The appearance of mad cow disease or bovine spongiform encephalopathy (BSE) during the 1980s has had an enormous and far-reaching effect on the processing of meat industry co-product materials. The BSE epidemic, first recognized in the United Kingdom (UK), has now been detected in the livestock of many countries (http://www.oie.int/eng/info/ en_esbincidence.htm).
The subsequent appearance of variant Creutzfeldt-Jacob disease (vCJD) in humans is due to the same agent that caused BSE in cattle (http://www. who.int/mediacentre/factsheets/fs113/en). Both of these related diseases, collectively referred to as transmissible spongiform encephalopathies (TSEs), are characterized by a sponge-like degeneration of the brain, and both diseases are fatal. TSEs continue to force radical changes to the way in which meat industry co-products are collected, handled, processed, marketed and regulated.
Initially, large numbers of cattle were culled in an attempt to limit the spread of BSE. As theories on the transmission of the infection were supported by scientific evidence, two primary lines of defence were suggested to curtail the bovine and human diseases. Firstly, the use of ruminant tissues in ruminant feeds must be prohibited to minimize further BSE infection. Secondly, all tissues that are likely to contain the infective agent (designated SRMs) must be excluded from any animal or human food chain. Uptake of these defensive measures into industry regulation was not rapid or uniform from one country to another.
Over time, these two lines of defence have been extended. At times, the changes were driven by new scientific evidence, and at times they were driven by political influences. The original UK ban on feeding ruminant protein to ruminants has extended to a European Union ban on the use of all animal protein in livestock rations.
The original UK ban on specified bovine offals (later SRMs) was altered and adopted by the European Union. This ban removes the tonsils, intestines (from duodenum to rectum) and mesentary from cattle of all ages. In cattle aged over 12 months old, the skull (including brains and eyes), spinal chord and vertebral column are also removed from any food chain (http:// www.food.gov.uk/bse/beef/controls). Once removed, this material can be rendered in dedicated rendering plants to generate meat and bone meal (MBM) and tallow. The only approved use of these products in the UK is as a combustible fuel. MBM has an energy content of about two-thirds that of coal, while the calorific value of tallow is approximately 90% of fuel oil
(http://www.ukra.co.uk/Factsheet6.htm). If no market can be found for these fuels, then disposal involves incineration or high-pressure sterilization prior to land-fill dumping.
These changes have had an enormous impact on rendering, which is an integral and vital part of the meat processing industry. Rendering operations have been forced by regulation to commission new plants and upgrade existing plants in order to cope with the fallout from the BSE epidemic, while at the same time, their traditional markets have disappeared. The future direction of BSE policy and the possible relaxation of the TSE Regulation in the European Union have been canvassed by the European Commission (2005).
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