Adjustments for heterogenous herd-year variances in a random regression model for genetic evaluations of Polish Black-and-White cattle

• Autorzy: Strabel T , Jankowski T , Jamrozik J
• Języki publikacji: EN

Abstrakty

EN

The study investigated the existence of heterogeneous variance in first-lactation daily milk yield of Polish Black-and-White cows across herds in different years. Bayesian Information Criterion was used to show that the model with unequal residual variances for different herd-years was more plausible than the model assuming equal variances. A method of adjusting phenotypic records was developed to account for unequal variability in herd-years. Factors used for the data adjustment considered variation of general residuals and residuals for specific herd-years. The size of herd-year was also taken into account. Varied power of corrections was used to analyze the effect of adjustment on estimated breeding values. The method was applied to daily milk records of 817 165 primiparous cows. The effectiveness of the data adjustment was evaluated by the analysis of differences between each bull’s breeding value and its parental index. Data correction reduced the average difference and variance of differences between breeding values and parental indices. Accounting for the size of herd-year classes in correction factors improved the efficiency of heterogeneous variance adjustment.

Słowa kluczowe

EN

heterogeneous variance; breeding value; genetics; Poland; cattle; genetic evaluation; random regression model; Black-and-White breed; dairy cattle

• Wydawca: -
• Czasopismo: Journal of Applied Genetics
• Rocznik: 2006
• Tom: 47
• Numer: 2
• Opis fizyczny: p.125-130,ref.

Twórcy

autor

Strabel T

• Department of Genetics and Animal Breeding, August Cieszkowski Agricultural University, Wolynska 33, 60-637 Poznan, Poland

autor

Jankowski T

• Department of Genetics and Animal Breeding, August Cieszkowski Agricultural University, Wolynska 33, 60-637 Poznan, Poland

autor

Jamrozik J

• Department of Animal and Poultry Science, Centre for Genetic Imrpovement of Livestock, University of Guelph, Canada
• Department of Animal Genetics and Breeding, National Research Institute of Animal Production, Balice, Poland

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