Characterization of variability in the U.S. pork supply

Abstract Text: Improving consistency in the U.S. pork supply has long been a goal of producers and processors, though factors contributing to variability in pork composition and quality are ill-defined. Therefore, variability in pork quality and composition and correlations among compositional and quality traits were characterized in multiple studies.  In boneless loins destined for export to a quality focused market (N=154), subjective color and marbling scores at 1 and 28 d postmortem were not correlated with sensory tenderness (P≥0.47), chewiness (P≥0.18), juiciness (P≥0.43), or off-flavor (P≥0.07).  In-plant loin firmness measures did not account for variability in sensory characteristics (P≥0.08).  In a larger study, 7,864 pigs were used to quantify variability in carcass traits attributable to marketing group (MG), sex, season (hot or cold), and production focus (lean growth or superior meat quality). The Levene’s test was used to determine differences in variability among MG, sex, season, and production focus.  The mivque0 option of PROC VARCOMP was used to evaluate the proportion of variability each effect contributed to total variance.  Marketing group contributed 4.1% and sex contributed 1.4% of the variation of HCW. Variation in fat depth was attributed to production focus (26.7%), sex (17.6%), and season (4.5%). Variation in loin depth was attributed to production focus (20.0%), season (16.1%), MG (2.0%), and sex (1.4%).  Production focus (34.6%), sex (15.8%), and season (10.2%) were large contributors to total variation in percent lean.  However, the random effect of pig contributed the greatest proportion of total variance to carcass traits (93.5% of HCW, 51.2% of fat depth, 60.5% of loin depth, and 39.4% of percent lean).  Barrows had greater variability than gilts for fat depth and percent lean (P≤0.01), but variability between sexes was not different for HCW and loin depth (P≥0.09).  Variability was greater in the hot season for HCW, but was less for fat depth and percent lean compared with variability of pigs from the cold season (P≤0.01); loin depth was not different (P=0.23). Variability was greater in pigs from the quality production focus than the lean focus for HCW, fat depth, and loin depth (P≤0.03).  Variability was different among MG for HCW, fat depth, and percent lean (P≤0.01) but not loin depth (P=0.20).  While segregating pigs by MG or production focus may limit variability in carcass composition, a larger amount of variability is attributed to sex, season, and pig, which are more difficult to control.

Keywords: pork composition, quality, variability