Erfðastuðlar fyrir íslenskar mjólkurkýr með mælidagalíkani

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.Financial support from the Icelandic Cattle Productivity Fond is acknowledged.Peer Reviewe

Samanburður á notkun mælidagalíkans og mjaltaskeiðslíkana við kynbótamat fyrir afurðir og frumutölu íslenskra kúa

Predicted genetic progress in production traits was compared using three different models for genetic evaluation of Icelandic dairy cows. The models were: a random regression (RR) test-day model, model using lactation yields until day 305 from calving (LAC1), and the model currently used for the national evaluation, based on lactation yield from calving to the end of lactation regardless of the length of the lactation (LAC2). Additionally, genetic evaluation for somatic cell score with RR and LAC1 were compared. Predicted genetic progress for protein yield was highest when using RR, or 0.170 σa/yr, compared with 0.167 σa/yr and 0.158 σa/yr for LAC1 and LAC2, respectively. Results for other production traits were similar. The main reason could be the shorter generation interval when records can be utilized before the end of lactation and reliable estimated breeding values thus obtained earlier. Application of an RR model will be beneficial for genetic evaluation for production traits and somatic cell score.Möguleg erfðaframför fyrir framleiðslueiginleika hjá íslenskum kúm var borin saman út frá þremur reiknilíkönum við útreikninga kynbótamats, þ.e. reiknað með slembiaðhvarfs mælidagalíkani, mjaltaskeiðslíkani fyrir afurðir að degi 305 frá burði og mjaltaskeiðslíkani sem hefur verið notað við opinbert kynbótamat og byggir á afurðum allt mjaltaskeiðið óháð lengd þess. Möguleg erfðaframför fyrir frumutölu var metin með tveimur fyrrnefndu líkönunum. Möguleg erfðaframför fyrir próteinafurðir var metin 0,170 staðalfrávik erfða á ári með því að byggja á niðurstöðum mælidagalíkansins, samanborið við 0,167 með mjaltaskeiðslíkani að degi 305 og 0,158 með mjaltaskeiðslíkani sem byggir á öllu mjaltaskeiðinu. Sambærilegar niðurstöður fengust fyrir aðra eiginleika. Munurinn skýrist einkum af mun á því hvenær naut í afkvæmaprófun fá nógu öruggt kynbótamat til þess að fara í framhaldsnotkun og þar með kynslóðabilinu. Innleiðing mælidagalíkans væri til bóta fyrir íslenska nautgriparækt.Financial support from the Cattle Productivity Fund is gratefully acknowledged.Peer Reviewe

Frequencies of genes for coat colour and horns in Nordic cattle breeds

Gene frequencies of coat colour and horn types were assessed in 22 Nordic cattle breeds in a project aimed at establishing genetic profiles of the breeds under study. The coat colour loci yielding information on genetic variation were: extension, agouti, spotting, brindle, dun dilution and colour sided. The polled locus was assessed for two alleles. A profound variation between breeds was observed in the frequencies of both colour and horn alleles, with the older breeds generally showing greater variation in observed colour, horn types and segregating alleles than the modern breeds. The correspondence between the present genetic distance matrix and previous molecular marker distance matrices was low (r = 0.08 – 0.12). The branching pattern of a neighbour-joining tree disagreed to some extent with the molecular data structure. The current data indicates that 70% of the total genetic variation could be explained by differences between the breeds, suggesting a much greater breed differentiation than typically found at protein and microsatellite loci. The marked differentiation of the cattle breeds and observed disagreements with the results from the previous molecular data in the topology of the phylogenetic trees are most likely a result of selection on phenotypic characters analysed in this study

Rotujen välisten erojen arviointi ei riitä rotujen suojelullisen arvon määrittämiseen

ei saatavill

Selection Signatures in Worldwide Sheep Populations

The diversity of populations in domestic species offers great opportunities to study genome response to selection. The recently published Sheep HapMap dataset is a great example of characterization of the world wide genetic diversity in sheep. In this study, we re-analyzed the Sheep HapMap dataset to identify selection signatures in worldwide sheep populations. Compared to previous analyses, we made use of statistical methods that (i) take account of the hierarchical structure of sheep populations, (ii) make use of linkage disequilibrium information and (iii) focus specifically on either recent or older selection signatures. We show that this allows pinpointing several new selection signatures in the sheep genome and distinguishing those related to modern breeding objectives and to earlier post-domestication constraints. The newly identified regions, together with the ones previously identified, reveal the extensive genome response to selection on morphology, color and adaptation to new environments

Genetic testing for TMEM154 mutations associated with lentivirus susceptibility in sheep

Stefan Hiendleder is a member of the International Sheep Genomics ConsortiumIn sheep, small ruminant lentiviruses cause an incurable, progressive, lymphoproliferative disease that affects millions of animals worldwide. Known as ovine progressive pneumonia virus (OPPV) in the U.S., and Visna/Maedi virus (VMV) elsewhere, these viruses reduce an animal’s health, productivity, and lifespan. Genetic variation in the ovine transmembrane protein 154 gene (TMEM154) has been previously associated with OPPV infection in U.S. sheep. Sheep with the ancestral TMEM154 haplotype encoding glutamate (E) at position 35, and either form of an N70I variant, were highly-susceptible compared to sheep homozygous for the K35 missense mutation. Our current overall aim was to characterize TMEM154 in sheep from around the world to develop an efficient genetic test for reduced susceptibility. The average frequency of TMEM154 E35 among 74 breeds was 0.51 and indicated that highly-susceptible alleles were present in most breeds around the world. Analysis of whole genome sequences from an international panel of 75 sheep revealed more than 1,300 previously unreported polymorphisms in a 62 kb region containing TMEM154 and confirmed that the most susceptible haplotypes were distributed worldwide. Novel missense mutations were discovered in the signal peptide (A13V) and the extracellular domains (E31Q, I74F, and I102T) of TMEM154. A matrix-assisted laser desorption/ionization–time-of flight mass spectrometry (MALDI-TOF MS) assay was developed to detect these and six previously reported missense and two deletion mutations in TMEM154. In blinded trials, the call rate for the eight most common coding polymorphisms was 99.4% for 499 sheep tested and 96.0% of the animals were assigned paired TMEM154 haplotypes (i.e., diplotypes). The widespread distribution of highly-susceptible TMEM154 alleles suggests that genetic testing and selection may improve the health and productivity of infected flocks.Michael P. Heaton, Theodore S. Kalbfleisch, Dustin T. Petrik, Barry Simpson, James W. Kijas, Michael L. Clawson, Carol G. Chitko-McKown, Gregory P. Harhay, Kreg A. Leymaster, the International Sheep Genomics Consortiu

Temporal changes in genetic variation of North European cattle breeds

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Weitzman approach and components of diversity in Northern European sheep greeds

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Intra- and inter-racial genetic variation in North-European cattle breeds

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Frequencies of genes for coat colour and horns in Nordic cattle breeds

Gene frequencies of coat colour and horn types were assessed in 22 Nordic cattle breeds in a project aimed at establishing genetic profiles of the breeds under study. The coat colour loci yielding information on genetic variation were: extension, agouti, spotting, brindle, dun dilution and colour sided. The polled locus was assessed for two alleles. A profound variation between breeds was observed in the frequencies of both colour and horn alleles, with the older breeds generally showing greater variation in observed colour, horn types and segregating alleles than the modern breeds. The correspondence between the present genetic distance matrix and previous molecular marker distance matrices was low $(r = 0.08 - 0.12)$. The branching pattern of a neighbour-joining tree disagreed to some extent with the molecular data structure. The current data indicates that 70% of the total genetic variation could be explained by differences between the breeds, suggesting a much greater breed differentiation than typically found at protein and microsatellite loci. The marked differentiation of the cattle breeds and observed disagreements with the results from the previous molecular data in the topology of the phylogenetic trees are most likely a result of selection on phenotypic characters analysed in this study.Fréquences génétiques pour la couleur de la robe et la présence de cornes chez des races de bovins nordiques. Dans le cadre d'un projet visant à établir leurs profils génétiques, on a estimé les fréquences génétiques à des locus gouvernant la couleur de la robe et la présence de cornes chez 22 races de bovins nordiques. Les locus informatifs pour évaluer la variation génétique étaient extension, agouti, spotting, brindle, dun dilution, colour sided et polled. On a mis en évidence une importante variation des fréquences de ces gènes entre les races, et les races les plus anciennes montraient généralement plus de variation que les races modernes. La correspondance entre la matrice des distances génétiques obtenue dans cette étude et celle trouvée précédemment à partir de marqueurs moléculaires était faible $(r=0.08-0.12)$. Le dendrogramme obtenu à partir de la méthode du "neighbour-joining "comportait certaines différences avec celui déjà construit à l'aide de marqueurs moléculaires. Notre étude indique que 70 % de la variation génétique totale pourrait être due aux différences entre les races, suggérant ainsi une différenciation entre races plus forte que celle anticipée à partir des locus de protéines ou des microsatellites. Ces différences entre les présents résultats et ceux obtenus à partir d'autres marqueurs sont vraisemblablement dues à la sélection qui a été menée sur les caractères phénotypiques correspondant aux locus analysés dans ce travail