Summary Three informative pig F2 families based on European Wild Boar (W), Meishan (M) and Pietrain (P) crosses have been used for genome‐wide linkage and quantitative trait loci (QTL) analysis. Altogether 129 microsatellites, 56 type I loci and 46 trait definitions (specific to growth, fattening, fat deposition, muscling, meat quality, stress resistance and body conformation) were included in the study. In the linkage maps of M × P, W × P and W × M families, average spacing of markers were 18.4, 19.7 and 18.8 cM, the numbers of informative meioses were 582, 534 and 625, and the total lengths of autosomes measured were 27.3, 26.0 and 26.2 Morgan units, respectively. Maternal maps were on average 1.3 times longer than paternal maps. QTLs contributing more than 3% of F2 phenotypic variance could be identified at p < 0.05 chromosome‐wide level. Differences in the numbers and positions of QTLs were observed between families. Genome‐wide significant QTL effects were mapped for growth and fattening traits on eight chromosomes (1, 2, 4, 13, 14, 17, 18 and X), for fat deposition traits on seven chromosomes (1, 2, 3, 4, 6, 7 and X), for muscling traits on 11 chromosomes (1, 2, 3, 4, 6, 7, 8, 12, 14, 15 and X), for meat quality and stress resistance traits on seven chromosomes (2, 3, 6, 13, 16, 18 and X), and QTLs for body‐conformation traits were detected on 14 chromosomes. Closely correlated traits showed similar QTL profiles within families. Major QTL effects for meat quality and stress resistance traits were found on SSC6 in the interval RYR1‐A1BG in the W × P and M × P families, and could be attributed to segregation of the RYR1 allele T derived from Pietrain, whereas no effect in the corresponding SSC6 interval was found in family W × M, where Wild Boar and Meishan both contributed the RYR1 allele C. QTL positions were mostly similar in two of the three families for body conformation traits and for growth, fattening, fat deposition and muscling traits, especially on SSC4 (interval SW1073‐NGFB). QTLs with large effects were also mapped on SSC7 in the major histocompatibility complex (MHC) (interval CYP21A2‐S0102) and affected body length, weight of head and many other traits. The identification of DNA variants in genes causative for the QTLs requires further fine mapping of QTL intervals and a positional cloning. However, for these subsequent steps, the genome‐wide QTL mapping in F2 families represents an essential starting point and is therefore significant for animal breeding.

MYOG and MYF6 belong to the MyoD gene family. They code for the bHLH transcription factors playing a key role in later stages of myogenesis: differentiation and maturation of myotubes. Three SNPs in porcine MYF6 and two in porcine MYOG were analysed in order to establish associations with chosen carcass quality and growth rate traits in Polish Landrace, Polish Large White and line 990 sows. No statistically significant effect of SNP in the promoter region of the MYF6 gene on its expression measured on mRNA level was found. Associations between the genotype at the MYF6 locus and carcass quality traits appeared to be breed-dependent. The C allele in the case of SNP in the promoter region and GC haplotype in exon 1 were advantageous for right carcass side weight in Polish Landrace sows and disadvantageous for this trait in Polish Large White sows. These gene variants were also the most advantageous for loin and ham weight in sows of line 990. The mutation in exon 1 of the MYOG gene had no statistically significant association with carcass quality traits and the mutation in the 3'-flanking region had the breed-dependent effect as well. These results suggest that SNPs analysed in this study are not causative mutations, but can be considered as markers of some other, still unrevealed genetic polymorphism that influences the physiological processes and phenotypic traits considered in this study.

The aim of the study was to evaluate the relations between genotype effects at porcine loci MYF3, MYF4, MYF5 and MYF6 on meat quality traits in pigs of the CC genotype at the RYR1 locus. Meat traits were analysed in longissimus lumborum muscle in 98 pigs (75 of PLW´PL and 25 [PLW´PL]´Pietrain crosses). The determined meat characteristics covered the pH 1 and pH u records, visual assessment of colour and exudation on fresh meat samples, water holding capacity, drip loss, spectrophotometric measurements of dominant wavelength, colour saturation and lightness, L, a*, b* values according to the CIE system, basic chemical constituents (water, protein, intramuscular fat and ash) and soluble protein fraction in meat. The distribution of animals within particular MyoD genotypes only in the MYF4 and MYF5 genotypes were spread uniformly. The gene effects at particular MyoD loci on studied meat traits were significant. The most pronounced effect on meat quality was exerted by the myogenin gene (MYF4). Individuals of the BB genotype in respect to the MYF4 locus showed a better water holding capacity (P<0.01), lower drip loss (P<0.05), darker colour score (P<0.01) and better wateriness score (P<0.01), darker and more desirable colour characteristic (P<0.01) than pigs with the AA genotype, whereas AB genotype animals had intermediate values. In respect to meat protein solubility the AA genotype pigs had a significantly lower level of soluble protein in meat than AB and BB (P<0.01). On basis of the present study it may be inferred that mutations in coding and the non-coding regions of MyoD genes exert significant effects on muscle traits related to oxidative metabolism, as well as related to glycolysis and contractile muscle properties, and thereby on meat quality.

The objective of this study was to determine hepatic expression levels of GHR, IGF1R, IGF1 and IGF2 genes in young growing gilts at different developmental ages (60-210 days) in five pig breeds: Polish Large White (PLW), Polish Landrace (PL), Pulawska (Pul), Duroc (Dur) and Pietrain (Pie). We studied the differences among pig breeds as well as within each breed for pigs in different developmental ages. Obtained results revealed major differences among breeds in hepatic gene expression of porcine GHR, IGF1R, IGF1 and IGF2 genes in different developmental ages. The differences among breeds of GHR expression were significantly higher in PLW, PL at the age of 60, 90, 120 days as compared to Pul, Dur and Pie. In turn, the highest level of IGF1R expression was observed in PL at age of 150, 180 and 210 days, whereas in case of IGF1 the highest level was recorded in Pie gilts at the age of 60 and 90 days. Moreover trait associated study revealed highly significant correlations between hepatic expressions of IGF1R and IGF2 genes and carcass composition traits (P < 0.01) The results of study suggest that porcine GHR, IGF1R, IGF1 and IGF2 genes may be potential candidate genes for postnatal growth and carcass composition traits. Therefore, the implementation of the hepatic expression of GH/IGF genes into the pig breeding and gene assisted selection program in different pig breeds should be considered. However, further population wide study is needed to clarify the hepatic expression association with economic traits, such as body growth, meat quality and carcass composition traits.

The aim of this study was to analyse the effect of polymorphism of calpastatin (CAST) and RYR1 genes for some meat quality traits taking into consideration the group of meatiness and their mutual interactions. Investigations were carried out on a group of 201 fatteners which were crosses of four breeds. The results obtained show that CAST/MspI genotype has an effect close to the major effect for drip loss from LL muscle tissue at 48 h as well as at 96 h postmortem (0.92 and 0.96 SD respectively). Among the meat quality traits analysed and that were affected by CAST/MspI genotype, the animals with BB genotype at this locus were characterized by the most profitable values of all these traits. Significant interactions between CAST and RYR1 genotypes observed indicate that the quality of meat influenced by RYR1 genotype may be modified by the simultaneous influence of genotype as regards the CAST locus.

No abstract

No abstract

No abstract