Depicting residual feed intake in Nellore cattle through gene expression, lipidomic profiling and pathway-based meta-analysis

• Ano de defesa: 2019
• Autor(a) principal: Duarte, Darlene Ana Souza
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa
• Palavras-chave em Português: Bovinos - Melhoramento genético; Eficiência alimentar; Genética e Melhoramento dos Animais Domésticos
• Link de acesso: http://www.locus.ufv.br/handle/123456789/24818

Increase in feed efficiency result in decrease in feed costs. Thus, to improve profitability in beef cattle production system is necessary to select animals more efficient in the use of feed sources. The residual feed intake (RFI) has become the preferable measure for feed efficiency, once that RFI is not correlated with growth rate or other production trait. Researchers have demonstrated that many physiological mechanisms contribute to variation in RFI, among them are protein turnover, tissue metabolism, synthesis and transportation of fatty acid, inflammatory response, glucose absorption and fatty acid oxidation. Even so, the molecular bases controlling this trait are not well elucidate yet. Thus, we aimed to investigate the biological bases that could be responsible for differences in animals classified for RFI. For that, we performed a pathway meta-analysis approach using several genome association studies results to search for significant pathways that may explain the genetic mechanism underlying this trait. We used an efficient permutation hypothesis test that takes into account the linkage disequilibrium patterns between SNPs. One significant pathway (valine, leucine and isoleucine degradation) related to RFI was found. This pathway is related to protein turnover and gluconeogenic process. In addition, we evaluated samples from muscle and liver tissue of 27 Nellore steers, classified as high, medium and low RFI. The samples were used to evaluate the mRNA expression of genes involved in the lipid metabolism and to carry out lipidomic analysis. None significant differences in mRNA expression were found. In the lipidomic analysis, it was found that animals from the high RFI group exhibited higher levels of fatty acids and triglycerides compared to medium and low RFI animals, indicating a possible increase in the requirement of lipid energy sources in the low RFI animals and also an increase in fat deposition in high RFI animals. In addition, it was observed differences in the lipid main components of cell membrane, which are related with cell signaling and molecules transportation. These results suggest that difference in RFI is associated with changes in lipid metabolism, but these changes are not caused by differences in the mRNA expression of the genes involved in this metabolism.