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Invited review: A quarter of a century-International genetic evaluation of dairy sires using MACE methodology

Nilforooshan, M.A. and Jorjani, Hossein (2022). Invited review: A quarter of a century-International genetic evaluation of dairy sires using MACE methodology. Journal of Dairy Science. 105 , 3-21
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Abstract

For the past few decades, the international exchange of genetic materials has accelerated. This acceleration has been more substantial for dairy cattle compared with other species. The industry faced the need to put international genetic evaluation (IGE) systems in place. The Interbull Centre has been conducting IGE for various dairy cattle breeds and traits. This study reviews the past and the current status of IGE for dairy cattle, emphasizing the most prominent and well established method of IGE, namely multiple across country evaluation (MACE), and the challenges that should be addressed in the future of IGE. The first IGE methods were simple conversion equations. Only a limited number of common bulls between pairs of countries were considered. These bulls were a biased sample of highly selected animals, with their daughters under preferential treatment in the importing countries. Genetic relationships among animals were not considered either. The MACE method was the first IGE method based on mixed-model theory that could handle genotype by environment interaction (G x E) between countries. The G x E between countries is handled by treating the same trait in different countries as different traits, with genetic correlations less than unity between the traits. The G x E between countries is not solely due to different genetic expressions in different environments (countries), but is also attributable to different units or ways of measuring the trait, data editing, and statistical approaches and models used in different countries. The MACE method also considers different genetic means, genetic groups for unknown parents, heterogeneous genetic and residual variances among countries, and heterogeneous residual variances (precision weights for observations) within countries. Other IGE methods that came after MACE are rooted in MACE. The genomic revolution of the industry created new needs and opportunities. However, an unwanted aspect of it was genomic preselection bias. Genomic preselection causes directional information loss from pre-culled animals (bias) in statistical models for genetic and genomic evaluations, and preselected progeny of a mating are no longer a random sample of possible progeny from that mating. National genetic evaluations without genotypes are input to MACE, and biases in national evaluations are propagated interna-tionally through MACE. Genomic preselection for the Holstein breed is a source of concern for introducing bias to MACE, especially when genomic preselection is practiced intensively in the population. However, MACE continues to be useful for other breeds, among other species, or for non-IGE purposes. Future methods will need to make optimum use of genomic information and be free of genomic preselection bias

Authors/Creators:Nilforooshan, M.A. and Jorjani, Hossein
Title:Invited review: A quarter of a century-International genetic evaluation of dairy sires using MACE methodology
Series Name/Journal:Journal of Dairy Science
Year of publishing :2022
Volume:105
Page range:3-21
Number of Pages:19
Publisher:ELSEVIER SCIENCE INC
ISSN:0022-0302
Language:English
Publication Type:Article Review/Survey
Article category:Scientific peer reviewed
Version:Published version
Copyright:Creative Commons: Attribution 4.0
Full Text Status:Public
Subjects:(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 402 Animal and Dairy Science > Animal and Dairy Science.
Keywords:MACE, international genetic evaluations, dairy cattle, deregressed proof
URN:NBN:urn:nbn:se:slu:epsilon-p-115195
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-p-115195
Additional ID:
Type of IDID
DOI10.3168/jds.2021-20927
Web of Science (WoS)000734351700002
ID Code:26666
Faculty:VH - Faculty of Veterinary Medicine and Animal Science
Department:(VH) > Dept. of Animal Breeding and Genetics
Deposited By: SLUpub Connector
Deposited On:10 Jan 2022 07:25
Metadata Last Modified:10 Jan 2022 07:31

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