Factors in Fresh Pork Quality

The quality of fresh pork is determined by many factors, including genetics, nutrition, handling and processing.

David Meisinger, assistant vice president for pork quality for the National Pork Producers Council, identifies nine key areas in the publication "A System for Assuring Pork Quality."

Of the nine key areas, four relate with on-farm issues that producers can control. Those points include:

In general, the Berkshire breed is superior for overall muscle quality, but suffers in carcass and performance traits. The Duroc breed has good muscle quality and other economically important traits. Commercial market hogs should have some percentage of Duroc and/or Berkshire or other lines with proven pork quality performance to enhance their production of high quality products.

There is a great deal of variation within each breed for pork loin quality. Therefore, producers should request both pork quality information and EPD status on all sire purchases. Traits of interest are loin color, loin intramuscular fat and drip loss. Ultimate loin pH (24-hour) is also a predictor of quality.

Producers should require that all breeding stock purchases be certified halothane or stress gene free.

The Napole (RN) gene has a negative impact on processing quality, but may have a positive or no impact on eating quality. Isolation of the gene and further clarification of its impact is necessary, he says.

NPPC pork quality targets set a level of 2-4% for loin intramuscular fat. Producers should continue to utilize breeds that contribute positively to marbling without increasing other fat depots, such as subcutaneous, abdominal and intermuscular fat.

DNA technologies can identify and exploit major genes, including the halothane, Napole and IM fat gene. Producers should ask for assurance that their breeding stock suppliers use DNA tests to identify pork quality traits.

Feeding Vitamin E to pigs offsets oxidation in pork chops packed at high oxygen atmospheres. Feeding Vitamin E is beneficial to pork quality, but may not be economical for producers. Similarly, adding magnesium to finishing hog diets for five days prior to slaughter is beneficial in reducing PSE pork, but may not be cost-effective.

Adjusting amino acid levels in the late finishing diet can affect pork quality. Adding 5 mg of tryptophan for five days before slaughter can reduce the incidence and severity of PSE.

Feeding a diet deficient in lysine (0.48%) for five weeks prior to slaughter can increase IM fat by 2%, but is not recommended due to other negative quality consequences.

Raising the dietary concentration of unsaturated fatty acids may increase meat tenderness, but adversely affect fat quality. Producers should moderate the use of fat in the diet by controlling the amount of saturated fat added. Consideration should also be given to the use of CLA (conjugated lioleic acid).

Producers should ensure total feed withdrawal time before slaughter is 12 to 18 hours. Proper feed withdrawal reduces deaths in transport, makes hogs easier to move and leads to less contamination during evisceration.

Pigs should be exposed to human activity and be moved from their pen at lease twice during the finishing period. This will reduce the stress of loading.

Pigs should be moved with minimal force and electric prods only used in case of emergency and by trained handlers. If a moving aid is required, handling panels and slappers should be used. Negative handling of pigs has a detrimental effect, including lower muscle pH, paler pork, higher incidence of PSE pork.

On-farm facilities should offer the least resistance and stress during handling and loading. Alleys should be 3 ft. wide. Pigs should be loading in small groups of five or six. Ramps should be made of a non-slip surface. Dual ramps with solid outside walls and a transparent middle partition allow for easier loading. Ventilation should be reversed so air is not blowing in pigs’ faces as they exit the building.

Electric prods should be eliminated from loading and unloading of hogs.

Trucks with possum belly trailers should be avoided as they require more time for removing pigs and often require the use of electric prods.

Producers or transporters should haul no more than 183 hogs in a standard 48-ft. by 102-ft. double-deck, flat-floor trailer. Stocking density should be 4.2-sq. ft. and allow pigs to lie down and stand in their natural position.

Producers should give special consideration to transporting of hogs in weather extremes. Wet sand, shavings or water sprays should be used when temperatures exceed 60º F. Trailers should be more enclosed and bedding used during extremely cold weather.

The remaining five points relate to pork quality issues at the processing plant. They include pre-slaughter handling; stun, stick and early postmortem; evisceration; carcass chilling and fabrication.

A complete version of "A System for Assuring Pork Quality" by David Meisinger is available from the National Pork Producers Council.