International cooperation: The pathway for cattle genomics

Abstract

• Genomic selection tools are radically changing the way dairy cattle genetics is organized worldwide by providing the means to reduce generation intervals and accelerate genetic progress. As a result, young genomically selected bulls are quickly replacing progeny-tested bulls in the top lists. • To achieve moderate reliabilities in genomic predictions, large reference populations of progeny-tested animals have to be assembled, and this number increases dramatically for traits with low heritability. International cooperation becomes imperative, both for joining databases of genotypes and for obtaining phenotypic information translated into the respective national scale (Interbull multiple-trait across-country evaluation estimates). • Keeping the Interbull conventional international evaluations (based on national conventional estimated breeding values) as a source of phenotypic information for the national genomic predictive models requires maintaining conventional evaluation models at the national level. • Interbull is establishing a new framework to incorporate genomics into international evaluations. The main actions include intensifying networking opportunities; validating national genomically enhanced breeding values; and developing genomically enhanced multiple-trait across-country evaluations, Intergenomics, and a genomic data repository. to express their estimated breeding values (EBV) in the scales adopted by the importing countries. Without a common basis for comparing breeding animals from different origins, the genetic merit of bulls used for artifi cial insemination has been derived from their progeny information, obtained, in most cases, only in the country of origin of the bull while ignoring differences in trait defi nition, evaluation model, measurement scale, management practices, environmental conditions, genetic makeup, and selection goals. Members of the scientifi c community and the dairy breeding industry acknowledged this challenge as early as 1975, and after years of cooperative work, the International Bull Evaluation Service (Interbull) was created in 1983 (Philipsson, 2005). The objective was to support the dairy industry with accurate genetic information on bulls of the major dairy breeds for use by importers and exporters, thereby facilitating selection of the best genetics for different countries, environments, or breeding goals. Interbull was developed as a joint effort of the International Committee for Animal Recording; the European Federation of Animal Science, or EAAP; and the International Dairy Federation to become the main international forum for the development and standardization of methods and procedures in dairy cattle evaluation. The information exchange promoted by Interbull has clearly helped participating countries improve national systems and benefi t greatly from the international genetic evaluations carried out by the Interbull Centre. As a cooperative action between the participating countries, Interbull does not compete with the national genetic evaluation centers, but is rather an auxiliary service. The authority over publication of breeding values in national scales remains with each of the countries. This very successful partnership among competitors, exporters, and importers is a result of permanent and intense networking, making all the actors involved jointly responsible for the choice of methods and for the quality of the results obtained. The Interbull international evaluations are computed by a linear multiple-trait across-country evaluation (MACE) of national conventional EBV from the participating countries (Schaeffer, 1994). In MACE, bull progeny contributions from different countries are treated as different traits, with genetic correlations lower than unity. Consequently, the use of foreign information is accounted for by considering genotype-environment interaction, as well as differences in modeling, the genetic base, and trait defi nitions. Currently, Interbull MACE evaluations yield international EBV (IEBV) for a range of 34 traits and 6 breeds, expressed on as many as 30 national scales (currently, data from 73 populations are included) that are used extensively worldwide for semen marketing. Interbull has been a reference for international cooperation since 1983 at both the scientifi c and the industry levels, but the dawn of genomic selection in dairy cattle has taken this cooperation to a completely new level. The aim of this article is to present how dependent the “genomic