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Title:Effects of sex and sire line on relationships among early postmortem loin quality and aged loin and pork chop quality characteristics
Author(s):Lowell, Jessica Erin
Director of Research:Dilger, Anna C.
Doctoral Committee Chair(s):Dilger, Anna C.
Doctoral Committee Member(s):Boler, Dustin D.; McKeith, Floyd K.; Stahl, Chad A
Department / Program:Animal Sciences
Discipline:Animal Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:Ph.D.
Genre:Dissertation
Subject(s):aged loin quality
correlation
loin quality
pork
quality
Abstract:Pork is the most consumed animal protein in the world. A primary goal of packers is to increase consumer satisfaction and purchase intent by providing a visually appealing product and a quality eating experience. Rapid assessment of pork quality by packers necessitates using early postmortem (~1 d) traits as an indication of aged pork quality (~14 d). Packers assess quality on a different surface and at a different time than consumers. Therefore, it is unknown if quality traits translate between the packer and the consumer. Carcass characteristics and meat quality are influenced by both intrinsic (sex and genotype) and extrinsic (environmental) factors. Failure to control these factors makes it difficult to separate true differences associated with sex or genotype from those associated with the environment. Furthermore, relationships between early and aged quality traits of pork loins may be influenced by differences in quality traits between sex or genotype. Therefore, the objectives were: 1) Determine correlations between early postmortem loin quality and aged loin and chop quality characteristics, 2) Determine if correlations between early and aged loin quality differ between barrows and gilts, 3) Control both inherent and environmental factors in order to determine specific effects of sire line on growth and carcass characteristics, fresh belly quality, and commercial bacon slicing yields, and 4) Determine if correlations between early postmortem loin quality and aged loin and chop quality differ between pigs sired by either Pietrain or Duroc boars. For the first two objectives, Early postmortem (~1 d) quality traits included: instrumental and subjective color, marbling and firmness, and loin pH on the ventral surface of the loin. Loins were aged until 14 d postmortem in vacuum packages. Aged quality traits included traits evaluated early postmortem as well as Warner-Bratzler shear force and cook loss. Correlations were compared between barrows and gilts using a Fisher’s z test. In both barrows (B) and gilts (G), early pH was correlated with subjective ventral color (r = 0.55, B; 0.41 G) and subjective chop color (r = 0.42 B; 0.44 G). Early lightness (L*) was correlated with aged L* (r = 0.60 B; 0.51 G). Early marbling was correlated with chop marbling (r = 0.57 B; 0.59 G). Correlations rarely differed between barrows and gilts and sex does not need to be accounted for when relating early and aged quality characteristics. To test the third and fourth objectives, a total of 320 barrows and gilts were used. Offspring shared a common dam line and all environmental contributions to variation were controlled. Pigs were housed in single-sex pens by sire line. Pigs were slaughtered at the end of a 98 d feeding program. There were no differences in growth performance or belly processing characteristics (P ≥ 0.08). Pietrain sired pigs had a greater lean yield (P ≤ 0.01). Duroc sired pigs had darker, more highly marbled loins (P ≤ 0.04) and thicker bellies (P < 0.001). Bacon from Pietrain sired pigs had a greater (P = 0.04) lean to fat ratio with a 1.58% increase (P = 0.04) in average bacon slice lean. Early and aged quality traits measured were the same as the first two. Correlations were compared between Pietrain and Duroc-sired pigs using a Fisher’s z test. Early ventral visual color was correlated with aged chop L* (Pietrain r = 0.46; Duroc r = 0.60) and aged chop visual color (Pietrain r = 0.45; Duroc r = 0.57). Early visual marbling was correlated (Pietrain r = 0.68; Duroc r = 0.84) with aged chop visual marbling. No early postmortem quality traits were correlated (|r| ≤ 0.34) with WBSF or cook loss for either sire line. In summary, correlations between early and aged quality traits rarely differed between Duroc and Pietrain-sired pigs. It is not necessary to account for sex or sire line when relating early and aged quality characteristics.
Issue Date:2019-03-15
Type:Text
URI:http://hdl.handle.net/2142/104756
Rights Information:Copyright 2019 Jessica Lowell
Date Available in IDEALS:2019-08-23
Date Deposited:2019-05


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