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The single-step method of genomic evaluation using both a uni-trait and a multi-trait animal model was applied for 20 linear type traits of Holstein cows in the Czech Republic. Phenotypic data on linear scoring were available for 143,208 Holstein cows first calved between years 2005 to 2010. Single nucleotide polymorphism (SNP) markers from the Illumina BovineSNP50 BeadChipV2 (Illumina Inc., San Diego, USA) were available for 631 sires. Breeding values (traditional breeding value, EBV) were estimated by uni-trait and multi-trait BLUP animal models using the pedigreebased relationship matrix. Genomic breeding value (GEBV) was estimated by single step genomic BLUP (ssGBLUP) using the pedigree-based relationship matrix augmented by the genomic relationship matrix. The model included fixed effects of herd-date of classification, classifier and season of calving, linear and quadratic regressions on age at calving and on days in milk and the random additive genetic effect of animal. Correlations between parent average, predicted GEBV and post-progeny test EBV were slightly higher for uni-trait analyses than for multi-trait analyses.Excluding udder traits, the average uni-trait correlations with the post-progeny test EBV were 0.44 for parent average and 0.46 for predicted GEBV, whereas multi-trait correlations were 0.42 and 0.44, respectively. When udder traits were included, average uni-trait correlations with the postprogeny test EBV were 0.09 for parent average and 0.14 for predicted GEBV, while multi-trait correlations were 0.29 and 0.33, respectively.
The method for approximating reliability of genomic breeding values in the single-step genomic BLUP evaluation was tested on milk production data from dairy cattle in the Czech Republic. The reliability of young dairy bulls without progeny increased by an average of 0.02 for heritability of 0.25 after genomic information was included in the evaluation. The increase was minimal for proven bulls with many progeny because much information was already known about these individuals. The overall increase in the reliability for the entire population of dairy cattle was small, but noticeable;the small increment of the increase resulted from the unfavourable ratio of genotyped bulls and the size of the population (1:2500). A relatively small increase in reliability by genotyping was due to the small number of reference bulls with known genomic information.
The objectives of this study were to evaluate systematic factors that influence longevity and to estimate the heritability of functional longevity by survival analysis of Suffolk sheep in the Czech Republic. A total of 20,502 ewes from 137 flocks were used. The longevity of Suffolk ewes was influenced to some extent by their average prolificacy. The effects of growth intensity and the development of muscularity and fattiness, as well as the effect of the prion protein gene PrP haplotype on the risk of the exclusion of the ewe from breeding were relatively low. Heritability estimates were h² = 0.438 for the length of production life in days (LPL), h² = 0.098 for the number of litters of the ewe during her lifetime (NL), h² = 0.111 for the total number of lambs born (TLB), and h2 = 0.103 for the total number of labs weaned (TLW). Correlations between the breeding values for LPL and NL, TLB or TLW were high. Therefore, these indicators of the ewe’s lifelong production, which are more desirable and understandable for sheep breeders, should be used in indirect selection for longevity.
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