Large mink dams tend to produce smaller litters and fewer weaned kits. This is a dilemma for the mink farmer since both size and fertility are important breeding goals.

The larger the mink, the larger the fur it delivers as the end product. A good-sized mink skin results in an improved price to the mink farmer, so size is an important breeding goal.

Unfortunately, size also matters in a negative way: Large mink dams have reduced fertility. These are the results of a study carried out by scientists from the Department of Genetics and Biotechnology at the Faculty of Agricultural Sciences, University of Aarhus.

Their calculations show that there is a negative correlation between female kit body weight in October on the one hand and her ensuing litter size and her kits’ survival rate on the other hand. In other words, large dams produce fewer kits.

- These results count for both mink and foxes that, as time has passed, have become larger and larger as the result of purposive breeding. At the same time, the animals are fed as though all of them will be pelted without differentiating between potential breeding stock and regular production animals. That is probably the most important reason for the lack of increase in litter size despite it being part of the breeding goal, says academic employee Bente Krogh Hansen, Department of Genetics and Biotechnology.

- Perhaps the degree of fatness of the animals is the reason for the problem. Exactly how it works is something we would like to investigate, says Bente Krogh Hansen.

Mink kits increase in body length until around September after which their growth mainly consists of putting on fat. When they are selected for breeding purposes it is on the basis of litter size, fur quality and body size. Since it is their body weight in November that is measured, both body length and fatness contribute to the result.

The results of the studies will be presented at a meeting about mink and the new fur animal departmental order on 18 September 2007 at the Faculty of Agricultural Sciences, Research Centre Foulum (in Danish). The programme, also in Danish, can be found at the faculty website www.agrsci.dk .

For more information please contact: Academic employee Bente Krogh Hansen, Department of Genetics and Biotechnology, Faculty of Agricultural Sciences, University of Aarhus, telephone: +45 8999 1337, e-mail: BenteK.Hansen@agrsci.dk

Text: Janne Hansen

Photo: Jesper Clausen