REDUCTION OF Salmonella typhimurium MONOPHASIC VARIANT SHEDDING BY ADMINISTRATION OF ORGANIC ACIDS AND PHYTOCHEMICAL IN PIGS

Salmonella Typhimurium (including S. Typhimurium 1,4,[5],12:i-), associated to other enteric pathogens and to other stressful factors, causes the Post Weaning Diarrhea in piglets. This disease is responsible for economic losses, for development of chronic infection and, thus, for the introduction of zoonotic bacteria into the slaughterhouse [1]. It is largely demonstrated the importance of controlling infection in farm for preventing disease in humans [2]. Furthermore, the increment of antibiotic resistance strains determines the necessity to find new control strategies, as administration of vaccines [3] or organic acids [4]. The aim of this trial was to assess the effects of organic acids and phytochemicals on controlling S. Typhimurium 1,4,[5],12:i- shedding. Animals were divided in three groups. In group A (460 piglets), animals were feed with a base diet added of additive (organic acids and phytochemicals) at the concentration of 1kg/t. In group B (460 piglets), additive was added to the water at the final concentration useful to obtain a final pH value equal to 4.5 in relation to water hardness. The last group (460 piglets) was the control group. Microbiological analyses were conducted on feces and environmental swabs to evaluate Salmonella-shedding in a representative number of animals (15 ear-tagged piglets) of each group. The sample timing was: a week before arrival (T0) and at day 0 (T1), 15 (T2), 22 (T3), 43 (T4) and 57 (T5) after arrival. Serum samples were collected a week before arrival (T0) and at day 0 (T1), 15 (T2), 43 (T4) and 57 (T5) after arrival to evaluate antibody titers against Salmonella sp. Results demonstrated that environmental swabs were positive before piglets arrival and after cleaning procedures. The shedding evidenced that animals were negative from breeding farm and started to shed Salmonella since day 15 post weaning. In treated animals (groups A and B), the shedding rapidly reduced and difference with control group was statistically significant at T5. The antibody titers reached the peak at the end of the trial, when bacterial load was extremely low especially in treated groups (A and B). In conclusion, all pens were contaminated with S. Typhimurium 1,4,[5],12:i- and animals generally got infected at post weaning, one week after their arrive. Probably, the reason is that site 2 is a re-adapted farm which has severe structural problems. Nevertheless, the shedding rapidly decreased in treated groups (A and B) and bacteria load in feces was statistically different in comparison to control group at T5.