By Chad Carr, University of Florida
I know we are all glad to turn the calendar to 2021. The start of a new year gives the promise of hope, but also provides a time to remember successes and failures from years past. As I reflect, one big U.S. pork industry success story comes to mind. In 2003, I was a finishing master’s student and just starting on my endeavor to become a pork quality nerd when the results of the pork carcass merit “report card” were released.
In the time between the report card of the 1993 Pork Quality Audit through the 2002 National Pork Benchmarking Study, the live weight of the average market hog increased by 13 pounds to 255 pounds, and last rib backfat decreased by almost half from 1.2 to 0.75 inches. Unfortunately, the percentage of pork carcasses producing low-quality, pale, soft and exudative lean, which will result in dry pork chops and/or unacceptable raw material for sausage manufacturing, also increased by 5.2% to 15.5%.
Why did this happen? Many genetic and environmental factors likely contributed to these changes, but collectively when we select to produce leaner, heavier muscled, faster growing pigs, at the cellular level we are primarily selecting to increase the proportion of larger, faster metabolizing muscle fibers.
All animals utilize energy within their muscle cells and, at death, the muscle will remain alive for a while. However, when the muscle runs out of energy, it results in rigor mortis or death stiffening. Prior to slaughter, pigs with those bigger, faster fibers can be more challenging to maintain at homeostasis when stressed or overly exerted, than pigs with more modest sized, slower fibers. After slaughter, pigs with the bigger, faster fibers will likely metabolize energy into lactic acid and develop rigor mortis at a faster rate than pigs with modest sized, slower fibers. This rapid accumulation of lactic acid while the muscle is still at a high temperature, somewhat cooks some of the proteins within the muscle of the pig, leading to the prototypical pale, soft, exudative pork. This pork will be white, floppy and unable to hold onto its own water.
Improved Animal Handling Pays Dividends
Since then, there has been an overwhelming focus within the pork industry to reduces stress and improve animal welfare when handling market hogs at the farm and packing plant. Additionally, most all large-scale U.S. pork processors have converted their facilities from electrical stunning to carbon dioxide (CO2) stunning. This method of stunning does not accelerate postmortem muscle metabolism as electrical stunning does. Also, pigs can generally be moved in small groups into the CO2 stunner, as compared to moving pigs in single file lines for electrical stunning, a process we know stresses pigs.
Collectively, these improvements in animal handling and stunning have improved consistency and reduced the incidence of unacceptable lean quality, despite pigs continuing to produce carcasses that are even heavier, but with comparable leanness to 2003. Only 2.4% of the more than 1,500 loin chops purchased at retail that represented all major pork processors in the 2012 National Pork Retail Benchmarking Study were prototypical “pale” or had a National Pork Board color score of 1.
Certainly, more recent work funded by the National Pork Board suggests the percentage of light colored (National Pork Board color scores 1 and 2) increased from the 2012 retail audit to the most recent 2018 retail audit. However, the percentage of chops quantified as prototypical pale, soft and exudative, would still be low.
There are still plenty of problems to solve and opportunities for pork quality nerds. But collectively, modern pork quality gets a good report card, and the successes on the farm and at the packing plant have helped deliver those improved grades, all while improving yield, efficiency and sustainability.
Dr. Chad Carr grew up on a diversified livestock operation including Hampshire hogs and commercial beef cattle in middle Tennessee. He received his bachelor’s and master’s degrees at Oklahoma State University and went on to obtain his Ph.D. at the University of Missouri. He is a meat Extension specialist at the University of Florida. Chad and his wife, Cathy, have two daughters.
More from Farm Journal’s PORK:
What’s the Big Deal About Pork Quality?
Meat Matters: Gen Z - Who Will They Believe?
Overcooking Pork Should be a Rare Occurrence
