Microencapsulated sorbic acid and pure botanicals affect Salmonella Typhimurium shedding in pigs: a close-up look from weaning to slaughter in controlled and field conditions.

The aim of this study was to assess the efficacy of a combination of sorbic acid, thymol, and carvacrol in reducing the prevalence and shedding level of Salmonella Typhimurium in pigs either in a controlled challenge environment or in a production setting. In the first study, 24 weaned piglets were separated in 4 isolation units (6 piglets/isolation unit). Each unit received either a basal diet (no treatment) or a microencapsulated mixture of sorbic acid, thymol, and carvacrol at 1, 2, or 5 g/kg of feed. After 21 d, pigs were orally challenged with 6 log10 colony-forming units of Salmonella Typhimurium. Blood samples and feces from rectal ampullae were collected every week. On d56 of the study, pigs were euthanized and necropsied to collect intestinal contents (jejunum through colon) and ileocecal lymph nodes. Samples were analyzed for Salmonella Typhimurium and serological analysis was also conducted. In the second study, an all-in-all-out multisite pig farm that was positive for monophasic Salmonella Typhimurium was followed throughout a production cycle from weaning to slaughter. Pigs received either a basal diet or the basal diet including 5 g/kg of the microencapsulated additive. Environmental, fecal, and blood samples were collected monthly, and cecal contents and ileocecal lymph nodes were collected at slaughter to isolate and enumerate Salmonella. The results indicate that the additive at 5 g/kg tended to reduce Salmonella fecal prevalence in both a controlled challenge (p=0.07) and in production conditions (p=0.03). Nevertheless, the additive did not reduce the number of pigs seropositive for Salmonella, nor it reduced the Salmonella prevalence at slaughter. The data indicate that these additives are not effective alone but must be used in conjunction with appropriate containment measures at lairage in order to prevent reinfection in pigs and to reduce the number of pigs carrying Salmonella entering the food chain.

Aflatoxin B1 Risk Management in Parmigiano Reggiano Dairy Cow Feed.

This study investigated aflatoxin B1 (AFB1) contamination in dairy cow feed and the risk management of AFB1 content in concentrates undertaken by feed industries in the Parmigiano Reggiano area. Data on aflatoxin contamination risk management applied in 29 feed industries were collected and the AFB1 content of 70 feed samples was analysed. Data were collected within the framework of a quality control programme promoted by the Parmigiano Reggiano Consortium in 2013 and 2014. Audit results showed that the control procedures to prevent AFB1 contamination mainly focused on maize and its by-products. AFB1 concentration resulted lower than 5 ppb [legal European Union (EU) limit] in all samples; in one out of 70 samples, AFB1 content was 3.8 ppb and in all the other samples it was lower than 3 ppb. Results showed that AFB1 risk management applied by Italian feed industries effectively monitors AFB1 levels in feed below the EU legal limit.

Gossypol Content of Cotton Free Commercial Feed for Dairy Cows.

Gossypol is a yellow pigment occurring in all parts of cotton plants, with the highest levels found in seeds, and it exhibits a variety of toxic effects. Few data are available on the content of gossypol in the commercial complementary feed and in feed raw materials. The present study was focused on the investigation of the presence of free gossypol in commercial complementary feed not containing cotton. A total of 50 samples of commercial complementary feed for dairy cows were performed in 29 feed mills both using and not using cotton as feed material. The free gossypol contamination resulted under the detection limit of the technique (4 mg/kg) in 12 out of 50 samples analysed and ranged from 4 to 20 mg/kg in 28 samples. In 10 samples the level of free gossypol ranged from 20 to 29.5 mg/kg. Average contamination of samples was 12.2±9.2 SD mg/kg. No significant difference (P=0.571) was shown in free gossypol concentration between feed produced in cotton free plants and in plants where cotton is used as feed material. Free gossypol content detected in the present study allows considering complementary feed for dairy cows not at risk. On the other hand, the detection of free gossypol in cotton free complementary feed, probably attributable to cross contamination of feed materials upstream of the feed mill, should be further investigated.

Temporal Variation of Faecal Shedding of Escherichia coli 0157:H7 in A Dairy Herd Producing Raw Milk for Direct Human Consumption.

The objective of this study was to analyse over time the evolution of E. coli O157:H7 faecal shedding in a dairy herd producing raw milk for direct human consumption. The study was performed between October 2012 and September 2013 in an average size Italian dairy farm where animals are housed inside the barn all over the year. The farm housed about 140 animals during the study - 70 cows and 70 calves and heifers. Twenty-six animals were randomly selected from both the cows and young animals group, and faecal sampling was performed rectally six times two months apart in each animal. Eleven animals were culled during the study and a total of 285 faecal samples were collected. At each faecal sampling, three trough water samples and two trough feed samples were also collected for a total of 36 water samples and 24 feed samples. Samples were analysed by real time polymerase chain reaction (RT-PCR) and culture. Overall, 16 (5.6%) faecal samples were positive for E. coli O157 by RT-PCR. Cultural examination found 9 (3.1%) samples positive for E. coli O157; all the isolates were positive for stx1, stx 2 and eae genes. One (4.1%) feed sample was positive for E. coli O157 by RT-PCR; none of the water samples was positive for E. coli O157. The model highlighted a general significant reduction of the number of positive samples observed during the study from the first to the sixth sampling (P=0.000) and a positive relation between the presence of positive samples and average environmental temperature (P=0.003). The results of the study showed that in an Italian dairy farm housing animals all year, faecal shedding of E. coli O157 followed the same temporal trend reported for other types of farming. The enhanced faecal shedding during warmer months may have a significant impact on environmental contamination and the safety of raw milk and its byproducts.

Four-year monitoring of foodborne pathogens in raw milk sold by vending machines in Italy.

Prevalence data were collected from official microbiological records monitoring four selected foodborne pathogens (Salmonella, Listeria monocytogenes, Escherichia coli O157:H7, and Campylobacter jejuni) in raw milk sold by self-service vending machines in seven Italian regions (60,907 samples from 1,239 vending machines) from 2008 to 2011. Data from samples analyzed by both culture-based and real-time PCR methods were collected in one region. One hundred raw milk consumers in four regions were interviewed while purchasing raw milk from vending machines. One hundred seventy-eight of 60,907 samples were positive for one of the four foodborne pathogens investigated: 18 samples were positive for Salmonella, 83 for L. monocytogenes, 24 for E. coli O157:H7, and 53 for C. jejuni in the seven regions investigated. No significant differences in prevalence were found among regions, but a significant increase in C. jejuni prevalence was observed over the years of the study. A comparison of the two analysis methods revealed that real-time PCR was 2.71 to 9.40 times more sensitive than the culture-based method. Data on consumer habits revealed that some behaviors may enhance the risk of infection linked to raw milk consumption: 37% of consumers did not boil milk before consumption, 93% never used an insulated bag to transport raw milk home, and raw milk was consumed by children younger than 5 years of age. These results emphasize that end-product controls alone are not sufficient to guarantee an adequate level of consumer protection. The beta distribution of positive samples in this study and the data on raw milk consumer habits will be useful for the development of a national quantitative risk assessment of Salmonella, L. monocytogenes, E. coli O157, and C. jejuni infection associated with raw milk consumption.