Control Points for Salmonella on the Farm 

The effective control of Salmonella on pig farms requires intervention at multiple critical points throughout the production system. Feed, pests, water, transport, holding pens, and slaughter practices all contribute to the introduction, persistence, and spread of the pathogen. 

Feed 

The feed is generally considered a low-risk source of Salmonella when it is manufactured under hygienic conditions, mainly due to the thermal treatments applied during processing. However, some pathogens may survive in feed ingredients even after heat treatment (Alarcón et al., 2021). The raw materials are usually rendered safe when they are exposed to temperatures above 85 °C approximately for four minutes and when the moisture content does not exceed 15%, but hygiene during storage, transport, and cooling remains essential (Doyle, 2011). 

Salmonella poses a particular risk due to its ability to form biofilms, allowing long-term persistence in feed mill environments (Santos et al., 2022). Dust, which is ubiquitous in feed mills, can harbor Salmonella for extended periods, emphasizing the importance of thorough cleaning (Magossi et al., 2019). The contamination may also occur during grain storage via rodents, birds, cats, and dogs; therefore, strict hygiene and, appropriated treatments of raw materials with mixtures of acids are highly recommended. 

Feed characteristics influence infection risk. Dry feed poses a higher risk than wet feed, as fermentation in liquid feed reduces pH through lactic and acetic acid production, inhibiting pathogen growth (Kranker, 2001). Additionally, pelleted feed may increase susceptibility by promoting mucin secretion, facilitating Salmonella adhesion, while fine particle size shortens intestinal transit time and reduces intestinal acidification (Wong et al., 2004). 

Pests and Water 

The pest control is essential, as birds, rodents, cockroaches, and flies can act as Salmonella carriers. The persistence up to 10 months in cockroaches has been reported, with fecal contamination of feed and water being a key risk (Ahmad et al., 2011). Salmonella can also survive for months in water under minimal flow conditions (Tajkarimi, 2007), and floodwaters may spread contamination from wastewater, animal waste, or soil (Watkiss & Hunt, 2012). It becomes critical the cleaning of the water  using peroxides or chlorine-based products. 

Transport, Holding Pens, and Slaughter 

The transport exposes pigs to stress and fecal contamination, increasing the risk of infection (Argüello, 2013). Salmonella has been detected in trucks, with prevalence linked to farm status (Mannion et al., 2008; Henry et al., 2018), and pigs may become infected within two hours in contaminated environments (Mannion et al., 2012). Effective cleaning includes removal of organic matter, washing, detergents, descaling, drying, and disinfection (Ruston, 2020). The longer stays in holding pens increase the risk (Rodríguez & Suárez, 2013). At the slaughterhouse, preventing gastrointestinal rupture and applying robust HACCP systems are essential. 

Conclusion 

The effective control of Salmonella on pig farms requires a multifactorial approach targeting feed hygiene, pest control, water sanitation, transport, and slaughter practices. Salmonella can persist in the environment and spread rapidly under stress or poor hygiene, failures at any control point may compromise the entire chain of production. Implementing integrated biosecurity measures from farm to slaughterhouse is therefore essential to protect animal health and reduce public health risk. “From the farm to the fork” will be the clue of the success in the control.