ANALIZA MASY CIAŁA RÓZNYCH ODMIAN BARWNYCH NORKI AMERYKA ˙ NSKIEJ ´ (NEOVISON VISON) ORAZ OCENA ZALEZNO ˙ SCI POMI ˛EDZY MAS ˛A CIAŁA SAMIC ´ A UZYSKIWANYMI WSKAZNIKAMI ROZRODU

Abstract

The aim of the study was to analyze the body weight of different color varieties of breeding mink and to assess the relationship between the body weight of females and the reproductive indexes obtained. The research material consisted of 3499 one-year-old American mink females of five color varieties: White Regal, Standard Black, Pearl, Silverblue and Black Cross. Six body-weight ranges of female mink were distinguished. The following were analyzed within each range: pregnancy length, fertility, average number of kits born in a litter, average number of kits born alive in a litter. It was also examined whether there was a relationship between the color variety and the average body weight of females attained during the pre-mating body condition adjustment. There were statistically significant differences in the body weight of the analyzed color varieties of mink. It was also found that the body weight of females obtained in the period of breeding preparation influences the resulting reproductive performance. Higher body weight positively influences fertility, while animals of an average body weight produce larger litters of kits.