The aims of this study were to estimate the inbreeding level and to evaluate inbreeding effects for birth (BW) and fourth week weight (FWW) in a multi-breed sheep population. The analyses were performed within eight lines and the total population. The data set of 36488 pedigreed individuals over twenty years was analysed. The inbreeding coeffi cients were derived from an additive relationship matrix. The inbreeding depression was expressed as a partial linear regression coeffi cient estimated via a single trait animal model including fi xed effects (fl ock, type of birth, sex, breed, inbreeding coeffi cient -as linear covariable) and random effects (additive genetic and residual). The number of pedigreed individuals varied considerably over time. The study has shown that the inbreeding of this population was very low (0.30%). However, the estimate is considerably infl uenced by incomplete pedigree information. Comparative analysis of inbreeding levels within lines and breeds indicated on differences between them. Both positive and negative inbreeding effects (ranged from -12.6 to 16.0 g for BW and from -61.9 to 18.1 g FWW) were found depending on line.

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Inbreeding and offspring sex ratio in the pygmy hippopotamus (Cheoropsis liberiensis) population kept in zoological gardens. Folia Biologica (Kraków) 63: 35-42. The aim of this study was to estimate the inbreeding level and its impact on offspring sex ratio in the pygmy hippopotamus population kept in zoological gardens. Records of pygmy hippopotamus born between 1873-2013 were extracted from the international studbook. Totally, 1357 individuals originating from 148 breeding units were included (individuals with unknown sex were omitted). The offspring sex ratio is defined as the number of sons to the total number of progeny of each dam and sire. Spearman's rank correlation was employed to examine the relationships between the inbreeding level and offspring sex ratio. Inbreeding coefficients and individual increase in inbreeding coefficients (included as a linear co-variable) were examined as well as the geographic region and birth period using general linear models. The average inbreeding coefficient was 5.39%. The following sex proportion was observed for the inbred population: 57% and 43% for females and males, respectively. A significant relationship between inbreeding level of parents and their offspring sex ratio were estimated for European zoological gardens, whereas in others geographic regions the dependencies were insignificant.