Effect of Diet and Location Within the Longissimus Dorsi Muscle on the Quality and Fat Composition of Pork Loins Collected from Market Hog

Abstract

Abstract In pigs, the longissimus muscle (LM) is an economically important tissue that largely dictates the quality grade assigned to the carcass. Still, this anatomically protracted muscle is not homogeneous in composition and these spatial differences across the LM can impact the overall predicted quality and quantity of pork produced. The objective of this study was to determine the impact of diet and location within the muscle on the quality and fatty acid composition of loins harvested from finishing pigs. A total of 80 pigs were subjected to 1 of 4 dietary treatments: lysine deficient diet (LysDef), vitamin A deficient diet (VitADef), lysine and vitamin A deficient diet (LysVitADef), and control diet (CON) formulated to meet NRC recommended requirements from weaning through finishing. The animals were then harvested to assess LM quality parameters including loin eye area, marbling score, and lean color. Samples from the proximal, medial, and distal portions of the LM were collected for fatty acid determination using gas chromatography and were expressed as a percentage of total fatty acids. Marbling score was greatest (P = 0.0024) in the proximal LM and was not impacted by treatment (P = 0.07). Treatment also had no effect (P = 0.14) on the percentage of saturated fatty acids (SFA); however, the percentage of SFA decreased (P < 0.001) from the proximal (40.9 ± 0.24) to distal (39.14 ± 0.24) portion. In contrast, the percentage of polyunsaturated fatty acids increased (P < 0.001) from the proximal (15.96 ± 0.57) to distal (19.27 ± 0.57) portion. Despite the lack of diet-induced differences in marbling scores, the biological data generated from the current study are informative in terms of the spatial and compositional marbling deposition patterns in the LM of the growing pigs and warrant further investigation to identify the mechanisms responsible for this paradigm.