Interpretive Summary: Correlation comparisons among early postmortem loin quality and aged loin and pork chop quality characteristics between finishing pigs from either Duroc or Pietrain sires.
By: Dr. Thomas Powell
Packers use predictive measurements to sort products into quality categories, particularly in selection for export markets. Lean color and marbling evaluated from the ventral surface of loins has been shown to predict aged quality. The University of Illinois recently published a study in the Journal of Animal Science reporting on comparisons of correlations among early postmortem quality characteristics and aged cut quality between pigs sired by either Pietrain or Duroc boars. Their goal was to determine if these predictive methodologies are equally valid in quality-focused and lean-focused breeding programs.
The research team sourced 160 pigs each from 2 sire lines – Pietrain and Duroc – mated with Camborough sows. Gilts and barrows were housed 4 to a pen and fed a 3-phase, 98 d grow-finish ration. At the end of feeding, the heaviest and third heaviest pigs from each pen (160 total) were slaughtered and used to calculate correlation coefficients. Extensive quality, yield and composition measurements were taken from the carcasses and then from the fabricated boneless Canadian back loins. This included instrumental color, marbling and firmness, and loin pH on the ventral surface of the loin. Loins aged for 14 d were evaluated for the traits evaluated early as well as for Warner-Bratzler shear force, cook loss, and proximate composition.
Most of the variation in results were in line with expected differences with Duroc-sired pigs producing more highly marbled meat and the Pietrain-sired pigs being leaner and having higher percent standardized fat-free lean. Confirming previously published research, early postmortem estimates across both sire lines of marbling on the ventral surface of the loin were moderately correlated with aged estimates of marbling. The study also revealed that it may be possible to use early L* and visual color measurements of the ventral side of the loin as indicators of aged chop color. Since there is a moderate amount of color variation between the anterior and posterior ends of the loin, the authors point out that location consistency is critical for ventral surface color evaluation.
Most importantly, most correlation comparisons did not differ between the Duroc- and Pietrain-sired pigs. The researchers concluded that regardless of the sire line, the same postmortem quality traits can be used to predict aged quality.
To view the full article, visit the Journal of Animal Science.