Skip to main content
ARS Home » Research » Publications at this Location » Publication #260303

Title: A new humane method of stunning broilers using low atmospheric pressure

item VIZZIER-THAXTON, Y - Mississippi State University
item CHRISTENSEN, K.D. - Ok Farms, Inc
item SCHILLING, M.W. - Mississippi State University
item Buhr, Richard - Jeff
item THAXTON, J.P. - Mississippi State University

Submitted to: Journal of Applied Poultry Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/30/2010
Publication Date: 12/1/2010
Citation: Vizzier-Thaxton, Y., Christensen, K., Schilling, M., Buhr, R.J., Thaxton, J. 2010. A new humane method of stunning broilers using low atmospheric pressure. Journal of Applied Poultry Research. 19:(4) 341-348.2010.

Interpretive Summary: There continues to be controversy surrounding the use of toxic gas mixtures to stun broiler chickens (controlled atmosphere stun/kill) prior to bleeding for preparation for slaughter. The controversy is over which gas mixture to use, the required structural modifications to the processing plant, and whether or not the methods are actually more humane than electrical stunning. In response to these questions a system was designed and constructed to produce a controlled atmosphere using reduced oxygen tension. In all of gas stunning systems the broilers are rendered unconscious from a lack of oxygen. Low atmospheric pressure is achieved using controlled slow decompression which allows the body to adjust to changes in pressure and thus lose consciousness with minimal discomfort. Advantages include the absence of toxic gases, minimal plant modification and the ability to view the birds throughout the process via a digital video feed which can be recorded. LAPS is a new humane controlled atmosphere method of poultry stunning which eliminates shackling of sentient birds and therefore makes the operation cleaner and easier. LAPS does not use gas mixtures which require storage under pressure, is therefore safer for humans than other CAS methods, and does not use green house gases reducing its carbon footprint when compared to other CAS systems.

Technical Abstract: This research project evaluated an alternative method of controlled atmosphere stunning of commercial broilers to induce anoxia utilizing a vacuum pump to reduce the oxygen tension, low atmospheric pressure stun (LAPS). A custom built 2 cage-module system (holding a total of 600 broilers each) with automatic controls was used in this research study at a commercial processing facility. Corticosterone concentration was greater in the electrical stunned broilers (1,625 pg/mL) compared to LAPS stunned (775 pg/mL) broilers. It is likely that the lower corticosterone level for the LAPS system was the result, at least in part from not dropping broilers onto the shackling belt or inverting the live broilers for shackling. Blood gas parameters revealed lower pCO2, pO2, and chloride for LAPS broilers but higher sodium levels, all of which are consistent with the change in atmospheric condition during stunning. Histopathology revealed only minor inflammatory foci found in tissues from LAPS processed broilers. At present the measured wing damage is greater in the LAPS carcasses at 7.4% than in the electrically stunned carcasses at 4.1%. Bleed-out blood loss was 59% and did not differ between stunning methods. LAPS processed birds do not present a problem with DOA’s greater than is expected with electrical stunning as they are easily detected at the time of shackling. No hemorrhagic lesions were observed through pathological examination in any of the submitted tissues from broilers processed using the LAPS or electrical stunning systems. Overall, the data indicate there is minimal discomfort or carcass damage from stunning with the tested system using low atmospheric pressure to create a controlled atmosphere stun.