat stress during chicken egg incubation.
The results of the study indicated that epigenetic mechanisms including chromatin organization, methylation, and acetylation of DNA are the central biological mechanisms involved in the general response of the animals to heat stress. These mechanisms are all involved in regulation of gene expression and cellular metabolism. Therefore, the conclusion of the authors is that the acclimatization and adaptation to heat stress required changing activities of the genome and physiology. In addition, the specific chicken lines showed different biological pathway activities, which may relate to the (natural) genetic selection applied to the specific animals.
As the authors stated, the biological mechanisms that are revealed in the study can be used to monitor the physiological response of chickens to heat stress. Consequently, this information can be used as a tool to breed animals that can better respond to heat stress and for management of animals to cope with heat stress, thereby improving chicken welfare.