Sire breed comparisons for meat and eating quality traits in Australian pig populations

Sire breed comparisons for carcase (n = 1169), meat and eating quality (n = 686) traits were obtained using data recorded on progeny of known pedigree sired by Duroc (DU), Large White (LW), Landrace (LR) and Duroc Synthetic (DS) boars from crossbred (LW/LR) sows. Animals were reared in eco-shelters in large single-sex contemporary groups and slaughtered on an age constant basis at 22 weeks of age. Compared to progeny from other sire groups, animals sired by purebred Duroc boars tended to have improved eating quality traits (higher intramuscular fat and lower shear force) at the expense of poorer carcase characteristics (higher subcutaneous and belly fat). Animals sired by DS boars tended to be heavier and leaner than those sired by LW, LR or DU boars; intramuscular fat but not belly fat was correspondingly lower, while tenderness was generally consistent with that of the DU progeny. Significant variability of sire progeny groups within sire breed suggests that sire breed selection, potentially used for improving traits such as meat quality in commercial progeny, will be less accurate in the absence of sire-specific information, which is typically poorly recorded in this class of traits.     

Effect of sire breed on carcass characteristics and meat and fat quality of heavy pigs reared outdoor and intended for dry-cured meat production

A trial was conducted to study the effect of sire line (Duroc (DU) and Pietrain (PI)) on carcass, meat and fat quality of pigs reared outdoor and destined to dry-cured meat production. No differences between sire genotypes were detected in carcass fat thickness (P > 0.10) but carcasses from DU-sired pigs were longer (P < 0.05) and tended to have a higher yield of trimmed shoulders (P = 0.07) and hams (P = 0.06) than carcasses from PI-sired pigs. Loins from DU-sired genotype showed higher (P < 0.05) L* value and lower (P < 0.01) a* value than loins from PI-sired genotype. Pork from DU-sired offspring tended to have higher (P = 0.09) intramuscular fat (IMF) percentage and lower (P < 0.05) moisture proportion than meat from PI-sired offspring. Also, loins from DU-sired pigs had lower (P < 0.001) thawing losses than loins from PI-sired pigs. The subcutaneous fat from the DU-sired line tended to show lower (P = 0.08) percentage of total polyunsaturated fatty acids (PUFAs) than that from the PI-sire line, mostly due to the higher proportion of C18:2 (P = 0.09) and C20:3 (P < 0.01). However, no effect of crossbreed was detected on the total proportion of saturated, monounsaturated fatty acid (MUFAs) or PUFAs of IMF (P > 0.10). We conclude that both sire lines can be used successfully under outdoor conditions but DU boars are more adequate than PI boars for the production of heavy pigs intended for the dry-cured meat industry.     

The footprint of recent and strong demographic decline in the genomes of Mangalitza pigs

The Mangalitza pig breed has suffered strong population reductions due to competition with more productive cosmopolitan breeds. In the current work, we aimed to investigate the effects of this sustained demographic recession on the genomic diversity of Mangalitza pigs. By using the Porcine Single Nucleotid Polymorphism BeadChip, we have characterized the genome-wide diversity of 350 individuals including 45 Red Mangalitza (number of samples; n=20 from Hungary and n=25 from Romania), 37 Blond Mangalitza, 26 Swallow-belly Mangalitza, 48 Blond Mangalitza × Duroc crossbreds, 5 Bazna swine, 143 pigs from the Hampshire, Duroc, Landrace, Large White and Pietrain breeds and 46 wild boars from Romania (n=18) and Hungary (n=28). Performance of a multidimensional scaling plot showed that Landrace, Large White and Pietrain pigs clustered independently from Mangalitza pigs and Romanian and Hungarian wild boars. The number and total length of ROH (runs of homozygosity), as well as F_ROH coefficients (proportion of the autosomal genome covered ROH) did not show major differences between Mangalitza pigs and other wild and domestic pig populations. However, Romanian and Hungarian Red Mangalitza pigs displayed an increased frequency of very long ROH (>30 Mb) when compared with other porcine breeds. These results indicate that Red Mangalitza pigs underwent recent and strong inbreeding probably as a consequence of severe reductions in census size.     

Pathological changes in the microstructure of longissimus lumborum muscle from five breeds of pigs

The aim of the study was to determine the extent of histopathological changes in m. longissimus lumborum of PL, PLW, Duroc, Pietrain, and Pu?awska pigs (N = 30 per breed) aged 210 days. Changes in fibre size (atrophy, hypertrophy - giant fibres), changes in fibre shape (angular fibres), degenerative lesions (necrosis with phagocytosis) and connective tissue hypertrophy were evaluated. The percentage of individual pathological changes in m. longissimus lumborum of the analysed pig breeds was relatively low. Significantly more normal fibres were found in the muscles of Pu?awska compared to Pietrain pigs. Muscle fibre atrophy was the most frequent and extensive histopathological change. The muscles of Pu?awska pigs had significantly fewer atrophic, giant and angular fibres, significantly less necrosis with phagocytosis, and less animals with connective tissue hypertrophy compared to the other pig breeds. On the other hand, Pietrain pigs were characterized by a greater number of animals with giant fibres and a significantly higher proportion of giant fibres compared to the other breeds. Also the diameter of giant fibres was the largest in Pietrain, intermediate in PL and PLW, and the smallest in Duroc and Pulawska pigs. Moreover, current findings indicate that giant fibres may arise from each muscle fibre type (I, IIA and IIB). It is concluded that selection of pigs for increased leanness contributes to the incidence of histopathological changes, which may decrease pork quality.     

Mitochondrial DNA sequence variation and phylogenetic relationships among Iberian pigs and other domestic and wild pig populations

Nucleotide sequences of mitochondrial DNA (mtDNA) cytochrome B gene (1140 bp) and control region (707 bp) were used to determine the phylogenetic relationships among 51 pig samples representing ancient and current varieties of Iberian pigs (26), Spanish wild boars (seven) and other domestic pigs (18) of cosmopolitan (Duroc, Large White, Landrace, Pietrain and Meishan) and local (Spotted Black Jabugo, Basque and Mangalitza) breeds. A neighbour-joining tree constructed from pairwise distances provide evidence of the European origin of both Iberian pigs and Spanish wild boars. The introgression of Asian mtDNA haplotypes in the genetic pool of the Iberian breed seems unlikely. Four estimates of sequence divergence between European and Asian clades were calculated from the two main domains of the D-loop region and the synonymous and nonsynonymous nucleotide substitutions in the cytochrome B gene. The time since the divergence of pig ancestors was estimated at about 600,000 years before present.     

Differential responses of Duroc, Hampshire, and crossbred pigs to a superimposed experimental infection with the intestinal threadworm, Strongyloides ransomi.

In both spring and fall, 12 Duroc, 12 Hampshire, and 12 Duroc times Hampshire F1 weanling pigs all reared under the same management were fed in pens of 3 to slaughter weights. Three Duroc and 4 Hampshire boars, essentially unrelated within breed, were used in sampling the breeds. Swine herd management allowed pig infection with Strongyloides ransomi and Ascaris suum, but neither clinical nor subclinical parasitism was evident in the herd. Pigs were percutaneously exposed by pens within breed and season, half to none (control) and half to 3,000,000 (exposed) S. ransomi infective larvae, Breed, treatment, and seasons were prominent sources of variation in pig response. Breeds failed to respond alike to parasitism in respect to experimental periods and exposure levels. This interaction response (P smaller than 0.01) showed that S. ransomi egg production increased rapidly for all breed groups but decreased quicker and greater in Durocs, slowest and least in Hampshires, with cross breds intermediate in these respects. The 2.0830 for mean of log A. suum EPG from exposed Durocs was near double that of control Durocs but the mean for exposed Hampshires was less than half that for controls; crossbreds tended to be intermediate in this respect. Daily gains of 0.70 and 0.73 for Durocs and crossbreds were similar (P greater than 0.10) but averaged 11.7% more (P smaller than 0.05) than the 0.64 kg for Hampshires and gains by control pigs were 20.6% above (P greater than 0.01) that of exposed pigs. Exposed pigs required more feed per kg of gain (P greater than 0.05) than control pigs (3.60 vs. 3.33 kg). Comparison of relative gains and feed efficiences of control and exposed pigs among and within breed groups supported the position that a superimposed exposure of 3,000,000 S. ransomi larvae was more severe for Hampshires, intermediate for crossbreds, and least severe for Durocs.     

Reproductive status effects of pair-housed male pigs on natural,agonistic and sexual behaviours

Boar rearing, which avoids pain and suffering caused by surgical castration, provides better performance, a greater deposition of muscle tissue and leaner carcasses and thus has beneficial effects on both animal welfare and the product. Some countries that do not slaughter boars must consider their boar taint and aggressive and sexual behaviours. Considering that pigs are housed in large groups, which may complicate the formation of social hierarchies and increase fighting and mounting behaviours, some studies have conducted research with reduced numbers of pigs per pen, but these behaviours continued to be observed. However, a study of the reproductive status of pair-housed male pigs has yet to be reported. The aim of this study was to determine whether the reproductive status of uncastrated, immunocastrated and surgically castrated pair-housed male pigs alters their natural, agonistic and sexual behaviours. A total of 48 male pigs from Agroceres PIC™ genetics were assigned to three groups: surgically castrated (barrows), immunocastrated and uncastrated (boars). Natural, aggressive and sexual behaviours of the pigs were assessed by direct observations during four periods of 12 h each (six, five and three weeks before slaughter and the slaughter week). The pigs were housed in pairs from the growing phase until slaughter. Animal behaviour was observed from the finishing phase to slaughter. Carcass lesions were assessed according to five different classes (one: no injury; two to five: severely injured). Overall, boars spent more time lying and less time eating and drinking than barrows. In total of all the periods (48 h), boars expressed more aggressive and sexual behaviours than barrows, whereas immunocastrated pigs displayed similar behaviours to boars, before and after the second vaccine dose. No differences in carcass lesions between treatments and no prevalence of carcasses with severe injuries were observed. In conclusion, the reproductive status of pair-housed male pigs did not change the natural behaviour of boars, immunocastrated pigs or barrows. The agonistic and sexual behaviours of boars and barrows remained unchanged. When housing pigs in pairs, immunocastrated pigs presented similar agonistic and sexual behaviours to boars before and after the second immunocastration vaccine dose. The use of pair-housed uncastrated male pigs has generated welfare benefits for these animals, as the number of carcasses with injuries did not differ from barrows and immunocastrated pigs.     

Distribution of the CD4 Alleles in Sus scrofa Demonstrates the Genetic Profiles of Western Breeds and Miniature Pigs

Widely used antipig CD4 monoclonal antibodies (mAbs) fail to recognize CD4 alleles characteristic of miniature pig lines such as the National Institutes of Health (NIH) miniature pigs and microminipigs. We surveyed polymorphisms in the coding sequence of the porcine CD4 gene among Western and Oriental pig breeds and Japanese wild boars and investigated their distribution. Of the 13 alleles that we identified among the 47 animals, 2 in group I and 3 in group II were found exclusively in Western breed pigs. Group IV alleles, which included mAb-nonbinding alleles, were found frequently in Oriental breed pigs, suggesting that the mAb-nonbinding allele arose from the gene pool of Oriental pigs. Group IV alleles were also found in Duroc and Large White pigs, suggesting genetic inflow from Oriental pig breeds into Western breeds. Comparison of the CD4 sequences of species in Cetartiodactyla suggested that the group IV alleles in Sus scrofa occurred before the divergence of this species from the other artiodactyls. The different antibody specificities of the various CD4 alleles may facilitate the discrimination of T-cell populations in transplantation studies using miniature pigs. The significance of the preservation of CD4 polymorphisms to immune function in pigs warrants further investigation.     

Gene expression in Large White or Duroc-sired female and castrated male pigs and relationships with pork quality

This study assessed expression of 12 genes in 24 pig longissimus samples earlier subjected to a proteomic study by our group. Genes were selected on the basis of the earlier proteomic results. Pigs differed in rearing environment (indoors or outdoors), sire breed (Duroc or Large White) and gender (female or castrated male). At slaughter they experienced different stress conditions. The proportion of gene expression changes influenced by treatment factors was consistent with the proportion of protein changes in an earlier proteomic analysis of the same pigs. Expression levels of genes were often correlated. Gene expression was generally not correlated with the levels of the corresponding protein. Finally, most meat quality traits were correlated with the expression of at least one of the studied genes. The most meaningful of these was the association of a slower pH decline with lower levels of HSP72 expression and higher levels of HSP72 protein. ANXA2 and cMDH expression were also associated with various meat quality traits. These relationships may be related to pre-slaughter stress levels and fibre type composition.     

In vivo body composition in autochthonous and conventional pig breeding groups by dual-energy X-ray absorptiometry and magnetic resonance imaging under special consideration of Cerdo Ibérico

The improvement of carcass quality is one of the main breeding goals in pig production. To select appropriate breeding animals, it is of major concern to exactly and reliably analyze the body composition in vivo. Therefore, the objective of the study was to examine whether the combination of dual-energy X-ray absorptiometry (DXA) and magnetic resonance imaging (MRI) offers the opportunity to reliably analyze quantitative and qualitative body composition characteristics of different pig breeding groups in vivo. In this study, a total of 77 pigs were studied by DXA and MRI at an average age of 154 days. The pigs originated from different autochthonous or conventional breeds or crossbreeds and were grouped into six breed types: Cerdo Ibérico (Ib); Duroc × Ib (Du_Ib); White Sow Lines (WSL, including German Landrace and German Large White); Hampshire/Pietrain (Pi_Ha, including Hampshire, Pietrain × Hampshire (PiHa) and Pietrain × PiHa); Pietrain/Duroc (Pi_Du, including Pietrain × Duroc (PiDu) and Pietrain × PiDu); crossbred WSL (PiDu_WSL, including Pietrain × WSL and PiDu × WSL). A whole-body scan was performed by DXA with a GE Lunar DPX-IQ in order to measure the amount and percentage of fat tissue (FM; %FM), lean tissue (LM; %LM) and bone mineral, whereas a Siemens Magnetom Open with a large body coil was used for MRI in the thorax region between 13th and 14th vertebrae in order to measure the area of the loin (LA) and the above back fat area (FA) of both body sides. A GLM procedure using SAS 9.2 was used to analyze the data. As expected, the native breed Ib followed by Du_Ib crossbreeds showed the highest %FM (27.2%, 25.0%) combined with the smallest LA (46.2 cm², 73.6 cm²), whereas Ib had the lowest BW at an average age of 154 days. Pigs with Pi_Ha origin presented the least %FM (12.4%) and largest LA (99.5 cm²). The WSL and PiDu_WSL showed an intermediate body composition. Therefore, it could be concluded that DXA and MRI and especially their combination are very suitable methods to reliably identify differences in body composition and carcass traits among different pig lines in vivo.     

Pancreatic secretion differs according to the genotype of growing pigs.

The objective of this study was to investigate the secretion of pancreatic enzymes and antibacterial activity in weaned pigs of three pure breeds, Pietrain, Duroc and Polish synthetic line 990, to look for eventual differences related to the genotype. Six male pigs of each breed, about 24 kg mean body weight, were equipped with chronic pancreatic duct catheters and duodenal cannulas to assess pure pancreatic juice, and jugular vein catheters for blood withdrawal. Pancreatic juice was collected before and after the morning feeding. Protein output and enzyme activities revealed two distinct profiles: strong manifestation of the prandial phase in Pietrain and line 990 pigs, and weak manifestation in Duroc. The antibacterial activity did not follow the enzyme kinetics, and it was the strongest in pancreatic juice from Pietrain pigs. Postprandial insulinaemia was reduced in the order of: line 990>Pietrain>Duroc. A slight (not significant) tendency towards a reduction of leptin after feeding in synthetic line 990 corresponded with elevated secretion of pancreatic enzymes and plasma insulin. The presented results suggest that the prandial secretion of pancreatic juice differs according to genotype, and the differences may be in part related to release of insulin.     

Identification of mitochondrial markers for genetic traceability of European wild boars and Iberian and Duroc pigs

Iberian pigs and wild boars are the source of highly priced meat and dry-cured products. Iberian maternal origin is mandatory for labeled Iberian products, making necessary the authentication of their maternal breed origin. Discrimination between wild and domestic pig maternal origin may be useful to distinguish labeled wild boar meat obtained from hunting or farming. In order to detect useful polymorphisms to trace Iberian, Duroc and wild boar maternal lineages, we herein investigated the complete porcine mitochondrial DNA (mtDNA) using three complementary approaches. Near-complete mtDNA sequences (16989 bp), excluding the minisatellite present in the displacement loop region (D-loop), were successfully determined in six Iberian pigs, two Duroc and six European wild boars. To complete the mtDNA analysis, the D-loop minisatellite region was also analyzed in the same set of samples by amplification and capillary electrophoresis detection. Finally, the frequencies of Asian and European Cytochrome B (Cyt B) haplotypes were estimated in Iberian (n = 96) and Duroc (n = 125) breeds. Comparison of near-complete mtDNA sequences revealed a total of 57 substitutions and two Indels. Out of them, 32 polymorphisms were potential Iberian markers, 10 potential Duroc markers and 16 potential wild boar markers. Fourteen potential markers (five Iberian and nine Duroc), were selected to be genotyped in 96 Iberian and 91 Duroc samples. Five wild boar potential markers were selected and tested in samples of wild boars (73) and domestic pigs including: 96 Iberian, 16 Duroc, 16 Large White and 16 Landrace. Genotyping results showed three linked markers (m.7998C>T, m.9111T>C, m.14719A>G) absent in Duroc and present in Iberian pigs with a frequency 0.72. Six markers (m.8158C>T, m.8297T>C, m.9230G>A, m.11859A>G, m.13955T>C, m.16933T>C), three of them linked, were absent in Iberian pigs and present in Duroc with a joint frequency of almost 0.50. Finally three linked markers (m.7188G>A, m.9224T>C, m.15823A>G) were solely detected in wild boars with a frequency 0.22. The D-loop minisatellite results showed overlapping ranges of fragment sizes and suggested heteroplasmy, a result that nullify the use of this region for the development of breed diagnostic markers. The Cyt B haplotype results showed the presence of European haplotypes in Iberian while one of the Asian haplotypes was detected in Duroc with a frequency 0.22, linked to the Duroc marker m.9230G>A. Our results are valuable to resolve the problems of Iberian and wild boar maternal origin determination but additional markers are required to achieve totally useful genetic tests.     

SNP variation in the promoter of the PRKAG3 gene and association with meat quality traits in pig

ABSTRACT: BACKGROUND: The PRKAG3 gene encodes the gamma3 subunit of adenosine monophosphate activated protein kinase (AMPK), a protein that plays a key role in energy metabolism in skeletal muscle. Nonsynonymous 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. RESULTS: PRKAG3 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. CONCLUSION: Gene 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.     

Relationship between carcass weight, adipose tissue androstenone level and expression of the hepatic 3β-hydroxysteroid dehydrogenase in entire commercial pigs

Boar taint is a major meat-quality defect in pigs and is due to excessive accumulation of skatole and androstenone in adipose tissue. The present work investigated the relationship between carcass weight, levels of skatole and androstenone in adipose tissue, and expression of the hepatic androstenone-metabolising enzyme 3β-hydroxysteroid dehydrogenase (3β-HSD), in 22 entire male and 22 entire female crossbred pigs (Large White (40%) × Landrace (40%) × Duroc (20%)). Animals of each gender were divided into two subgroups (11 pigs in each subgroup): (i) conventional weight (carcass weight 59 to 77 kg) and (ii) heavy weight (carcass weight 84 to 95 kg). No relationship between carcass weight and adipose tissue skatole level was found for entire male pigs (r2 = 0.013, P > 0.05). There was a significant negative relationship between carcass weight and expression of the hepatic 3β-HSD protein (r2 = 0.502, P < 0.001) and a significant negative relationship between 3β-HSD protein expression and androstenone level in adipose tissue (r2 = 0.24, P < 0.05) in entire males. No relationship was found between carcass weight and 3β-HSD protein expression in female pigs (r2 = 0.001, P > 0.05). 3β-HSD expression was 59% higher in conventional-weight male pigs when compared with heavy-weight animals (P < 0.05) and 36% higher in heavy-weight females when compared with heavy-weight males (P < 0.05). It is concluded that an increase in slaughter weight of entire commercial crossbred Large White pigs is accompanied by inhibition of expression of the hepatic 3β-HSD protein, which might result in a reduced rate of hepatic androstenone clearance with its subsequent accumulation in adipose tissue. It is suggested that regulation of pig hepatic 3β-HSD expression is under the control of sex hormones.     

Influence of breed and slaughter weight on boar taint prevalence in entire male pigs

Piétrain (P), Large White (LW) and Belgian Landrace stress negative (BN) boars were slaughtered at 50, 70, 90 or 110 kg live weight to investigate breed differences and the effect of slaughter weight on boar taint prevalence. Boar taint was quantified by four different methodologies: sensory evaluation of neckfat heated with a hot iron in the slaughterhouse, sensory evaluation of meat by consumer panels, sensory evaluation of fat and meat by expert panels and laboratory analysis of indole, skatole and androstenone in backfat. Skatole levels in backfat were significantly higher for LW and BN than for P boars. The androstenone levels and the hot iron method revealed a significant interaction between breed and slaughter weight. On the other hand, experts detected an effect of weight on the androstenone odour perception, which was significantly higher in fat from boars slaughtered at 90 kg compared with 50 kg, and significantly higher in meat from boars slaughtered at 110 kg compared with 50 kg. Consumers did not detect differences in the sensory characteristics among breeds or slaughter weight. These results indicate opportunities to minimise the risk of boar taint in entire male pigs by carefully selecting a combination of breed and slaughter weight. Along with the optimal slaughter weight, the effectiveness of reducing boar taint by lowering slaughter weight appeared to be breed dependent.     

Association of restriction fragment length polymorphisms of swine leucocyte antigen class I genes with production traits of Duroc and Hampshire boars

Restriction fragment length polymorphism analyses of swine leucocyte antigen (SLA) class I genes were performed on 70 Duroc and 38 Hampshire boars from the 1986-87 national performance tests of each breed in the USA. Few boars were inbred. Southern blotting and hybridization procedures were performed on genomic DNA, isolated from white blood cells, using PvuII endonuclease and a swine major histocompatibility complex (MHC) class I probe. Durocs had an average of 11 restriction fragments, with the most common being in 63% of the boars and the least common appearing in only one boar. Hampshire boars had an average of 12 restriction fragments, with the most common appearing in 73% of the boars and the least common appearing in only one boar. Least squares procedures and stepwise regression methods were used to examine the association between DNA restriction fragments and the selection index (INDEX), average daily gain (ADG), average backfat thickness (BF), loin muscle area (LEA), and age at 104 kg (DAY104). In the Duroc breed one DNA restriction fragment was associated with decreased INDEX (P less than 0.05) and decreased ADG (P less than 0.05) whereas two other fragments were associated with increased BF (P less than 0.05). In the Hampshire breed two restriction fragments were associated with an increase in INDEX (P less than 0.05). Cluster analyses were used to group pigs of each breed on the basis of similar RFLP patterns. One cluster group in the Duroc breed was associated with lower average INDEX values (P less than 0.05), greater average DAY104 (P less than 0.05), and a larger mean LEA (P less than 0.05). In the Hampshire breed one cluster group was associated with lower INDEX (P less than 0.05). These results suggest there may be an association between swine MHC class I genes and performance traits in swine. The use of SLA class I restriction fragments, as genetic markers, may have potential in the future for improving pig performance.     

Association of restriction fragment length polymorphisms of swine leucocyte antigen class I genes with production traits of Duroc and Hampshire boars

Summary. Restriction fragment length polymorphism analyses of swine leucocyte antigen (SLA) class I genes were performed on 70 Duroc and 38 Hampshire boars from the 1986-87 national performance tests of each breed in the USA. Few boars were inbred. Southern blotting and hybridization procedures were performed on genomic DNA, isolated from white blood cells, using Pvu II endonuclease and a swine major histocompatibility complex (MHC) class I probe. Durocs had an average of 11 restriction fragments, with the most common being in 63% of the boars and the least common appearing in only one boar. Hampshire boars had an average of 12 restriction fragments, with the most common appearing in 73% of the boars and the least common appearing in only one boar. Least squares procedures and stepwise regression methods were used to examine the association between DNA restriction fragments and the selection index (INDEX), average daily gain (ADG), average backfat thickness (BF), loin muscle area (LEA), and age at 104kg (DAY104). In the Duroc breed one DNA restriction fragment was associated with decreased INDEX ( P < 0.05) and decreased ADG ( P < 0.05) whereas two other fragments were associated with increased BF ( P < 0.05). In the Hampshire breed two restriction fragments were associated with an increase in INDEX ( P < 0.05). Cluster analyses were used to group pigs of each breed on the basis of similar RFLP patterns. One cluster group in the Duroc breed was associated with lower average INDEX values ( P < 0.05), greater average DAY104 ( P < 0.05), and a larger mean LEA ( P < 0.05). In the Hampshire breed one cluster group was associated with lower INDEX ( P < 0.05). These results suggest there may be an association between swine MHC class I genes and performance traits in swine. The use of SLA class I restriction fragments, as genetic markers, may have potential in the future for improving pig performance.     

SIM1基因第8外显子的SNP对猪背膘厚的影响

采用PCR-SSCP方法检测了约克夏、杜洛克、皮特兰、长白猪、嘉兴黑猪和金华猪6个品种共169头猪的SIM1基因外显子8的SNP及其基因型频率。结果共发现CC、CT、TT 3种基因型, 其基因型频率在国内外猪品种之间具有较大差异。其中, 国内猪种嘉兴黑猪和金华猪只存在TT基因型, 而国外猪种约克夏、杜洛克、皮特兰、长白猪则都存在3种基因型。用最小二乘法分析SNP对长白猪、约克夏猪和杜洛克猪的背膘厚的效应的结果表明, 纯合基因型个体的背膘厚大于杂合基因型个体。SIM1基因型对国外猪种背膘厚有显著效应(P< 0.05), 并且不同部位效应不同。