Pietrain Sires Research Articles

Evolution of viscera and muscle fractional protein synthesis rate in lean meat selected hybrids and castrated Duroc pigs fed under moderate crude protein restriction

Differences in producing performance and organoleptic meat characteristics among pig genotypes and/or producing types are widely known. These parameters are also subjected to the animal’s development, feeding and management. Detailed knowledge of the effects of production phase (PP), pig producing type (PT), dietary protein availability and their interactions on nutrient digestibility, nitrogen balance and protein metabolism is essential information to improve precision feeding techniques. The experiment was a 2 (PP) × 2 (PT) × 2 (diet) factorial design conducted with 32 male pigs, 16 entire F2 pigs progeny of Pietrain sires and Duroc × Landrace dams, and 16 castrated purebred Durocs belonging to two production phases (growing: 29.5 ± 3.19 v. fattening: 88.6 ± 6.26 kg BW), and assigned to one of two dietary CP levels, either standard (SP: 17% in growing and 15% in fattening) or low (LP: 15% in growing and 13% in fattening). Viscera and muscle fractional protein synthesis rates (FSRs; %/day) were conducted through a single infusion of 15% L-[ring-2H5]-phenylalanine, with subsequent blood sampling from 12 to 40 min, and sample collection of liver, duodenum, biceps femoris and longissimus dorsi skeletal muscles after sacrifice. Fattening animals acquired a greater feed ingestion capacity, average daily gain (P < 0.01) and apparent ileal digestibility, whereas growing pigs showed higher FSRs in both viscera (duodenum and liver) and in longissimus dorsi. F2 pigs showed higher average daily gain, nitrogen retention rates and FSR in liver and longissimus dorsi (P < 0.01). Nevertheless, apparent ileal digestibility in all essential amino acids was lower in F2 compared with Duroc pigs (P < 0.05). Protein metabolism was barely influenced by dietary CP content, although animals fed LP registered the lowest apparent ileal digestibility for CP and also for most of the essential amino acids compared with SP-fed pigs. This information may reveal differences in amino acid requirements between both PTs, with Duroc pigs receiving excess of dietary amino acids.

The share of tissues in the pig round depending on the genotype, gender and season

The study included 201 offspring (108 castrated males and 93 females) of Landrace (L), Large White (LW) and Pietrain (P) sires. The studied animals were of following genotype: Landrace (L; n = 48); two breed crosses with 50:50 share of parental breeds (LWxL, n=32; and PxL, n=23), two breed crosses with 75% of paternal breed [Lx(?LWxL), n=35] and [LWx(?LxWL) n=38] and three breed crosses [Px(?LWxL) n=25]. Animals included in this study were born during four seasons: winter (n=38), spring (n=65), summer (n=40) and autumn (n=58). Studies have shown that, at an average weight of warm carcass side of 81.20 kg, the highest average values for the weight of round (RW; 10.204 kg), the weight of intermuscular fatty tissue (RINT; 0.478 kg), bone tissue (RBT; 0.850 kg) and muscle tissue (RMT, 7.552 kg) in the round, were established in three-breed crosses of Px (LWxL) genotype compared to other genotypes. The least skin and subcutaneous fatty tissue (RST; 1.269 kg) was recorded in two breed crosses PxL. They had less skin and subcutaneous fatty tissue by 454 g and 467 grams, respectively, compared to two breed crosses (LWxL) and LWx (?LxLW). Research has shown that there is a genotype on a farm that gives more muscle tissue in the round by 1.521 kg [Px (?LWxL): LWx (?LWxL)] with the same weight of warm carcass side, which is a very large difference. With the same average weight of warm carcass side, female animals had higher average weight of the round and yield of muscle tissue compared to male castrated animals. The effect of genotype (P&lt;0.001) on all investigated traits was recorded, also the effect of the season of birth on the skin and subcutaneous fat tissue and on the weight of intermuscular fat in the round was recorded. The effect of sex/gender was significant (P&lt;0.01) on the weight of skin and subcutaneous fat and on the weight of the muscle tissues in the round but no significant effect on other tested properties (P&gt; 0.05) was observed.

A major gene for host response to porcine reproductive and respiratory syndrome is not unfavorably associated with overall performance under nonchallenging conditions in commercial pig lines

ABSTRACTA QTL for host response to porcine reproductive and respiratory syndrome (PRRS) was identified in a previous study. The SNP WUR10000125 (WUR) is used as a tag SNP for this QTL. The favorable (B) allele at this SNP is in low frequency in commercial populations, possibly because this allele is unfavorably associated with an important trait under nonchallenging conditions and, therefore, may have been selected against. Therefore, objectives of this study were to estimate the effect of WUR on traits under selection in commercial lines under nonchallenging conditions and to estimate the effect of WUR genotype of parents on performance of crossbred progeny in a commercial-like environment. Data were collected on 4 purebred lines: a Landrace dam line (D1), a Large White dam line (D2), a synthetic sire line (S1), and a Pietrain sire line (S2). Traits analyzed included total number born, number stillborn, farrowing survival, lactation survival, litter mortality, daily feed intake (DFI), backfat, average test daily gain (TGR), average lifetime daily gain (LGR), and Topigs Norsvin selection index (TSI) value, indicative of overall economic value. Deregressed EBV were calculated for each trait (except TSI) and analyzed within line. In the S1 line, AB and BB pigs had significantly lower TGR (P = 0.002) and LGR (P = 0.001) than AA pigs but also lower DFI (P = 0.004). Conversely, AB and BB pigs had significantly higher DFI (P < 0.001) and AB pigs had significantly higher TGR (P = 0.03) than AA pigs in the S2 line. The effect of WUR on TSI was not significant for any line (P ≥ 0.15). Analyses of phenotypic records collected on crossbred progeny of S1 sires and D1 × D2 F1 females showed no significant effect of parent WUR genotype on DFI, backfat, TGR, or LGR (P ≥ 0.07). In conclusion, the effect of WUR was nonsignificant for most traits but the magnitude and direction of the effect differed by trait and by line. The favorable allele for host response to PRRS was associated with greater DFI and a tendency for greater TGR in the S2 line, but the opposite direction of effect was detected for the S1 line. Regardless of the effect on individual traits, no significant effect of WUR on TSI was detected for any line. Therefore, selecting for the B allele is expected to result in progeny with increased resistance to PRRS without compromising overall economic value under normal, nonchallenging conditions.

Growth performance and carcass quality of crossbreds pigs from two Pietrain sire lines fed isoproteic diets varying in energy concentration

The effects of net energy (NE) content of isoproteic diets on growth performance and carcass and meat quality traits were studied in crossbreds from Landrace×Large White females and two Pietrain sire lines (PIC L62 vs. German Pietrain). Feed intake (FI) decreased (Lineal, P<0.001) and feed efficiency improved (Lineal, P<0.001) as the NE content of the diet increased. Crossbreds from PIC L62 had greater (P<0.001) FI and average daily gain (ADG) but were less efficient (P<0.01) than crossbreds from German Pietrain. German Pietrain crossbreds were leaner (P<0.001) and had higher shoulder yield (P<0.01) and less fat at m. Gluteus medius (P<0.001) than carcasses from PIC L62 crossbreds. In summary, an increase in the NE concentration of the diet improved feed efficiency but did not affect ADG. Crossbreeds from PIC L62 sires grew faster and had fatter carcasses than crossbreds from German Pietrain.

Genome-wide association analyses for boar taint components and testicular traits revealed regions having pleiotropic effects.

BackgroundThe aim of this study was to perform a genome-wide association analyses (GWAS) for androstenone, skatole and indole in different Pietrain sire lines and compare the results with previous findings in purebred populations. Furthermore, the genetic relationship of androstenone and skatole were investigated with respect to pleiotropy. In order to characterize the performance of intact boars, crossbred progenies of 136 Pietrain boars mated to crossbred sows from three different breeding companies were tested on four test stations. A total of 598 boars were performance tested according to the rules of stationary performance testing in Germany. Beside common fattening and carcass composition traits, the concentrations of the boar taint components and testicular size parameters were recorded. All boars were genotyped with the PorcineSNP60 Illumina BeadChip. The GWAS were performed using the whole data set as well as in sub groups according to the line of origin. Besides an univariate GWAS approach, principal component (PC) techniques were applied to identify common expression pattern affecting the biosynthesis and the metabolism of androstenone.ResultsIn total, 33 SNPs were significantly associated with at least one of the boar taint components. Only one SNP was identified being significant in both subgroups. The analyses of the testes size parameters revealed 31 significant associations. The numbers of significant SNPs within the genetic groups evidenced the strong population specific effects. A multivariate approach using PC revealed 33 significant associations for five different PC.ConclusionsBased on Pietrain sired cross bred boars, the mayor objective of our study was to identify QTL for boar taint components and to detect pleiotropy among boar taint and testes traits. The high number of identified QTL revealed that boar taint traits are influenced by a large number of loci. Analyzing pleiotropy allowed identifying a QTL affecting androstenone and the gonasomatic index. In this region, QTL for ovulation rate and age at puberty of sows have been described in literature. This supports the physiological findings that the androstenone level of boars and reproduction performance of sows might be linked by an antagonistic relationship.Electronic supplementary materialThe online version of this article (doi:10.1186/s12863-015-0194-z) contains supplementary material, which is available to authorized users.

Estimation of residual energy intake and its genetic background during the growing period in pigs

The aims of this study were to (i) compare models estimating residual energy intake (REI) using either lean and fat tissue growth or their proxy traits (average daily gain (ADG) and backfat thickness (BF)); (ii) determine genetic characteristics of REI at different growth stages and the entire test period; and (iii) examine 9 genetic and phenotypic relationships of REI with other production traits. Data from 315 pigs of an F2 generation were used which originated from crossing Pietrain sires with a commercial crossbred dam population. Average daily protein (APD) and lipid deposition (ALD), as measurements of lean and fat tissue growth, were obtained using the deuterium dilution technique on live animals. During growth from 60 to 140kg, REI was estimated using 4 different models for energy intake that included, besides other systematic effects, (1) ADG and BF; (2) APD and ALD; (3) and (4) incorporated the same covariables as the first two models, respectively, but pre-adjusted for systematic effects. Genetic parameters and estimated breeding values were obtained based on univariate animal models using REML analysis. Over the entire growing period, heritabilities of different REI using different models were all estimated at 0.44 and their genetic correlations were at unity. At different growth stages heritabilities for REI were greater ranging from 0.47 to 0.50. Genetic correlations between REI estimates at different stages of growth, obtained using genetic model 4, indicated that REI at 60 to 90kg was non-significantly (P>0.05) associated with REI at 90–120kg (0.32±0.29) and 120–140kg (0.28±0.28), but REI of the latter growth stages showed a significant (P<0.05) moderate genetic correlation (0.58±0.21). REI had favourable genetic correlations with feed conversion ratio (FCR, 0.84±0.13) and total nitrogen excretion (TNE, 0.85±0.11). The results indicate that REI estimated based on models using proxy traits for lean and fat tissue deposition resulted in slightly lower accuracies compared to models fitting APD and ALD, which explained a greater variation of energy intake. There is great potential for improvement of REI due to its large heritability. Genetic selection for REI should consider the stages of growth, because of their differences in genetic background. REI explained a large portion of variance in FCR and TNE, therefore selection for REI is expected to result in, besides improvement of feed efficiency, a substantial reduction in the environmental pollution of pig production.

Welfare of recently weaned piglets transported on unpaved roads: the effect of age and the use of straw bedding

This study evaluated the physiological responses of piglets weaned at three different ages and transported immediately over unpaved roads with and without the use of straw bedding in the transport vehicle. The study included 270 hybrid piglets born of York–Landrace dams and Pietrain sires. The piglets were weaned and then transported at 8 days old (n = 90), 15 days old (n = 90) or 22 days old (n = 90). The duration of each trip, from the time the transport vehicle left the original site until its arrival at the destination (site 2) on the same farm, was 1 h. The piglets in each one of the three groups were divided into two subgroups: (1) transported over unpaved roads with straw bedding; (2) transported over unpaved roads without straw bedding. Three repetitions were performed for each experimental condition. To assess physiological responses to the stress caused by transport, blood samples were taken as soon as the piglets arrived at site 2. The blood variables evaluated were: pH, haematocrit (%), glucose (mg/dL), electrolytes (Na+, K+ and Ca2+) (mmol/L), lactate levels (mg/dL), partial pressures of carbon dioxide (pCO2) and oxygen (pO2) (mm Hg), bicarbonate (HCO3–), and total carbon dioxide (TCO2C). Piglets that were weaned at 8 and 15 days of age and then transported without straw bedding were found to be more susceptible to metabolic, acid–base, hydric, and gas exchange imbalances (P &lt; 0.05). Blood concentrations of pO2, Na+, K+, Ca2+ and pH were not affected by transport in piglets weaned at 22 days of age in vehicles using straw bedding. Hence, we conclude that regardless of age and trip conditions, the transport of recently weaned piglets constitutes a stressful situation, because just 1 h of transport time was sufficient to cause imbalances in their physiological blood indicators.

Genetic relationship between boar taint compounds, human nose scores, and reproduction traits in pigs1

A reduction in boar taint, an unpleasant odor arising in pork from some intact males, is desirable if routine castration of piglets needs to be stopped. Commercial slaughter pigs are typically crosses between sire lines mainly selected for finishing traits and dam lines mainly selected for reproduction traits. Previous studies suggest the possibility of reducing boar taint in sire lines due to favorable genetic correlations between boar taint and finishing traits. However, there are indications of unfavorable genetic associations between boar taint and female reproduction traits, but a lack of genetic correlation estimates remain a major roadblock in reducing boar taint in dam lines. This study was conducted to estimate genetic correlations between boar taint traits and female reproduction traits, investigate differences in these genetic relationships among sire and dam lines, and evaluate possible consequences of selection against boar taint in dam lines. The data consisted of 32,549 reproduction records from a Landrace dam line, 23,874 records from a Yorkshire dam line, and 3,745 records from a Pietrain sire line. Androstenone, skatole, and indole were measured on 1,896 carcasses, and human nose scores were recorded on 7,742 carcass samples. In general, the level of boar taint was significantly greater (P < 0.05) in the two dam lines than in the sire line. A majority of genetic correlations of boar taint compounds with reproduction traits were either low or nonsignificant, except for those of skatole and indole, with age at first insemination in dam lines that were -0.32 and -0.46, respectively. Genetic correlations also differed (P < 0.05) between sire and dam lines. The consequences of selection against boar taint in dam lines were evaluated, using selection indexes based on reproduction traits only, boar taint traits only, and both boar taint and reproduction traits. Selection on an index of only reproduction traits increased the number of carcasses with boar taint from 4 to 7.3% in 5 generations. Selection on a combined index reduced carcasses with boar taint from 4 to <0.1% in 19 generations at the cost of a 10% less economic gain in reproduction traits. In markets for intact males, overall economic gain is 78% greater than with selection for reproduction only. Breeding programs for boar taint in commercial production should include boar taint in breeding goals of dam lines as the levels of boar taint and the risk of a further increase are greater.

Growth performance and carcass quality of immunocastrated and surgically castrated pigs from crossbreds from Duroc and Pietrain sires1

In total, 240 pigs were used to compare growth performance and carcass quality traits of immunocastrated males (ICM), surgically castrated males (SCM), and intact females (IF) of crossbreds from Large White × Landrace females and Duroc (DU) or Pietrain (PI) sires destined to the dry-cured industry. Between the 2 Improvac injections (87 and 137 d of age), ICM and IF had less ADG than SCM (P < 0.01). Also, ICM ate less feed than IF and both less than SCM (2.33, 2.55, and 2.77 kg/d; respectively; P < 0.001) and consequently, ICM had better G:F than SCM and IF (P < 0.001). From second Improvac injection to slaughter (137 to 164 d of age), ICM were more efficient than IF and both more efficient than SCM (0.346, 0.323, and 0.300 g/g; respectively; P < 0.001). The differences in growth performance among genders observed in this period were more pronounced for the PI than for the DU crossbreds (P < 0.05 for the interaction). For the entire experimental period (87 to 164 d of age), gender did not affect ADG for DU crossbreds but for PI crossbreds ICM and SCM had greater ADG than IF (P < 0.05 for the interaction). The ICM pigs had better feed efficiency (0.406, 0.364, and 0.380; g/g; P < 0.001) and lower carcass yield (76.6, 78.1, and 78.8%; P < 0.001) than SCM or IF. Carcasses from IF were leaner than carcasses from SCM with carcasses from ICM being intermediate (P < 0.01). Ham and loin (P < 0.001) yields were greater for IF than for ICM or SCM. Intramuscular fat content was lower for IF than for SCM with that of ICM being intermediate (3.5 vs. 3.9 and 3.7%; P < 0.05). Cumulatively, crossbreds from DU sires had greater ADG (1.167 vs. 0.986 kg/d; P < 0.001) and ADFI (3.07 vs. 2.56 kg/d; P < 0.001) and more intramuscular fat (P < 0.001) but less ham and loin yields (P < 0.01) than crossbreds from PI sires. It is concluded that growth performance was better but carcass yield less for ICM than for SCM and IF. Intramuscular fat content in LM was less for IF than for SCM with ICM intermediate. Crossbreds from Duroc sires grew faster and had more intramuscular fat but less ham yield than crossbreds from Pietrain sires. Therefore, ICM should be preferred to SCM and Duroc crossbreds should be preferred to Pietrain crossbreds to produce carcasses destined to the production of primal cuts for the dry-cured industry.

SNP variation in the promoter of the PRKAG3gene and association with meat quality traits in pig

BackgroundThe PRKAG3 gene encodes the γ3 subunit of adenosine monophosphate activated protein kinase (AMPK), a protein that plays a key role in energy metabolism in skeletal muscle. Non-synonymous single nucleotide polymorphisms (SNPs) in this gene such as I199V are associated with important pork quality traits. The objective of this study was to investigate the relationship between gene expression of the PRKAG3 gene, SNP variation in the PRKAG3 promoter and meat quality phenotypes in pork.ResultsPRKAG3 gene expression was found to correlate with a number of traits relating to glycolytic potential (GP) and intramuscular fat (IMF) in three phenotypically diverse F1 crosses comprising of 31 Large White, 23 Duroc and 32 Pietrain sire breeds. The majority of associations were observed in the Large White cross. There was a significant association between genotype at the g.-311A>G locus and PRKAG3 gene expression in the Large White cross. In the same population, ten novel SNPs were identified within a 1.3 kb region spanning the promoter and from this three major haplotypes were inferred. Two tagging SNPs (g.-995A>G and g.-311A>G) characterised the haplotypes within the promoter region being studied. These two SNPs were subsequently genotyped in larger populations consisting of Large White (n = 98), Duroc (n = 99) and Pietrain (n = 98) purebreds. Four major haplotypes including promoter SNP’s g.-995A>G and g.-311A>G and I199V were inferred. In the Large White breed, HAP1 was associated with IMF% in the M. longissmus thoracis et lumborum (LTL) and driploss%. HAP2 was associated with IMFL% GP-influenced traits pH at 24 hr in LTL (pHULT), pH at 45 min in LTL (pH45LT) and pH at 45 min in the M. semimembranosus muscle (pH45SM). HAP3 was associated with driploss%, pHULT pH45LT and b* Minolta. In the Duroc breed, associations were observed between HAP1 and driploss% and pHUSM. No associations were observed with the remaining haplotypes (HAP2, HAP3 and HAP4) in the Duroc breed. The Pietrain breed was monomorphic in the promoter region. The I199V locus was associated with several GP-influenced traits across all three breeds and IMF% in the Large White and Pietrain breed. No significant difference in promoter function was observed for the three main promoter haplotypes when tested in vitro.ConclusionGene expression levels of the porcine PRKAG3 are associated with meat quality phenotypes relating to glycolytic potential and IMF% in the Large White breed, while SNP variation in the promoter region of the gene is associated with PRKAG3 gene expression and meat quality phenotypes.

Nitrogen excretion at different stages of growth and its association with production traits in growing pigs1

The objectives of this study were to determine nitrogen loss at different stages of growth and during the entire growing period and to investigate the associations between nitrogen excretion and production traits in growing pigs. Data from 315 pigs of an F(2) population which originated from crossing Pietrain sires with a commercial dam line were used. Nitrogen retention was derived from protein retention as measured using the deuterium dilution technique during different stages of growth (60 to 90 kg, 90 to 120 kg, and 120 to 140 kg). Pigs were fed ad libitum with 2 pelleted diets containing 17% (60 to 90 kg) and 16.5% (90 to 120 and 120 to 140 kg) CP. Average daily nitrogen excretion (ADNE) within each stage of growth was calculated on the basis of the accumulated difference between average daily nitrogen intake (ADNI) and average daily nitrogen retention (ADNR). Least ADNE, nitrogen excretion per BW gain (NEWG) and total nitrogen excretion (TNE) were observed during growth from 60 to 90 kg. In contrast, the greatest ADNE, NEWG, and TNE were found during growth from 120 to 140 kg. Statistical analyses indicated that gender, housing type, the ryanodine receptor 1 (RYR1) gene, and batch influenced nitrogen excretion (P < 0.05), but the degree and direction of influences differed between growth stages. Gender differences showed that gilts excreted less nitrogen than barrows (P < 0.05), which was associated with decreased feed conversion ratio (FCR; feed:gain) and lipid:protein gain ratio. Single-housed pigs showed reduced nitrogen excretion compared with group-housed pigs (P < 0.05). In comparison to other genotypes, pigs carrying genotype NN (homozygous normal) at the RYR1 locus had the least nitrogen excretion (P < 0.05) at all stages of growth except from 60 to 90 kg. The residual correlations indicated that NEWG and TNE have large positive correlations with FCR (r = 0.99 and 0.91, respectively) and moderate negative correlations with ADG (r = -0.53 and -0.48, respectively), for the entire growing period. Improvement in FCR, increase in ADG and reduction in lipid:protein gain ratio by 1 phenotypic SD reduced TNE per pig by 709 g, 307 g, and 211 g, respectively, over the entire growing period. The results indicate that nitrogen excretion changes substantially during growth, and it can be reduced most effectively by improvement of feed efficiency and to a lesser extent through the improvement of BW gain or body composition or both.

Epistatic quantitative trait loci affecting chemical body composition and deposition as well as feed intake and feed efficiency throughout the entire growth period of pigs

Numerous quantitative trait loci (QTL) have been identified for growth and feed intake in pigs, however, there are currently no reports of interactions between QTL (epistasis) for these traits at different stages of growth. A genomic scan for epistatic QTL was conducted on animals from a three generation full-sib population, created by crossing Pietrain sires with a crossbred dam line. All types of two-locus interactions were fitted in the model using Cockerham's decomposition, by regressing on a linear combination of the individual QTL origin probabilities. This study is the first to report epistatic QTL for growth, feed intake and chemical body composition in pigs. Eighteen significant epistatic QTL pairs were identified, seven affecting growth, six affecting feed intake or food conversion ratio, and five affecting chemical body composition. Most interacting QTL resided on different chromosomes; only two were located on the same chromosome. The identified QTL pairs explained substantial proportions of the phenotypic variance, from 5% to 10.3%. All types of digenic epistatic effects were identified with the additive-by-additive effect being the most prevalent. These findings suggest that epistasis is important in the genomic regulation of growth, feed intake and chemical body composition. Furthermore, interactions occur between different pairs of epistatic QTL for the same trait depending on the growth stage, increasing the complexity of genomic networks. This agrees with studies on gene expression levels which showed that those are time and tissue dependent.

Epistatic analysis of carcass characteristics in pigs reveals genomic interactions between quantitative trait loci attributable to additive and dominance genetic effects1

The present study focused on the identification of epistatic QTL pairs for body composition traits (carcass cut, lean tissue, and fat tissue weights) measured at slaughter weight (140 kg of BW) in a 3-generation full-sib population developed by crossing Pietrain sires with a crossbred dam line. Depending on the trait, phenotypic observations were available for 306 to 315 F(2) animals. For the QTL analysis, 386 animals were genotyped for 88 molecular markers covering chromosomes SSC1, SSC2, SSC4, SSC6, SSC7, SSC8, SSC9, SSC10, SSC13, and SSC14. In total, 23 significant epistatic QTL pairs were identified, with the additive x additive genetic interaction being the most prevalent. Epistatic QTL were identified across all chromosomes except for SSC13, and epistatic QTL pairs accounted for between 5.8 and 10.2% of the phenotypic variance. Seven epistatic QTL pairs were between QTL that resided on the same chromosome, and 16 were between QTL that resided on different chromosomes. Sus scrofa chromosome 1, SSC2, SSC4, SSC6, SSC8, and SSC9 harbored the greatest number of epistatic QTL. The epistatic QTL pair with the greatest effect was for the entire loin weight between 2 locations on SSC7, explaining 10.2% of the phenotypic variance. Epistatic associations were identified between regions of the genome that contain the IGF-2 or melanocortin-4 receptor genes, with QTL residing in other genomic locations. Quantitative trait loci in the region of the melanocortin-4 receptor gene and on SSC7 showed significant positive dominance effects for entire belly weight, which were offset by negative dominance x dominance interactions between these QTL. In contrast, the QTL in the region of the IGF-2 gene showed significant negative dominance effects for entire ham weight, which were largely overcompensated for by positive additive x dominance genetic effects with a QTL on SSC9. The study shows that epistasis is of great importance for the genomic regulation of body composition in pigs and contributes substantially to the variation in complex traits.

Investigation of uniformity in pig carcass and meat quality traits

The study was carried out to provide information on uniformity of commercial pigs on some of the most important traits determining pork quality: carcass, loin, ham and shoulder weights, fatness, drip loss, pH and colour. Three batches of pigs raised at the same farm and slaughtered at four different dates in the same commercial abattoir were considered. Batches included halothane-free females and castrated males, Duroc and Pietrain sire lines and two slaughter weights, but a common maternal line. The first batch was obtained using commercial Duroc sire boars, and included a total of 112 animals (56 castrated males and 56 females). The second batch used Duroc and Pietrain sire boars with the target to achieve two different final weights (105 and 115 kg live weight); 128 animals were controlled (64 castrated males and 64 females), 16 for each combination of sire boar, sex and final weight. The last batch used only Pietrain sire boars with 96 controlled pigs (48 castrated males and 48 females). The uniformity was measured by the coefficient of variation (CV) and the coefficient of dispersion (CD) for all data available, and for groups of common sex, sire breed and slaughter weight. Differences in uniformity were tested among traits and groups by using confidence intervals (CIs) at 95% confidence level (CI95%) for the CV and CD. Results showed a significantly lower uniformity for drip loss (CV = 40.4%, CI95% 36.9% to 44.7%; CD = 32.1%, CI95% 28.7% to 35.4%) and backfat (CV = 22.8%, CI95% 21.1% to 24.8%; CD = 18.3%, CI95% 17.1% to 20.2%) the pH being the most uniform trait (CV = 3.2%, CI95% 3.0% to 3.5%; CD = 2.6%, CI95% 2.4% to 2.9%). When comparing different ‘sire breed–sex–slaughter weight’ groups, no consistent sex and slaughter weight differences in uniformity were found, but animals from Pietrain sire breed showed a tendency to be less uniform for carcass traits than animals from Duroc sire breed. Nevertheless, variability within those groups was very high and often similar to that observed when considering all the animals from all the groups. Small differences were found comparing uniformity when using the CV or the CD. CIs of these coefficients have proved to be a simple and useful tool for testing differences in uniformity.

Genomic scan for quantitative trait loci of chemical and physical body composition and deposition on pig chromosome X including the pseudoautosomal region of males.

A QTL analysis of pig chromosome X (SSCX) was carried out using an approach that accurately takes into account the specific features of sex chromosomes i.e. their heterogeneity, the presence of a pseudoautosomal region and the dosage compensation phenomenon. A three-generation full-sib population of 386 animals was created by crossing Pietrain sires with a crossbred dam line. Phenotypic data on 72 traits were recorded for at least 292 and up to 315 F2 animals including chemical body composition measured on live animals at five target weights ranging from 30 to 140 kg, daily gain and feed intake measured throughout growth, and carcass characteristics obtained at slaughter weight (140 kg). Several significant and suggestive QTL were detected on pig chromosome X: (1) in the pseudoautosomal region of SSCX, a QTL for entire loin weight, which showed paternal imprinting, (2) closely linked to marker SW2456, a suggestive QTL for feed intake at which Pietrain alleles were found to be associated with higher feed intake, which is unexpected for a breed known for its low feed intake capacity, (3) at the telomeric end of the q arm of SSCX, QTL for jowl weight and lipid accretion and (4) suggestive QTL for chemical body composition at 30 kg. These results indicate that SSCX is important for physical and chemical body composition and accretion as well as feed intake regulation.

Effect of crossbreeding and gender on meat quality and fatty acid composition in pork

This study considers the effect of crossbreeding and gender (barrows; gilts) on meat quality and intramuscular and subcutaneous fatty acid composition in pork. The sire lines included Large White (LW), Duroc (D) and Pietrain (P) and the dam line was Landrace (LR) × LW, producing LW × (LR × LW), D × (LR × LW) and P × (LR × LW). Pork samples were removed from Longissimus dorsi (LD) and Semimembranosus (SM) muscles and subcutaneous fat (SCF). There were no important differences in meat quality parameters but D × (LR × LW) had the highest percentage of intramuscular fat. Castrated males had more intramuscular fat and more intense meat colour than female pigs. The Large White and Duroc sire line had saturated fatty acids (SFA) in SM, whereas the Pietrain sire line was significantly higher than Duroc sire line in the concentration of polyunsaturated fatty acids (PUFA), PUFA/SFA (P/S) and the n−6/ n−3 ratio. The concentrations of SFA and monounsaturated fatty acids (MUFA) in SCF were significantly higher in LW × (LR × LW) and P × (LR × LW), respectively. No differences were found in the percentage of PUFA, P/S and n−6/ n−3 ratio between D × (LR × LW) and P × (LR × LW). Female pigs had the most polyunsaturated intramuscular and subcutaneous fat. The results demonstrate small differences in fatty acid compositions among sires.

Quantitative trait loci for chemical body composition traits in pigs and their positional associations with body tissues, growth and feed intake

In this study, quantitative trait loci (QTL) for chemical and physical body composition, growth and feed intake in pigs were identified in a three-generation full-sib population, developed by crossing Pietrain sires with a commercial dam line. Phenotypic data from 315 F(2) animals were available for protein and lipid deposition measured in live animals by the deuterium dilution technique at 30-, 60-, 90-, 120- and 140-kg body weight. At 140-kg body weight, carcass characteristics were measured by the AutoFOM grading system and after dissection. Three hundred and eighty-six animals from 49 families were genotyped for 51 molecular markers covering chromosomes SSC2, SSC4, SSC8, SSC9, SSC10 and SSC14. Novel QTL for protein (lipid) content at 60-kg body weight and protein (lipid) accretion from 120 to 140 kg were detected on SSC9 near several previously detected QTL for lean and fat tissue in neck, shoulder and ham cuts. Another QTL for lipid accretion was found on SSC8, closely associated with a QTL for intramuscular fat content. QTL for daily feed intake were detected on SSC2 and SSC10. The favourable allele of a QTL for food conversion ratio (FCR) on SSC2 was associated with alleles for increased lean tissue and decreased fat tissue. Because no QTL for growth rate were found in the region, the QTL for FCR is most likely due to a change in body composition. These QTL provide insights into the genomic regulation of chemical or physical body composition and its association with feed intake, feed efficiency and growth.

A comparison of halothane homozygous negative and positive pietrain sire lines in relation to carcass and meat quality, and welfare traits

Barrows ( n=164) and gilts ( n=249) from crosses of a Pietrain homozygous halothane recessive (Pi nn) and two Pietrain homozygous dominant (Pi NN-a and Pi NN-b) sire lines with Landrace×Large White NN sows, were used to study the effect of terminal sire and pre-slaughter treatment on meat quality and animal welfare. The pigs from each of the two farms where they were finished were delivered to the abattoir in two batches differing in the pre-slaughter conditions. A total of 90 pigs (54 NN and 36 Nn) were assigned to a long pre-slaughter treatment (6 h transport and 14.5 h lairage) and 89 (57 NN and 33 Nn) to a short pre-slaughter treatment (4.5 h transport and 2.5 h lairage) in Farm 1, and 118 (65 NN and 53 Nn) to the long (7 h transport and 14 h lairage) and 114 (66 NN and 48 Nn) to the short pre-slaughter treatment (1.5 h transport and 2 h lairage) in Farm 2. In Farm 1, heart rate of 3 NN and 3 Nn gilts was recorded throughout loading and transport and blood samples from 5 NN and 5 Nn were collected before loading and after transport to measure cortisol, creatine phosphokinase (CPK) and lactate dehydrogenase (LDH). Carcasses were classified and commercial cutting was carried out. At 24 h, meat quality was assessed on the Longissimus thoracis muscle by measuring electrical conductivity (PQM), colour (Minolta CR 200 and Japanese scale), pHu and drip losses. Halothane carriers showed a higher mean heart rate and higher increase in CPK levels ( P<0.05) after transport in the short pre-slaughter treatment than halothane free pigs. No effect was observed in cortisol or LDH values. Pi NN-a sired pigs had a higher live and carcass weight ( P<0.001) and loin depth ( P<0.05), but lower killing out percentage ( P<0.01) and leg yield ( P<0.01) compared with the progeny of the other two terminal sires. Gilts were leaner ( P<0.001), had a higher killing out percentage ( P<0.001) and higher yields of primal cuts ( P<0.001) compared with barrows. Pi nn sired pigs had poorer meat quality (higher PQM values in both farms, P<0.01) than Pi NN-a sired pigs. Long pre-slaughter treatment resulted in darker meat ( P<0.01) in both farms and in higher pHu ( P<0.001) in Farm 1 than short pre-slaughter treatment. Conversely, pigs subjected to the short pre-slaughter treatment showed higher PQM values ( P<0.01) in Farm 1 and higher PSE percentage ( P<0.05) in both farms compared to the ones subjected to the long pre-slaughter treatment. These results suggest that Pietrain halothane free sire lines could produce similar results on carcass quality to halothane carriers, without compromising meat quality and welfare.

Pork quality variation is not explained by glycolytic enzyme capacity

Our objective was to determine if increased glycolytic enzyme capacity accommodates rapid glycolysis, which leads to inferior pork color and water-holding capacity. Progeny from HAL-1843 free Duroc ( n=16) or Pietrain ( n=16) sires were harvested over a 2-week period. Coupled enzyme assays were used to quantify total capacity of pyruvate kinase (PK) and phosphofructokinase (PFK) in the sarcoplasmic fractions and crude homogenates of longissimus muscle (LM), respectively. Capacity of PK was not correlated with LM pH (20, 45, 180 min or 24 h), purge, drip loss, or CIE L* ( P > 0.2). However, PFK capacity was inversely related to fluid loss ( P<0.05). This finding was unexpected, but may result from PFK becoming partially denatured and inactivated by 20 min postmortem in samples that undergo a rapid pH decline. These data indicate that lighter pork color and reduced water-holding capacity are not associated with an increase in the capacity of enzymes that catalyze regulated steps of glycolysis.

Is the porcine RN locus a pleiotropic QTL? A Bayesian marker assisted segregation analysis

The question of possible pleiotropic effects of the porcine RN locus on production traits was addressed. Chromosome 15 microsatellite data, mapping results and performance data from the Kiel RN mapping experiment were used to compare heterozygous RN-/rn carrier animals and rn non-carriers. Progenies from 14 Hampshire x Pietrain sires, all of which were heterozygous at both the RN and RYR1 loci, were recorded for 24 traits. Dams were either Landrace Large White crossbreds or Landrace or Large White purebreds. The number of progeny with valid records ranged from 323 to 418, depending on the trait. A mixed polygenic-major gene inheritance model was applied, using a Bayesian approach. Reflectance and terminal pH were lowered in carriers. Additionally, a 2.42 mm increase in muscle depth in the loin, an enlargement of loin eye area by 1.39 cm and a 0.46 % increase in estimated lean meat content due to the RN- allele were observed. It was shown that the increased lean meat content was not high enough to outweigh the economic loss from poor technological yield. The proportion of genetic variance in progeny which could be attributed to the RN locus ranged from 5 to 55 %. More than 40 % of the total genetic variance in eye muscle depth was generated by the joint action of RN and RYR1. This is discussed with respect to uniformity of end products in a crossbreeding scheme. The results suggest that not only loci which are involved in glycogen metabolism, but also those which are related to muscular development, may be regarded as possible candidate genes for the RN locus. © Inra/Elsevier, Paris major genes / pig meat quality / chromosome substitution effects / Gibbs sampler