Sampling plan for the establishment of a serologic Salmonella surveillance for slaughtery pigs with meat juice ELISA

The guidelines of the German Ministery of Food, Agriculture and Forestry outlining a Salmonella surveillance programme, "Leitlinien fur ein Programm zur Reduziemng des Eintrags von Salmonellen durch Schlachtschweine in die Fleischgewinnung" (February 5(th), 1998), provide a staggered spot-check size depending on the annual production of slaughtery pigs. A classification of farms into three quality categories (< 20 %, 20-40 %, and > 40 %) is performed by salmonella antibody levels detected in meat samples using ELISA. Beside a fundamental inquiry into the salmonella status, the programme ought to lead to a decreased burden on slaughtery pigs and finally to a reduced salmonella entry into meat handling and processing companies. The spot-check plan is based on an unfavourable initial position and does not consider the real situation of salmonella load in pig fattening farms. For many farms the procedure will lead to an unjustified expenditure of examinations. In simple model calculations it is shown how a significant reduction of testing amount can be reached and statistical reliability is guaranteed, too. At the same time, we attempt to find a compromise between optimal spot check size and practicability. For reasons of free enterprise, an additional category would be desirable containing farms without any positive antibody titres in the samples. The results achieved so far indicate that a large number of German slaughter pig producers would fall into this category, without the necessity of a higher examination effort.