Pig breed comparison for body composition at maintenance: analysis of computerized tomography data by mixture distributions

Measurement of belly composition variability in pigs by in vivo computed tomographic scanning

The belly region composition of a representative commercial pig sample of 130 castrates was examined by in vivo spiral computed tomographic (CT) scanning. The lean meat percentage, the muscle/fat tissue ratio within the total body and separately within the bacon part were estimated by image analysis. The lean meat content of the total body was determined by the EU reference method. A correlation of r = 0.97 was found between lean meat content of the total body determined by CT estimation and the slaughtering results. The pigs were divided into seven groups on the basis of their lean meat content. The muscle percentage of the bacon part was 26% and 67%, respectively, in the two groups representing the two extremes of lean meat percentage (36% and 67%, respectively). The total volume of the bacon part was relatively constant (8.6 +/- 1 dm3) in the groups representing different lean meat categories. At the same time, the fat tissue volume of the bacon part was considerably higher while its muscle tissue volume was markedly lower in the group of the lowest than in that of the highest lean meat content (6.6 vs. 2.5 dm3 and 2.4 vs. 5.5 dm3, respectively). To describe changes in the tissue composition of the bacon part during fattening, 10 castrates were scanned repeatedly at 70, 90 and 110 kg of liveweight. A linear regression model was developed to characterise the continuous decrease observed in the muscle/fat ratio within the bacon part due to increasing liveweight.

Characterisation of porcine peroxisome proliferator-activated receptors gamma 1 and gamma 2: detection of breed and age differences in gene expression

Two isoforms of peroxisome proliferator-activated receptor gamma (PPAR gamma) cDNAs, gamma 1 and gamma 2, have been isolated and characterised in swine. The relative expression of the two transcripts was studied by northern blot analysis using total RNA isolated from several porcine tissues taken at three different ages (day 1, after 5 weeks and at 100 kg weight). Hybridisation were carried out with two different probes, one binding to both PPAR gamma transcripts and the other being PPAR gamma 2 specific. Strongest hybridisation signals with the PPAR gamma probe binding both variants were detected in adipose tissues and spleen at all three ages, whereas only faint or no signals were detected in other tissues. The tissue distribution pattern of PPAR gamma 1 and gamma 2 suggests a modulation of tissue distribution for the two transcripts and obvious age and breed differences in gene expression in swine.