P29 | Hygienic-sanitary monitoring in sheep farms: milk, milking environment surfaces, and microbiological risks to food safety

G. Siddi, F. Piras, F. Simbula, M. Migoni, E. Parodi, I. Grussu, M. Casula, F. Manca, E. Serra, L. Crobu, A. Sau, M.P. Meloni, M. Cuccu, E.P.L. De Santis, C. Scarano | Dipartimento di Medicina Veterinaria, Università di Sassari, Sassari, Italy

Purpose. The study is part of the AGRITECH_PNRR project, "National Research Center for Agricultural Technologies" (CN00000022; CUP: J83C21000300006), aimed at improving dairy production thru the optimization of feed rations and the reduction of antibiotic and anthelmintic resistance. The specific objectives were: to assess the hygienic-sanitary quality of sheep's milk and milking surfaces; to analyze the presence and antibiotic resistance profiles of pathogens and non-aureus staphylococci isolated from milk and milking environments, in order to identify potential public health risks. Methods. Three sheep farms in Sardinia (NU, OR, VM) with controlled feeding were monitored during two consecutive lactations (2024–2025). In 2024, 218 individual milk samples and 27 environmental samples (teats, refrigerated tank, expansion vessel, washing tank, operators' hands) were collected. In 2025, 265 milk samples and 45 environmental samples were collected. The microbiological analyzes included: total bacterial count (ACC), Enterobacteriaceae (EB), Staphylococcus aureus and non-aureus staphylococci (NAS), Listeria monocytogenes, Yersinia enterocolitica, and Salmonella spp. The isolates were identified by MALDI-TOF mass spectrometry and subjected to automated antimicrobial susceptibility testing. Results. In 2024, the average values of ACC, EB, and CNS in milk samples remained stable, except for a significant increase in May at the VM farm (p<0.05). All values were below legal limits and in line with what is reported in the literature. Environmental samples showed wide variability between companies, with values generally >4 log CFU/cm² in the tank and on operators' hands, highlighting hygiene issues. L. monocytogenes and Salmonella spp. were not detected; S. aureus was isolated in only one environmental sample (operator's hand). In 2025, average milk values did not show significant changes, but a progressive increase in the median was observed from April to June. S. aureus was isolated in three milk samples (prevalence 1.1%) and in one environmental sample (washing tank) from two farms. No other pathogens were identified from milk or surfaces, except for the widespread presence of Listeria spp. in all environmental samples, indicating hygiene deficiencies. Comparative analyzes based on diet type are ongoing. Identification was performed using MALDI-TOF on S. aureus and 50 representative NAS isolates, followed by antimicrobial susceptibility testing (MIC). The predominant species were found to be S. auricularis and S. epidermidis. The main resistances observed were toward beta-lactams (oxacillin, penicillin) and macrolides (erythromycin). Conclusions. The hygienic-sanitary quality of milk and surfaces varied between farms, with a decline in the warmer months. The presence, albeit sporadic, of pathogens highlights the importance of constant monitoring and the rigorous application of GHP even in the primary production stage. Operators' hands are a critical route of contamination. The spread of resistance among NAS, potential reservoirs of resistance genes, poses a cross-cutting risk throughout the entire dairy chain.