Improvement of Reproduction in Scanblack Mink

Scanblack and wildtype have identical colour-genotypes. But scanblack have one kit less per litter than wildtype.
The aim of the presented experiment was to investigate:
1) The possibility of creating a scanblack line with the same good reproduction as wildtype by crossing scanblack and wildtype followed by selection within the cross-line?
2) The difference between reproduction result depending on whether the male is scanblack or wildtype.