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.

A novel method for assessing the role of air in the microbiological contamination of poultry carcasses

This paper describes a novel method of measuring the contamination of raw foods with airborne bacteria during primary processing. To demonstrate the approach, this study aimed to quantify the role of airborne bacteria in the contamination of broiler chicken carcasses undergoing processing in an evisceration room. Settle plates and broiler carcasses were exposed to the evisceration room air or to ultra-clean air provided by a high efficiency particulate air (HEPA) unit located within the room. The use of ultra-clean air reduced the total aerobic counts on horizontal settle plates by 68-fold, and on vertical settle plates by 14-fold. The use of ultra-clean air had no significant effect on the total aerobic counts on carcasses as measured by sponging (3.5 log(10) CFU cm(-2)) or skin excision (4.0 log(10) CFU cm(-2)). The novel approach was able to show that the carcasses entering the room were so heavily contaminated that the airborne bacteria in the evisceration room contributed less than 1% of the total numbers of bacteria on the carcasses.

Occupational exposure of poultry stockmen in current barn systems for egg production in the United Kingdom

1. The occupational exposure to inhalable dust and ammonia of 12 stockmen working in barn systems conforming to the UK Royal Society for the Prevention of Cruelty to Animals (RSPCA) Freedom Foods requirements was measured and compared with established limits for occupational exposure. The influence of the type of task upon the daily exposure was assessed and comparisons of daily exposure were made with that of battery cage system stockmen. 2. The mean inhalable dust exposures experienced by poultry stockmen working in barn systems was 10.8 mg/m3 (9.5 mg/m3, time-weighted average), for a complete working day. This was greater (P < 0.01) than the mean dust exposure measured in current cage systems of 4.8 mg/m3 (4.4 mg/m3, time-weighted average). The individual values of dust exposure for 4 of the 12 barn stockmen exceeded the occupational exposure standard (OES) of 10.0 mg/m3 for inhalable dust, whereas that of all of the individual cage stockmen taking part in this study did not. 3. The mean ammonia exposure experienced by poultry stockmen working in barn systems was 14 ppm (11 ppm, time-weighted average), for a complete working day. This also was greater (P < 0.01) than the mean ammonia exposure measured in current cage systems of 8 ppm (7 ppm, time-weighted average). None of the individual values of ammonia exposures for both barn and cage system stockmen taking part in this study exceeded the OESs of 25 ppm, although the short-term limit of 35 ppm for 15 min was exceeded on a number of occasions. 4. Current methods for assessing the combined effects of dust and ammonia indicated that 8 of the 12 barn stockmen were at risk compared with 1 of the 8 cage system stockmen. 5. The average dust burden in daily common tasks such as maintenance and collecting floor eggs ranged from 5 to 15 mg/m3, while intermittent common tasks such as nest box checks and litter spreading ranged from 13 to 35 mg/m3. Tasks that had the highest exposure values included sweeping and partition removal, ranging from 63.3 to 70.7 mg/m3. 6. Designs of the typical barn systems investigated offer little scope for reducing airborne dust for common daily tasks. Personal respiratory protection while carrying out tasks that result in high dust concentrations in barns is advisable.

Assessment and development of procedures and apparatus to reduce contamination of lamb carcasses during pelt removal in low-throughput abattoirs

Two series of experiments were carried out to investigate methods of reducing contamination of lamb carcasses in low-throughput abattoirs, where cradle dressing is normally employed. In the first series, cradle design and pelt removal procedure were investigated, and a method was developed for assessing gross visible contamination. Significant improvements in microbiological and gross visible contamination (P < 0.01) were achieved by procedural changes only; modifications to the cradle design had no effect. In the second series of experiments, two improved methods of pelt removal and the effect of hand washing prior to carcass contact during the pelt removal procedure were investigated. The improved methods comprised a Frame system, in which the pelt was removed in a manner similar to that in a high-throughput inverted line, and a Hybrid system, in which the pelt was removed from the forequarters on a conventional cradle before the carcass was suspended in an "inverted" vertical position for removal of the pelt from the abdomen and hindquarters. The results of microbiological and gross visible contamination from these methods, with and without hand washing, were compared with the conventional Cradle method of pelt removal. Both the Hybrid and Frame systems had significantly less microbiological and gross visible contamination (P < 0.01). However, hand washing had no significant effect on the level of carcass contamination for all three methods of pelt removal. Greatest reductions in microbiological and gross visible contamination were achieved using techniques that minimized hand contact with the carcass during pelt removal by adoption of inverted dressing procedures. Equipment redesign did not reduce carcass contamination.

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.

The postural support of seats: a study of driver preferences during simulated tractor operation

The overall comfort of four current production tractor seats and some individual features of seat design have been assessed by a method of paired comparisons. The experiment was carried out under both static and dynamic conditions and subjects had to adopt natural postures similar to those adopted when ploughing. The results suggest that operators can differentiate seat comfort differences reliably. Subjects' posture has proved important particularly when assessing the height of the back rest. On the other hand most appraisals were not significantly affected by the conditions (dynamic or static) of the simulation. An exception to this was the cushion length. This experiment has finally produced enough information on the relative importance of various aspects to enable us to design an experimental seat to be used in a series of experiments to assess specific features of seat aspects. The ultimate objectives of this investigation are to determine what aspects of seat and workplace design affect the comfort of the operator and how these can be altered to improve the tractor driver's posture.