Topigs Norsvin is breeding two synthetic dam lines. The origin of the TN60 line is the Yorkshire/Large White breed. The origin of the TN70 line is the Norsvin Landrace and the Yorkshire/Large White breed. The TN60 sow is used in countries where less emphasis is paid on lean meat and the focus is on a premium meat quality. The TN70 sow is use in countries with more emphasis on lean meat and extra meat quality.
A dam line consists of more than 2,000 great-grandparents (GGPS) and grandparent sows (GPS) distributed in minimally 2 herds. Those animals are tested for fertility, robustness, longevity, and maternal traits and produce over 26,000 gilts that are performance tested for growth traits and carcass composition, and relevant selection candidates are genotyped. The sow replacement rate is about 150% at the GGPs level, which significantly reduces generation interval. Male selection candidates from litters with a high selection index are selected and genotyped to preselect the highest indexing boars to the Delta central performance test station. Annually, about 60 GGP boars are selected with a high intensity out of the 2500 boars yearly and are performance tested at feed stations and CT scanned. Besides information from the nucleus, data is collected from sows in multiplication herds and commercial crossbred parent sows to also provide additional information on fertility and stayability for selecting the nucleus animals.