L. Andersson-Eklund

A paternally expressed QTL affecting skeletal and cardiac muscle mass in pigs maps to the IGF2 locus.

A paternally expressed QTL affecting skeletal and cardiac muscle mass in pigs maps to the IGF2 locus

Fine-mapping QTL for mastitis resistance on BTA9 in three Nordic red cattle breeds.

A QTL affecting clinical mastitis and/or somatic cell score (SCS) has been reported previously on chromosome 9 from studies in 16 families from the Swedish Red and White (SRB), Finnish Ayrshire (FA) and Danish Red (DR) breeds. In order to refine the QTL location, 67 markers were genotyped over the whole chromosome in the 16 original families and 18 additional half-sib families. This enabled linkage disequilibrium information to be used in the analysis. Data were analysed by an approach that combines information from linkage and linkage disequilibrium, which allowed the QTL affecting clinical mastitis to be mapped to a small interval (<1 cM) between the markers BM4208 and INRA084. This QTL showed a pleiotropic effect on SCS in the DR and SRB breeds. Haplotypes associated with variations in mastitis resistance were identified. The haplotypes were predictive in the general population and can be used in marker-assisted selection. Pleiotropic effects of the mastitis QTL were studied for three milk production traits and eight udder conformation traits. This QTL was also associated with yield traits in DR but not in FA or SRB. No QTL were found for udder conformation traits on chromosome 9.

Fine mapping of quantitative trait loci for mastitis resistance on bovine chromosome 11

Quantitative trait loci (QTL) affecting clinical mastitis (CM) and somatic cell score (SCS) were mapped on bovine chromosome 11. The mapping population consisted of 14 grandsire families belonging to three Nordic red cattle breeds: Finnish Ayrshire (FA), Swedish Red and White (SRB) and Danish Red. The families had previously been shown to segregate for udder health QTL. A total of 524 progeny tested bulls were included in the analysis. A linkage map including 33 microsatellite and five SNP markers was constructed. We performed combined linkage disequilibrium and linkage analysis (LDLA) using the whole data set. Further analyses were performed for FA and SRB separately to study the origin of the identified QTL/haplotype and to examine if it was common in both populations. Finally, different two-trait models were fitted. These postulated either a pleiotropic QTL affecting both traits; two linked QTL, each affecting one trait; or one QTL affecting a single trait. A QTL affecting CM was fine-mapped. In FA, a haplotype having a strong association with a high negative effect on mastitis resistance was identified. The mapping precision of an earlier detected SCS-QTL was not improved by the LDLA analysis because of lack of linkage disequilibrium between the markers used and the QTL in the region.

Genetic analyses of pathogen-specific mastitis.

The aims of this study were to investigate the presence of genetic variation for susceptibility to pathogen-specific mastitis and to examine whether haplotypes of an identified quantitative trait locus with effect on unspecific mastitis resistance had different effects on specific mastitis pathogens. Bacteriological data on mastitis pathogens were obtained from the diagnostic laboratory at the Swedish National Veterinary Institute. The data were mainly from subclinical cases of mastitis but also clinical cases were included. Variance components were estimated for incidence of the six most frequent pathogens using Markov Chain Monte Carlo methodology via Gibbs sampling. Genetic variation for susceptibility to pathogen-specific mastitis was higher compared to estimates of general resistance to clinical mastitis in most other studies. However, because of the non-random nature of data collection, comparisons to other studies should be made by caution. The effect of haplotype on the risk of being infected by a given mastitis pathogen, relative to other pathogens, was studied using an allele substitution model. Although there were no significant haplotype substitution effects on the resistance to any of the six mastitis pathogens, there was a significant difference between the effects of two of the haplotypes regarding the risk of acquiring a Streptococcus dysgalactiae infection.

Association of the transferrin locus on chromosome 13 with early body weights in pigs

SUMMARY The effect of the genotypes of five different blood protein loci (α1B-glycoprotein, A1BG; glucose phosphate isomerase, GPI; phosphogluconate dehydrogenase, PGD; postalbumin 1A, PO1A; transferrin, TF) on early body-weight traits was studied in one large population of Swedish Yorkshire breed pigs. A highly significant association was observed, between the transferrin genotypes and the piglet body weights, at 6 and 9 weeks of age. The TF BB type pigs were heavier than those of TF AB types at 3, 6, and 9 weeks of age, by 130, 340, and 370 g, respectively. In the light of previously published data, it was discussed that TF is an additional chromosome 13 marker that may affect early body weights in pigs. The other four loci studied, located on chromosomes 6 and 7, did not show any significant effect. ZUSAMMENFASSUNG: Zusammenhänge zwischen Transferrinlocus an Chromosom 13 und Ferkelgewichten Die Wirkung von fünf verschiedenen Blutproteinloci (αB-Glykoprotein, A1BG; Glukose Phosphat Isomerase, GPI; Phosphoglukonat Dehydrogenase, PGD; Postalbumin 1A, PO1A; Transferrin, TF) auf Ferkelwichte wurde bei Schwedischen Yorkshire Schweinen untersucht. Der Zusammenhang zwischen Transferrin Genotypen und 6 und 9 Wochen Gewichten war hochsignifikant, TF BB Ferkel waren bei 3, 6 und 9 Wochen Alter um 130, 340 und 370 g schwerer als TF AB Ferkel. In zusammenhang mit früheren Studien wird TF als ein weiterer Chromosom 13 Marker für Ferkelgewicht erörtert. Die anderen vier Loci an Chromosomen 6 bzw. 7 zeigten keine signifikante Wirkung.