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Genetic parameters for Icelandic dairy cows using a random regression test-day model

Genetic parameters for Icelandic dairy cows using a random regression test-day model


Title: Genetic parameters for Icelandic dairy cows using a random regression test-day model
Alternative Title: Erfðastuðlar fyrir íslenskar mjólkurkýr með mælidagalíkani
Author: Eiríksson, Jón Hjalti
Sigurdsson, Agust   orcid.org/0000-0003-0450-548X
Johannesson, Gudmundur H.   orcid.org/0000-0003-0560-5888
Eythorsdottir, Emma   orcid.org/0000-0001-6105-2013
Date: 2019
Language: English
Scope: 3-16
University/Institute: Landbúnaðarháskóli Íslands
Agricultural University of Iceland
Department: Auðlinda- og umhverfisdeild (LBHÍ)
Faculty of Natural Resources and Environmental Sciences (AUI)
Series: Icelandic Agricultural Sciences;32(2019)
ISSN: 2298-786X
DOI: 10.16886/IAS.2019.01
Subject: Milk production; Genetic parameters; Kýr; Mjólk; Erfðabreytileiki
URI: https://hdl.handle.net/20.500.11815/1337

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Citation:

Eiríksson, J. H., Sigurdsson, Á., Jóhannesson, G., & Eythórsdóttir, E. (2019). Genetic parameters for Icelandic dairy cows using a random regression test-day model. Icelandic Agricultural Sciences, 32, 3-16.

Abstract:

 
A total of 480,495 test-day yield records of 33,052 cows were used to estimate the genetic parameters for daily milk yield (MY), fat yield (FY), protein yield (PY) and somatic cell score (SCS) of Icelandic dairy cows in the first three lactations with a random regression model. Heritability of all traits was lowest in early lactation in all lactations and highest in mid- or late lactation. Heritability of lactation yields for the first lactation was 0.43, 0.39 and 0.41 for MY, FY and PY, respectively, but was estimated as lower when using a lactation model. Heritability of SCS in the first lactation was 0.23 using the random regression model but 0.15 using the lactation model. Heritability of persistency of lactation MY, FY and PY were 0.14-0.24 in all lactations and genetic correlations to the whole lactation SCS were -0.08 to -0.13. Heritability of yields had increased from previous estimates for the breed. Genetic variation of persistency in the population makes change of the lactation curve possible through selection.
 
Alls voru 480.495 mælingar á daglegri nyt 33.052 íslenskra kúa notaðar til að meta erfðastuðla fyrir mjólkur-magn, fitumagn, próteinmagn og frumutölu á fyrstu þremur mjaltaskeiðum með slembiaðhvarfslíkani. Arfgengi allra eiginleika var lægst í upphafi mjaltaskeiðs en hæst um eða eftir mitt mjaltaskeið. Arfgengi mjaltaskeiðsafurða á fyrsta mjaltaskeiði var 0,43, 0,39 and 0,41 fyrir mjólk, fitu og prótein í þessari röð, samkvæmt slembiaðhvarfslíkaninu en lægri miðað við mjaltaskeiðslíkan. Arfgengi frumutölu á fyrsta mjaltaskeiði var 0,23 samkvæmt slembiaðhvarfslíkaninu en 0,15 samkvæmt mjaltaskeiðslíkani. Arfgengi mjólkurþols var á bilinu 0,14 til 0,24 fyrir mjólk, prótein og fitu á öllu mjaltaskeiðum og hafði erfðafylgni á bilinu -0,08 til -0,13 við frumutölu á sama mjaltaskeiði. Arfgengi afurðaeiginleika var metið hærra í þessari rannsókn en í eldri rannsóknum á stofninum. Erfðabreytileiki á mjólkurúthaldi í stofninum gerir kleift að breyta lögun mjaltakúrfunnar fyrir íslenskar kýr með úrvali.
 

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