Identification of proteomic biomarkers in M. Longissimus dorsi as potential predictors of pork quality.

Meat quality traits have low heritability and large environmental influences. To predict, improve and manage meat quality, proteomic biomarkers are superior to genetic markers. The objectives of this research were (1) to find associations between proteome profiles of longissimus muscle at slaughter and meat quality accuracies of prediction of traits ranged from 20 up to 80%. Differentially expressed proteins related to drip loss and ultimate pH were identified by NanoLC-FTMSMS. The proteins highlight biological mechanisms that may explain how these traits develop biologically and how they are related to each other.

Effect of different Duroc line sires on carcass composition, meat quality and dry-cured ham acceptability.

Carcasses of 399 malignant hyperthermia gene free pigs from crosses sired by three types of Duroc (Virgen de la Fuente, DU1; Diputación de Teruel, DU2; DanBred, DU3) were analyzed for carcass and meat quality. Carcass leanness and fat parameters were measured at the last rib and at the space between the 3rd and 4th last ribs counting from the last one. Weights, pH, electrical conductivity, colour and intramuscular fat were also measured. A sample of 133 legs per cross were processed by dry-curing. The ham portion including Biceps femoris, Semimembranosus and Semitendinosus muscles was evaluated for instrumental texture and colour, biochemical and sensory analyses and acceptability (trained panel and consumers). DU3 carcasses were well conformed but lean. DU1 carcasses had a lower conformation but higher marbling. DU2 carcasses were intermediate. Dry-cured hams from DU1-sired pigs had a higher overall acceptability, although fat content influenced a consumers group negatively. Leaner DU3 hams had the lowest acceptability.

Differences in open field behavior between heterozygous and homozygous negative gilts for the RYR(1) gene.

A test widely used to assess fear and novelty responses in domestic species is the open field. The aim of this study was to investigate the effect of RYR(1) genotype on open field behavior in growing pigs. The study subjected 15 heterozygous (Nn) and 15 RYR(1)-free (NN) gilts of 19 weeks of age to 3 replicates of an open field test 2 days apart from each other. The study measured the number of grid lines crossed and defecation score in the test arena. There was a significant individual correlation among the 3 replicates of the test, both for number of grid lines crossed and defecation score (p <.05). RYR(1) genotype had a significant effect on number of grid lines crossed, with NN gilts showing more overall activity than Nn gilts (p <.05). The study observed no significant differences in defecation score between genotypes. This result suggests that the RYR(1) genotype may have an effect on the appraisal of novelty. Thus, it would be interesting to take this factor into account when using this methodology to assess fear responses in pigs and in interpreting the results with respect to welfare.

The relationship between pig genetics, myosin heavy chain I, biochemical traits and quality of M. longissimus thoracis.

The relationship between muscle biochemical traits, myosin heavy chain I and meat quality of longissimus thoracis was studied using gilts from five divergent porcine lines (A to E) (carcass weight: 83.7±8.7 kg). Intramuscular fat (IMF) and haem pigments content as well as myosin heavy chain 1 (MyHC I) percentage and the activity of lactate dehydrogenase (LDH) and isocitrate dehydrogenase (ICDH) were determined. Only group E, a well conformed line of pigs, included the halothane positive genotype. The presence of the Hal gene in this line resulted in meat of poorer quality in terms of meat of higher exudate compared to line D, also a well conformed line of predominantly Pietrain origin but being halothane gene free. Line C presented the highest IMF content (2.02%) as well as high oxidative characteristics (MyHC I, 10.0%; LDH/ICDH, 1.92 µmol nmol(-1); ICDH activity, 1.78 nmol min(-1) g(-1)) and the lowest drip losses (5.3%). According to a principal component analysis including MyHC I, biochemical traits and meat quality parameters, line C was characterized by a high IMF content and oxidative traits, and line B by a high glycolytic metabolism. Line E was distinguished by high drip losses and by low pH(45) and pH(u). In conclusion, several observed differences in muscle metabolism between lines free of the halothane gene (A, B, C and D) must be caused by other "genetic background" factors.