Zum tierschutzgerechten Betäuben und Töten von Aal

Slaughtering of eels should be done not only under animal welfare aspects but as well under consumer protection and economical aspects with respect to technical feasibility. Methods must be practicable for enterprises slaughtering quantities of several kilograms up to several tons per day. Most methods applied up to now in whole Europe were (are) not in accordance with animal welfare mainly due to lacking prescriptions and alternative methods. The great number of experiments carried out within the frame of this project demonstrates the difficulties to combine optimal welfare demands with economical and technical fesibility aspects in one method. Measurements of EEG (electroencephalogram) and ECG (electrocardiogram) have shown that the method laid down in the german legislation does not perfectly stun all eels. This method was improved by applying a „prestun“ with 220 V for 1sec., followed by a 5 min phase at 45 V to prolongue the time of unconsciousness after the stun. Inflating nitrogen gas into the stunning bath additionally causes asphyxia during the stun. By this method 93% of the eels were stunned or even killed. Applying 220 V for bigger batches of eels (~400 kg) will cause big problems with the energy supply. Therefore this method is restricted to batches of 20 - 50 kg. The method laid down in the german legislation probably can be improved. Eels were stunned successfully without water, avoiding the problems of regional differences in the conductivity of the water. Other types of current and other frequencies and a combination of both should be tested as well as alternative electrode geometries also with respect to blood spots which occasionally occurred in the muscles preferably of bigger eels (>800 g). For the time being the method laid down in the german legislation is a reasonable compromise and under animal welfare aspects represents a considerable improvement.

The myogenic automatism of the systemic heart of Octopus vulgaris (Cephalopoda: Coleoidea): evidence for localized stretch sensitivity and pacing activity

The localization of the stretch sensitivity and myogenic automatism in the systemic heart of Octopus vulgaris has been studied on an isolated preparation in which the ventricle was zoned by ligatures. Each region has been submitted to two different levels of internal hydrostatic pressure (1 and 2 kPa). Only the two atrio-ventricular regions were able to contract regularly when submitted to internal pressure, with a frequency dependent from the pressure value, while the ventricle-aortic region was insensitive to the stretching by internal pressure. This result supports the hypothesis that the automatism in this heart is localized. Electrocardiogram recordings from different areas of an isolated and perfused preparation of the systemic heart ventricle are also reported, which suggest that the electrical activity of the ventricle originates in two narrow areas near the atrio-ventricular valves.