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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 gene (Cbg) encoding cortisol-binding globulin (CBG) has been proposed as a candidate gene to explain genetic variation in cortisol secretion and carcass composition in pigs. The objective of this study was to evaluate the association between CBG and pork quality in 5 European breeding lines, Piétrain, Large White (LW), and Landrace purebred lines, a Duroc synthetic line, and a Meishan (MS) × LW advanced intercross. Cortisol-binding globulin maximum binding capacity (CBG-Bmax) was twice as high (P< 0.05) in MS × LW pigs compared with the other lines. There was no (P≥ 0.364) association between CBG-Bmax and carcass quality traits in Piétrain gilts, but CBG-Bmax was associated with increased loin yields in LW (P= 0.010) and Landrace (P= 0.103) gilts, decreased ham yields (P= 0.082) in Duroc gilts, and increased fat depth (P= 0.064) and leaf fat (P= 0.001) in MS × LW gilts. There was no association between CBG-Bmax and pork quality traits in Piétrain (P≥ 0.269) and Duroc (P≥ 0.114) gilts. Conversely, CBG-Bmax was associated with lighter (higher L* values; P< 0.05) pork in Land-race gilts, as well as lower (P≤ 0.055) ultimate pH in the LM and semimembranosus, and a tendency for lower (P= 0.095) L* values of pork from LW gilts. Within MS × LW pigs, CBG-Bmax was associated with increased drip loss (P= 0.001) and decreased i.m. fat in the semimembranosus (P= 0.005). Because drip loss is an economically important pork quality trait, results of this study could be used in the selection of improved water-holding capacity of pork from synthetic lines involving the MS breed.