가축의 다수준 열 스트레스 반응: 육계, 젖소 및 한우를 대상으로 한 개별 연구 = Multi-Level Responses to Heat Stress: Species-Specific Independent Studies in Broilers, Holstein and Hanwoo

다국어 초록 (Multilingual Abstract)

Heat stress responses, still not fully understood, were investigated at the physiological, blood transcriptome, blood metabolome, and gut microbiome levels in three species-specific, independent studies, one in each species. In broilers, 14-day heat stress reduced weight gain, while feed conversion ratio, respiration rate and temperature increased. The 230 upregulated differentially expressed genes (DEGs) were included the enriched terms associated with protein quality control, energy metabolism and MAPK signaling pathway. In Holstein exposed to 7-day heat stress, concentration of nine metabolites including linoleic acid and fructose were decreased. The 154 upregulated DEGs were associated with energy and immune processes, while Intestinimonas and Pseudoflavonifractor were included as butyrate-producing bacteria. Multi-omics analysis revealed interconnections among metabolites, DEGs and microbiota. In Hanwoo, 3-day heat stress led to downregulated DEGs related to ion binding and actin-associated processes, while Butyricicoccus was identified as butyrate-producing bacteria. In the 4-day recovery group, several microbial functions related to energy metabolisms were predicted. Overall, heat stress responses appeared to represent recovery and adaptive processes linked to maintaining homeostasis, but they often work against productivity and reproduction in livestock. Based on these findings and prior evidence, repeated phenotypic and gene expression indicators are potentially applicable for assessing heat load and health status, and provide a basis to develop indicators for the selection and reproduction of heat tolerant livestock under future climate change.

목차 (Table of Contents)

• Ⅰ. General Introduction 1
• 1. Livestock Health and Productivity under Climate Change 1
• 2. Physiological Responses to Heat Stress 4
• 2.1 Poultry 4
• 2.2 Cattle 5
• 3. Heat Stress and Gut Microbiota in Livestock 7
• Ⅱ. Literature Review 10
• 1. Heat Stress Indicators 10
• 1.1 Physiological Indicators 10
• 1.2 Biochemical Indicators 12
• 2. Molecular Response to Heat Stress 13
• 2.1 Heat Shock Proteins 13
• 2.2 Immune and Inflammatory Responses 15
• 2.3 Energy Metabolism and Oxidative Stress 17
• 3. Gut Microbiota under Heat Stress 20
• 3.1 Microbial Products 20
• 3.1.1 Amino Acids 20
• 3.1.2 Short-Chain Fatty Acids 21
• 3.2 Gut Microbiota Composition and Interactions with Host 23
• Ⅲ. Materials and Methods 27
• 1. Materials 27
• 1.1 Broilers 27
• 1.2 Holstein 28
• 1.3 Hanwoo 28
• 2. Methods 29
• 2.1 Phenotype Data 29
• 2.1.1 Broilers 29
• 2.1.2 Holstein 29
• 2.2 Next-Generation Sequencing 30
• 2.2.1 Differentially Expressed Genes 30
• 2.2.2 Gut Microbiota Abundance 32
• 2.2.3 Functional Analysis 34
• 2.3 Data Integration 34
• IV. Results and Discussion 35
• 1. Broilers 35
• 1.1 Physiological Indicators 35
• 1.2 Functional DEGs 38
• 2. Holstein 51
• 2.1 Blood Metabolic Indicators 51
• 2.2 Functional DEGs 56
• 2.3 Gut Microbiota Abundance and Functional Prediction 66
• 2.4 Multi-Omics Analysis 76
• 3. Hanwoo 80
• 3.1 Functional DEGs 80
• 3.2 Gut Microbiota Abundance and Functional Prediction 89
• V. General Discussion 99
• 1. Similar Functional Categories between Broilers and Holstein 99
• 2. Shared Microbial Functions in Holstein and Hanwoo 101
• Ⅵ. Conclusions 104
• 1. Broilers 104
• 2. Holstein 105
• 3. Hanwoo 105
• 4. Overall Conclusions 106
• Ⅶ. Korean Abstract 108
• Ⅷ. References 109