ZBJA.htm

NR ZBJA

AU Schütt,I.

TI [Effect of humane electric stunning of poultry on the degree of bleed-out and the development of the pH-value of the carcase]

OT Auswirkungen einer tierschutzgerechten Elektrobetäubung bei Schlachtgeflügel auf den Ausblutungsgrad und die pH-Wert-Entwicklung der Tierkörper

QU Vet. med. Dissertation Freie Universität Berlin, 1982, Journal-Nr. 1065

PT Thesis

AB The voltages recommended from the view of animal protection for adequate electrical stunning of poultry in a water bath stunner include the risk of electrocution by inducing heart fibrillation. This is opposed by the demands of food hygiene, which claim heart action indispensable for sufficient bleeding. This study was undertaken to investigate the influence of electrically induced heart stoppage on blood loss and the development of pH-value in the carcase. 84 broilers weighing from 2250 - 2400 grams were submitted to a head-to-legs-passage of a current of 55 - 110 milliamperes by applying 100 volts for 4 seconds. Heart action was monitored by electrocardiogram. All animals were bled manually 30 seconds after the onset of current flow. Blood loss was measured from the collected blood after 90 seconds of bleeding and from the weight difference between the bled and unbled animal after 180 seconds of bleeding. 210 seconds after the cut all broilers were scalded for 1 minute by 60 degC, plucked mechanically for 30 seconds, and processed. 15 minutes and 2 hours after the cut the pH-value of the breast muscles was measured at 8 different sites per animal and averaged. The investigation led to the following results: 1.) The electrical shock triggered heart fibrillation in 36 broilers and was survived by 48. Just after the shock both groups showed tonic and clonic spasms, followed by complete relaxation. 2.) 30 seconds after the onset of current flow all broilers in which heart fibrillation was found were obviously dead and could thus be distinguished by sight from the survivors: Irreversible loss of corneal reflex and muscle tension, which latter led to"rised" hackles because of the upward down position of the animals, marked loss of heart funtion. Smooth hackles, a positive remaining corneal reflex, and spasms during bleeding were signs of maintained heart action. 3.) Neither total blood loss after 180 seconds of bleeding (69 grams or 2.96% of live weight with heart action versus 65 grams or 2.78% of live weight without), nor pH-values 15 minutes (6.03 with heart action versus 6.05 without) or 2 hours after the cut (5.98 in both cases) showed any significant differences between the two groups. 4.)However, blood loss after 90 seconds of bleeding was significantly greater in live bled animals which lost 58 grams or 2.48% of live weight, than in dead bled broilers, from which only 48 grams or 2.08% of live weight were obtained. 5.) Within the first 90 seconds of bleeding animals with maintained heart action thus lost 83.7% of their total blood loss during slaughter while broilers with heart stoppage lost only 73.8%. From these results is concluded that loss of heart function tends to decrease the speed of bleeding rather than the total amount of blood loss. The lower speed of bleeding can be compensated without deterioration of meat quality by simply providing a longer bleeding period. This prolongation will probably require changes in the design of slaughter lines for which suggestions are made. The disadvantage of a longer bleeding period is made up for by the easier fixation of the broilers before entering the mechanical killer and the excluded risk of scald water aspiration in these animals. Confirmation of these results under practical conditions provided the recommendation to rise the voltage in the water bath stunner for the sake of animal protection should be followed.

AD Institut für Veterinärmedizin (Robert von Ostertag-Institut) des Bundesgesundheitsamtes, Postfach, D-1000 Berlin 38

SP englisch

PO Deutschland

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