When a rainbow trout stock from a single breeding program is reared in diverse production environments, genotype-by-environment interaction (GxE) may present itself. Growth and its uniformity are considered as two of the most important traits by trout producers worldwide. However, GxE for uniformity of growth has not been studied. Using a double hierarchical generalized linear model and data from the Finnish breeding program, we quantified the genetic variance and correlation of body weight (BW) and its uniformity, as well as the degree of GxE for uniformity of BW in a breeding (BE) and a production (PE) environment. To investigate whether scale effect (high variance related to high mean) affected the estimated parameter, the data were also log-transformed. Although heritability for uniformity () in the BE (0.014) and in the PE (0.012) was low and of similar magnitude, the genetic coefficient of variation for uniformity was 19 and 21%, respectively, revealing high potential for response to selection. The low heritability for uniformity implies that a large number of relatives are needed to obtain moderate accuracy of selection. Genotype re-ranking of uniformity was moderate (rg = 0.56) but became strong after log-transformation (rg = -0.08), indicating independent ranking of genotypes in uniformity across the two environments when the scale effect was accounted for. Due to the strong GxE, especially after log-transformation, the use of sib-testing in the PE is recommended when uniformity is required to be improved across environments. The genetic correlation between BW and uniformity was 0.30 in the BE and 0.79 in the PE, but for the log-transformed BW, the genetic correlations were switched to -0.83 in the BE and -0.62 in the PE. The opposite sign of genetic correlations between BW and uniformity from the raw and log-transformed BW data, respectively, indicate that increased BW is genetically related to increased variance of BW, but to decreased variance of BW after accounting for the scale effect. Hence, the scale effect substantially influences the genetic parameters of uniformity, especially the sign and magnitude of its genetic correlations.
|Title of host publication||Abstract Book ISGA XII - The International Symposium on Genetics in AquacultureI|
|Publication status||Published - 2015|
|Event||ISGA XII, Santiago de Compostella, Spain - |
Duration: 21 Jun 2015 → 27 Jun 2015
|Conference||ISGA XII, Santiago de Compostella, Spain|
|Period||21/06/15 → 27/06/15|
Sae-Lim, P., Kause, A., Janhunen, M., Vehvilainen, H., Koskinen, H., Gjerde, B., Lillehammer, M., & Mulder, H. A. (2015). Genotype-by-environment interaction for uniformity of growth in rainbow trout (Oncorhynchus mykiss). In Abstract Book ISGA XII - The International Symposium on Genetics in AquacultureI (pp. 57-57) http://www.isga2015.com/isga-2015-Abstract-Book.pdf