|Van Vleck, Lloyd|
Submitted to: Livestock Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/9/2001
Publication Date: N/A
Interpretive Summary: From the available data on Piedmontese cattle, the following conclusions can be made: 1) the use of inbreeding coefficients for animal and/or for dam appeared not to have important effects on estimates of variance components and heritability for the studied traits; 2) the use of inbreed- ing for animal and/or for dam in the model for analysis appeared toaffect sire rankings very little, and 3) inbreeding has definite effects on all traits studied as increases in inbreeding delayed reproductive times and resulted in lighter weights at 120 and 360 days. Inbreeding co- efficients do not seem to be needed as covariates in models for variance component estimation and prediction of genetic values for these data. Nevertheless, possible inbreeding coefficients should be considered when deciding on mating of sires and dams, in order to limit the possible negative effects of inbreeding on productive and reproductive traits.
Technical Abstract: 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-d 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-d 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.