No abstract

High quality pork is consumed as fresh meat, whereas other carcasses are used in the processing industry. Meat quality is determined measuring technical muscle variables. The objective of this research was to investigate the molecular regulatory mechanisms underlying meat quality differences of pork originating from genetically different Piétrain boars. Piétrain boars were approved for high meat quality using a DNA marker panel. Other Piétrain boars were indicated as average. Both groups produced litters in similar Piétrain sows. The LM were sampled from 9 carcasses produced by approved boars and 8 carcasses of average boars. Total RNA was isolated, and an equal portion of each sample was pooled to make a reference sample representing the mean of all samples. Each sample was hybridized on microarrays against the reference in duplicate using a dye swaps design. After normalization and subtraction of 2 times the background, only genes expressed in at least 5 carcasses were analyzed. For all analyses the mean of the M-values relative to the reference (i.e., fold change), were used. Sixteen genes showed significant linear or quadratic associations between gene expression and meat color (Minolta a* value, Minolta L* value, reflection, pH 24 h) after Bonferroni correction. All these genes had expression levels similar to the reference in all carcasses. Studying association between gene expression levels and meat quality using only genes with expression statistically differing from the reference in at least 5 carcasses revealed 29 more genes associating with the technological meat quality variables, again with meat color as a main trait. These associations were not significant after Bonferroni correction and explained less of the phenotypic variation in the traits. Bioinformatics analyses with The Database for Annotation, Visualization and Integrated Discovery (DAVID) using the list of genes with more than 2-fold changed expression level revealed that these genes were mainly found in muscle-specific processes, protein complexes, and oxygen transport, and located to muscle-specific cellular localizations. Pathway analysis using the Kyoto Encyclopedia of Genes and Genomes (KEGG) database revealed pathways related to protein metabolism, cellular proliferation, signaling, and adipose development differing between the 2 groups of carcasses. Approved meat carcasses showed less variation in gene expression. The results highlight biological molecular mechanisms underlying the differences between the high meat quality approved and average boars.

The objectives of this study were to evaluate the influence of different pure pig breeds and muscle types on the expression of muscle proteins, as well as their interactions, and second, to find biomarkers for breed and muscle types. A total of 126 male pigs, including 43 Landrace, 21 Duroc, 43 Large White, 13 Pietrain, and 6 Belgian Landrace, were slaughtered at the age of 174 +/- 6 d. Samples from the semimembranosus muscle (SM) and LM were collected 24 h postmortem. Proteomic spectra were generated on an anion exchanger (Q10), a cation exchanger (CM10), and on immobilized metal affinity capture (IMAC30) ProteinChip arrays and analyzed using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry ProteinChip techniques. Breed and muscle type did not affect the number of peaks per spectrum but, interestingly, affected the average intensity of the peaks. Of these peaks, a total of 4 proved to be potential protein biomarkers to differentiate LM or SM muscles, and 2 to classify specific breed types. Additionally, several peaks influenced by the interaction between muscle and breed types could correctly classify pig muscles according to their breed. Further studies need to be carried out to validate and identify these potential protein biomarkers for breed and muscle types in finishing pigs.

The relationship between protein profiles of Gluteus medius (GM) muscles of raw hams obtained from 4 pure breed pigs (Duroc, Large White, Landrace, and Piétrain) with the final quality of the Semimembranosus and Biceps femoris muscles of dry-cured hams was investigated. As expected, Duroc hams showed higher levels of marbling and intramuscular fat content than the other breeds. Piétrain hams were the leanest and most conformed, and presented the lowest salt content in dry-cured hams.Even if differences on the quality traits (colour, water activity, texture, composition, intramuscular fat, and marbling) of dry-cured hams were observed among the studied breeds, only small differences on the sensory attributes were detected. Surface-enhanced laser desorption/ionisation time-of-flight mass spectrometry (SELDI-TOF-MS) was used to obtain the soluble protein profiles of GM muscles. Some associations between protein peaks obtained with SELDI-TOF-MS and quality traits, mainly colour (b*) and texture (F 0 , Y 2 , Y 90 ) were observed. Candidate protein markers for the quality of processed drycured hams were identified.

Expression of water soluble proteins of fresh pork Longissimus thoracis from 4 pure breed pigs (Duroc, Large White, Landrace, and Piétrain) was studied to identify candidate protein markers for meat quality. Surface-enhanced laser desorption/ionisation time-of-flight mass spectrometry (SELDI-TOF-MS) was used to obtain the soluble protein profiles of Longissimus thoracis muscles. The pure breeds showed differences among the studied meat quality traits (pHu, drip loss, androstenone, marbling, intramuscular fat, texture, and moisture), but no significant differences were detected in sensory analysis. Associations between protein peaks obtained with SELDI-TOF-MS and meat quality traits, mainly water holding capacity, texture and skatole were observed. Of these peaks, a total of 10 peaks from CM10 array and 6 peaks from Q10 array were candidate soluble protein markers for pork loin quality. The developed models explained a limited proportion of the variability, however they point out interesting relationships between protein expression and meat quality.