Sources of bias, genetic trend and changes in  genetic correlation in carcass and ultrasound traits in  the icelandic sheep population

Eiríksson, Jón Hjalti; Sigurdsson, Agust

Sources of bias, genetic trend and changes in genetic correlation in carcass and ultrasound traits in the icelandic sheep population

Title:	Sources of bias, genetic trend and changes in genetic correlation in carcass and ultrasound traits in the icelandic sheep population
Alternative Title:	Ástæður bjögunar, erfðaframför og breytingar á erfðafylgni fyrir kjötmat og ómmælingar í íslenska sauðfjárstofninum.
Author:	Eiríksson, Jón Hjalti Sigurdsson, Agust orcid.org/0000-0003-0450-548X 2 authors Show fewer authors
Date:	2017-04
Language:	English
Scope:	3-12
University/Institute:	Landbúnaðarháskóli Íslands (LBHÍ) Agricultural University of Iceland (AUI)
Department:	Auðlinda- og umhverfisdeild (LBHÍ) Faculty of Natural Resources and Environmental Sciences (AUI)
Series:	Icelandic Agricultural Sciences;30(2017)
ISSN:	2298-786X
DOI:	10.16886/IAS.2017.01
Subject:	Multitrade model; Animal breeding; Kvikfjárrækt; Kynbætur; Sauðfjárrækt
URI:	https://hdl.handle.net/20.500.11815/375
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Citation: Eiriksson, J. H., & Sigurdsson, Á. (2017). Sources of bias, genetic trend and changes in genetic correlation in carcass and ultrasound traits in the icelandic sheep population. ICELANDIC AGRICULTURAL SCIENCES, 30, 3-12.
Abstract: Genetic parameters for carcass conformation, carcass fat, ultrasound eye muscle depth and ultrasound fat depth over eye muscle were estimated with data from Icelandic farms during three periods, 2001-2003, 2006-2008 and 2011-2013. Heritability ranged from 0.30 to 0.42. Genetic correlation between carcass conformation and carcass fat was 0.41, 0.29 and 0.26 in 2001-2003, 2006-2008 and 2011-2013, respectively. Breeding values based on carcass scoring records of 5,796,474 lambs in 2000-2013 were estimated with a bivariate model and compared to the results of a multitrait model, including 715,771 ultrasound records. The genetic merit of rams for carcass conformation was underestimated in the bivariate analysis in the cases where many offspring were kept for replacement. Applying the multitrait model reduced this bias and gave more accurate results for both traits.The genetic trend was -0.05 and 0.08 genetic standard deviations per year for carcass fat and carcass conformation, respectively, in the period 2000-2013. Markmið rannsóknarinnar var að kanna hvort kynbótamat fyrir kjötmatseiginleika hjá íslensku sauðfé væri bjagað vegna vals á grundvelli dóma á lifandi lömbum. Einnig að athuga áhrif úrvals á erfðafylgni fitu og gerðar sláturlamba og erfðaframfarir í stofninum. Erfðastuðlar voru metnir með gögnum fyrir árin 2000-2013 frá Bændasamtökum Íslands aðskilið fyrir mismunandi tímabil. Niðurstöður kynbótamats með tvíbreytugreiningu á kjötmatseiginleikum voru bornar saman við kynbótamat einnig keyrt með ómmælinganiðurstöður. Erfðafylgni var metin 0,41 árin 2001-2003 en 0,29 og 0,26 fyrir 2006-2008 og 2011-2013. Kynbótamat fyrir gerð reyndist bjagað hjá hrútum sem mikið er sett á undan í tvíbreytugreiningunni en engin merki svipfarsvals sáust gagnvart fitunni. Erfðaframfarir voru metnar -0,05 staðalfrávik erfða á ári fyrir fitu og 0,08 staðalfrávik erfða á ári fyrir gerð. Fjölbreytu kynbótamat og minnkandi erfðafylgni getur stuðlað að enn meiri ræktunarframförum til framtíðar