Investigating the genetic architecture of heat stress response and related traits in pig populations

• Ano de defesa: 2024
• Autor(a) principal: Oliveira, Letícia Fernanda de
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa; Zootecnia
• Palavras-chave em Português: Suíno; Genômica; Genética animal; Efeitos da temperatura; Genética e Melhoramento dos Animais Domésticos
• Link de acesso: https://locus.ufv.br//handle/123456789/32304; https://doi.org/10.47328/ufvbbt.2024.140

Global warming presents a significant challenge to livestock production, impacting animal welfare and performance. The resulting increase in temperatures promotes heat stress (HS) as a major concern in animal production, highlighting the need to breed for more resilient animals. Enhancing heat tolerance could improve animals’ ability to cope with HS conditions. To make genetic progress in HS resilience, it is crucial to understand the genetic architecture of traits related to resilience and the genetic mechanisms underlying the heat stress response. This study aimed to investigate the genetic architecture of HS response indicators and related traits in pigs, with three main objectives. First, to assess the impact of non-additive genetic effects on variance components estimation in two independent datasets: crossbred and purebred populations, and in genomic prediction in a purebred population. Second, to identify genomic regions, candidate genes, and potential pleiotropic variants significantly associated with indicators of HS response in lactating sows using imputed whole-genome sequence (WGS) data. Third, to detect copy number variations (CNVs) and CNV regions (CNVRs) in pigs and explore their associations with physiological and anatomical indicators of HS response measured in crossbred (Large White x Landrace) lactating sows. The inclusion of non- additive genetic effects in the models did not improve the accuracy of genomic breeding values for performance traits in purebred pigs. However, there was a significant re- ranking of selection candidates depending on the model fitted. Low non-additive genetic variance estimates were observed for most heat tolerance indicators in crossbred pigs, except for the panting score and hair density. Physiological and anatomical indicators of HS response in lactating sows were found to have additive genetic variation but they are highly polygenic. Candidate genes associated with heat shock protein activities, immune response, and cellular oxidative stress were identified, indicating their importance in HS response. Various CNVs and CNVRs were identified in the genome of the crossbred pig population evaluated. Fifteen CNVRs were significantly associated with physiological and anatomical indicators of HS response in lactating sows. Several genes involved in immune and stress responses overlapped with the CNVRs, suggesting that these CNVRs might contribute to climatic resilience in pigs during the lactation stage. Keywords: climatic resilience; genomic prediction; non-additive genetic effects; pleiotropy; genome-wide association study; copy number variation.