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.
From traditional meat inspection to development of meat safety assurance programs in pig abattoirs – The European situation
Abstract The main goal of the present paper is to overview, using the example of pigs/pork, the developments in official meat inspection in the European Union that occurred from 2000 onwards. The developments aim at transition from traditional, macroscopic examination of slaughtered animals to a risk and meat-chain based, comprehensive meat safety assurance system. The scientific reasoning for those developments and the generic framework of a modernised system as proposed by the European Food Safety Authority, as well as the current status and future perspectives of related changes, are considered. Also, the main factors hampering the implementation of the changes in practice and possible directions for further work needed to overcome them are outlined.
On the fractionation of β-lactoglobulin and α-lactalbumin
Abstract Existing methods for the preparation of α-lactalbumin and β-lactoglobulin are examined critically. It is proposed that the most satisfactory method for the preparation of the whey protein fraction from bovine milk is (NH 4 ) 2 SO 4 fractionation. A number of new gentle procedures for the fractionation of the whey proteins are compared with some existing methods. The distribution of total protein at various stages is determined by total Kjeldahl nitrogen and the kind of protein by starch-gel electrophoresis. The effect of variables, such as pH, salt concentration and temperature on the separation of α-lactalbumin and serum albumin from β-lactoglobulin is studied. Differences in the behavior ( e.g. solubility) of genetic variants of β-lactoglobulin are noted. The solubility of each of the major whey proteins, under similar conditions to those used in the fractionation, is compared with its solubility in the whey protein mixture. The understanding gained of factors important in the fractionation is used in recommending new procedures for α-lactalbumin and β-lactoglobulin isolation.