OICC Press International Journal of Recycling of Organic Waste in Agriculture 2251-7715 2026 08 05 Assessment of Composting Process for The Degradation of Ivermectin Residues and Elimination of Parasite Eggs in Equine Manure 10.57647/ijrowa.fzz7.dd0188 EN Milagros Junco Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Veterinarias. Departamento de Sanidad Animal y Medicina Preventiva. Tandil, Buenos Aires, Argentina https://orcid.org/0000-0001-7358-8974 Lucia Emilia Iglesias Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Veterinarias. Departamento de Sanidad Animal y Medicina Preventiva. Tandil, Buenos Aires, Argentina. https://orcid.org/0000-0001-5015-3951 Federico Azcarate Instituto de Procesos Biotecnológicos y Químicos (IPROBYQ); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), Rosario, Argentina. https://orcid.org/0009-0000-0124-7820 Andrea Alonso Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Agronomía. Azul, Buenos Aires, Argentina. Silvia Mestelan Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Agronomía. Azul, Buenos Aires, Argentina. https://orcid.org/0000-0003-0299-2851 Carlos Boschetti Instituto de Procesos Biotecnológicos y Químicos (IPROBYQ); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), Rosario, Argentina. https://orcid.org/0000-0003-1029-958X Juan Manuel Sallovitz Instituto de Procesos Biotecnológicos y Químicos (IPROBYQ); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), Rosario, Argentina. https://orcid.org/0009-0004-2024-1415 Gisele Anahí Bernat Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Veterinarias. Departamento de Sanidad Animal y Medicina Preventiva. Tandil, Buenos Aires, Argentina. Carlos Alfredo Saumell Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Veterinarias. Departamento de Sanidad Animal y Medicina Preventiva. Tandil, Buenos Aires, Argentina. https://orcid.org/0009-0000-0883-2635 Journal Article 2026 08 05 Purpose: this study aimed to evaluate the fate of veterinary pharmaceutical residues, such as ivermectin (IVM), and their impact on parasitic forms during and after composting of equine feces mixed with straw. Method: in this study, composting trials were conducted using equine fecal matter added with IVM under controlled conditions. Physicochemical parameters of the composting process, including temperature, pH, electrical conductivity, and extractable phosphorus, were monitored over a 120-day period. High performance liquid chromatography (HPLC) was employed to quantify IVM residues in compost samples. Additionally, parasitological assessments were performed to evaluate the elimination of gastrointestinal nematodes (GIN) eggs during composting. Results: IVM residues persisted throughout the composting period, albeit with decreasing concentrations over time. The composting process influenced physicochemical parameters, such as pH and electrical conductivity, with variations observed in response to straw additions and microbial activity. Parasitological analysis revealed the presence of GIN eggs, predominantly belonging to the Strongylus genus, up to day 60 of composting. However, larval development from these eggs was not observed beyond day 30, suggesting limited viability under composting conditions. Conclusion: overall, composting reduced IVM concentrations and compromised GIN eggs viability. However, complete elimination of the compound was not achieved within the time of the study. These findings highlight the importance of further research to optimize composting strategies for pharmaceutical residue degradation and parasite control thereby enhancing the safety and efficacy of composted manure in agricultural applications.