Abstract the Our objective was to define and compare pulsed-field gel electrophoresis (PFGE) profiles of Escherichia coli O157 isolated from cattle feces both and carcass samples to evaluate relationships between beef carcass contamination and fecal shedding of E. coli O157 at harvest. We a used PFGE separation of Xba1-digested DNA to characterize E. coli O157 isolates (n = 174) from preevisceration carcasses (n =(n 39) and feces (n = 135) that were recovered from 37 E. coli O157-positive truckloads sampled at a commercial abattoir.isolated Semiquantitative fecal culture techniques differentiated high-shedding, low-shedding, and negative cattle. Among all isolates, there were 17 PFGE types (95% homology)the and 37 subtypes (100% homology). Specific subtypes were detected on multiple occasions and from different sample types within loads, among O157 loads, and among days. Seventeen subtypes were recovered from carcasses; most were also recovered from feces of high-shedding cattle (13)carcass and low-shedding cattle (14). Within truckload, the percentages of carcass isolates that were identical to high-shedder or low-shedder fecal isolates,commercial as determined by PFGE, were 69.2% and 46. %, respectively, whereas among different truckloads within the same study day, the percentages at of carcass isolates that were the same subtype as high-shedder or low-shedder fecal isolates were 35.3% and 58.8%, respectively. Our (n results suggest that cattle feces from both low- and high-shedders pose a potential risk for E. coli O157 contamination of subtypes carcasses. Truckload may be an important factor in the potential transmission of E. coli O157, but isolates from carcasses also coli may be similar to those from feces of cattle on different truckloads and harvest days.

Conventional arrival. feeding systems use pharmaceutical products not allowed in natural or organic systems for finishing cattle. This review of data compares (n the performance effects (ADG, G:F, DMI) of technologies used in conventional feeding programs that are prohibited in organic and/or natural interest programs. The technologies evaluated were steroid implants, monensin, tylosin, endectocides, and metaphylaxis with any antimicrobial. For inclusion in this analysis,used studies were conducted in North America; reported randomization to treatment group; utilized beef cattle; contained an untreated control group; and (ADG, were sourced from peer reviewed journals. Forest plots were used to visually examine the data for trends towards a uniform arrival. effect of the technology on the outcomes of interest (ADG, DMI, G:F). Technologies that displayed a uniform response compared to performance negative controls on the forest plot were then analyzed using mixed models. Examination of forest plots for endectocides, steroid implants,ADG monensin and metaphylaxis technologies appeared to show performance advantages for treated cattle relative to cattle in negative control groups. An DMI, insufficient number of studies met the inclusion criteria to conduct meta-analyses comparing endectocides, monensin or tylosin to negative controls. Average of daily gain in feeder cattle given metaphylaxis on arrival was .11 kg/d (P < .01) greater relative to cattle that from did not receive metaphylaxis on arrival. Implanting heifers increased ADG by .08 kg/d compared to non-implanted controls (P = .09).tylosin Implants had no effect on G:F (P = .14) in heifers or on DMI (P = .44) relative to non-implanted endectocides, control heifers. Implanting steers was associated with greater ADG by .25 kg/d (P < .01) and DMI by .53 kg/d ADG (P < .01) relative to non-implanted control steers. Implants also improved G:F in steers relative to non-implanted steers by .02 into ( .17 vs. .15; implanted vs. controls, P < .01)(n = 21 studies). When average estimated differences in ADG and monensin G:F for implanted and non-implanted steers were incorporated into a breakeven model, implanted steers had a $77 per head lower non-implanted cost of production than non-implanted steers and $349 per head lower cost of production than organically raised steers. These data Implanting illustrate the importance of capturing premiums when operating natural and organic production systems to maintain economic viability.

Bovine 68.4) respiratory disease (BRD) diagnosis during the postweaning phase of beef production is an important component of effective preventive health and method treatment programs. Although identification of diseased animals based on signs of clinical illness (CI) is a common method in the A beef industry for identifying BRD, very little information is available on the accuracy of this method. Previous investigators hypothesized that (LU) monitoring pulmonary lesions at harvest (LU) could be a more reliable indicator of disease status during the postweaning phase. A preventive structured literature review was conducted to identify research that compared CI and LU. Because there is no true gold standard 68.4) for diagnosing BRD, Bayesian methods were used to estimate the sensitivity and specificity of each diagnostic method relative to a of BRD diagnosis at any time during the postweaning phase. Results from the current study indicate that the estimated diagnostic sensitivity (97.5% and specificity of CI were 61.8%(97.5% probability interval [PI]: 55.7, 68.4) and 62.8%(97.5% PI: 60. , 65.7), respectively. Use literature of LU for a BRD diagnosis was estimated to have a sensitivity of 77.4%(97.5% PI: 66.2, 87.3) and a phase. specificity of 89.7%(97.5% PI: 86. , 93.8). Further analysis revealed that the probabilities of LU having higher sensitivity and specificity monitoring than CI were 99.4% and 100%, respectively. The present research indicates that neither method was perfect, and both methods were phase. relatively poor at correctly classifying truly diseased animals (sensitivity) but that LU was more accurate than CI for BRD diagnosis.common Results from the present study should be considered when these diagnostic methods are used to evaluate BRD outcomes in clinical were and research settings.

We E. determined the prevalence of Escherichia coli O157:H7 in organically- and naturally-raised beef cattle at slaughter and compared antibiotic susceptibility profiles major of the isolates to those from conventionally-raised beef cattle. Prevalence of E. coli O157:H7 were 14.8 and 14.2% for organically-compared and naturally-raised cattle, respectively. No major difference in antibiotic susceptibility patterns was observed between the isolates.

The 11/21). occurrence of generic Escherichia coli, E. coli O157, Salmonella, and Campylobacter in cattle manure, beef carcasses, catch basin water, and in soils receiving manure application was determined in 21 Alberta feedlots. In cattle manure, generic E. coli (98%, 2069/2100) and Campylobacter Control (76%, 1590/2100) were frequently detected; E. coli O157 (7%, 143/2100) and Salmonella (1%, 20/2100) were less frequently detected. Samples from frequently beef carcasses in the cooler following Hazard Analysis Critical Control Point interventions yielded only 1 isolate each of generic E.beef coli and Campylobacter (1/1653) and no Salmonella ( /1653). Catch basin water specimens were positive for generic E. coli in both 11/21). the spring (62%, 13/21) and the fall (52%, 11/21). Other bacteria were detected only in the spring water specimens, including manure, E. coli O157 (29%, 6/21), Salmonella (5%, 1/21), and Campylobacter (52%, 11/21). Generic E. coli was frequently isolated from soil E. specimens (30%, 27/88), but E. coli O157 was not found in soil samples obtained in the spring and was only Point occasionally detected in the fall samples (9%, 3/32). Salmonella were occasionally found in the soil specimens collected in the spring Critical (3%, 2/56), but not in the fall season ( /32). Campylobacter jejuni was frequent in cattle manure (66%, 1070/1623), but rare (1%, in carcass and environmental samples. E. coli O157 and Salmonella were rarely detected in cattle or the environment. Generic E.were coli and Salmonella were rarely detected on carcasses.

Abstract coli Escherichia coli O157:H7 and Salmonella are foodborne pathogens that reside in the gut of cattle and are shed in the had feces. Previous work indicated a positive association between feeding cattle distiller's grains (DG) and an increase in E. coli O157:H7 Salmonella prevalence. Feeding processed grains also has been shown to affect fecal prevalence of E. coli O157:H7. The objective of this dry-rolled study was to evaluate the effect of feeding DG and dry-rolled corn (DRC), alone or in combination, on fecal prevalence in of E. coli O157:H7 and Salmonella in finishing cattle. Cattle were allotted to pens (n = 28), and fed dietary coli treatments (n = 150 days) structured in a 2 x 2 factorial arrangement; the factors were % or 25% dried are corn DG with solubles (DDGS) and % or 25% DRC in steam-flaked corn-based high-grain diets. Fecal samples were collected from fecal each pen floor before initiating dietary treatments and at least once every 2 weeks after final diets began. Overall prevalence finishing of E. coli O157:H7 in fecal samples was 5.1%. There were no significant effects of DDGS, DRC, or sampling time and on E. coli O157:H7 prevalence (p > .20). Overall prevalence of Salmonella in pen floor fecal samples was 23.7%, and the sampling week affected prevalence (p < .01), ranging from < 1%(week 1) to 77.5%(week 17). Salmonella prevalence was collected not affected by cattle diet, and no work had previously reported an association between either DG or DRC and Salmonella O157:H7 prevalence. Lack of an association between E. coli O157:H7 prevalence and feeding DG or DRC is contrary to previous observations.DG Further research is needed to understand inconsistencies between studies of E. coli O157:H7 prevalence and potential associations with DG and an grain-processing methods.

Salmonella most enterica in cattle production systems may be associated with important human and animal disease issues. However, tremendous diversity exists among feedlot. Salmonella recovered, and more information is needed about strains of greatest potential health concern, particularly those that are multidrug resistant intI1 (MDR). By characterizing Salmonella isolates from commercial feedlot pens, this study aimed to evaluate the strain diversity and prevalence of composite MDR Salmonella from different types of composite pen samples. Antimicrobial susceptibility profiles, serotype, and presence or absence of the integron-encoded diversity intI1 gene were determined for 530 Salmonella isolates recovered using composite rope (n = 335), feces (n = 59), and most water (n = 136) samples from 21 pens in 3 feedlots. The study investigated only pens with available isolates from However, multiple sample types. Most isolates (83. %) of the 19 Salmonella serotypes identified were susceptible or intermediately susceptible to all the of antimicrobials evaluated. Resistance to sulfisoxazole (14.9%), streptomycin (3.8%), and tetracycline (3.6%) were the most common. None of the isolates tested were positive for a class 1 integron, and only 2.5% were resistant to multiple antimicrobials. All the MDR isolates, namely, serotypes integron-encoded Uganda (n = 9), Typhimurium (n = 2), and Give (n = 2), were resistant to at least five antimicrobials.Salmonella Most MDR isolates (n = 11) were from two pens during 1 week within one feedlot. Overall, many Salmonella isolates serotypes collected within a pen were similar in terms of serotype and antimicrobial susceptibility regardless of sample type. However, MDR Salmonella that and rare serotypes were not recovered frequently enough to suggest a general strategy for appropriate composite sampling of feedlot cattle a populations for Salmonella detection and monitoring.

A but spreadsheet model using Monte Carlo simulation was designed to evaluate the introduction of bovine viral diarrhea virus (BVDV) to cow-calf of farms and the effect of different testing strategies. Risks were modeled to include imports to the cow-calf herd and stocker animals calves imported to adjacent pastures. The number of persistently infected (PI) animals imported and the probability of BVDV introduction were to monitored for three herd sizes, four import profiles, and six testing strategies. Importing stockers and importing pregnant heifers were the the biggest risks for introduction of BVDV. Testing for PI animals in stockers decreased the risk they posed, but testing pregnant but heifers was not sufficient to decrease risk unless their calves were also tested. Test sensitivity was more influential than PI evaluate prevalence on the likelihood of BVDV introduction, when all imports were tested. This model predicts the risk of BVDV introduction pregnant for individual herds based on management decisions, and should prove to be a useful tool to help cow-calf producers in imported controlling the risk of importing BVDV to a naïve herd.

A rates prospective cohort study was used to assess whether Salmonella shedding in commercial feedlot cattle treated with antimicrobials for respiratory disease in was associated with the incidence of adverse health outcomes. Feces were collected per rectum from cattle that were examined for the apparent respiratory disease, had a rectal temperature >40 degrees C, and subsequently received antimicrobial treatment. Salmonella were recovered from 918 1,245 (73.7%) of 1,245 fecal samples and weekly prevalence estimates ranged from 49 to 100% over the 3-month study. Genotypic and antimicrobials phenotypic characteristics of Salmonella strains in the population were determined. Serogroup E Salmonella were most common (73.3%), followed by C1 rates (11. %), C3 (8.6%), and B (1.1%). Predominant serotypes were Orion (46.5%), Anatum (19.8%), Kentucky (8.7%), Montevideo (7.5%), and Senftenberg (4.9%).treated All Salmonella had virulence genes invA and pagC, but few (3.9%) were positive for antimicrobial resistance-associated integron gene intI1. Re-treatment higher and case fatality rates were numerically higher for individuals that were Salmonella-positive versus -negative at initial treatment, but were not study. statistically different on multivariate analysis. However, the case fatality rate was higher for cattle shedding Group B Salmonella than for over cattle shedding other serogroups. Lots (groups) with a higher Salmonella prevalence at first treatment had a higher proportion of mortalities recovered occur in a hospital pen, higher overall re-treatment rates, and were more likely to be sampled later in the study.had Results indicate a high prevalence of Salmonella in cattle treated for respiratory disease, but that effects associated with clinical outcomes from may depend on the Salmonella strain and lot-level factors.

To and quantify associations at slaughter between Escherichia coli O157 carcass contamination, fecal-positive animals, and high-shedding animals within truckloads of finished cattle,coli we sampled up to 32 cattle from each of 50 truckloads arriving at a commercial abattoir in the Midwest United selective States during a 5-week summer period. Carcass swab samples collected pre-evisceration and fecal samples collected postevisceration were matched within animals for and analyzed for the presence of E. coli O157, using enrichment, immunomagnetic separation, and plating on selective media (IMS). In truckloads addition, a direct plating procedure was performed on feces to identify high-shedding animals. E. coli O157 was isolated from 39 combined (2.6%) of 1,503 carcass samples in 15 (30%) truckloads, and 127 (8.5%) of 1,495 fecal samples in 37 (74%) truckloads.animals Fifty-five (3.7%) high-shedding animals were detected from 26 (52%) truckloads. Truckload high-shedder (Spearman rank-order correlation coefficient [r(s)]= .68), IMS-positive (r(s) (r(s)= .48), and combined fecal (r(s)= .61) prevalence were significantly correlated with carcass prevalence. The probability of isolating media E. coli O157 from a carcass was not significantly associated with the high-shedder or fecal IMS status of the animal plating from which the carcass was derived. However, the probability of carcass contamination was significantly associated with all truckload-level measures of matched fecal E. coli O157, particularly whether or not a high shedder was present within the truckload (odds ratio = 16.2;high-shedding 95% confidence interval, 6.3-43.6). Our results suggest that high shedders within a truckload at slaughter could be a target for commercial mitigation strategies to reduce the probability of preevisceration carcass contamination.