Bayesian analysis of genetic and environmental effects on litter traits in a red fox (Vulpes vulpes) herd under long‐term selection

The economic efficiency of fur animal farms is considerably influenced by reproductive performance. The objectives of this study are to determine the effects of individual and maternal inbreeding, birth year, and dam and sire age on litter size at birth (LSB) and at weaning (LSW) and on preweaning mortality (PWM) in a red fox herd under long-term selection, and to determine the heritability of these traits. In total, 37,973 pedigreed individuals were used to calculate the inbreeding coefficients, based on records of 14,527 litters of 3856 dams born from the year 1958 to 2015. Two data sets (all data and data for the Polish variety) were analyzed. The highest heritability was estimated for PWM (0.292, 0.306) and the lowest for LSW (0.114, 0.115). In contrast to paternal and maternal inbreeding, litter inbreeding was found to exert a significant influence. The absence of significant effects of most varieties may suggest relatively large genetic similarity in the world red fox population. This corresponds with the similarity of the results obtained for the total herd and for the Polish variety. Favorable genetic trends were observed for the studied traits, indicating that the selection applied had been a relatively effective approach to improving these traits.