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Linkage maps of Sus scrofa chromosome 1 (SSC1) have been produced using 10 markers in three different F2 families based on crosses of Meishan (M), Pietrain (P) and Wild Boar (W). The maps were similar for the different families and show higher paternal recombination, especially in the interval SW2130-SW803. Quantitative trait loci (QTLs) affecting body conformation, carcass composition, fat deposition and numbers of teats were identified in all three families. Major QTLs were mapped in chromosomal intervals centred at approximately 60, 120 and 170 cM. The QTLs explain up to 8.4% of phenotypic variance in the F2 generation. Pietrain QTL alleles were superior in comparison with Wild Boar andMeishan alleles for most of the trait values. Meishan alleles were associated with highest fat deposition. Additive gene effects were generally larger than dominance effects. QTL profiles on SSC1 differed between families, with the W x P family being most distinct. [ABSTRACT FROM AUTHOR]

Linkage maps have been constructed for Sus scrofa chromosome 6 (SSC6) based on 17 markers, of which 10 were used in all three F2 families of Wild Boar (W), Meishan (M) and Pietrain (P) crosses. The coverage of the linkage maps of SSC6 was almost complete. All loci were ordered identically in the families, but two intervals (RYR1-A1BG-EAH, S0146-S0003-SW824) differed from published maps. Major quantitative trait loci (QTLs) for meat quality, stress resistance and carcass composition explaining up to 59% of F2 phenotypic variance have been mapped in the M x P and W x P families centred on the segregating R YR1 T and C alleles. In the W × M family, which was homozygous for the RYR1 C allele, no QTL effects for meat quality and stress-resistance, but moderate effects for carcass composition have been observed in this region. These findings indicate further loci closely linked with the RYR1 or/and further alleles at the RYR1 locus, involved in the variation of carcass and growth traits. [ABSTRACT FROM AUTHOR]

Linkage maps of Sus scrofa chromosome 7 (SSC7) for three informative F2 families, based on Wild Boar (W), Meishan (M) and Pietrain (P) crosses, were constructed using 16 marker loci. Maps were consistent for the families, except the order of the markers PI2-PO1A-S0212 in the W × M family which was inverted in the M x P and W x P families. Important quantitative trait loci (QTLs) were localized in the region of the SLA complex in the M x P and W × M families. These explained up to 16% of F2 phenotypic variance for body conformation, fat deposition and muscling. In the W × P family, minor QTLs were mapped outside the SLA region. The highly significant QTL alleles were mainly additive (a > d). The Meishan alleles for QTL located in the SLA region were associated with higher head weights and carcass lengths, but with lower carcass fat contents than those from Wild Boar and Pietrain. The cryptic Meishan QTL allele, which reduces carcass fat, provides one of the first examples of transgressive segregation in animals and emphasizes that usefulgenetic variation can be hidden in the genetic background of a breed. [ABSTRACT FROM AUTHOR]

Linkage maps of Sus scrofa chromosome 4 (SSC4) based on 19 markers were similar in lengths for three F2-families [Wild Boar (W), Meishan (M) and Pietrain (P) crosses] and in agreement with the previously published maps. Quantitative trait loci (QTLs) on SSC4 affect mainly muscle and fat mass. Compared with others, Pietrain alleles were associated with longer carcass, higher body weight and higher meat content. In all three families, the profiles of F ratio values for these traits showed peaks close to the positions of candidate genes V-ATPase, ATP1A2 and ATP1B1. Additional more proximally mapped QTLs, significant at the p < 0.05 chromosome-wide level, were found in the M x P and W x P families. The W × M family revealed highly significant QTLs located in the vicinity of AMPD1 and NGFB. The SSC4 QTLs explained up to 12% of F2 phenotypic variance. [ABSTRACT FROM AUTHOR]