Analyse des Einflusses der gewählten Faktoren auf die Wurfgröße bei Nerzen mit Berücksichtigung verschiedener Farbschläge (Kurzmitteilung)
Abstract. Title of the paper: Analyze of effect selected indices on litter size of minks in relation to colour variety (short communication)
The studies were carried out in 2003–2004 on a farm located in West Pomerania, Poland, with an annual production output exceeding 75,000 pelts. The breeding stock comprised 25,000 females and 4,000 males, managed in genetic groups comprising 40 females related to each other and 8 males related to each other, For the experiments, we selected at random 1769 females in 7 colour varieties: Black Cross, Buff Sapphire, Perl, Sapphire, Sprinkler, Scan Black, and Scan Brown. The following reproduction indices were analysed: litter size at birth and at weaning, litter size in relation to number of services and birth date. Moreover, all the indices were estimated in relation to the year of the female's reproduction management. The Buff Sapphire proved to be the most fertile variety, and produced 7.6 born and 7.3 weaned offspring. This result was tested statistically and the differences were highly significant compared to the Sapphire, Sprinkler, and Black Cross, which yielded 6.4–6.5 born and 5.9–6.3 weaned offspring. In the second year of reproduction management, all the varieties but Sapphire exhibited increased number of litters. The date of birth significantly affected litter size; the largest litters were obtained in the 16th week of year.