Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Estimation of litter size variability phenotypes in Large White sows
    Dobrzański, Jan ; Mulder, Han A. ; Knol, Egbert F. ; Szwaczkowski, Tomasz ; Sell-Kubiak, Ewa - \ 2020
    Journal of Animal Breeding and Genetics (2020). - ISSN 0931-2668
    pigs - reproductive traits - total number born - trait's variation

    The objective of this study was to obtain new phenotypes of phenotypic variability for the total number born (TNB) in pigs using the residual variance of TNB. The analysis was based on 246,799 Large White litter observations provided by Topigs Norsvin. Three animal models were used to obtain estimates of residual variance for TNB: the basic model (BM) containing fixed effects of farm–year and season and random effects of animal and permanent environmental sow, the basic model with an additional fixed effect of parity (BMP) and a random regression model (RRM). The within-individual variance of the residuals was calculated and log-transformed to obtain three new variability traits: LnVarBM, LnVarBMP and LnVarRRM. Then, (co)variance components, heritability, the genetic coefficient of variation at the standard deviation level (GCVSDe) and genetic correlations between the three LnVar's and between the LnVar's and mean total number born (mTNB) were estimated with uni-, bi- and trivariate models. Results indicated that genetically LnVar's are the same trait and are positively correlated with the mTNB (~0.60). Thus, both traits should be included in breeding programmes to avoid an increase in TNB variability while selecting for increased TNB. Heritability of the LnVar's was estimated at 0.021. The GCVSDe for LnVar's showed that a change of 8% in residual standard deviation of TNB could be obtained per generation. Those results indicate that phenotypic variability of litter size is under genetic control, thus it may be improved by selection.

    Different models for estimation of litter size variability phenotypes
    Dobrzanski, J. ; Mulder, H.A. ; Knol, Egbert ; Szwaczkowski, T. ; Sell-Kubiak, E.B. - \ 2019
    - p. 186 - 186.
    Selection to increase litter size in pigs has simultaneously increased its variability. In Large White differences in litter size between sows can be larger than 20 piglets, which causes additional labour and affects welfare of animals.
    Thus there is a need to dene phenotypes describing variability of litter size in order to reduce it. The main objective of this study was to obtain and compare new phenotypes of phenotypic variability of total number born (TNB) by
    using the residual variance of TNB. The dataset contained 246,799 litter observations from 53,803 sows from Topigs
    Norsvin multiplication farms. Three models were used to obtain estimates of residual variance for TNB in ASReml 4.1: basic (BM), basic with parity as fixed effect (BMP), and random regression (RRM). The within individual’s variance of the residuals was calculated and log-transformed, to obtain three new variability traits: LnVarBM, LnVarBMP and LnVarRRM. Then, variance components, heritability (h2), genetic coefficient of variation (GCV) and genetic correlations (r
    g) between LnVar’s and between LnVar’s and mean TNB were estimated with multi-variate models. Results for additive genetic component (0.026-0.028), residuals (1.23-1.29), h2 (0.02) and GCV (0.081-0.083) indicated that LnVar’s as variability phenotype were robust and not affected by model applied for
    their estimation. Furthermore, rg between additive genetic components of LnVar’s (~0.98) proved that genetically LnVar’s are the same trait. The positive r
    g between LnVar’s and mean TNB (~0.60) conrmed that selection for
    increased TNB increases its variability. Whereas GCV for LnVar’s indicated that TNB variability can be reduced by 1.1 piglet within four generations. These results indicate that phenotypic variability of litter size is under genetic
    control and could be reduced by selection. The project was nanced by Polish National Center for Science (grant no. 2016/23/D/NZ9/00029).

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