Transcriptomic profiles of muscle, heart, and spleen in reaction to circadian heat stress in Ethiopian highland and lowland male chicken

Temperature stress impacts both welfare and productivity of livestock. Global warming is expected to increase the impact, especially in tropical areas. We investigated the biological mechanisms regulated by temperature stress due to the circadian temperature cycle in temperature adapted and non-adapted chicken under tropical conditions. We studied transcriptome profiles of heart, breast muscle, and spleen tissues of Ethiopian lowland chicken adapted to high circadian temperatures and non-adapted Ethiopian highland chicken under lowland conditions at three points during the day: morning, noon, and evening. Functional annotations and network analyses of genes differentially expressed among the time points of the day indicate major differences in the reactions of the tissues to increasing and decreasing temperatures, and also the two chickens lines differ. However, epigenetic changes of chromatin methylation and histone (de)acetylation seemed to be central regulatory mechanisms in all tissues in both chicken lines. Finally, all tissues showed differentially expressed genes between morning and evening times indicating biological mechanisms that need to change during the night to reach morning levels again the next day.</p

Animal Breeding Considerations for Improved Animal Performance in Hot Environments

A variety of options are available for improved performance including altering genotype with genetic improvement of indigenous breeds through selective breeding; upgrading through crossbreeding of indigenous females with semen from genetically superior exotic males with a possible goal of developing a new breed; and introduction of new breeds through transfer of embryos from genetically superior exotic breeds into indigenous females or importation of exotic animals of the desired breeding. Each option has its advantages and disadvantages. The most rapid gains mightbe possible new environment can be a problem.  In the interest of adaptation and survival, systems that utilize the maternal influences of indigenous females are advantageous. In consideration of this maternal influences along with rate of improvement and potential for extensive improvement, both crossbreeding programs that use semen from genetically superior exotic males and those that involve transfer of genetically superior embryo survival and neonatal survival will affect management of any option chosen for genetic improvement but should be of less concern in programs that utilize indigenous females