Investigations on non-aversive gas anesthesia procedures for slaughter pigs
Project code: MRI-FL-08-1070-Gasnarkose
Contract period: 01.07.2011 - 31.07.2012
Budget: 127,000 Euro
Purpose of research: Applied research
Today, most of the slaughter pigs are anesthetized with carbon dioxide. However, the anesthetizing effect of the gas does not occur immediately, so that the animals suffer suffocation for up to 20 seconds. This feeling is caused less by the lack of oxygen, but by the excess of CO2 in the blood. Therefore, the inert gas helium (He) is to be tested as an anesthetic gas. Helium is a colorless, odorless and non-toxic gas.
In the experiment, animals were anesthetized with 98.5 vol. % Helium at 1.5 vol. % residual air and a residence time of 180 seconds. A CO2 anesthetic (90 vol. % CO2) was used as a comparison in a commercial dip - lift system from the company Butina (3.5 m deep pit, max. 2 pigs per gondola). In each case 40 pigs were anesthetized and the behavior of the animals at gas contact was described. In order to check a sufficient depth of anesthesia, reflexes were checked after leaving the helium atmosphere. The catecholamines noradrenaline and adrenaline were then examined in the sticking blood. During the gas contact with helium the animals showed no defensive behavior and also the reflexes were negative until bleeding. The two measured stress hormones were present in a highly significant lower concentration after helium anesthesia (p less than 0.001).The data of the classification showed no significant differences, so a genetically similar animal population should be assumed. With regard to the meat quality parameters, different muscle groups were examined. In examining the long back muscle (M. longissimus dorsi) there is a highly significant differences (p less than 0.01) at the temperature 45 min p.m. (post mortem) and an extremely significant differences (p less than 0.001) at the temperature 24 h p.m. All other examined parameters (pH, conductivity, grilling loss and color measurement) showed no significant differences between the both examination cohorts. In parts of the leg (M. semimembranosus), there were clearer differences between the individual anesthetic gases. pH1 showed 45 min. an extremely significant increase in helium animals. The measured temperature was 45 min. as well as 24 h p.m. significantly lower for the helium animals than for the CO2 comparison group. The color measurement the CO2 animals showed 48 h p.m. highly significantly lighter meat slices with a lower red content. Conductivity and grilling loss showed no significant differences. In the sensory examination of the two experimental groups, no significant differences in flavor, juiciness and tenderness were found.