Genome-wide identification of quantitative trait loci in a cross between Hampshire and Landrace I: carcass traits.

We report the identification of quantitative trait loci (QTL) affecting carcass composition, carcass length, fat deposition and lean meat content using a genome scan across 462 animals from a combined intercross and backcross between Hampshire and Landrace pigs. Data were analysed using multiple linear regression fitting additive and dominance effects. This model was compared with a model including a parent-of-origin effect to spot evidence of imprinting. Several precisely defined muscle phenotypes were measured in order to dissect body composition in more detail. Three significant QTL were detected in the study at the 1% genome-wide level, and twelve significant QTL were detected at the 5% genome-wide level. These QTL comprise loci affecting fat deposition and lean meat content on SSC1, 4, 9, 10, 13 and 16, a locus on SSC2 affecting the ratio between weight of meat and bone in back and weight of meat and bone in ham and two loci affecting carcass length on SSC12 and 17. The well-defined phenotypes in this study enabled us to detect QTL for sizes of individual muscles and to obtain information of relevance for the description of the complexity underlying other carcass traits.

Effect of stunning conditions on occurence of PSE defects in hams of rn+/RN(-) pigs.

Pigs of the same genetic type at the RN and HAL loci, i.e. rn(+)RN(-)/NN were reared in similar conditions of feeding and housing. They were slaughtered in two abattoirs (referred to as A1 and A2) using a mixture of air (30%) and CO(2) (70%), at a rate of 300 pigs per hour per slaughterline. One hundred and thirty-two pigs from 11 farms were slaughtered in A1 using a corusinga restrainer and 127 pigs from 5 farms were slaughtered in A2 with the backloading technique. pH at 40 min, 2.5 h and 24 h after slaughter and colour (L*, a*, b*) at 24 h after slaughter were measured in the semimembranosus muscle. Meat quality of the ham was scored as follows: 1, no PSE-zone; 2, doubtful; 3, PSE-zones in the semimembranosus and sometimes on the internal flexor muscles; 4, PSE-zones in all the flexor muscles. The muscle pH value was higher in A2 than in A1 at 40 min post mortem (P<0.01), but not at 2.5 and 24 h. L* (P<0.001) and b* (P<0.05) were higher in A1 than in A2. There was a remarkable difference in meat quality scores, with 50% of the hams scoring 3 or 4 in A1, vs 13% in A2. Lairage time before slaughter affected (P<0.01) the pH value at 2.5 h (5.69 vs 5.93). The values of pH1 and pH2.5 decreased with increasing the meat quality score. The values of L* and b* increased markedly with the score. The results of the present study indicate that the method of bringing the slaughter pigs to the stunning device affects the frequency and importance of PSE meat in the ham. The automated driving of groups of animals to the stunning machine combined with the backloading of a nacelle, compared to a traditional system driving pigs in single file using electrical goads and a restrainer was beneficial with respect to both meat quality and animal welfare.

An international study on the importance of androstenone and skatole for boar taint: IV. Simulation studies on consumer dissatisfaction with entire male pork and the effect of sorting carcasses on the slaughter line, main conclusions and recommendations.

An international study has been conducted in order to determine the respective contributions of androstenone and skatole to boar taint and their possible variations according to production systems and consumer populations. The presentation of the study and the main results concerning skatole and androstenone levels and data from sensory evaluation or consumer surveys are reported in companion papers. The present paper summarises the main conclusions of the study and gives tentative recommendations. A simulation study was conducted, based on the skatole and androstenone levels currently observed in European populations of entire male pigs and on the results of the consumer surveys. The first part of the simulation study demonstrated that, overall, 6.5% (odour) and 3.0% (flavour) more consumers were dissatisfied with entire male than with gilt pork. The differences were, however, very variable according to countries. Consumer dissatisfaction for the odour of entire male pork was mostly associated with high skatole levels, while androstenone had little influence on it. On the other hand, androstenone and skatole had similar contributions to the level of dissatisfaction for flavour. From the present study it is not possible to determine clear cut-off levels for androstenone/skatole. The regression equations presented in [Matthews, K. R., Homer, D. B., Punter, P., Béague, M. P., Gispert, M., Siret, F., Leask, H., Fonti i Furnols, M., & Bonneau, M. (2000). An international study on the importance of androstenone, skatole for boar taint: III. Consumer survey in seven European countries. Meat Science, 54, 271-283] provide a basis for decision making. However, due to methodological limitations, the results may underestimate consumer reaction to entire male pork. The second part of the simulation study demonstrated that sorting carcasses on the basis of androstenone/skatole would reduce, but not eliminate, differences in consumer dissatisfaction between entire male and gilt pork. For odour, taking androstenone into account did not improve the efficiency obtained from sorting using skatole only. For flavour, sorting using both compounds was more efficient than sorting using skatole only. Sorting out 15% of the entire males, on the basis of skatole only, would result in a difference in the proportion of dissatisfied consumers of 4.2% (odour) or 2.0% (flavour) between entire male and gilt pork. The results of the last part of the simulation study demonstrated that decreasing skatole in entire male pig populations, to levels as low as 0.10 ppm, would still result in a difference in the proportion of dissatisfied consumers of 3.2% (odour) or 1.6% (flavour). To reduce this difference further, the levels of both compounds would have to be reduced still further. The lowest difference that can be achieved is 2.3% (odour) or 0.4% (flavour). The conclusions of the present study may differ according to whether immediate commercial applications or long-term goals are considered. On the basis of the skatole and androstenone levels currently observed in entire male pig populations, sorting out procedures based on skatole is the easiest way to rapidly achieve a significant decrease in consumer dissatisfaction with entire male pork. In most countries, however, this will not be sufficient to obtain the same level of acceptability as with gilts. In the long term, a sharp reduction in both skatole and androstenone would have to be achieved in entire male pig populations to obtain low differences in acceptability between entire male and gilt pork.