Human health is a major concern in agriculture (e.g. – Salmonella). Contamination of human food begins at the crop level from vectors such as bird feces and other vermin. The industry is well aware of risks such as these, so there are quality processes in place to monitor quality control. However, consumers in the UK are suspicious that quality control measures are not enough to prevent the spread of Salmonella from pigs to humans. Surveillance data shows that this is not that case at all and that only 5 to 30% of carcasses may be Salmonella positive. If hygienic food preparation measures and thorough cooking are performed then there is minimal risk. Cross contamination from poor food handling procedures is the biggest concern.

Pelleted feeds have shown to be a vector of Salmonella contamination within pigs. This is due to the fact that non-pelleted feeds require more time in the stomach to digest; therefore the organisms are exposed to more stomach acid, which can be enough to kill the organism. There has been great success in Europe in lowering Salmonella contamination by feeding liquid diets. Liquid diets have been fermented by lactic acid, which increases the acidity of the feed, thereby making it inhabitable by Salmonella species. This fermentation benefits the feed because of the lactic acid content of the feed from the mill will help reduce the risk of contamination after the mill stage of processing. Predictable fermentation can be achieved by inoculating liquid feed with lactic acid bacteria that produce lactic acid rapidly and have a high terminal lactic acid concentration. This does not appear to affect complete diets that contain no synthetic amino acids.

Piglets have poor stomach acid concentrations. Feeding fermented liquid feed (FLF) increases the acidity of the stomach, therefore reducing the amount of bacteria in the stomach. In fact, when piglets are weaned directly onto FLF the amount of lactic acid bacteria is greater than the amount of coliforms in the stomach, which is a similar attribute to piglets that continue to suckle.