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This Article Full Text Full Text (PDF) All Versions of this Article: jas.2007-0031v1 86/1/33    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Steinheim, G. Articles by Klemetsdal, G. Search for Related Content PubMed PubMed Citation Articles by Steinheim, G. Articles by Klemetsdal, G.

Genotype by environment interaction for lamb weaning weight in two Norwegian sheep breeds¹

Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, Ås, Norway

² Corresponding author: geir.steinheim{at}umb.no

Genotype x environment interaction (G x E) effects on live weaning weights of lambs were studied by using the 2 breeds Norwegian White sheep (NWS; heavy, long-tailed) and Spel sheep (Spel; lighter, short-tailed) as genetic groups (G). A total of 37,338 NWS lambs and 30,075 Spel lambs born from 1989 to 1999 on 40 farms that kept both breeds together were included in the analyses. Environment was characterized by farm x year (E). In a mixed linear model framework, significance of the random G x E effect and breed-specific environmental variances were tested by using a log-likelihood approach. Directions and magnitudes of the effect were described through variance component estimates. An across-genotype environmental correlation was also used. There was a significant G x E effect on lamb BW; significant breed differences were found for variance of flock x year effects, indicating different phenotypic plasticities with changing flock x year environments, with the NWS being more sensitive to environmental change. Further, the breed-specific residual variance was greater for NWS, indicating that the effects of environmental variation were larger for the weaning weights of the NWS breed within flock and year. Further, the correlation between flock x year effects for the 2 breeds was significantly different from unity (0.82 ± 0.02), indicating that the common environment is "perceived" differently in the 2 breeds. The best environment for one breed is not necessarily best for the other breed, and vice versa. Solutions of flock x year effects may be used to describe how environmental characteristics such as climate and topography affect the production of different genotypes, and for clustering of environments, thus facilitating improvement of breeding programs and management schemes for domestic and wild ungulate populations.

Key Words: breed • genotype by environment interaction • phenotypic plasticity • sheep • weaning weight