## 4 Discussion
For this reason, a limited efficacy of preventive action (implementing good hygiene and manufacturing practices, and risk management procedures) could be obtained during slaughtering to control contamination, even though it is considered crucial to avoid carcass cross-contamination [36]. A combined farm-abattoir approach would likely have cumulative benefits [13; 37]. Furthermore, the European approach to meat safety involves the prevention of carcass contamination through proper implementation of hygienic procedures as no pig carcass treatments are allowed [38]. Additionally, even if it is generally reported that large farms of finishing herds are more prone to high _Salmonella_ prevalence than small farms (farrow to finish), other aspects, such as farm management and structures, and the implementation of biosafety measures, could have an impact on _Salmonella_ prevalence and mitigate the differences, as reported in the present study [39]. Moreover, other important factors that have to be monitored, such as the transport and holding at the abattoir, could spread contamination among animals of the same batch before slaughtering [16]. The abovementioned hypotheses could be corroborated by the absence of seasonal differences, which could be due to the high presence of the hazard at the farm level [40]. These data are not in agreement with other authors who found a higher _Salmonella_ prevalence in pig herds during the fall in the USA, compared to the spring and summer, but was due to seasonal contamination at a feed mill [41]. The results of the identification of the serovar confirm that the major ones are Derby and 4,[5],12:i-, which are the two servovars typically isolated from pigs [1]. No difference was registered for the two main _S. enterica_ servovars detected according to the considered factors; their presence was equally distributed between small and medium-sized abattoirs, and between the different seasons. Uneven distribution of minor strains, in terms of slaughterhouse size, season, and year, was observed. In particular, medium-sized abattoirs showed greater variability in the detected servovars than small ones. The larger number of animals slaughtered could be responsible for a greater probability of finding different servovars [42], but further investigation is needed. Integrated surveillance based on the \"One Health\" approach, combined with effective containment measures along the entire food chain (based on the application of biosecurity measures, effective surveillance and vaccination at the farm level, good manufacturing, and hygienic practices during slaughtering and food processing, and in the retail and consumer phases) is crucial to controlling the spread of _Salmonella_, especially the current and emergent epidemic clones [10]. Prior to the implementation of such interventions to prevent and manage _Salmonella_ in pigs, it would be advisable to define specific, suitable, and harmonized sampling and testing strategies aiming to determine, with the highest possible degree of certainty, the real prevalence of _Salmonella_ in the slaughterhouse [19]. In light of the above, the results of self-monitoring plans should be integrated with thorough surveillance by CAs. In this regard, following the EFSA suggested approach [23], the EU has set community targets for the reduction of the prevalence of zoonoses and zoonotic agents through national control programs [43], including pig breeding herds and herds of slaughtering pigs. The aims are to ensure that effective measures are taken to detect and control _Salmonella_ at all relevant stages of production, processing, and distribution, in order to reduce its prevalence and public health risks. These control programs in pig herds are not harmonized between the Member States [19], so in some EU countries, such as Italy, to date, they are limited to the minimum sampling requirements: sampling only at slaughterhouse level [43] with a low number of samples collected and analyzed [44].