Nilforooshan, Mohammad Ali
(2011).
Multiple-trait multiple country genetic evaluation of fertility traits in dairy cattle.
Diss. (sammanfattning/summary)
Uppsala :
Sveriges lantbruksuniv.,
Acta Universitatis Agriculturae Sueciae, 1652-6880
; 2011:31
ISBN 978-91-576-7566-8
[Doctoral thesis]
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Abstract
Female fertility is one of the most economically important traits for the dairy cattle industry. Because of a few decades of selection mainly for higher milk production, many dairy farms around the world suffer from the consequences of female fertility loss. The aims of this thesis were to study the international genetic evaluation of female fertility traits, to quantify the bias of analyzing multiple female fertility traits per country with the current method in use for international genetic evaluations (MACE), to study the implementation of a new method (MT-MACE) for the analysis of multiple traits per country, and also to study the effect of across country selection for milk yield on the international genetic evaluation of female fertility traits, when MT-MACE is applied.
Female fertility traits are low heritable, each describing a part of the female fertility complex. International genetic evaluation is useful for improving the accuracy of female fertility evaluations and making the across country comparisons of bulls possible. Despite the low heritability values of female fertility traits, the estimated across country genetic correlations were moderate to high, making the international genetic evaluations feasible for female fertility traits.
Results for female fertility traits showed that including multiple traits per country in a MACE analysis would lead to considerable bias. This bias is due to ignoring covariances from multiple-trait national models. Avoiding bias by performing several unbiased MACE analyses, each including one trait per country is not advantageous, because it is computationally prohibitive and it does not make an optimal use of the available data.
MT-MACE was applied to female fertility data, which led to higher reliabilities compared to the (unbiased) MACE evaluations. The reliability gains were larger for foreign bulls and the Top 100 bulls in each country-trait. The results showed that when the within country selection for milk yield is already taken care of by the multiple-trait national models, the across country selection for milk yield did not make significant bias in the international evaluation of female fertility traits.
Authors/Creators: | Nilforooshan, Mohammad Ali | ||||||||||
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Title: | Multiple-trait multiple country genetic evaluation of fertility traits in dairy cattle | ||||||||||
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Series Name/Journal: | Acta Universitatis Agriculturae Sueciae | ||||||||||
Year of publishing : | May 2011 | ||||||||||
Number: | 2011:31 | ||||||||||
Number of Pages: | 48 | ||||||||||
Papers/manuscripts: |
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Place of Publication: | Uppsala | ||||||||||
Publisher: | Swedish University of Agricultural Sciences | ||||||||||
ISBN for printed version: | 978-91-576-7566-8 | ||||||||||
ISSN: | 1652-6880 | ||||||||||
Language: | English | ||||||||||
Additional Information: | This thesis gives an overview of the current international genetic evaluations of female fertility traits for the dairy breeds included in Interbull services. For the Holstein breed, a new method was tested. The new method was also applied to study the effect of across country selection for milk yield on the international genetic evaluation of female fertility. Using the new method, the quality of international genetic evaluations can be further improved by considering data from multiple traits per country. | ||||||||||
Publication Type: | Doctoral thesis | ||||||||||
Full Text Status: | Public | ||||||||||
Subjects: | Obsolete subject words > FORESTRY, AGRICULTURAL SCIENCES and LANDSCAPE PLANNING > Animal production > Animal breeding (A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 402 Animal and Dairy Science > Animal and Dairy Science. (A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 404 Agricultural Biotechnology > Genetics and Breeding | ||||||||||
Agrovoc terms: | dairy cows, fertility, milk yield, genetic correlation, genetic inheritance | ||||||||||
Keywords: | MACE, Multiple-trait, Interbull, female fertility, milk yield, bias, genetic correlation, reliability, genetic trend | ||||||||||
URN:NBN: | urn:nbn:se:slu:epsilon-e-77 | ||||||||||
Permanent URL: | http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-e-77 | ||||||||||
ID Code: | 8094 | ||||||||||
Department: | (VH) > Dept. of Animal Breeding and Genetics | ||||||||||
Deposited By: | Dr. Mohammad Ali Nilforooshan | ||||||||||
Deposited On: | 02 May 2011 11:39 | ||||||||||
Metadata Last Modified: | 02 Dec 2014 10:45 |
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