A comparison of florfenicol-flunixin meglumine versus tulathromycin for the treatment of undifferentiated fever in fall-placed feedlot calves.

The purpose of this study was to compare the efficacy of a new combination drug, florfenicol-flunixin meglumine, with tulathromycin for initial treatment of undifferentiated fever (UF) in fall-placed calves that received metaphylactic tilmicosin on arrival at the feedlot. No significant differences were observed in UF relapses between the two drugs. Calves treated with florfenicol-flunixin had a lower crude case fatality rate (P = .0447) than calves treated with tulathromycin but did not have a significantly lower respiratory disease and histophilosis case fatality rate (P = .12). Whether the new florfenicol-flunixin product is more cost-effective than tulathromycin for the treatment of UF in fall-placed feedlot calves will depend on how the new product is priced in the marketplace relative to tulathromycin.

Efficacy of a florfenicol-flunixin meglumine combination product versus tulathromycin or ceftiofur crystalline free acid for the treatment of undifferentiated fever in feedlot calves.

In this field trial, a new combination product containing florfenicol and flunixin meglumine (FLOR-FM) was compared with commercially available products that contained only tulathromycin (TULA) or ceftiofur crystalline free acid (CCFA) for the treatment of undifferentiated fever (UF; rectal temperature >/=105.0 degrees F) in beef calves that received long-acting oxytetracycline at feedlot arrival. The overall mortality rate of the FLOR FM group (2.0%) was significantly (P less than .050) lower than the rates in the TULA and CCFA groups (10.0% and 20.0%, respectively; 50 animals/group), even though the first UF relapse rate of the FLOR FM group was significantly (P less than .050) higher than that of the TULA group. In the FLOR FM group, this resulted in per-animal economic advantages of Can$46.23 (versus TULA) and Can$108.77 (versus CCFA) based on equal costs for initial UF therapy. These results demonstrate that it is more cost-effective to administer FLOR FM than TULA or CCFA for initial UF therapy in feedlot calves at high risk for bovine respiratory disease that receive metaphylactic long-acting oxytetracycline at feedlot arrival.

Detection and determinants of Escherichia coil O157:H7 in Alberta feedlot pens immediately prior to slaughter.

Food safety risks due to Escherichia coli O157:H7 may be affected by variability in prevalence in or on live cattle at slaughter. Our objectives were to assess the prevalence and risk factors associated with E. coli O157:H7 in feedlot pens immediately prior to slaughter, and assess relationships among methods of monitoring the E. coli O157:H7 status of pre-harvest pens. We studied 84 pens containing a total of nearly 27,000 head of cattle in commercial feedlots in Alberta during 2003 and 2004. Sampling devices (ROPES) prepared from manila ropes were used to detect high prevalence pens. Forty of 84 pens (48%) were classified ROPES-positive. Within pens, fecal prevalence ranged between 0% to 80% (median = 20%) and the hide prevalence ranged between 0% and 30% (median = 0%). Pens that were ROPES-positive had a higher median prevalence for feces (40%) and for hides (3.8%) than those that were ROPES-negative (13.3% and 0%, respectively). The prevalence of E. coli O157:H7 in pens immediately prior to slaughter was found to be quite high or very low even within feedlots and seasons. Factors such as sampling month, temperature, precipitation, pen floor conditions, and water tank cleanliness were associated with E. coli O157:H7 outcome measures, although associated factors were not completely consistent among years and outcome measures. Fecal and hide prevalence are considered primary pre-harvest indicators of potential carcass contamination, but other methods such as ROPES that are associated with these outcomes may provide logistic advantages to efficiently classify pens of cattle as high or low risk to food safety.

Comparison of florfenicol and tulathromycin for the treatment of undifferentiated fever in Alberta feedlot calves.

The purpose of this study was to compare the efficacy and cost-effectiveness of florfenicol versus tulathromycin for initial treatment of undifferentiated fever in fall-placed steer calves that received metaphylactic tilmicosin on arrival at the feedlot. No significant differences (P > .10) were observed in undifferentiated fever relapses or the crude case fatality rate. Calves treated with florfenicol had a lower case fatality rate (P = .04) for bovine respiratory disease and Histophilus disease than did calves treated with tulathromycin. The net economic advantage of florfenicol over tulathromycin (Can$17.70/treated animal) was based on differences in costs for the trial drug and calf replacement owing to bovine respiratory disease and Histophilus disease case fatality.

A comparison of florfenicol and tulathromycine for the treatment of undifferentiated fever in feedlot calves.

The purpose of this study was to compare the relative cost-effectiveness of florfenicol with that of tulathromycin for treatment of undifferentiated fever (UF) in feedlot calves at ultra-high risk of developing UF that receive metaphylactic tulathromycin on arrival at the feedlot. Calves that received therapeutic florfenicol had lower overall mortality (P=.045) and bovine respiratory disease mortality (P=.050) compared with calves that received therapeutic tulathromycin, but no significant differences were detected in feedlot performance, carcass characteristics, or other animal health variables. There was a net advantage of Can$41.19/treated animal in the florfenicol group versus the tulathromycin group. This study demonstrates that it is more cost-effective to use florfenicol than tulathromycin for the initial treatment of UF in feedlot calves at ultra-high risk of developing UF that receive on-arrival metaphylactic tulathromycin.

Escherichia coli O157:H7 excretion by commercial feedlot cattle fed either barley- or corn-based finishing diets.

Effective preharvest control measures for Escherichia coli O157:H7 in cattle may significantly reduce the incidence of human disease caused by this organism. The prevalence and magnitude of fecal E. coli O157:H7 excretion was evaluated in 15 pens (300 to 500 cattle per pen) of commercial feedlot cattle fed a barley-based finishing ration and compared with that in 15 pens of cattle fed a corn-based ration. Average E. coli O157:H7 prevalence was 2.4% in barley-fed cattle and 1.3% in the corn-fed cattle (P < 0.05), and average magnitude of fecal E. coli O157:H7 excretion was 3.3 log CFU/g in the barley-fed cattle and 3.0 log CFU/g in the corn-fed cattle (P < 0.01). Corn-fed cattle had lower average fecal pH values (5.85) than did barley-fed cattle (6.51) (P < 0.01), and the average total generic fecal E. coli concentration in this group of animals (6.24 log CFU/g) was greater than that in the barley-fed cattle (5.55 log CFU/g) (P < 0.01). Specific feed ingredients may impact the frequency and magnitude of fecal excretion of E. coli O157:H7 by cattle.

Rectoanal junction colonization of feedlot cattle by Escherichia coli O157:H7 and its association with supershedders and excretion dynamics.

Feedlot cattle were observed for fecal excretion of and rectoanal junction (RAJ) colonization with Escherichia coli O157:H7 to identify potential "supershedders." RAJ colonization and fecal excretion prevalences were correlated, and E. coli O157:H7 prevalences and counts were significantly greater for RAJ samples. Based on a comparison of RAJ and fecal ratios of E. coli O157:H7/E. coli counts, the RAJ appears to be preferentially colonized by the O157:H7 serotype. Five supershedders were identified based on persistent colonization with high concentrations of E. coli O157:H7. Cattle copenned with supershedders had significantly greater mean pen E. coli O157:H7 RAJ and fecal prevalences than noncopenned cattle. Cumulative fecal E. coli O157:H7 excretion was also significantly higher for pens housing a supershedder. E. coli O157:H7/E. coli count ratios were higher for supershedders than for other cattle, indicating greater proportional colonization. Pulsed-field gel electrophoresis analysis demonstrated that isolates from supershedders and copenned cattle were highly related. Cattle that remained negative for E. coli O157:H7 throughout sampling were five times more likely to have been in a pen that did not house a supershedder. The data from this study support an association between levels of fecal excretion of E. coli O157:H7 and RAJ colonization in pens of feedlot cattle and suggest that the presence of supershedders influences group-level excretion parameters. An improved understanding of individual and population transmission dynamics of E. coli O157:H7 can be used to develop preslaughter- and slaughter-level interventions that reduce contamination of the food chain.

Increasing prevalence of Campylobacter jejuni in feedlot cattle through the feeding period.

The prevalence of Campylobacter jejuni in commercial feedlot cattle was monitored throughout the feeding period by repeated bacteriologic culture of feces. Fecal pats (n = 10) in 20 feedlot pens were sampled at 2-weeks interval beginning at entry into the feedlot and continuing until slaughter. The least-squares mean C. jejuni prevalence increased from 1.6% at the first sampling to 61.3% at the final sampling just prior to slaughter. Diverse C. jejuni pulsed-field gel electrophoresis macrorestriction profiles (MRP) were identified among the cattle isolates, but five prevalent MRP and minor variants accounted for >80% of all typed isolates. Chlorination of the water supplied to the water troughs of half of the pens did not affect C. jejuni prevalence in the cattle. Overall, the least-squares mean C. jejuni prevalences were 45.6 and 43.6% in chlorinated and nonchlorinated feedlot pens, respectively. The results of this study demonstrate apparent transmission of C. jejuni among feedlot cattle during the feeding period, unaffected by water chlorination, resulting in a high prevalence of C. jejuni excretion by cattle approaching slaughter.