After the pork industry decided to eliminate the Napole and Halothane genes, you would think the incidence of pale soft exudative pork would decline – and you’d be wrong.
The 2002 Pork Quality Survey shows that the PSE incidence has increased from 10.2 percent in 1992 to 15.5 percent in 2002. There are several explanations for this, says David Meisinger, assistant vice president of educational services for the National Pork Board.
Many packers feel due to selecting darker pork for export to Japan some pork that would be considered normal is now being called PSE. The industry also may be doing a better job of measuring for PSE today.
“PSE has gone up, primarily due to genetic changes and more heavily muscled hogs, which stress more easily,” notes Meisinger. “I was surprised to see the results, because I thought PSE had been declining. But, the rise does make sense because of today’s heavily muscled hogs.”
Rhonda Miller, Texas A & M University meat scientist, says the three major factors in maintaining pork quality are genetics, animal handling and carcass chilling.
Genetic selection for leaner, more heavily muscled hogs may have brought along some unforeseen pork-quality issues.
One example is muscle fiber type. Type 2, or fast-twitch, muscle fibers are more glycolytic, which produce a high incidence of PSE. However, Meisinger says it is unknown if selecting for heavy muscling inadvertently selects for the fibers that cause PSE, or whether selecting for heavy muscling selects for PSE and the fibers come with it.
Another factor involves new technologies, like ractopamine, which makes more hogs heavily-muscled, thereby exacerbating the situation.
“I don’t think we’ve gone too far in terms of muscling. But we didn’t bring along the changes in animal handling that the heavily muscled hogs need,” says Meisinger.
Animal handling is always an issue with PSE. To address handling, the NPB initiated a Trucker Quality Assurance program. This year, the on-farm Swine Welfare Assurance Program will provide further guidance for producers.
“Even if a hog shows no genetic predisposition to stress, rough handling can stress the animal,” says Miller.
Handling guidelines do need to be flexible enough to adapt to changes in the type of hogs. “Hogs today are temperamental. You can have DOA’s, downers and PSE pork if you stress the hogs at all,” says Meisinger. “The hogs just don’t have the energy stores to deal with all that muscle.”
Meisinger likens today’s hogs to cars that have huge engines (muscling) but very little fuel (fat). When the hogs have burned all their fuel, they can’t simply fill up at a gas station. Instead the energy depletion can cause PSE, downed or dead hogs.
Despite the pork-quality audit’s disappointing results, the entire pork chain continues to work to reduce PSE and improve pork quality.
Meisinger again points to the TQA program. The incidence of dead-on-arrival (DOA) hogs declined in 2002 from 2001, and the TQA program was the only logical explanation, he contends. DOA’s dipped 0.04 percent in 2002, which amounted to about $4 million in return to producers.
“It’s not all handling, though. I’d still like to see more people test seedstock and put more of a premium on being Halothane- and Napole-gene negative,” says Miller
She adds that changes in pork quality are not likely to be made until it affects producers’ pocketbooks. She points to the shift to leaner hogs, which really only occurred when packer buying systems changed.
Packers also have done their part to reduce PSE. They’ve retrofitted plants, have split lines that move hogs a bit slower and adopted technologies, like CO2 stunning and blast chilling to reduce PSE.
But there’s still more to do. There is research that shows carcass-bleeding time may not need to be as long, and scalding time and de-hairing might be able to be done quicker. Anything that can get the carcass in the cooler quicker could help pork quality.
NPB conducted a consumer study, asking about opinions on normal quality pork and PSE pork. The consumers said they didn’t like the PSE pork, and that it was drier, tougher and had less flavor than other pork, says Miller. Consumers also were not willing to pay as much for the PSE pork as normal pork.
PSE is still a serious problem, and it hits you in the pocketbook. It accounts for 90 cents per head in losses to the industry annually.
“While there was a significant increase in PSE, it still represents a small incidence,” says Meisinger. “The U.S. pork industry can still supply a high-quality product.”