Controlling microbial contamination on beef and lamb meat during processing

SUMMARY The microbiological quality of carcases, meat and environmental surfaces was evaluated in commercial boning rooms processing beef and lamb. There was considerable variation in the level of microbial contamination on both carcases and meat, with counts ranging from less than 20 to 10⁸/cm² on carcases and to 2 times 10⁷/cm² on meat. The level of microbial contamination on meat was influenced by the level of carcase contamination at boning and by the boning process itself. Carcase contamination was the major determinant of microbiological quality, as more than 70% of carcases had microbial counts greater than 10³/cm². Cutting boards were a major source for microbial dissemination during boning, particularly when carcase counts were less than 10³/cm². If carcases were heavily contaminated, the contamination of processing surfaces was irrelevant in determining microbial loads on meat. Where carcase contamination was at low to moderate levels, the contribution of the boning process to the contamination on meat assumed increased significance. Under these conditions, improved sanitation of cutting surfaces in the boning room resulted in a significant reduction in microbial contamination on the surface of meat. These results can form the basis for ensuring that improvements made in carcase management before boning, to improve microbiological quality, will be preserved through attention to cutting board hygiene during boning.     

Effectiveness of passive gas-scavenging canisters attached to isoflurane anesthesia systems under standard-use conditions in a laboratory animal facility

Chronic exposure to trace levels of waste anesthetic gases has been linked to higher incidences of neurologic and reproductive dysfunction, hepatic and renal toxicity, and neoplasia in health care professionals. We have shown that low levels of isoflurane emissions are likely in conventional laboratory animal treatment rooms during the use of standard anesthesia delivery systems equipped with activated charcoal canisters for passive gas scavenging. In the present study, we surveyed the effectiveness of canisters (attached to well‐maintained precision isoflurane vaporizers) in current use throughout our AAALAC‐accredited laboratory animal facility. Canisters (Omnicon f/air) had been weighed prior to use and then attached to dual‐loop systems (face mask and induction box circuits) from 1 week to 6 months of service. Isoflurane emissions were measured using a pre‐calibrated, portable infrared spectrophotometer by attaching each canister to the face‐mask circuit, occluding the face mask and closing the stopcock to the induction circuit, and running the system at uniform isoflurane concentration (2%) and oxygen flow rate (1 L minute^?1). Samples were taken in animal procedure rooms (size range, 45–80 m³) in which the air turnover rate ranged between 20 and 30 nonrecirculating changes per hour. Nine of the 60 canisters (15%) in current use were found to have exceeded the manufacturer's recommended use‐life (defined as a weight increase of 50 g). Of these nine, seven canisters did not scavenge isoflurane at all (indicated by emissions greatly exceeding 100 ppm). Isoflurane was not detected in the operator's breathing zone under normal use conditions (i.e. gas directed to both circuits at once). Of the 51 canisters that had not exceeded their rated use‐life, 12 (23.5%) exhausted isoflurane at >2 ppm. Our data show that (i) the potential for exposure to waste isoflurane emissions will depend on the configuration of the delivery system and that (ii) enhanced attention to canister surveillance may be warranted even in well‐run facilities.     

The isolation of salmonella from kangaroos and feral pigs processed for human consumption

A total of 154 feral pig carcases and 81 kangaroo carcases were examined for the presence of Salmonella, coliforms and total aerobic counts. Approximately 34% of pig carcases yielded one or more serotypes of Salmonella, while about 11% of kangaroo carcases were contaminated with salmonella. The results differed widely between sampling occasions. A total of 13 serotypes were isolated from feral pigs with S. anatum (31 isolates) and S. typhimurium (9 isolates) being the predominant serotypes. Coliforms were isolated from approximately 90% of carcases. The mean log10 coliform count on feral pigs was 4.39 +/- 1.45/g and the mean log10 total count was 6.15 +/- 1.15/g. About 21% of carcases were contaminated with more than 100,000 coliforms/g. A total 3 serotypes were isolated from kangaroos (S. bahrenfeld, S. binza, and S. onderstepoort). The mean log10 coliform count on kangaroos was 3.54 +/- 1.04. More than 50% of kangaroo carcases were contaminated with less than 100 coliforms/g. About 15% of carcases were contaminated with more than 10,000 coliforms/g. The mean log10 total count was 5.2 +/- 1.01/g.     

Effects of two adenoviruses (type 1 and type 8) on functional properties of bovine alveolar macrophages in vitro.

Cultures of bovine alveolar macrophages were inoculated with type-1 and type-8 adenoviruses, initially isolated from calves with respiratory tract disease, and functional properties of the cells were observed over a period of 10 to 11 days. Both viruses replicated in macrophages; viral titers were low (less than 3.75 log10 TCID50/0.1 ml), and intranuclear inclusions were detected by indirect immunofluorescence in 5 to 10% of the cells from 3 days after inoculation. Highest titers were induced by type-1 adenovirus, which also induced the greatest functional changes. Expression of Fc and complement receptors was reduced by both viruses, although the greatest effects were seen with type 1. Phagocytosis of Candida krusei cells was reduced following type 1 infection, whereas phagocytosis in type-8-infected cells was not different from that of noninfected macrophages. Ability to kill ingested Candida cells also was reduced following type-1 infection, whereas type-8-infected macrophages had lower killing ability only at 2 to 4 days after inoculation. Neither virus had substantial effects on the production of neutrophil chemotactic factors by the macrophages.     

Blood bactericidal assay (Pasteurella haemolytica) comparison of morbidity in marketed feeder calves

An in vitro bactericidal assay that used bovine heparinized blood was investigated for its usefulness in detecting differences in the bactericidal immunity of calves against Pasteurella haemolytica serotype 1 (Ph1). Greater than 90% of killing occurred within 30 minutes. The substitution of fetal calf serum for autologous calf plasma caused loss of bactericidal activity of the blood. Decomplemented calf serum also was low in bactericidal activity. The blood bactericidal assay appears to be opsonin antibody-dependent and complement-dependent. The coefficient of variation (CV) that can be expected with this assay was established by use of a group of 8 calves; within-day CV maximum was 0.9, and between-day CV maximum was 2.1. The blood bactericidal assay was used to evaluate 30 calves under typical market stress from 4 farms in eastern Tennessee. All calves had decreased bactericidal activity, as they moved into a feedyard in Texas. The bactericidal activity was reduced among sick calves, based on the severity of clinical signs. Morbidity was highest during the first 14 days in the feedlot. During this period, healthy calves had a decreased bactericidal index (BI) of 4 points, and calves with clinical signs of bovine respiratory tract disease for 3 days had a decreased BI of 8 points. The average reduction in the BI of calves with clinical signs of bovine respiratory tract disease for 6 or more days was 14 points.     

Comparison of direct and indirect blood pressure measurements in anesthetized dogs.

The precision and accuracy of an indirect oscillometric blood pressure measurement technique (Dinamap 8100) was assessed in 11 anesthetized Beagle dogs weighing 8 to 11.5 kg. Direct blood pressure measurements were made by catheterization of the lingual artery, and simultaneous indirect measurements were determined by placing a cuff over the median artery (midradial area). Blood pressure measurements at 2 different planes of anesthesia (light and deep) were recorded in triplicate. At a light plane of anesthesia, the Dinamap 8100 underestimated diastolic and mean arterial pressure, and at a deep anesthetic plane overestimated systolic pressure. The indirect technique had good repeatability of systolic pressures. Regression analysis for the 2 techniques showed excellent correlation (r = 0.93). The results indicate that the indirect oscillometric blood pressure measurement technique provides a good estimate of systolic, diastolic, and mean arterial pressure in dogs weighing 8-11.5 kg.     

Efficacy of an in-feed ivermectin formulation against gastrointestinal helminths, lungworms, and sarcoptic mites in swine

The efficacy of ivermectin as an in-feed formulation was evaluated against naturally acquired gastrointestinal helminths, lungworms, and sarcoptic mites (experiment 1; n = 24) and against induced infection with intestinal nematodes (experiment 2; n = 24) in pigs. Treatments consisted of ivermectin administered in feed at concentrations calculated to provide 100 or 200 micrograms/kg of body weight/d for 7 days or of nonmedicated feed (controls) for 7 days. At concentration of 100 micrograms of ivermectin/kg/d, efficacy against naturally acquired infections was 97.7% for Ascaris suum, 97.8% for Metastrongylus spp, greater than 99% for Oesophagostomum spp, 100% for Macracanthorhynchus hirudinaceus, and 89.7% for Ascarops strongylina. Against induced infections (fourth-stage larvae), efficacy was 100% for A suum and 96.9% for Oesophagostomum spp. At concentration of 200 micrograms of ivermectin/kg/d, efficacy against naturally acquired infections was 100% for A suum, Hyostrongylus rubidus, Metastrongylus spp, and Ascarops strongylina; greater than 99% for Oesophagostomum spp; and 85.9% for Macracanthorhynchus hirudinaceus. Against induced infections (fourth-stage larvae), efficacy was 100% for A suum and 95% for Oesophagostomum spp. At concentrations of 100 and 200 micrograms of ivermectin/kg/d, efficacy against Sarcoptes scabiei var suis was evidenced by elimination of the mite by posttreatment day 14.     

The relative importance of traits reported in the first three gosford random sample tests

An analysis was performed on the published results of the first, second and third Gosford Random Sample Tests to determine which of the various biological traits reported had the greatest influence upon the overall ranking. Ten traits were considered. It was found that regression on survivors’ average egg production and laying house mortality removed 88.1 per cent of the variation in financial return. The addition of average egg weight and daily food consumption increased this figure to 93.3 per cent. The remaining traits, number of unsaleable birds at 500 days, body weight at 500 days, age at 50 per cent production, blood spots, meat spots and shell thickness, did not produce significant reductions except in so far as they were correlated with those previously mentioned.

The financial returns expected from improvements in the four important traits were:

• Per bird

• + 12 in survivors egg production 2S. 4¼d. ± 1¼d.

• —5 in percentage laying mortality is. 5d.± 1d.

• + 1 g. in average egg weight 10½d. + 1 ½d.

• —5 g. in food consumed per day 43/4d.± 1¼d.

Laying house mortality was found to be positively correlated among the entries with survivors’ average egg production and with average egg weight.