A case-control study involving 128 selected dairy farms was conducted to assess the association of several suspected risk factors with the odds of contamination of raw milk by Listeria monocytogenes. Using logistic regression, we found that poor quality of silage (pH > 4.0), inadequate frequency of cleaning the exercise area, poor cow cleanliness, insufficient lighting of milking barns and parlors, and incorrect disinfection of towels between milkings were significantly associated with milk contamination by L. monocytogenes. More attention to preparing silage and good milking and barn hygiene are important for diminishing the risks of exogenous contamination of raw milk by L. monocytogenes.

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Pelletrng of feed was recommended in the past to reduce the risk of Introduction of Salmonella rn swine herds. However 11 was shown more recently that consumption of pelleted feed was associated with an increased probability of seropositivity Furthermore, several studies showed that the prevalence of Salmonella IS decreased when mash feed IS used. The object1ve of th1 s study was to evaluate the effect of mash feed as a pre-harvest intervention strategy to prevent Salmonella colonization, to mod1fy of intestinal microflora and to stimulate of the 1mmune system 1n swrne Two expenmental groups of 45 and 43 p1glets were g1ven respectively conventional cornbased pelleted feed or mash feed from 10 weeks of age to slaughter Rectal swabs and blood samples were taken periodically from each pig. Fecal swabs were cultured for the presence of Salmonella wh1le a sem1-quantitallve evaluat1on of vanous fecal bactenal populations was also done. Phagocytosis rates of FITC marked Salmonella us1ng whole blood of both groups of antmals were evaluated by flow cytometry as an rndirect measurement of non-specific immune response At slaughter, mesenteric lymph nodes (MLN) were collected and cultured for Salmonella and an evaluation of presence of stomach ulcera or hyperkerotas1s was done for each group. Although prevalence of Salmonella in both groups was to low to observe difference in prevalence, our results indicated that mash feed promoted some gram pos1t1ve bactenal populations 1n companson to pelleted feed group The percentages of phagocytosis by PMN in the mash feed group was higher than rn the pelleted feed group In the mash feed fed group, all stomach were normal wh1le m the pelleted fed group, only 40% of p1g stomachs were normal These results suggest that mash feed influence bacterial content of intestine by promoting protective microbial flora , it positively affect the stomach mucosal Integrity as well as 11 may st1mulate non spec1fic immune system of p1gs

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