[Different CO2-stunning procedures and post mortem obtained lung lesions in response to the corneal reflex and parameters in blood of slaughtered pigs].

The effect of different CO2-stunning on the corneal reflex response and blood parameters in (arterio-venous) killing blood was investigated in n = 614 slaughter pigs (carcass weight = 92-94 kg) at two different abattoirs. CO2-anaesthesia lead to remarkable decrease of PO2 (hypoxaemia), increase of PCO2 (hypercapnia), decrease of pH (respiratory acidosis) and increase of [strong ion difference = SID3] (basic reaction caused by electrolytes). Pigs with subclinical post mortem obtained lung lesions showed no significant modified value of the reflex answer or changes in parameters of killing blood compared to the animals with healthy lungs. The CO2-stunning with 90% CO2 and 120 s exposure time resulted in notably less undesired positive reflex responses (6% of slaughter pigs) than the CO2-stunning with 90% CO2 and only 90 s exposure time (15% of slaughter pigs). The occurence of the positive reflex response, which means an inadequate depth of anaesthesia, in slaughter pigs can be safely eliminated by use of qualified cut off values of killing blood parameters. These parameters can be measured rapidly and validly with ion-sensitive electrodes, making a beneficial monitoring of the used CO2-stunning possible.