Studies of the Genetic Background of a Teat Defect in Pigs Born in Germany and Sweden

E. Jonas¹, H. Chalkias¹, C. Neuhoff², G. Lindgren¹ and D.J. de Koning¹

¹Swedish University of Agricultural Sciences, Uppsala, ²Institute of Animal Sciences, University of Bonn, Germany

Selection of pigs uses many aspects, such as growth and meat quality. But it is also very important that many piglets are born alive. Litter size is included in the breeding goal of breeding organizations in many countries, including Sweden and Germany. But piglets need, to survive and grow, enough milk, especially colostrum in the first hours after birth. All pigs must have access to their own functioning teat to reduce the risk of not receiving colostrum.

A few years ago had researchers in Germany the goal to find genetic markers to select sows without inverted teat (mammillae invertitae). This defect was also studied in Sweden. The goal of the study in Sweden was to estimate the prevalence (occurrence) and heritability for inverted teat. Both studies analyzed the effects of individual genetic markers.
We apply a combined association analysis using SNP chip data from Swedish Yorkshire pigs and microsatellite data from the German maternal parental lines. A combined study should help to find the significant connection with the inverted teat or functional teats. Information from 130 families of German pigs (one pig with inverted and one sibling without defect and both parents) and 230 siblings of Swedish pigs (one with and one without defect) were collected. Samples were genotyped (microsatellites and SNPs) in previous investigations and analyzed. Combining this information enable us to perform analysis based on haplotypes for some of the chromosomes. Associations on chromosomes 1, 4, 6, 11, 14 and 18 have been found.
This study is particularly interesting as we can show how to use ' old ' data sets and combine these with the ' new ' data sets to increase the power of finding relevant genomic markers in combined association studies. This or a similar method can be used if grants for the genotyping of more animals are not available.