Heterosis and genetic variation in the litter size of purebred and crossbred mink.
Crosses between different mink lines from 3 Danish mink farms that use different breeding strategies were studied to estimate heterosis and variance components for litter size. The study was designed to analyze crosses between lines of the same color type, between different color types, and between animals originating from different farms. Effect of heterosis, color type, and variance components were estimated using Average information REML (AI-REML) algorithm implemented in the DMU package for analyzing multivariate mixed models. Females from 7 generations that gave birth to at least 1 offspring were analyzed and the effects of parity and production year were included in the analyses. Genetic trend and the proportions of the total variance explained by the effects of additive genetics (h2), common environment (due to repeated litters from the same female; c2), and dam of the female (granddame of the born litter; d2) were estimated. The results showed that mink of the Black color type potentially produced smaller litters compared to mink of the other studied color types. We found significant general maternal effect of heterosis for litter size. Analyses of specific heterosis showed a significant positive effect of crossing between lines of the same color type. Estimates of variance components revealed h2 levels for farm A, B, and C of 0.15, 0.06, and 0.09, respectively; thus litter size could be selected for in the future. The effect of common environment on litter size was also considerable, with c2 values of 0.005, 0.11, and 0.15 at farms A, B, and C, respectively. In conclusion, we recommend genetic selection as a means of increasing litter size in farmed mink.
Institute for Molecular Biology and Genetics, Faculty of Science and Technology, Aarhus University, 8830 Tjele, Denmark Janne.Thirstrup@agrsci.dk.
J P
JP
Thirstrup
Kopenhagen Research, Agro Food Park 15, 8200 Aarhus, Denmark.
P F
PF
Larsen
Department of Biotechnology, Chemistry and Environmental Engineering- Section of Biology and Environmental Science, Aalborg University, 9000 Aalborg, Denmark Aalborg Zoo, 9000 Aalborg, Denmark.
C
C
Pertoldi
Institute for Molecular Biology and Genetics, Faculty of Science and Technology, Aarhus University, 8830 Tjele, Denmark.
J
J
Jensen
D000818:Animals; D001835:Body Weight / Q000235:genetics; D001947:Breeding / Q000379:methods*; D005260:Female; D014644:Genetic Variation; D006823:Hybrid Vigor / Q000235:genetics; D008098:Litter Size / Q000235:genetics*; D008907:Mink / Q000235:genetics* / Q000502:physiology; D010298:Parity / Q000235:genetics; D011247:Pregnancy; D012641:Selection, Genetic
DMU package; Neovison vison; heterosis; litter size; mink; selection; univariate mixed models