Effects of repetitive use of hormonal implants on beef carcass quality, tenderness, and consumer ratings of beef palatability

Effects of repetitive use of anabolic implants on beef carcass quality, tenderness, and consumer ratings for palatability were investigated using crossbred steer calves (n = 550). Steers from five ranches were randomly allocated to one of 10 different lifetime implant strategies or to a nonimplanted control group. Cattle were implanted at some or all of five phases of production (branding, weaning, backgrounding, feedlot entry, or reimplant time). Carcasses from the control group had higher (P < 0.05) marbling scores than carcasses from steers in all other treatment groups. Implanting steers at branding, weaning, or backgrounding vs. not implanting steers at these production stages did not affect (P > 0.05) marbling scores. Steers implanted twice during their lifetime produced carcasses with higher (P < 0.05) marbling scores than did steers receiving a total of four or five implants. Steaks obtained from carcasses in the control group had lower (P < 0.05) shear force values and were rated by consumers as more desirable (P < 0.05) for tenderness like/dislike than steaks obtained from carcasses in all other treatment groups. Implanting steers at branding or weaning production stages did not affect (P > 0.05) steak shear force values, consumer ratings for like/dislike of steak tenderness, or percentage of consumers rating overall eating quality of steaks as satisfactory. Implanting steers at backgrounding vs. not implanting steers at this production stage increased (P < 0.05) steak shear force values, but did not influence (P > 0.05) consumer ratings for like/dislike of steak tenderness or percentage of consumers rating overall eating quality of steaks as satisfactory. Steaks from nonimplanted steers were rated as more desirable (P < 0.05) for overall eating quality than steaks from steers implanted two, three, four, or five times. Use of implants increased (P < 0.05) average daily gain by 11.8 to 20.5% from weaning to harvest compared with nonimplanted controls. Implant strategies increased (P < 0.05) hot carcass weight of steers by 8.9 to 13.8% compared with the control group. Use of implants also increased (P < 0.05) longissimus muscle area and decreased (P < 0.05) estimated percentages of kidney/pelvic/heart fat, but did not affect (P > 0.05) dressing percentage or adjusted fat thickness. Our findings suggest that beef quality, palatability, and production characteristics are influenced by lifetime implant protocols.

Modeling control of rabies outbreaks in red fox populations to evaluate culling, vaccination, and vaccination combined with fertility control

A predictive model of spread and control of rabies in red fox (Vulpes vulpes) populations was used to evaluate efficacy of culling, oral vaccination, and oral vaccination and fertility control (V + FC) as rabies control strategies. In addition, effects of season, fox population density, and a delay in starting control were modeled. At fox densities of 0.5 fox families/km2 or greater, a single oral vaccination campaign with bait uptake rates of less than 50% resulted in ineffective rabies control. An uptake rate of at least 80% was required to give a better than 80% chance of eliminating rabies. Vaccination was least effective at controlling rabies if applied 1 or 2 mo before the foxes gave birth. Seasonal timing of poison or V + FC had little effect on efficacy, which was always more successful than the oral vaccination alone. The longer the delay between the simulated start of the rabies infection and the application of a single vaccination campaign, the less successful was the control, particularly at the higher fox densities tested. At a fox density of 0.25 families/km2, all the strategies were equally successful at eliminating rabies. At higher fox densities V + FC was slightly less successful than culling, whereas vaccination-only was considerably less successful. The sole use of vaccination is not considered a viable control method for areas with high fox densities. The model suggests that an area of culling centered on the disease focus, plus an outer ring of vaccine or V + FC, could be the best strategy to control a point-source wildlife rabies outbreak.

Online prediction of beef tenderness using a computer vision system equipped with a BeefCam module

Four experiments were conducted in two commercial packing plants to evaluate the effectiveness of a commercial online video image analysis (VIA) system (the Computer Vision System equipped with a BeefCam module [CVS BeefCam]) to predict tenderness of beef steaks using online measurements obtained at chain speeds. Longissimus muscle (LM) samples from the rib (Exp. 1, 2, and 4) or strip loin (Exp. 3) were obtained from each carcass and Warner-Bratzler shear force (WBSF) was measured after 14 d of aging. The CVS BeefCam output variable for LM area, adjusted for carcass weight (cm2/kg), was correlated (P < 0.05) with WBSF values in all experiments. The CVS BeefCam lean color measurements, a* and b*, were effective (P < 0.05) in all experiments for segregating carcasses into groups that produced LM steaks differing in WBSF values. Fat color measurements by CVS BeefCam were usually ineffective for segregating carcasses into groups differing in WBSF values; however, in Exp. 4, fat b* identified a group of carcasses that produced tough LM steaks. Quality grade factors accounted for 3, 18, 21, and 0% of the variation in WBSF among steaks in Exp. 1 (n = 399), 2 (n = 195), 3 (n = 304), and 4 (n = 184), respectively, whereas CVS BeefCam output variables accounted for 17, 30, 19, and 6% of the variation in WBSF among steaks in Exp. 1, 2, 3, and 4, respectively. A multiple linear regression equation developed with data from Exp. 2 accurately classified carcasses in Exp. 1 and 4 and thereby may be useful for decreasing the likelihood that a consumer would encounter a tough (WBSF > 4.5 kg) LM steak in a group classified as "tender" by CVS BeefCam compared with an unsorted population. Online measurements of beef carcasses by use of CVS BeefCam were useful for predicting the tenderness of beef LM steaks, and sorting carcasses using these measurements could aid in producing groups of beef carcasses with more uniform LM steak tenderness.

Effectiveness of the SmartMV prototype BeefCam System to sort beef carcasses into expected palatability groups

This study was conducted to determine the effectiveness of the SmartMV prototype BeefCam Video Imaging System (prototype BeefCam) for classifying beef carcasses into palatability ("certified" or "not certified" as palatable) groups. Carcasses (n = 769) were selected from four beef-packing plants to represent three USDA quality grade groups (Top Choice, TC; Low Choice, LC; and Select, SE). Following chilling, a prototype BeefCam image of the longissimus muscle was obtained for each carcass. Strip loins were collected from the left side of each carcass and aged for 10 d; Warner-Bratzler shear force (WBSF; n = 769) values and consumer panel ratings (hedonic, end-anchored, 9-point ratings for overall like/dislike; n = 500 carcasses) were obtained for cooked steaks. Using information from the images, two regression models were developed to predict the first principal component of WBSF and consumer panel ratings for sorting carcasses based on expected eating quality. Model I used only prototype BeefCam output, whereas Model II used prototype BeefCam output and a coded value for quality grade group. For both models, carcasses with a predicted value of less than 0.0 were certified as producing palatable beef Additional carcasses (n = 292) were evaluated at a fifth and separate packing plant by prototype BeefCam to validate Models I and II. A strip loin was collected from each carcass and WBSF was measured after 14 d of aging. The percentages of validation carcasses that generated tough (WBSF > or = 4.5 kg) steaks were 6.5,5.8,10.7, and 7.9% for, TC, LC, SE, and all carcasses, respectively. Use of Model I certified 51.9, 47.6, 43.8, and 47.3% of TC, LC, SE, and all carcasses, respectively. Of the carcasses certified by use of Model I, 0.0,0.0, 4.1, and 1.4% of TC, LC, SE, and all carcasses, respectively, generated tough steaks. Use of Model II certified 59.7, 47.6, 25.0, and 42.1% of TC, LC, SE, and all carcasses, respectively. Of the carcasses certified by use of Model II, 2.2, 0.0, 3.6, and 1.6% of TC, LC, SE, and all carcasses, respectively, generated tough steaks. For both models, the frequency of carcasses that produced tough steaks in the certified group was lower (P < 0.05) for all validation carcasses sampled compared with that of the original carcass population. Based on the decrease in the frequency of carcasses that produced tough steaks, further development of a commercial BeefCam system is warranted.

Response of native plants of northeastern United States and southern Spain to ozone exposures; determining exposure/response relationships

Tropospheric ozone has been identified as the most important regional scale air pollutant across much of eastern United States of America and many areas of Mediterranean climes in southern Europe. Recent field surveys in the northeastern USA and in southeastern Spain have revealed many additional plant species that exhibit symptoms typical of ozone-induced injuries. Objectives of this study were to confirm ozone as the cause of the observed foliar symptoms, determine ozone induced exposure/response relationships, and identify possible bio-indicator species. Thirteen native species of northeastern USA and 27 native species of southeastern Spain were selected for study. Plant species were exposed to ozone within 16 CSTR chambers in a greenhouse during the summer seasons of 2000 and 2001; ozone exposures of 30, 60, 90, and 120 ppb were delivered for 7 h/day, 5 days/week. Results have confirmed that with few exceptions, symptoms observed in the field were induced by exposures to ambient ozone. Species differed significantly in terms of the exposures required for the initiation of visible symptoms and subsequent injury progression.

Biofilm formation by acid-adapted and nonadapted Listeria monocytogenes in fresh beef decontamination washings and its subsequent inactivation with sanitizers

The antimicrobial effects of sodium hypochlorite (SH, 200 ppm, at an adjusted pH of 6.80 +/- 0.20 and at an unadjusted pH of 10.35 +/- 0.25), quaternary ammonium compound (pH 10.20 +/- 0.12, 200 ppm), and peroxyacetic acid (PAA, pH 3.45 +/- 0.20, 150 ppm) on previously acid-adapted or nonadapted Listeria monocytogenes inoculated (10(5) CFU/ml) into beef decontamination water washings were evaluated. The effects of the sanitizers on suspended cells (planktonic or deattached) and on cells attached to stainless steel coupons obtained from inoculated washings stored at 15 degrees C for up to 14 days were studied. Cells were exposed to sanitizers on days 2, 7, and 14. The pathogen had formed a biofilm of 5.3 log CFU/cm2 by day 2 of storage (which was reduced to 4.6 log CFU/cm2 by day 14), while the total microbial populations showed more extensive attachment (6.1 to 6.6 log CFU/cm2). The sanitizers were more effective in reducing populations of cells in suspension than in reducing populations of attached cells. Overall, there were no differences between previously acid-adapted and nonadapted L monocytogenes with regard to sensitivity to sanitizers. The total microbial biofilms were the most sensitive to all of the sanitizers on day 2, but their resistance increased during storage, and they were at their most resistant on day 14. Listeria monocytogenes displayed stronger resistance to the effects of the sanitizers on day 7 than on day 2 but had become sensitized to all sanitizers by day 14. SH at the adjusted pH (6.80) (ASH) was generally more effective in reducing bacterial populations than was SH at the unadjusted pH. PAA generally killed attached cells faster at 30 to 300 s of exposure than did the other sanitizers, except for ASH on day 2. PAA was more effective in killing attached cells than in killing cells treated in suspension, in contrast to the other sanitizers.

Intake estimation of polychlorinated dibenzo-p-dioxins, dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) in salmon: the inclusion of uncertainty

Dioxins and dioxin-like PCBs are given toxic equivalency factors (TEFs) in order to calculate the combined toxic equivalence (TEQ) of these contaminants in a sample of food. This study calculates the probability of an average consumer exceeding the recommended tolerable daily intake of 1-4 pg WHO-TEQ kg(-1) bw day(-1) as the amount of salmon in the diet is increased. Probabilistic risk analysis is used to account for the known uncertainties in this calculation. When the TEF uncertainty was excluded with no salmon consumption, the background dietary intake ranged from 1.36 to 1.78 pg TEQ kg(-1) bw day(-1). A weekly consumption of three standard salmon portions resulted in a 36% chance of exceeding the upper limit of the TDI. Inclusion of the TEF uncertainty increased the background dietary intake range from 2.1 to 4.4 pg TEQ kg(-1) bw day(-1), and the weekly consumption of one salmon portion resulted in a 79% chance of the average consumer exceeding the upper TDI. The most important factors contributing to the uncertainty in these results were, in order of magnitude, the TEF for PCB 126 and the sampling uncertainty (sample size) followed by the measurement uncertainty of PCB 126. We recommend that it is more important to increase sample size and produce more precise estimates in the TEF than to improve analytical accuracy.

Online evaluation of a commercial video image analysis system (Computer Vision System) to predict beef carcass red meat yield and for augmenting the assignment of USDA yield grades. United States Department of Agriculture

Objective quantification of differences in wholesale cut yields of beef carcasses at plant chain speeds is important for the application of value-based marketing. This study was conducted to evaluate the ability of a commercial video image analysis system, the Computer Vision System (CVS) to 1) predict commercially fabricated beef subprimal yield and 2) augment USDA yield grading, in order to improve accuracy of grade assessment. The CVS was evaluated as a fully installed production system, operating on a full-time basis at chain speeds. Steer and heifer carcasses (n = 296) were evaluated using CVS, as well as by USDA expert and online graders, before the fabrication of carcasses into industry-standard subprimal cuts. Expert yield grade (YG), online YG, CVS estimated carcass yield, and CVS measured ribeye area in conjunction with expert grader estimates of the remaining YG factors (adjusted fat thickness, percentage of kidney-pelvic-heart fat, hot carcass weight) accounted for 67, 39, 64, and 65% of the observed variation in fabricated yields of closely trimmed subprimals. The dual component CVS predicted wholesale cut yields more accurately than current online yield grading, and, in an augmentation system, CVS ribeye measurement replaced estimated ribeye area in determination of USDA yield grade, and the accuracy of cutability prediction was improved, under packing plant conditions and speeds, to a level close to that of expert graders applying grades at a comfortable rate of speed offline.

National Beef Quality Audit-2000: survey of targeted cattle and carcass characteristics related to quality, quantity, and value of fed steers and heifers

The National Beef Quality Audit-2000 was conducted to assess the current status ofthe quality and consistency of U.S. fed steers and heifers. Between May and November 2000, survey teams assessed hide condition (n = 43,415 cattle for color, brands, mud/manure), bruises (n = 43,595 carcasses), offal and carcass condemnation (n = 8,588 cattle), and carcass quality and yield information (n = 9,396 carcasses) in 30 U.S. beef packing plants. Hide colors were black (45.1%), red (31.0%), yellow (8.0%), Holstein (5.7%), gray (4.0%), white (3.2%), brown (1.7%), and brindle (1.3%). Brand frequencies were no (49.3%), one (46.2%), and two or more (4.4%), and brands were located on the butt (36.3%), side (13.7%), and shoulder (3.6%). Most cattle had no (18.0%) or a small amount (55.8%) of mud/manure on their hides, and they had no (77.3%) horns. Most carcasses (53.3%) were not bruised, 30.9% had one bruise, and 15.8% had multiple bruises. Bruise location and incidence were round (14.9%), loin (25.9%), rib (19.4%), chuck (28.2%), and brisket, flank, and plate (11.6%). Condemnation item and incidence were liver (30.3%), lungs (13.8%), tripe (11.6%), heads (6.2%), tongues (7.0%), and carcasses (0.1%). Carcass evaluation revealed these traits and frequencies: steer (67.9%), heifer (31.8%), and bullock (0.3%) sex-classes; dark-cutters (2.3%); A (96.6%), B (2.5%), and C or older (0.9%) overall maturities; and native (90.1%), dairy-type (6.9%), and Bos indicus (3.0%) breed-types. Mean USDA yield grade traits were USDA yield grade (3.0), carcass weight (356.9 kg), adjusted fat thickness (1.2 cm), longissimus muscle area (84.5 cm2), and kidney, pelvic, and heart fat (2.4%). USDA yield grades were Yield Grade 1 (12.2%), Yield Grade 2 (37.4%), Yield Grade 3 (38.6%), Yield Grade 4 (10.4%), and Yield Grade 5 (1.3%). Mean USDA quality grade traits were USDA quality grade (Select85), marbling score (Small23), overall maturity (A66), lean maturity (A65), and skeletal maturity (A67). Marbling score distribution was Slightly Abundant or higher (2.3%), Moderate (4.8%), Modest (13.1%), Small (33.3%), Slight (43.3%), and Traces (3.4%). USDA quality grades were Prime (2.0%), Choice (49.1%), Select (42.3%), Standard (5.6%), and Commercial, Utility, Cutter, and Canner (0.9%). This information will help the beef industry measure progress compared to the past two surveys and will provide a benchmark for future educational and research activities.

Improved cine cardiovascular magnetic resonance using Clariscan (NC100150 injection)

We evaluated the use of Clariscan 0.75, 2, and 5 mg Fe/kg body weight in six patients to determine optimal dosing for short repetition time cine imaging. Breathhold cine images were acquired in the vertical and horizontal long axes and the short axis. Blood-pool signal-to-noise ratio increased significantly in all planes (p < 0.01) but was least marked in the short axis. Myocardial signal-to-noise ratio increased by a lesser amount (p < 0.05). Myocardial to blood-pool signal-difference-to-noise ratio improved significantly in the long axes (p < 0.05) and was greatest at 2 mg Fe/kg body weight, but changes in the short axis were minor. With the 5-mg Fe/kg body weight dose, the response was reduced or reversed due to T2* effects. Visual assessment improved in all planes (p < 0.05) and was optimal at 2 mg Fe/kg body weight. In conclusion, Clariscan improves short repetition time cardiac breathhold cine imaging, particularly in the long axis planes, with an optimal dose of 2 mg Fe/kg body weight.

Comparison of sampling methods for microbiological testing of beef animal rectal/colonal feces, hides, and carcasses

This study compared sampling methods for detecting Escherichia coli O157:H7 and Salmonella in beef cattle feces and on hides and carcasses and for enumerating E. coli biotype I counts (ECC) on carcasses. Fecal samples were collected by rectal/colonal palpation and colonal sponge swabbing. Hides were sampled by sponge swabbing three sites, hair clipping, excision, rinsing, and gauze swabbing, whereas carcasses were sampled by three-site thoracic and pattern-mark sponge swabbing and tissue excision. Overall, irrespective of sampling method, 36.7, 13.3, and 0.0% of lots contained at least one E. coli O157:H7-positive hide, fecal, and carcass sample, respectively, while the corresponding prevalence of Salmonella was 70.0, 16.7, and 6.7%, respectively. For hide sampling, excision and gauze swabbing yielded the fewest (13.3%) E. coli O157:H7-positive samples, while hair clipping and sponge swabbing yielded the most (23.3%). None of the carcass-sampling methods detected E. coli O157:H7 or differed (P > 0.05) in their ability to enumerate ECC. Colonal swabbing was the most effective (10.0%) method for detecting E. coli O157:H7 in feces. No differences (P > 0.05) in Salmonella prevalence were observed between carcass-sampling methods, although three-site sponge swabbing and tissue excision detected the most (3.3%). Hide rinsing was the most effective (P < 0.05) Salmonella detection method (63.3%), but dangers associated with its application may preclude its use by industry; there were no differences (P > 0.05) among other hide-sampling methods. No differences (P > 0.05) in Salmonella detection were observed between fecal-sampling methods. Overall, three-site sponge swabbing was the most feasible and effective sampling method for the detection of E. coli O157:H7 and Salmonella on hides and carcasses.

Exposure to non-acid fresh meat decontamination washing fluids sensitizes Escherichia coli O157:H7 to organic acids

AIMS

To investigate whether Escherichia coli O157:H7 maintains acid tolerance in water meat decontamination washing fluids.

METHODS AND RESULTS

A rifampicin-resistant derivative of E. coli O157:H7 strain ATCC 43895 was inoculated (10(5) cfu ml(-1)) in spray-washings from meat sprayed with cold (10 degrees C) or hot (85 degrees C) water, stored at 10 degrees C for up to 14 days, and its acid tolerance was assessed at 2 and 8 days by exposure to broth or new washings adjusted to pH 3.5 or 3.7 with lactic or acetic acid. The pathogen survived in the water washings, but it was outgrown by the natural, Pseudomonas-like flora, and it was sensitized to acid.

CONCLUSIONS

The acid tolerance of E. coli O157:H7 decreases following exposure to non-acid, but otherwise stressful, conditions prevailing in water meat washings at 10 degrees C.

SIGNIFICANCE AND IMPACT OF THE STUDY

These findings suggest that the more intense use of water-based technologies should be included in meat decontamination strategies because they may contribute to enhanced meat safety by inducing acid sensitization in E. coli O157:H7.

Frequencies of injection-site lesions in muscles from rounds of dairy and beef cow carcasses

The frequency of injection-site lesions in muscles from top sirloins and rounds in fed cattle carcasses is well documented; this study characterizes the frequency and severity of lesions in muscles from rounds of beef and dairy cow carcasses. Audits were conducted in 1998, 1999, and 2000 on 3190 rounds from cow carcasses. Outside round muscles were cut into 1.25-cm slices to characterize lesions. In 1998, 31% of beef rounds and 60% of dairy rounds had an injection-site lesion. Frequency of lesions in beef rounds significantly declined 5 percentage points between 1998 and 1999 and 6 percentage points between 1999 and 2000. The frequency of lesions in dairy rounds significantly declined 9 percentage points between 1998 and 1999 and 16 percentage points between 1999 and 2000. Frequencies of injection-site lesions in muscles of beef rounds were significantly lower than those in muscles of dairy rounds in all 3 yr. Injection-site lesions were most common between the hooks and pins of the hindquarter of beef cattle and between the pins and hocks of the hindquarter of dairy cattle. Clear lesions and woody calluses exceeded 89% and occurred more frequently than did other kinds of lesions in muscles of beef and dairy rounds in 1998, 1999, and 2000 audits. Of all injection-site lesions, between 3 and 5% were cystic in muscles of beef rounds, similar to the 2 to 4% of cystic lesions found in muscles of dairy rounds. Although yearly data indicate trends in declining frequencies of injection-site lesions, the need remains for educational programs and continued improvements in beef quality assurance practices among both beef and dairy producers.

An evaluation of the USDA standards for feeder cattle frame size and muscle thickness

This study was conducted to determine the live weights at which large-, medium-, and small-framed feeder steers and heifers attain a degree of finish associated with a carcass quality grade of low Choice and to examine the relationship of feeder cattle muscle thickness to carcass yield grade traits. Feeder steers (n = 401) and heifers (n = 463) representing three age classes (calf, yearling, long yearling) were selected randomly at a commercial feedlot to exhibit wide ranges in frame size and muscularity. Individual weights were recorded and a panel of five experienced evaluators scored each animal for frame size, muscle thickness, and flesh condition. The cattle were finished on a high-concentrate finishing diet and harvested at an estimated carcass fat thickness of 10 mm. Final weights and USDA carcass grade data were collected for all cattle. Frame size scores effectively predicted finished weight at a marbling end point of Small(00) for both heifers (r2 = 0.89, SE = 16 kg) and steers (r2 = 0.94, SE = 13 kg). For heifers, the Small/Medium and Medium/ Large frame score intersects corresponded to live weights of 460 kg and 520 kg, respectively. For steers, the Small/Medium and Medium/Large frame score lines corresponded to live weights of 504 kg and 577 kg, respectively. These weights were greater than weights specified in the 1979 USDA grade standards. Evaluations of feeder cattle muscling, based on 1979 USDA Standards, were associated (P < 0.05) with differences in longissimus muscle area but were not related (P = 0.08) to differences in numerical carcass yield grades. An alternative muscle thickness classification scheme, involving the use of four thickness classes, was effective for stratifying feeder cattle according to eventual differences (P = 0.004) in carcass yield grade. Our findings suggest that USDA feeder cattle grade standards developed in 1979 are no longer adequate for describing today's population of feeder cattle.

Prevalence and antibiotic susceptibility of Salmonella isolated from beef animal hides and carcasses

This study determined the prevalence of Salmonella on beef animal hides and carcasses and antimicrobial susceptibility profiles against a panel of 13 antibiotics. In each of the eight commercial packing facilities, of which five processed primarily heifers and steers and the remaining three processed primarily cows and bulls, hide and carcass sponge swab samples were obtained immediately before hide removal and before carcass chilling, respectively. Overall, prevalence of Salmonella on external surfaces (hides) of cattle was 15.4% (49 of 319), whereas prevalence after dehiding and other slaughtering/dressing processes, including the application of decontamination treatments, was, as expected, reduced (P < 0.05) to 1.3% (4 of 320) on carcass surfaces. From 53 total Salmonella-positive hide and carcass samples, 526 biochemically confirmed isolates were obtained to determine antimicrobial susceptibility profiles. Of 53 Salmonella-positive samples, individually, 24 (45.3%), 17 (32.1%), 17 (32.1%), 11 (20.8%), 8 (15.1%), 8 (15.1%), 8 (15.1%), 4 (7.5%), and 2 (3.8%) samples yielded at least one isolate resistant to amoxicillin/clavulanic acid, tetracycline, streptomycin, sulfonamides, ampicillin, ampicillin/sulbactam, chloramphenicol, gentamicin, and trimethoprim/sulfamethoxazole, respectively. None of the Salmonella-positive samples yielded an isolate resistant to ceftriaxone, ciprofloxacin, enrofloxacin, or levofloxacin. Although none of the samples yielded an isolate simultaneously resistant to three or four antimicrobials, a total of eight samples yielded at least one isolate resistant to five or more antimicrobials tested. Included among the 18 group B-positive samples were three samples that, individually, yielded at least one Salmonella Typhimurium var. Copenhagen DT104 isolate resistant to at least six antimicrobials tested. Results from this study support current prudent therapeutic and subtherapeutic antimicrobial use recommendations.

Antimicrobials in the formulation to control Listeria monocytogenes postprocessing contamination on frankfurters stored at 4 degrees C in vacuum packages

Postprocessing contamination of cured meat products with Listeria monocytogenes during slicing and packaging is difficult to avoid, and thus, hurdles are needed to control growth of the pathogen during product storage. This study evaluated the influence of antimicrobials, included in frankfurter formulations, on L. monocytogenes populations during refrigerated (4 degrees C) storage of product inoculated (10(3) to 10(4) CFU/cm2) after peeling of casings and before vacuum packaging. Frankfurters were prepared to contain (wt/wt) sodium lactate (3 or 6%, as pure substance of a liquid, 60% wt/wt, commercial product), sodium acetate (0.25 or 0.5%), or sodium diacetate (0.25 or 0.5%). L. monocytogenes populations (PALCAM agar and Trypticase soy agar plus 0.6% yeast extract [TSAYE]) exceeded 10(6) CFU/cm2 in inoculated controls at 20 days of storage. Sodium lactate at 6% and sodium diacetate at 0.5% were bacteriostatic, or even bactericidal, throughout storage (120 days). At 3%, sodium lactate prevented pathogen growth for at least 70 days, while, in decreasing order of effectiveness, sodium diacetate at 0.25% and sodium acetate at 0.5 and 0.25% inhibited growth for 20 to 50 days. Antimicrobials had no effect on product pH, except for sodium diacetate at 0.5%, which reduced the initial pH by approximately 0.4 U. These results indicate that concentrations of sodium acetate currently permitted by the U.S. Department of Agriculture-Food Safety and Inspection Service (USDA-FSIS) (0.25%) or higher (0.5%) may control growth of L. monocytogenes for approximately 30 days, while currently permitted levels of sodium lactate (3%) and sodium diacetate (0.25%) may be inhibitory for 70 and 35 to 50 days, respectively. Moreover, levels of sodium lactate (6%) or sodium diacetate (0.5%) higher than those presently permitted by the USDA-FSIS may provide complete control at 4 degrees C of growth (120 days) of L. monocytogenes introduced on the surface of frankfurters during product packaging.

Synthesis, crystal structure determination, and biological properties of the DNA-dependent protein kinase (DNA-PK) inhibitor 3-cyano-6-hydrazonomethyl-5-(4-pyridyl)pyrid-[1H]-2-one (OK-1035)

The first reported synthesis of the DNA-PK inhibitor 3-cyano-6-hydrazonomethyl-5-(4-pyridyl)pyrid-[1H]-2-one (OK-1035) is described. The structure of OK-1035 was validated by X-ray crystallography. An IC(50) value of 100 microM was determined for inhibition of DNA-PK, and this is approximately 12-fold higher than that reported previously.

Organic acids and their salts as dipping solutions to control listeria monocytogenes inoculated following processing of sliced pork bologna stored at 4 degrees C in vacuum packages

Postprocessing contamination of cured meats with Listeria monocytogenes has become a major concern for the meat processing industry and an important food safety issue. This study evaluated aqueous dipping solutions of organic acids (2.5 or 5% lactic or acetic acid) or salts (2.5 or 5% sodium acetate or sodium diacetate, 5 or 10% sodium lactate, 5% potassium sorbate or potassium benzoate) to control L. monocytogenes on sliced, vacuum-packaged bologna stored at 4 degrees C for up to 120 days. Organic acids and salts were applied by immersing (1 min) in each solution inoculated (10(2) to 10(3) CFU/cm2) slices of bologna before vacuum packaging. Growth of L. monocytogenes (PALCAM agar) on inoculated bologna slices without treatment exceeded 7 log CFU/cm2 (P < 0.05) at 20 days of storage. No significant (P > 0.05) increase in L. monocytogenes populations occurred on bologna slices treated with 2.5 or 5% acetic acid, 5% sodium diacetate, or 5% potassium benzoate from day 0 to 120. Products treated with 5% potassium sorbate and 5% lactic acid were stored for 50 and 90 days, respectively, before a significant (P < 0.05) increase in L. monocytogenes occurred. All other treatments permitted growth of the pathogen at earlier days of storage, with sodium lactate (5 or 10%) permitting growth within 20 to 35 days. Extent of bacterial growth on trypticase soy agar plus 0.6% yeast extract (TSAYE) was similar to that on PALCAM, indicating that the major part of total bacteria grown on TSAYE agar plates incubated at 30 degrees C was L. monocytogenes. Further studies are needed to evaluate organic acids and salts as dipping solutions at abusive temperatures of retail storage, to optimize their concentrations in terms of product sensory quality, and to evaluate their effects against various other types of microorganisms and on product shelf life. In addition, technologies for the commercial application of postprocessing antimicrobial solutions in meat plants need to be developed.

Incidence of injection-site lesions in beef top sirloin butts

Damaged beef muscle tissue resulting from intramuscular injections of animal-health products represents a "quality control" problem and an economic loss to the beef industry. Fifteen individual and sequential national audits of injection-site lesions in beef top sirloin butts have been conducted at the steak provisioner/cutting level between November 1995 and July 2000. The national incidence of injection-site lesions in top sirloin butts (n = 240,080) decreased (P < 0.05) between November 1995 (11.4%) and July 2000 (2.1%). From November 1995 to July 1997, mean weight per injection-site lesion, across all lesion classes, increased (P < 0.05) from 192.5 g to 435.8 g, respectively; mean weight per lesion subsequently decreased (P < 0.05) to 249.8 g in July 2000 but was still heavier (P < 0.05) than in November 1995. Results of these audits suggest that producers have changed injection practices. These changes have likely been in response to educational efforts, such as those made by National Cattlemen's Beef Association and through state beef quality assurance programs. Analyses of results for lesion classes, partitioning lesions according to chronological stages of the healing process, suggested that the majority of lesions were induced at times that coincide with cow-calf, stocker, or early finishing-period stages of cattle production.

Models of Mycobacterium bovis in wildlife and cattle

Following the first model of wildlife tuberculosis (in European badgers) there has been a spate of papers modelling wildlife TB. These have looked at population parameters and disease dynamics in the badger and possum. Recent papers in particular have looked at various methods of controlling the wildlife vector to reduce the incidence of TB in cattle. The author examines the role of modelling to show what insights it has given us, which issues have not been addressed, and where the shortfalls lie. Particular attention will be paid to a comparison between models of badgers and possums, and between simple and more complex models, and possible areas of future research will be revealed.

Teenage pregnancy and risk of adverse perinatal outcomes associated with first and second births: population based retrospective cohort study

OBJECTIVE

To determine whether first and second births among teenagers are associated with increased risk of adverse perinatal outcomes after confounding variables have been taken into account.

DESIGN

Population based retrospective cohort study using routine discharge data for 1992-8.

SETTING

Scotland.

MAIN OUTCOME MEASURES

Stillbirth, preterm delivery, emergency caesarean section, and small for gestational age baby among non-smoking mothers aged 15-19 and 20-29.

RESULTS

The 110 233 eligible deliveries were stratified into first and second births. Among first births, the only significant difference in adverse outcomes by age group was for emergency caesarean section, which was less likely among younger mothers (odds ratio 0.5, 95% confidence interval 0.5 to 0.6). Second births in women aged 15-19 were associated with an increased risk of moderate (1.6, 1.2 to 2.1) and extreme prematurity (2.5, 1.5 to 4.3) and stillbirth (2.6, 1.3 to 5.3) but a reduced risk of emergency caesarean section (0.7, 0.5 to 1.0).

CONCLUSIONS

First teenage births are not independently associated with an increased risk of adverse pregnancy outcome and are at decreased risk of delivery by emergency caesarean section. However, second teenage births are associated with an almost threefold risk of preterm delivery and stillbirth.

Detection of eastern equine encephalitis virus in infected mosquitoes using a monoclonal antibody-based antigen-capture enzyme-linked immunosorbent assay

Surveillance of mosquito populations for virus activity is not often performed by small, vector-control districts because they do not have the financial resources to use virus isolation, or newer methods such as the polymerase chain reaction. Consequently, development and refinements of rapid, sensitive, and simple enzyme-linked immunosorbent assays (ELISAs) applicable to a wide variety of public health settings are justified. We have developed an antigen-capture ELISA for the detection of eastern equine encephalitis (EEE) virus in mosquitoes that uses both monoclonal capture and detector antibodies. The sensitivity of this assay is 4.0-5.0 log10 plaque-forming units/ml, which is comparable to previously published EEE antigen-capture assays developed with polyclonal antibody reagents. This test identifies only North American strains of EEE virus and does not react with either western equine encephalitis or Highlands J viruses. Test sensitivity was enhanced by sonicating mosquito pools, treating them with Triton X-100, and increasing the time and temperature of antigen incubation. The conversion of this ELISA to a monoclonal antibody-based format should result in a readily standardizable and transferable assay that will permit laboratories lacking virus isolation facilities to conduct EEE virus surveillance.

Fate of Escherichia coli O157:H7, Salmonella typhimurium DT 104, and Listeria monocytogenes in fresh meat decontamination fluids at 4 and 10 degrees C

Bacterial pathogens may colonize meat plants and increase food safety risks following survival, stress hardening, or proliferation in meat decontamination fluids (washings). The objective of this study was to evaluate the ability of Escherichia coli O157:H7, Salmonella Typhimurium DT 104, and Listeria monocytogenes to survive or grow in spray-washing fluids from fresh beef top rounds sprayed with water (10 or 85 degrees C) or acid solutions (2% lactic or acetic acid, 55 degrees C) during storage of the washings at 4 or 10 degrees C in air to simulate plant conditions. Inoculated Salmonella Typhimurium DT 104 (5.4 +/- 0.1 log CFU/ml) died off in lactate (pH 2.4 +/- 0.1) and acetate (pH 3.1 +/- 0.2) washings by 2 days at either storage temperature. In contrast, inoculated E. coli O157:H7 (5.2 +/- 0.1 log CFU/ml) and L. monocytogenes (5.4 +/- 0.1 log CFU/ml) survived in lactate washings for at least 2 days and in acetate washings for at least 7 and 4 days, respectively; their survival was better in acidic washings stored at 4 degrees C than at 10 degrees C. All inoculated pathogens survived in nonacid (pH > 6.0) washings, but their fate was different. E. coli O157:H7 did not grow at either temperature in water washings, whereas Salmonella Typhimurium DT 104 failed to multiply at 4 degrees C but increased by approximately 2 logs at 10 degrees C. L. monocytogenes multiplied (0.6 to 1.3 logs) at both temperatures in water washings. These results indicated that bacterial pathogens may survive for several days in acidic, and proliferate in water, washings of meat, serving as potential cross-contamination sources, if pathogen niches are established in the plant. The responses of surviving pathogens in meat decontamination waste fluids to acid or other stresses need to be addressed to better evaluate potential food safety risks.

Use of time to event analysis to estimate the normal duration of human pregnancy

BACKGROUND

Current estimates of the average duration of human pregnancy are flawed by inaccurate estimation of the time of conception and by failure to account adequately for the effect of routine elective delivery post-term.

METHODS

In this study, 1514 healthy pregnant women were studied in whom the discrepancy between the menstrual history and first trimester crown-rump length estimated gestational age was within -1 to +1 day difference. The duration of gestation was estimated using time to event analysis: non-elective delivery was taken to be the event, and elective delivery was taken to be censoring.

RESULTS

The median time to non-elective delivery using the Kaplan-Meier product limit estimate was 283 days after last menstrual period (LMP) and there was no difference comparing male and female fetuses. The median was significantly greater for nulliparous women compared with multiparous women (284 versus 282 days, P < 0.0001). Multivariate analysis using Cox's proportional hazards model confirmed the independent effect of nulliparity on duration of pregnancy [hazard ratio, 0.75; 95% confidence interval (CI) 0.67-0.85] and demonstrated no effect of maternal age, previous abortions, fetal sex, high parity, or bleeding before 24 completed weeks of gestation. Bleeding in the third trimester of pregnancy was, however, associated with an earlier onset of spontaneous labour (hazard ratio, 1.38; 95% CI 1.03-1.84).

CONCLUSION

This study provides a basis for predicting the probability of labour at a given gestational age at term.

Effects of three levels of alpha-tocopheryl acetate supplementation to feedlot cattle on performance of beef cuts during retail display

Retail packages (n = 288; 24 of each product in each treatment group) of inside round steaks, T-bone steaks (strip loin and tenderloin), top sirloin steaks, and ground beef were used to evaluate effects of dietary supplementation of vitamin E to cattle on product performance during retail display. Products from control animals and cattle fed 500 IU x animal(-1) x d(-1) or 1,000 IU x animal(-1) x d(-1) were evaluated. Except for ground beef, dietary supplementation of vitamin E increased (P < 0.05) alpha-tocopherol concentrations in beef muscle from cattle fed 1,000 IU x animal(-1) x d(-1). Although not all differences were statistically significant, retail display-life was greater for all steaks from cattle fed 1,000 IU x animal(-1) x d(-1) than for those from control cattle. Ten percent of the inside round and tenderloin steaks from cattle fed 1,000 IU x animal(-1) x d(-1) had mean overall appearance scores of 3 ("moderately undesirable") at 72 to 78 h and 54 to 60 h, respectively, whereas 10% of the inside round and tenderloin steaks from control cattle had mean overall appearance scores of 3 at 54 to 60 h and 42 to 48 h, respectively. Each of the retail cuts in this study (irrespective of the amount of alpha-tocopheryl acetate that was fed to the animal that generated it) was categorized as "high," "medium," or "low," based on the alpha-tocopherol concentration in the primal cut or ground beef batch from which it originated. Retail cuts in the medium a-tocopherol concentration category had increased retail display life of 4.0 h for ground beef (P < 0.05) over those in the low alpha-tocopherol category. Retail cuts in the high alpha-tocopherol concentration category had increased retail display life of 10.7 h for inside round steaks and 4.0 h for ground beef (P < 0.05) over those in the medium concentration category. Vitamin E supplementation of cattle at 1,000 IU x animal(-1) x d(-1) for at least 100 d can be used to increase retail caselife and to improve the overall color acceptability of steaks and ground beef products. Although far from a perfect relationship, these data strongly suggest that increasing the alpha-tocopherol concentration in a beef cut will increase its retail case life.