Quick service restaurant (QSR) chains Wendy's International Inc. and Burger King Corp. have announced preferences for chicken meat from suppliers who use controlled atmosphere stunning (CAS) systems in the broiler slaughter process. McDonald's Corp.'s Web site states that around 30 percent of its chicken sourced in Europe is slaughtered using CAS. Each of these three QSR chains has its own animal welfare council. There is no consensus on whether CAS is more humane than electrical stunning, but CAS systems are making inroads in the USA.

In May of 2007, the Food Marketing Institute (FMI) and the National Council of Chain Restaurants (NCCR) Animal Welfare Expert Advisory Panel announced that it could not recommend a preference for CAS or controlled atmosphere killing (CAK) over electrical stunning at that time. The panel did state, "CAK/CAS may improve some aspects of animal welfare, because it does not require shackling of (unstunned) birds. There is a need for objective, peer-reviewed, scientific research to further assess the humaneness of the process."

In April of 2008, the American Humane Certified Scientific Advisory Committee published a statement which said, "Research is not conclusive or complete at this time to support CAS as the preferred method for slaughtering poultry." John McGlone, Ph.D., professor of animal and food sciences, Texas Tech University, and scientific advisory fellow of the American Humane Certified program, said, "Each current method of poultry stunning has issues that may be resolved in the interim, through close audit and further research and development. Neither animal processing facilities nor retail food operations should be forced to implement costly new technologies that do not generate clear improvements in animal welfare."

In this environment, where some customers are calling for the implementation of CAS while others are not, the broiler and turkey industries in the USA have not moved into CAS at the same rate. At time of press, industry sources report that eight USA turkey slaughter plants are employing CAS as their primary means of stunning birds while only one broiler plant is doing so. Industry sources report that there is a lot of interest in CAS among both broiler and turkey processors.

Big toms drive adoption of CAS

CAS systems developed for turkeys stun the birds while they are still in the cage. Stunning birds in the cage improves the ergonomics of the live hanger's job and can increase the pounds hung per man hour by 100 percent or more. Commercially available CAS systems from Linco Food Systems, Anglia Autoflow, Ltd., and Stork Food Systems are designed around cages which can be removed from the live-haul trailers and then moved into the CAS system.

Linco, Anglia Autoflow and Stork all have turkey CAS installations in Europe which have been featured in WATT PoultryUSA, but none of these systems are installed at U.S. turkey plants. Linco has one system in a Canadian plant,

Michigan Turkey Producers, Wyoming, Mich.; Dakota Provisions, Huron, S.D.; and Jennie-O Turkey Store, multiple locations; have each developed and use their own CAS systems. Removable cages are employed which can be mechanically unloaded after exiting the CAS.

The typical U.S. turkey company does not use live trailers with removable cages. CAS systems that stun individual cages require the processor to modify trailers and make modifications to the plant's live receiving area. Praxair, Inc., has developed a CAS system which stuns turkeys while they are still on the trailers. Over the course of the last two years, Cooper Farms, St. Henry, Ohio; Sara Lee, Inc., Storm Lake, Iowa; and Farbest Foods, Inc., Huntingburg, Ind.; have each installed a Praxair CAS system. One European turkey processor has also installed a Praxair system. No system has been developed for removing the stunned birds from the trailer mechanically, yet.

Eight U.S. turkey plants are employing CAS at this time and, according to industry sources, several others are considering switching to this technology. There were 37 turkey slaughter plants in WATT PoultryUSA's February 2008 Top Turkey Company Survey. To date, the plants adopting CAS systems generally process large toms. Several turkey companies employing CAS report improved deboning yield because of a reduction in bruising, broken wings, hemorrhaging and blood spots in meat.


More CAS for broilers?

MBA Poultry, LLC, Tecumseh, Neb., is the only U.S. broiler plant employing a CAS system. Industry sources report that several large processors are experimenting with CAS systems. Linco Food Systems, Anglia Autoflow, Ltd., Stork Food Systems and Praxair, Inc., each offer CAS systems for the USA broiler market.

Linco's and Anglia Autoflow's CAS systems were both originally designed to stun birds while they are in the cages designed as part of that company's bird handling system. Linco's CAS is still marketed to run with the company's Maxi-Load cage system, and in addition to installations overseas, there is one broiler CAS system in Nova Scotia, Canada. Anglia Autoflow now offers a modified CAS system which can stun broilers after they have been "tipped" out of an industry standard cage. The company also markets its CAS system to function as an integral part of its Easyload cage and drawer system.

Stork's CAS system is employed at MBA Poultry. Broilers are stunned after they have been mechanically unloaded from the cages. Luciano Maradona, director of quality assurance, MBA Poultry, LLC, reported at a USPOULTRY Processor Workshop that the CAS system had improved overall carcass and meat quality at the plant.

Praxair has recently developed a CAS system for broilers which stuns birds while they are still in an industry standard cage. The company reports that a full-scale 140 bird-per-minute test has been completed at a USA broiler plant. Praxair's concept is to fit the CAS system around the processor's existing infrastructure.

CAS and automation

Can CAS eliminate the need for human live hangers? Researchers at the Food Processing Technology Division of the Georgia Tech Research Institute have been working to develop systems to automatically hang live unstunned birds on a shackle line.

Craig Wyvill, division chief, Georgia Tech Research Institute, said, "With previous attempts to automate live-bird transfer, the challenge was controlling the bird while using their natural reactions to make the shackling process work. As with any live animal, however, birds occasionally react in ways unanticipated and that can be a problem. With an unconscious bird, the problem shifts to locating the feet and accurately grasping them." Wyvill suggested that some of the principles that Georgia Tech researchers have developed for an automated system for orienting, grasping and hanging birds after they come out of the chiller may be applicable for hanging stunned birds as well.

Electrical stunning versus CAS

Users of CAS systems cite improvements in ergonomics of the live hanging job and, in many applications, increases in pounds hung per-man-hour. Processors employing CAS also cite improvements in deboning yield resulting from decreased bruising, lower incidence of broken wings and fewer blood spots in the meat. Proponents of electrical stunning are quick to point out that many of the "improvements" experienced by users of CAS systems result from the fact that with many CAS systems the birds are stunned prior to being unloaded from the cage, not from a reduction in carcass damage which occurs during stunning itself.

It is important to evaluate the entire live-bird handling, stunning and killing process at a facility the evaluation should not focus on just one part of the process. Problems with blood in wing sockets or in the breast meat can result from improper electrical stunning, but they can also result from an improper neck cut. Step-up electrical stunners have been improved in the last decade. Processors who are evaluating the use of CAS should make sure that CAS is being compared to one of the newer models of electrical stunners.