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Genetic evaluation of susceptibility to- and recoverability from mastitis in dairy cows

Welderufael, Berihu (2017). Genetic evaluation of susceptibility to- and recoverability from mastitis in dairy cows. Diss. (sammanfattning/summary) Uppsala, Sweden : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2017:71
ISBN 978-91-7760-032-9
eISBN 978-91-7760-033-6
[Doctoral thesis]

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Mastitis has been the focus of many dairy cattle research projects over the last decades. However, in the genetic evaluation of udder health, only susceptibility to mastitis has been considered, leaving aside the other aspect of the disease - the recoverability. The aim of this thesis was to improve the genetic evaluation of udder health by introducing a new approach and models that can make use of the information contained in both directions: susceptibility to- and recoverability from mastitis.

In paper I, extensive simulation analyses were performed to develop a bivariate model for joint genetic evaluations of susceptibility to- and recoverability from mastitis. In paper II, the bivariate model with an added time function as well as several systematic effects was applied to real data to estimate genetic parameters in Danish Holstein cows. In paper III, genome-wide association studies were conducted to identify associated single-nucleotide polymorphisms and thereof candidate genes. In paper IV, a dynamic health classification, which takes severity of possible infection into account was introduced to further improve the genetic evaluation of mastitis.

Findings in paper I demonstrated that both traits can be modelled jointly and genetic parameters could be correctly reproduced. In paper II, we detected presence of genetic variation that resulted to heritability (ranging from 0.06 to 0.08) of similar size for both traits. The between trait genetic correlation was -0.83. Despite the strong negative genetic correlation, association signals in paper III did not overlap, suggesting that the traits are at least partially regulated by different genes. Complexity of the traits was manifested with the absence of strong association signals. In paper IV, considerable genetic variation was detected for cows’ presence in health classes defined for longer periods, whereas the variations in health classes defined for short-term and sudden changes (e.g., acute) were mostly attributed to environmental factors. Although susceptibility to- and recoverability from mastitis are strongly negatively correlated, recoverability which is as heritable as susceptibility could be considered a new trait for selection. Evaluating and modelling the ability of animals to overcome infection could be of specific benefit in situations of high disease incidence.

Authors/Creators:Welderufael, Berihu
Title:Genetic evaluation of susceptibility to- and recoverability from mastitis in dairy cows
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :2017
Depositing date:23 October 2017
Number of Pages:81
IWelderufael, B.G., D.J. de Koning, L.L.G. Janss, J. Franzén, and W.F. Fikse (2016). Simultaneous genetic evaluation of simulated mastitis susceptibility and recovery ability using a bivariate threshold sire model. Acta Agriculturae Scandinavia, Section A - Animal Science 66 (3): 125-134.
IIWelderufael, B.G., L.L.G. Janss, D.J. de Koning, L.P. Sorensen, P. Lovendahl, and W.F. Fikse (2017). Bivariate threshold models for genetic evaluation of susceptibility to and ability to recover from mastitis in Danish Holstein cows. Journal of Dairy Science 100 (6), 4706-4720.
IIIWelderufael, B.G., P. Lovendahl, D.J. de Koning, L.L.G. Janss and W.F. Fikse. Genome-wide association study for susceptibility to- and recovery from mastitis in Danish Holstein cows (submitted to journal: Frontiers in Genetics section Livestock Genomics).
IVSorensen, L.P., M. Bjerring, B.G. Welderufael, D.J. de Koning, L.L.G. Janss and P. Lovendahl. Dynamic udder health classification scheme in dairy cows using online cell count (manuscript).
Place of Publication:Uppsala, Sweden
Publisher:Dept. of Animal Breeding and Genetics, Swedish University of Agricultural Sciences
ISBN for printed version:978-91-7760-032-9
ISBN for electronic version:978-91-7760-033-6
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:L Animal production > L10 Animal genetics and breeding
Subjects:(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 402 Animal and Dairy Science > Animal and Dairy Science.
Agrovoc terms:dairy cows, mastitis, udder health
Keywords:bivariate model, dairy cow, genetic evaluation, mastitis, recoverability, susceptibility
Permanent URL:
ID Code:14648
Faculty:VH - Faculty of Veterinary Medicine and Animal Science
Department:(VH) > Dept. of Animal Breeding and Genetics
Deposited By: Mr. Berihu Gebremedhin Welderufael
Deposited On:25 Oct 2017 08:32
Metadata Last Modified:09 Sep 2020 14:17

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