Date of this Version
Effects of inbreeding of animal and dam on estimates of genetic parameters and predictions of breeding values for five productive and reproductive traits of Piedmontese cattle were studied. Traits were (a) age at first insemination, (b) age at first calving, (c) 120-day weight, (d) yearling weight of males, and (e) yearling weight of females. Data for animals born from 1970 to 1995 were used. Inbreeding coefficients were computed using pedigree records back to 1900. A sire model was used for estimating genetic parameters and predicting breeding values. Two models were used for each trait. Model 1 included fixed effects of herd–year (for traits a, b, d, and e) or herd–year and sex–age of dam (trait c) and covariates for inbreeding coefficient of animal for traits a and b and inbreeding of animal and dam for traits c, d and e. Random effects were associated with sires and dams for traits c, d, and e. Model 2 did not include covariates for inbreeding. Inbreeding increased age at first insemination and calving and decreased 120-day and yearling weights of males and females. Inbreeding was not needed in the model for estimation of variance components or for prediction of breeding values for this population.