@article{payne_li_santos_williams_sheldon_2011, title={Survey of Salmonella populations from swine waste-treatment technologies}, volume={19}, number={2}, journal={Journal of Swine Health and Production}, author={Payne, J. B. and Li, X. and Santos, F. B. O. and Williams, M. and Sheldon, B. W.}, year={2011}, pages={100–106} }
 @article{santos_ferket_santos_nakamura_collier_2008, title={Change in the ileal bacterial population of turkeys fed different diets and after infection with Salmonella as determined with denaturing gradient gel electrophoresis of amplified 16S ribosomal DNA}, volume={87}, ISSN={["1525-3171"]}, DOI={10.3382/ps.2006-00462}, abstractNote={Changes in ileal bacterial populations of Salmonella-infected turkeys fed different diets were analyzed by using 16S-V3 PCR denaturing gradient gel electrophoresis. Turkeys raised on litter flooring were fed wheat- and corn-based diets with and without enzyme preparations (XY1 and XY2, respectively) from 0 to 126 d. Preparation XY1 contained exclusively endoxylanase, whereas preparation XY2 contained endoxylanase, protease, and alpha-amylase (Danisco, , Wiltshire, UK). The dietary activity levels of XY1 and XY2 were 2,500 and 650 endo-1,4-beta-xylanase units/kg of feed, respectively. Microbial DNA was extracted from the ileal content of 16-wk-old turkeys, and the 16S rDNA gene was amplified by PCR and analyzed by denaturing gradient gel electrophoresis. Diversity indexes, including richness (number of species, S), evenness (relative distribution of species, EH), diversity (using Shannon's index, H'), and Sorenson's pairwise similarities coefficient (measures the species in common between different habitats, Cs) were calculated. Additionally, diversity indexes were associated with Salmonella prevalence determined from fresh fecal droppings collected from each pen. On the basis of contrast analysis, the wheat-based diets resulted in higher microbial diversity indexes than the corn-based diets (S = 10 vs. 12; EH = 0.9 vs. 0.8; H' = 2.2 vs. 1.9, P < 0.05). Likewise, enzyme supplementation stimulated growth of the microbiota and increased the diversity indexes in comparison with unsupplemented treatments (S = 13 vs. 10; EH = 0.9 vs. 0.8; H' = 2.2 vs. 1.9, P < 0.05). Salmonella prevalence was higher (P < 0.05) at 15 wk in turkeys fed the corn-based diet (Salmonella prevalence = 50%) than in turkeys fed the corn-enzyme (Salmonella prevalence = 13%) and wheat-based (Salmonella prevalence = 0%) dietary treatments. Therefore, contrast analysis showed that birds fed the corn control diet had lower microbiota diversity but higher Salmonella prevalence than birds fed the enzyme-supplemented and wheat-based diets. In contrast, birds fed the wheat-based diets had higher diversity but lower Salmonella prevalence than birds fed the corn-based diets. High dietary nonstarch polysaccharides from wheat and dietary exogenous enzyme supplementation promoted microbial community diversity and apparently discouraged Salmonella colonization through competitive exclusion. Nonstarch polysaccharides and dietary exogenous enzyme supplementation may be practical tools to control enteric pathogens and benefit the intestinal health and food safety of the birds.}, number={7}, journal={POULTRY SCIENCE}, author={Santos, A. A., Jr. and Ferket, P. R. and Santos, F. B. O. and Nakamura, N. and Collier, C.}, year={2008}, month={Jul}, pages={1415–1427} }
 @article{santos_sheldon_santos_ferket_2008, title={Influence of housing system, grain type, and particle size on Salmonella colonization and shedding of broilers fed triticale or corn-soybean meal diets}, volume={87}, ISSN={["1525-3171"]}, DOI={10.3382/ps.2006-00417}, abstractNote={Salmonella colonization in poultry may be influenced by grain type and particle size. Broilers reared either in nonlitter cage-based housing or in a conventionally floored litter house from 0 to 42 d were assigned to 1 of 4 dietary treatments: 1) ground corn-soybean meal (C, 560 microm), 2) coarsely ground corn-soybean meal (CC, >1,700 microm), 3) ground triticale-soybean meal (T, 560 microm), or 4) whole triticale-soybean meal (WT). A 4-strain cocktail of Salmonella enterica was orally gavaged into each chick at placement. Growth performance, cecal and fecal Salmonella populations, gizzard and proventriculus pH, intestinal size, jejunum histomorphometry, and carcass yields were measured. Broilers responded differently to the dietary treatments according to the housing system used. At 42 d, birds reared on litter and fed ground grain had greater BW than those fed coarse grain (2.87 vs. 2.71 kg), whereas cage-reared broilers fed ground triticale were heavier than those fed corn (2.75 vs. 2.64 kg). Broilers raised on litter had a better feed conversion ratio than those raised in cages (1.71 vs. 1.81 g/g). Independent of the housing system, relative eviscerated carcass weights of birds fed T and C were heavier than those of CC- and WT-fed broilers (762 vs. 752 g/kg). Generally, the jejunum villus area and mucosal depth were larger, whereas the small intestine was lighter and shorter in broilers raised on litter. Relative gizzard weights of broilers raised on litter and fed the coarser diets were heavier than those of broilers reared in cages and fed finely ground diets. Feeding whole or coarsely ground grains decreased cecal Salmonella populations in 42-d-old broilers (3.8, 3.9, 4.4, and 4.4 log most probable number/g for CC, WT, C, and T, respectively). Additionally, 42-d-old broilers reared on litter had lower cecal Salmonella populations than those in cages (3.8 vs. 4.4 log most probable number/g). In conclusion, as a feed ingredient, triticale is a good alternative to corn, resulting in improved BW and reduced Salmonella colonization. Broilers raised on litter may have achieved lower cecal Salmonella populations than caged birds because access to litter may have modulated the intestinal microflora by increasing competitive exclusion microorganisms, which discouraged Salmonella colonization.}, number={3}, journal={POULTRY SCIENCE}, author={Santos, F. B. O. and Sheldon, B. W. and Santos, A. A., Jr. and Ferket, P. R.}, year={2008}, month={Mar}, pages={405–420} }
 @article{santos_sheldon_santos_ferket_lee_petroso_smith_2007, title={Determination of ileum microbial diversity of broilers fed triticale- or corn-based diets and colonized by Salmonella}, volume={16}, ISSN={["1537-0437"]}, DOI={10.3382/japr.2006-00105}, abstractNote={SUMMARY Diversity of the bacterial communities in the ileum of broilers was characterized using denaturing gradient gel electrophoresis. Denaturing gradient gel electrophoresis separation of polymerase chain reaction amplicons of the V2-V3 variable regions of the 16S rDNA is a common method to profile community diversity and has been used to assess the effects of diet and antibiotics on the ileal bacterial community of chickens. Broilers raised either on litter floor or in cage batteries were fed either a finely ground corn- (control), a finely ground triticale-, or a whole triticale-based diet from 0 to 42 d. Microbial DNA was extracted from the ileum content of 42-d-old broilers, and the 16S rDNA gene was amplified by polymerase chain reaction and the amplicons separated by denaturing gradient gel electrophoresis. Diversity indexes including richness, evenness, diversity, and pairwise similarity coefficients were calculated. Diversity indexes were related to the dietary treatments, housing designs, and to changes in Salmonella colonization of broiler ceca as characterized by the most probable number method. Higher microbial diversity indexes were observed among birds fed whole triticale-based diets and reared on litter floors. In contrast, finely ground grain treatments had lower diversity and higher Salmonella prevalence than the whole triticale treatment. The data indicated that combination of high dietary fiber content and increased coarseness of the diet by feeding whole triticale stimulated microbial community diversity and discouraged Salmonella colonization, perhaps through a competitive exclusion-type mechanism.}, number={4}, journal={JOURNAL OF APPLIED POULTRY RESEARCH}, author={Santos, F. B. O. and Sheldon, B. W. and Santos, A. A., Jr. and Ferket, P. R. and Lee, M. D. and Petroso, A. and Smith, D.}, year={2007}, pages={563–573} }
 @article{santos_d'souza_jaykus_ferket_sheldon_2007, title={Genotypes, serotypes, and antibiotic resistance profiles of Salmonella isolated from commercial North Carolina Turkey farms}, volume={70}, ISSN={["1944-9097"]}, DOI={10.4315/0362-028X-70.6.1328}, abstractNote={This study was designed to determine the serotypes, genotypes, and antibiotic resistance (AbR) patterns of 42 Salmonella isolates recovered from either fecal or litter samples of 12 commercial turkey farms across two seasons (summer and winter) and two ages (3 and 19 weeks). Isolates were serotyped on the basis of the Kauffmann-White scheme. Genotyping was done by restriction digestion of cDNA (XbaI) and subsequent pulsed-field gel electrophoresis (PFGE). The AbR was determined with Sensititre susceptibility plates. Serovar Kentucky was the most prevalent serotype (26%), followed by Senftenberg (19%), Muenster (17%), Mbandaka (10%), Javiana (7%), Hadar (5%), Heidelberg (5%), 8,(20):nonmotile (5%), Agona (2%), Infantis (2%), and 4,12:r:-(2%). Serovars Kentucky, Heidelberg, Hadar, and 8,(20):nonmotile were isolated only from the 19-week-old bird samples, whereas Senftenberg and Muenster were isolated only from the young birds (3 weeks old). Isolates within any one serotype showed minor PFGE banding pattern differences, but dendogram analysis indicated that sequence variability between serotypes was more significant than within serotypes. Isolates were resistant to tetracycline (86%), sulfisoxazole (71%), streptomycin (64%), gentamicin (41%), ampicillin (36%), kanamycin (26%), sulfamethoxazole-trimethoprim (7%), nalidixic acid (5%), cefoxitin (2%), and ceftiofur (2%). One isolate (Muenster) was resistant to nine antibiotics (2%), and the others were resistant to six (7%), five (12%), four (10%), three (21%), two (24%), and one (10%) antibiotic. Only two isolates (5%) were susceptible to all antibiotics tested. The AbR patterns were affected by age; on average, strains recovered from young birds were resistant to more than four drugs compared with fewer than three in older birds (P < 0.05). This study showed that Salmonella enterica subsp. enterica serotypes, genotypes and AbR patterns were affected by bird age but not by season or farm.}, number={6}, journal={JOURNAL OF FOOD PROTECTION}, author={Santos, F. B. O. and D'Souza, D. H. and Jaykus, L. and Ferket, P. R. and Sheldon, B. W.}, year={2007}, month={Jun}, pages={1328–1333} }
 @article{li_payne_santos_levine_anderson_sheldon_2007, title={Salmonella Populations and Prevalence in Layer Feces from Commercial High-Rise Houses and Characterization of the Salmonella Isolates by Serotyping, Antibiotic Resistance Analysis, and Pulsed Field Gel Electrophoresis}, volume={86}, ISSN={0032-5791}, url={http://dx.doi.org/10.1093/ps/86.3.591}, DOI={10.1093/ps/86.3.591}, abstractNote={Salmonella species are recognized as a major cause of foodborne illnesses that are closely associated with the consumption of contaminated poultry and egg products. The objectives of this study were to evaluate the Salmonella populations and prevalence in layer feces during the laying cycle and molting of the hen and to characterize the layer fecal Salmonella isolates by serotyping, antibiotic resistance analysis, and pulsed field gel electrophoresis. Fecal samples were collected from a commercial layer complex consisting of 12 houses. Composite fecal samples across each row were collected as a function of bird age [18 wk (at placement), 25 to 28 wk (first peak of production cycle), 66 to 74 wk (molting), and 75 to 78 wk (second peak of production cycle)]. Bird ages and molting practice did not significantly affect (P > 0.05) Salmonella populations with an average of 1.25, 1.27, 1.20, and 1.14 log most probable number/g for the 18-, 25- to 28-, 66- to 74-, and 75- to 7-wk birds, respectively. However, the 18-wk birds had the highest prevalence of Salmonella (55.6%), followed by the 25- to 28-wk birds (41.7%), 75- to 78-wk birds (16.7%), and 66- to 74-wk birds (5.5%). Of the 45 Salmonella isolates characterized, the most predominant serovar was Salmonella Kentucky (62%). Thirty-five percent of the Salmonella isolates were resistant to at least 1 antibiotic. As expected, considerable genetic diversity was observed within and across the different serovars.}, number={3}, journal={Poultry Science}, publisher={Elsevier BV}, author={Li, X. and Payne, J.B. and Santos, F.B. and Levine, J.F. and Anderson, K.E. and Sheldon, B.W.}, year={2007}, month={Mar}, pages={591–597} }
 @article{santos_li_payne_sheldon_2005, title={Estimation of most probable number Salmonella populations on commercial North Carolina turkey farms}, volume={14}, ISSN={["1537-0437"]}, DOI={10.1093/japr/14.4.700}, abstractNote={Abstract Salmonellae are one of the primary causes of human gastroenteritis in the United States. Although there are many foods that may be contaminated with Salmonella, poultry products are one of the major vehicles for transmitting this organism to humans. However, the national incidence of poultry product contamination with Salmonella has declined since adoption of the Hazard Analysis and Critical Control Point (HACCP) food safety program. Further reductions in carcass contamination may require other approaches such as the adoption of on-farm pathogen reduction strategies. In this study Salmonella prevalence and populations from fresh excreta and litter composite samples taken from 12 commercial turkey farms were enumerated using the most probable number (MPN) method and compared as a function of farm, season (summer and winter), and bird age (3 vs. 19 wk). Moreover, litter pH, temperature, moisture content, water activity, and ammonia levels were monitored. All farms were Salmonella positive for at least one season, and populations ranged from 5.3 log MPN/g. Of the 48 separate fecal and litter composite samples analyzed, 70 and 79% were Salmonella-positive, respectively. Although the MPN enumeration method is much more labor intensive and costly than the prevalence method, it yields estimates of Salmonella populations instead of merely indications of presence or absence of the organism. Moreover, our findings demonstrated that the MPN method is significantly more sensitive compared with the prevalence procedure (for fecal samples). This study also demonstrated that Salmonella can be present at high populations during turkey production and that their populations and prevalence were significantly impacted by flock age (litter) and season by farm interactions (fecal). Furthermore, litter Salmonella populations appear to be associated with the interrelated parameters of litter pH, ammonia and moisture content.}, number={4}, journal={JOURNAL OF APPLIED POULTRY RESEARCH}, author={Santos, FBO and Li, X and Payne, JB and Sheldon, BW}, year={2005}, pages={700–708} }