Survey of numbers and types of lesions detectable in pig heads and the implications for human and animal health
subclinical sheep scab in bighorn sheep when mite numbers have been very low (Boyce and others 1991). More important, however, is how early in the progression of the disease a diagnosis can be made by serological methods. ELISAs are one of the most frequently used methods for this but there is a wide variation in the time at which ELISA seropositivity occurs, usually coinciding with the onset of clinical signs, an increase in the number of mites and lesion spread. While diagnosis of scab can be made by ELISA as early as seven days after infestation in experimentally infested cattle (Lonneux and others 1998), this does not appear to be the case in sheep in which circulating antibodies detectable by ELISA appear only after about four weeks, coinciding with the onset of the rapid growth phase of the disease (Bates 1997). The present observations would appear to confirm this. In a separate experiment (not reported here), two sheep were experimentally infested with P ovis and serum taken from them at weekly intervals was assayed by immunoblotting and ELISA. The sheep were positive by immunoblotting two and three weeks after infestation whereas they were unequivocally ELISA positive only five and six weeks after infestation (one was just positive after four weeks) (Fig 1). In the serological investigations of the second outbreak on the affected farm, the two methods were compared. The most significant finding was that immunoblotting was superior to ELISA not only in early diagnosis, but also in differential diagnosis of sheep scab in cases where the ELISA results were negative. The reason for this is not clear, but it is worth noting that native antigens were used in ELISA, while denatured antigens were used in immunoblotting.
Meat safety consequences of implementing visual postmortem meat inspection procedures in Danish slaughter pigs
The consequences of a change from a traditional meat inspection procedure, including manual handling, palpation and incision, to an entirely visual postmortem meat inspection procedure in Danish slaughter pigs were assessed by a comparative study of the two methods in 183,383 slaughter pigs. Out of 58 lesion codes (selected with a prevalence ≥5.5 x 10−5), 26 (45 per cent) were assessed either as merely aesthetic or as the healed stage of an earlier lesion and nine (15 per cent) as active, but local processes, occurring only in non-edible tissue. Five lesion codes (9 per cent) were assessed as active, nonabscessal processes occurring in edible tissue, caused by swine-specific pathogens and 10 (17 per cent) were abscessal or pyaemic lesions occurring in edible tissue. Seven lesion codes (12 per cent) may be associated with consumer health hazards (two frequently and five rarely), and one with occupational health hazards. It was estimated that per 1000 carcases, an additional 2 5 with abscessal or pyaemic lesions (in edible tissue) containing Staphylococcus aureus, 4 x 10−4 containing ochratoxin, 0.2 with arthritis due to Erysipelothrix rhusiopathiae, 0.1 with caseous lymphadenitis, 0.7 faecally contaminated with Salmonella species, and 3.4 faecally contaminated with Yersinia enterocolitica would remain undetected as a result of changing from the traditional to the visual inspection procedure. Two valuable reasons for implementing a visual control system are the potential for decreased cross-contamination (no handling, cutting and incision) and reduced inspection costs. The resources released as a result may be reallocated to hygiene and surveillance programmes.
Evaluation of Lapping Grains based on Shape Characteristics.
The shape and size of abrasive grains during lapping varies complicately and irregularly. In this study, the aspect ratio of grain size and the fractal dimension of the grain external form were used as shape characteristics of grain in order to evaluate grains with lapping time. The results obtained are summarized as follows : (1)The fractal dimension increases due to microscopic fracture and decreases due to macroscopic fracture or attritious wear. (2)The aspect ratio and the fractal dimension, which are grain shape characteristicsis of the macroscopic shape and the microscopic surface complication of grain respectively, can be used for evaluating grain shape variation during lapping.