Best available technology for European livestock farms: Availability, effectiveness and uptake.

Concerns over the negative environmental impact from livestock farming across Europe continue to make their mark resulting in new legislation and large research programs. However, despite a huge amount of published material and many available techniques, doubts over the success of national and European initiatives remain. Uptake of the more cost-effective and environmentally-friendly farming methods (such as dietary control, building design and good manure management) is already widespread but unlikely to be enough in itself to ensure that current environmental targets are fully met. Some of the abatement options available for intensive pig and poultry farming are brought together under the European IPPC/IED directive where they are listed as Best Available Techniques (BAT). This list is far from complete and other methods including many treatment options are currently excluded. However, the efficacies of many of the current BAT-listed options are modest, difficult to regulate and in some cases they may even be counterproductive with respect to other objectives ie pollution swapping. Evaluation of the existing and new BAT technologies is a key to a successful abatement of pollution from the sector and this in turn relies heavily on good measurement strategies. Consideration of the global effect of proposed techniques in the context of the whole farm will be essential for the development of a valid strategy.

The impact of fouling on the process performance of the thermal treatment of pig slurry using tubular heat exchangers.

The aim of this study was to determine the kinetics of fouling and their influence on the performance of a thermal treatment process used for sanitisation of pig slurry. Two temperatures (55 °C and 80 °C) were investigated. One trial was carried out at 55 °C and 80 °C in which the slurry was not re-circulated and one trial at 80 °C in which 100% or 50% of the slurry was re-circulated. Fouling of the heat exchangers was assessed by on-line monitoring of the drop in pressure, changes in treatment temperature, heat transfer coefficients, heat recycling rate, and energy consumption. Similar energy consumption of around 38 kWh m(-3) of effluent was observed at the two temperatures. The operating periods prior to excessive fouling or blockage were 18 days at 55 °C and four days at 80 °C. Recycling treated manure to obtain 50% dilution of the raw feed increased the viable operating period to 14 days at 80 °C but doubled energy consumption. At 55 °C, the significant drop in the target temperature (>7 °C) with fouling severely jeopardised the process. The nature of the decline in performance suggests that the main fouling mechanisms were bio-fouling at 55 °C and organic/mineral deposits at 80 °C. Recycling treated manure enabled the operating period to be extended but increased the total cost of heating. One hundred percent recycling showed that the fouling potential of the manure was largely eliminated after one thermal treatment, suggesting a pretreatment may be advantageous.

Characteristics and composition of fouling caused by pig slurry in a tubular heat exchanger--recommended cleaning systems.

The structure and composition of the fouling deposits caused by pig slurry heated in a tubular heat exchanger were characterized to understand their formation and thus be able to minimize fouling and define effective routine cleaning methods. Two temperatures (55 °C and 80 °C) were investigated. Two types of fouling were identified: organic/mineral and biofilm. The first only formed at temperatures above 50 °C, often during the heating phase, and was the main problem encountered in treatments at 80 °C. Organic/mineral deposits formed a thin compact sub-layer and a thick porous top layer composed of 67-76% minerals, 9-15% proteins, 8-20% carbohydrates and 0-5% fats. Biofilms formed at temperatures between 25 °C and 70 °C in both the cooling and heating sections of the exchanger. This type of fouling predominated at temperatures below 55 °C. The biofilm covered a thin mineral base layer. Strongly acidic or alkaline washing cycle are recommended to clean Type I deposits, while in-line gas-rumbling is recommended for Type II fouling.

Using temperature and time criteria to control the effectiveness of continuous thermal sanitation of piggery effluent in terms of set microbial indicators.

AIM: To determine the minimal conditions (temperature-time), necessary to achieve set sanitation targets for selected microbial indicators during the continuous thermal treatment of pig slurry. METHODS AND RESULTS: The effectiveness of thermal treatment between 55 and 96°C was studied using Escherichia coli, enterococci, sulfite-reducing Clostridia (SRC), mesophilic culturable bacteria (MCB), F+-specific and somatic phages. Identification of SRC and MCB was performed using 16S rRNA gene analysis. Ten minutes at 70°C or 1 h at 60°C was sufficient to reduce the vegetative bacteria by 4-5 log(10), but it had little effect on somatic phages nor on spore formers, dominated by Clostridium sp. At 96°C, somatic phages were still detected, but there was a reduction of 3.1 log(10) for SRC and of 1.4 log(10) for MCB. At 96°C, Clostridium botulinum was identified among the thermotolerant MCB. CONCLUSION: Only those hygienic risks relating to mesophilic vegetative bacteria can be totally eliminated from pig slurry treated at 60°C (60 min) or 70°C (<10 min). SIGNIFICANCE AND IMPACT OF THE STUDY: Hygiene standards based on the removal of the indicators E. coli and enterococci can easily be met by treatment as low as 60°C (enabling, a low-cost treatment using heat recovery). However, even at 96°C, certain pathogens may persist.

Effect of ultrasonic treatment during cleaning on the microbiological condition of poultry transport crates.

1. Small sections cut from commercial crates used to transport live poultry to the processing plant were artificially contaminated with effluent taken from a commercial crate-cleaning system. 2. Laboratory trials, involving the immersion of these sections in an ultrasonic water bath (4 kW energy) showed that aerobic plate counts (APC) and counts of Enterobacteriaceae were progressively reduced as the immersion time was increased from 0 to 120 s and the water temperature raised from 35 to 58 degrees C. 3. In subsequent trials at a processing plant, using commercially cleaned crates, there was relatively little effect of ultrasound (or pressure washing) on the biofilm present. However, ultrasonic treatment in combination with an immersion temperature of 60 degrees C reduced counts of Enterobacteriaceae to below the detection limit (log(10) 2.3 cfu) within 1 to 3 min, while APC were reduced by >2 log(10) units after 3 min. 4. It was concluded that ultrasonic treatment has a possible role in the crate-cleaning process, when used in conjunction with higher immersion temperatures. In this way, it could contribute significantly to hygiene control.

Evaluation of the performance of different cleaning treatments in reducing microbial contamination of poultry transport crates.

1. The present systems for cleaning the plastic crates (drawers) used to transport live poultry to the processing plant are known to be inadequate for removing microbial contamination. 2. To investigate possible improvements, a mobile experimental rig was constructed and operated in the lairage of a poultry processing plant. The cleaning rig could simulate the conditions of commercial cleaning systems and utilise freshly emptied crates from the processing plant. 3. The aim of the study was to improve cleaning by enhancing the removal of adherent organic material on the crates and by reducing microbial contamination by at least 4 log(10) units. 4. Trials showed that the most effective treatments against Campylobacter were either (a) the combination of soaking at 55 degrees C, brushing for 90 s, washing for 15 s at 60 degrees C, followed by the application of disinfectant (Virkon S in this study) or (b) the use of ultrasound (4 kW) at 65 degrees C for 3 to 6 min, with or without mechanical brushing of crates. 5. Both of these treatments also achieved a 4 log(10) reduction or more in the counts of Enterobacteriaceae but were less effective in reducing aerobic plate counts. 6. It was noted that there was little correlation between the visual assessment of crate cleanliness and microbiological counts. 7. It was concluded that the demonstrated enhanced cleaning could contribute significantly to overall hygiene control in poultry meat production.

Assessing the effect of interventions on the risk of cattle and sheep carrying Escherichia coli O157:H7 to the abattoir using a stochastic model.

Escherichia coli O157:H7 persists in being a threat to food safety. The mechanisms behind the spread of E. coli O157:H7 on the farm are complex and poorly understood. The objective of this study was to apply a Monte Carlo model, constructed to simulate the propagation of E. coli O157:H7 in cattle and sheep on the farm, to both test the effect of different interventions on the risk of animals carrying E. coli O157:H7 to the abattoir and to develop understanding of the underlying processes, including the identification of areas that could benefit from further research. An overview of the model including key assumptions is given. The output statistics from batches of 100 runs of the model were collected. From the model output, a cumulative frequency distribution of the prevalence and specific shedding level for the groups of cattle or sheep being sent to the abattoir were generated. Stochastic dominance was used to compare the results of the model outputs. Using the shorthand that "risk" means the likelihood of carrying E. coli O157:H7 to the abattoir, key conclusions from the study included: mixing sheep and cattle increases the risk in both groups; merging groups of animals of the same species into larger groups increases the risk substantially; increasing stocking density increases the risk independently of group size; decreasing the group size decreases the E. coli O157:H7 prevalence independently of stocking density; a very high level of barn hygiene reduces the risk; a shorter time between spreading farmyard manure and grazing and an increased background level of E. coli O157:H7 in the model increases the risk. The background level could be influenced by the presence of wild animals carrying the organism. The parameters to which the model is most sensitive are those related to transmission from grass and enclosures to animals, pathogen survival on grass, in slurry and in barns and contact between animals.

The source and abatement of nitrous oxide emissions produced from the aerobic treatment of pig slurry to remove surplus nitrogen.

The removal of surplus nitrogen from pig slurry can be necessary in order to avoid pollution such as nitrate leaching. However, the treatment itself can create significant pollution; up to 20% of the removed slurry nitrogen has been shown to be released as nitrous oxide (N2O), which contributes to global warming and the breakdown of the ozone in the stratosphere. Avoiding such emission requires conditions that encourage the complete conversion of the nitrogen to the environmentally safe di-nitrogen gas (N2), and a clear understanding of the underlying biochemistry; for example, whether the nitrous oxide is the bi-product of incomplete nitrification (chemical oxidation) or denitrification (chemical reduction). The stable isotope of nitrogen ( N) was used in this investigation as a label. Results indicated a new route for substantial release of N2O: via nitrification (rather than denitrification), caused by a combination of high aeration levels and the presence of nitrification products. Sequential aeration, which leads to a cycling between nitrification and complete denitrification, was proposed as an abatement in view of this new mechanism. This process achieved 89% removal of ammoniacal nitrogen in laboratory scale treatment, with 94% of the nitrogen removed in the form of N2. These findings suggest that the possibility of N2O emissions from nitrification be considered in the design of treatment schemes. Increased aeration would be the intuitive response to incomplete nitrification. However, the results of this study suggested that although this response can increase nitrogen removal, this may be as N2O rather than N2.

Hygiene aspects of modern poultry chilling.

An evaluation was made of six commercial poultry chilling systems in relation to factors affecting microbial-contamination of carcasses. These systems included water immersion chilling, air chilling and air chilling with evaporative cooling using water sprays. Samples of neck skin and body cavity were taken from carcasses, together with samples from the chilling environment. These were examined for total aerobic mesophilic microbes and counts of presumptive coliform bacteria and Pseudomonas spp. at specific points in the chilling process. Physical measurements included surface and deep-muscle temperatures of carcasses, water temperatures and chlorine concentrations in the immersion system and air speed and temperature during air chilling. The results obtained for water immersion chilling confirmed previous experience that the washing effect reduces microbial contamination of carcasses, although initially the numbers of pseudomonads tended to increase. The air chillers varied in design and mode of operation, but had little overall effect on microbial contamination of the skin. When a completely dry process was used, microbial numbers were reduced approximately ten-fold in the body cavity. However, the use of water sprays tended to increase contamination of the cavity, while relatively heavy spraying using non-chlorinated water, resulted in a substantial increase in the numbers of pseudomonads.

Microbial cross-contamination during air chilling of poultry.

1. Cross-contamination during air chilling of poultry carcases was investigated using a nalidixic acid-resistant strain of Escherichia coli K12 as a marker organism. 2. Experiments were carried out on 2 types of commercial chiller, with and without the use of water sprays (evaporative cooling), and a pilot-scale chiller in which conditions could be varied as required. 3. In the commercial chillers, the marker was dispersed in all directions from a single inoculated carcase and transmission was increased by the use of chlorinated water sprays. 4. Similar results were obtained with the pilot-scale chiller, where the marker was recovered from 45/54 uninoculated carcases; cross-contamination was not prevented by spraying carcases with water containing 50 mg/l of free available chlorine. 5. Despite the ease of microbial transmission from inoculated carcases, cross-contamination during air chilling is likely to be less than that occurring at earlier stages of poultry processing, when carcases are more heavily contaminated.

Investigation of hygiene aspects during air chilling of poultry carcases using a model rig.

1. An experimental rig, designed and built to simulate conditions found in commercial poultry chilling systems, was used to investigate the effects of varying air temperature and chilling duration, and the effect of chlorinated water sprays, on the microbial load present on the skin and in the body cavity of freshly eviscerated poultry carcases; deep muscle and skin temperatures were monitored during chilling at three different temperatures. 2. During dry chilling for 2 h, total viable microbe counts (TVC) and counts of coliforms and pseudomonads from the body cavity fell by between half and one log unit; smaller reductions were observed in samples from the breast skin. 3. The situation changed when chlorinated water sprays (50, 100 or 250 ppm available chlorine) were applied for the first hour of chilling; spraying carcases enhanced the reduction in numbers on the skin; the effect was most pronounced with 250 ppm chlorine; conversely in the body cavity, the general effects of sprays was to increase contamination by up to one log unit. 4. There was no evidence that sprays increased the rate of chilling. 5. When carcases were held overnight in the rig at 11 degrees C after chilling, microbe counts on dry-chilled carcases remained stable, but increased on carcases that had been sprayed with chlorinated water.

Pilot scale thermal treatment of pig slurry for the inactivation of animal virus pathogens.

This paper describes a pilot scale treatment plant that has been designed and built for the thermal inactivation in pig slurry of two viruses that infect pigs--African swine fever virus (ASFV) and swine vesicular disease virus (SVDV). The plant treats pig slurry continuously at a rate of up to 100 litres/hour and functions by heating the slurry, maintaining at least 99.99% of the slurry at the required temperature for a minimum period of 5 minutes, and then recovering the heat to raise the temperature of the incoming slurry. Results obtained indicated that SVDV was inactivated in pig slurry to below detectable levels with an alkaline pH (pH 7.5 to 8, as is usually the case) at a temperature of between 50 and 55 degrees C. In acidified slurry (pH 6.4), inactivation occurred between 55 and 60 degrees C. The difference in inactivation temperatures was probably due to the presence of free ammonia in the unacidified slurry. ASFV was inactivated by operating the plant at a temperature of 53 degrees C at a pH of 8.

Unusual aetiology of persistent back pain in a patient with multiple myeloma: infectious discitis.

A 47 year old man with multiple myeloma presented with persistent back pain caused by infectious discitis. Aspiration of the affected vertebral disc space was carried out, guided by computed tomography, and microbiological examination of the aspirate revealed Staphylococcus aureus and Mycobacterium tuberculosis. Antituberculous and antistaphylococcal antibiotic treatment resulted in a dramatic clinical response with complete resolution of the vertebral abscess. Detailed radiological and microbiological investigations are necessary to diagnose unusual causes of chronic bone pain such as discitis or infectious bone disease in patients with multiple myeloma.

The late development of oral pyogenic granuloma as a complication of pregnancy: a case report.

An oral pyogenic granuloma can develop during or just after the first trimester of pregnancy. Usually, an oral pyogenic granuloma is an early, slow-growing mass that, on excision, does not leave a large defect in the periodontium that requires surgical repair. This article presents an unusual case of a very late, rapidly growing, large tumor that developed as a complication of pregnancy and an undiagnosed isolated area of periodontal disease.

Electrooptic Fabry-Perot filter: development for the study of solar oscillations.

Observations of nonradial solar oscillations require Doppler velocity measurement at many points over the photosphere with a velocity resolution better than 1 m/s. An attractive form of imaging spectrophotometer for such a task utilizes a thin, solid, electrically tunable Fabry-Perot interference filter or etalon made of an electrooptic material such as lithium niobate (LiNbO(3)). The problems to be overcome in producing such an etalon for an imaging spectrophotometer are discussed and practical solutions demonstrated on the basis of measurements made on prototype devices.

A computerized system for retrieval of case information in a veterinary diagnostic laboratory.

Morbidity and mortality data are necessary bases for the decision-making processes relevant to allocation of public funds for animal disease diagnoses and research. A system for information storage and retrieval capable of handling diagnostic data such as results of microbiology, parasitology, necropsy, and histopathology as well as demographic data such as owner, species, sex, breed, or geographic origin of the animal is described. This information is available to veterinarians, epidemiologists, herdsmen, and others involved in disease prevention or control efforts. The system described utilizes natural language, thus overcoming difficulties encountered in systems with numerical intermediates. Used and revised for the last 10 years, the system described has proved useful for annual administrative quantitation of services performed. In fact, the Concordance Index serves as the annual report of the University of Missouri Veterinary Medical Diagnostic Laboratory. Having accurate detailed information on individual cases, as well as a variety of composite data, has been extremely helpful in the documentation necessary for attracting funding for study of specific disease states.