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- Halkjer Jakobsen, Jette, et al.
(författare)
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Detection of Genomic Pre-Selection with Mendelian Sampling Variance Test
- 2013
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Ingår i: Interbull bulletin. - 2001-340X. ; 47, s. 197-202
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Genomic pre-selection of bull calves is potentially one additional source of bias in the international evaluations, given it has not been adequately accounted for in the national evaluations. The aim of this simulation study was to investigate whether it is possible to detect the effect of genomic pre-selection in the MS means or variances obtained by the MS-trend validation test. In total, 50 replicates were generated under control and genomic pre-selection schemes utilizing structures of the real data and pedigree from a medium size cow population during a 20-year time interval. All bulls in the last 10 birth year classes were assumed to be genomically pre-selected. Therefore, their Mendelian sampling terms were inflated with a value corresponding to the selection of best 10% of the genomically tested bull calves. After start of genomic pre-selection, both the true and estimated means of Mendelian sampling terms and breeding values rose sharply in bulls, although the effects of estimated means were more moderate. A clear decrease was found in true and estimated genetic variances of bulls, but the effect was temporary and thus hard to exploit. Daughters of genomically pre-selected bulls had higher true and estimated breeding values compared to the control scheme, only slightly elevated MS means and no effect in the genetic variances.
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- Halkjer Jakobsen, Jette
(författare)
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GMACE without Variance Estimation
- 2014
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Ingår i: Interbull bulletin. - 2001-340X. ; 48, s. 46-49
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Genomic variances have been estimated and used in GMACE since 2011, to adjust for differences among countries in the scaling of young bull genomic evaluations relative to progeny-tested bulls. Interbull has implemented validation tests for national genomic evaluations, which countries must pass in order to participate in GMACE, and the sharing of data and knowledge among countries for genomic evaluations has also increased. Each of these factors can improve consistency of genomic results among countries, and may reduce the need for genomic variance adjustments in GMACE. Cross-validation tests have been used previously to compare GMACE results when using versus not using genomic variance adjustments, and have shown clear advantages for including genomic variance adjustments. When repeated on current data for the present study, however, the cross-validation results no longer showed this clear advantage. Genomic variance adjustments were helpful for some traits and countries but not for others. On balance across all traits and countries, there was no longer a clear advantage either way. The international sharing of data and knowledge, combined with genomic validation tests of Interbull are likely helping to reduce differences among countries in the relative scaling of genomic versus progeny-test evaluations within the same country.
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- Haugaard, Katrine, et al.
(författare)
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Interbull Technical Workshop 2023 Overview of the New Traits Session
- 2023
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Ingår i: Interbull bulletin. - 2001-340X. ; , s. 1-6
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- New phenotypes have been systematically collected by national genetic centres, often leading to implementation of national genetic evaluation for several economically important dairy traits. However, the MACE portfolio has remained fixed to seven publishable trait groups since workability (including milking speed and temperament traits), was added in 2009. Streamlining the procedure for identifying new suitable traits for the MACE portfolio has been identified as a key goal in the 2020-2023 Interbull strategic plan. The first stage to achieve such objective is surveying the available data across countries on a more routinely basis: countries could be on different stages of data collection, research or development of national evaluation, and that there could be also differences in the above stages per breed.Information about national genetic evaluations for traits included in MACE evaluations have, for several decades, been collected and published on the Interbull Centre website in the form of word or pdf documents. In 2022, with the introduction of the Performance Recording, Evaluation and Publication database (PREPdb), electronic forms, rather than flat files, were developed for collecting such information. The “Other Traits” form, dedicated to traits not (yet) included in international evaluations, was also introduced. Prior to the Interbull Technical Workshop held in Rome in February 2023, Interbull Centre encouraged all its members to fill in the Other Traits form with as much information on additional traits they record nationally as possible. The aim was to identify possible new trait(s) to include in the Interbull portfolio. Upon review of the information collected, gestation length, retained placenta and milk fever/hypercalcemia were identified as the most frequently reported traits, and were chosen as the traits to be further discussed during the workshop’s session. This report provides an overview of the discussion that took place both during the panel session and the groups’ discussion that characterised the workshop’s session on new traits.
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