02940naa a2200217 a 450000100080000000500110000800800410001902400310006010000180009124501340010926000090024350000760025252021890032865300160251765300150253365300370254865300300258570000180261570000160263377300730264910607312020-01-31       2000    bl uuuu     u00u1 u    #d7 a10.2527/2000.7882121x2DOI1 aDE MATTOS, D.  aInvestigation of genotype × environment interactions for weaning weight for Herefords in three countries.h[electronic resource]  c2000  aArticle history: Received September 16, 1999 // Accepted April 3, 2000.  aABSTRACT: The objective of this study was to investigate the possibility of genotype × environment interactions for weaning weight (WWT) between different regions of the United States (US) and between Canada (CA), Uruguay (UY), andUSfor populations of Hereford cattle. Original data were composed of 487,661, 102,986, and 2,322,722 edited weaning weight records from CA, UY, and US, respectively. A total of 359 sires were identified as having progeny across all three countries; 240 of them had at least one progeny with a record in each environment. The data sets within each country were reduced by retaining records from herds with more than 500 WWT records, with an average contemporary group size of greater than nine animals, and that contained WWT records from progeny or maternal grandprogeny of the across-country sires. Data sets within each country were further reduced by randomly selecting among remaining herds. Four regions within US were defined: Upper Plains (UP), Cornbelt (CB), South (S), and Gulf Coast (GC). Similar sampling criteria and common international sires were used to form the within-US regional data sets. A pairwise analysis was done between countries and regions within US (UP-CB vs S-GC, UP vs CB, and S vs GC) for the estimation of (co)variance components and genetic correlation between environments. An accelerated EM-REML algorithm and a multiple-trait animal model that consideredWWTas a different trait in each environment were used to estimate parameters in each pairwise analysis. Direct and maternal (in parentheses) estimated genetic correlations for CA vs UY, CA vs US, US vs UY, UPCB vs S-GC, UP vs CB, and S vs GC were .88 (.84), .86 (.82), .90 (.85), .88 (.87), .88 (.84), and .87 (.85), respectively. The general absence of genotype × country interactions observed in this study, together with a prior study that showed the similarity of genetic and environmental parameters across the three countries, strongly indicates that a joint WWT genetic evaluation for Hereford cattle could be conducted using a model that treated the information from CA, UY, and US as a single population using single population-wide genetic parameters.  aBEEF CATTLE  aGANADERÍA  aGENOTYPE ENVIRONMENT INTERACTION  aINTERNATIONAL COMPARISONS1 aBERTAND, J.K.1 aMISZTAL, I.  tJournal of Animal Science, Augustgv. 78, no. 8, p. 2121-2126, 2000.