Emissão de gases de efeito estufa das excretas de ovinos em sistemas pastoris

• Ano de defesa: 2026
• Autor(a) principal: Miranda, Lucas Biscaglia
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Santa Maria; Brasil; UFSM; Programa de Pós-Graduação em Zootecnia; Centro de Ciências Rurais
• Palavras-chave em Português: Fatores de emissão; Sistemas de pastejo; Mitigação de gases de efeito estufa; Emissões de N₂O; Excretas de ruminantes; Emission factors; Grazing systems; Greenhouse gas mitigation; N₂O emissions; Ruminant excreta; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA
• Link de acesso: http://repositorio.ufsm.br/handle/1/38607

Given the significant contribution of animal excreta to climate change, this study evaluated greenhouse gas (GHG) emissions from sheep grazing Italian ryegrass (Lolium multiflorum Lam.) overseeded on Tifton 85 pasture. Three management systems were compared: pasture only (G), concentrate supplementation (GS), and legume inclusion (GL). Field experiments were conducted over two consecutive years. N₂O and CH₄ emissions from fresh urine and feces were quantified using static chambers, with gas samples collected over time. In both years, CH₄ emission factors were low and were not influenced by treatments (P > 0.05), remaining close to zero regardless of excreta type. In contrast, N₂O emissions were more sensitive to management. In 2023 (Experiment I), urinary N₂O emission factors were significantly higher in G (6.363%) compared with GS (2.946%) (P = 0.03), indicating that supplementation reduced the proportion of applied N lost as N₂O. In 2024 (Experiment II), fecal N₂O emission factors differed among systems (P = 0.03), with the highest value observed in G (0.147%), intermediate in GS (0.047%), and the lowest in GL (0.004%), highlighting the mitigation potential of legume inclusion. Per excretion event, significant differences were also observed (P = 0.02), with the highest emission factor in G and the lowest in GL. Overall, urine was the main driver of N₂O emissions, whereas CH₄ had a negligible contribution. Nutritional strategies reduced emission factors, although the magnitude of the response varied between experimental years.