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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Record number 530340
Title Fitting the ‘parity curve’: application of random regression to litter size in pigs
Author(s) Sell-Kubiak, E.B.; Knol, E.F.; Mulder, H.A.
Source In: Book of Abstracts of the 68th Annual Meeting of the European Federation of Animal Science. - Wageningen : Wageningen Academic Publishers (Book of abstracts 23) - ISBN 9789086863129 - p. 110 - 110.
Event Wageningen : Wageningen Academic Publishers (Book of abstracts 23) - ISBN 9789086863129 EAAP 68th Annual Meeting of the Animal Science (EAAP), Tallinn, 2017-08-28/2017-09-01
Department(s) Animal Breeding and Genetics
Publication type Abstract in scientific journal or proceedings
Publication year 2017
Abstract The objective of this study is to analyze the genetic background of variation in reproductive performance between parities of a sow with application of random regression. Performance of a sow (e.g. litter size) changes with the parity. Usually, the 1st and 2nd parity sows have smaller litters than sows in their 3rd to 5th parity. After parity 6, the performance declines again. The shape of litter size across parities closely resembles the lactation curve observed in dairy cattle. Fitting the ‘parity curve’ could help reducing differences between parities of a sow, preferably, keeping only the first parity with the lowest performance. Litter size data of Large White sows from commercial farms were provided by Topigs Norsvin. The records of 246,799 litters (total number born) came from 53,794 sows with at least two observations in parities 1-10. The analysis was performed in ASReml 4.1. Firstly, the 3rd order polynomials were selected as the best fit for the fixed parity curve. Secondly, the comparison of 3 models with respect to order of polynomials for random effects, indicated that the best fit was the model with 3rd order polynomials for both additive genetic and permanent environmental effects with simultaneous accounting for heterogeneity of residual variance per parity (10 levels). The heritability estimates were increasing with the lowest value in parity 1 with 0.11 and the highest value in parity 9 with 0.21. Genetically, parity 1 is the most different from parities 7-10 (rg from 0.56 to 0.60), whereas it is most similar to parities 2 (rg=0.96) and 3 (rg=0.85). Already the 2nd parity has correlations between 0.72 to 0.96 with other parities, whereas parities 3 to 10 are genetically almost identical traits with rg from 0.84 to 0.99. The non-unity genetic correlations between parities 1 and 2 with parities 3-10 show existence of genetic variation to genetically change the parity curve, e.g. to make litter size more equal among parities.
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