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Reaction norms for the study of genotype by environment interaction in animal breeding

Kolmodin, Rebecka (2003). Reaction norms for the study of genotype by environment interaction in animal breeding. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae. Agraria, 1401-6249 ; 437
ISBN 91-576-6484-6
[Doctoral thesis]

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A reaction norm describes the phenotype of an individual as a function of the environment. A reaction norm model is useful for describing traits that change gradually and continuously over an environmental gradient, for example temperature or feed quality. In this thesis the usefulness of reaction norm models for studying genotype by environment interaction (GxE) was evaluated. Field data of Nordic red dairy cattle were analysed using reaction norm models, with the purpose of describing the amount and pattern of GxE. Effects of various environmental variables on milk protein yield, days open and length of productive life were studied. The results showed that over the range of environments commonly encountered within Sweden and the Nordic countries, re-ranking of sires due to GxE was negligible. The slope of a linear reaction norm measures the sensitivity of an individual towards a change in the environment. A simulation study of environmental sensitivity showed that, in the presence of GxE, the average environmental sensitivity is expected to increase in a population selected for high phenotypic value in a continuously improving environment. As genetic variation was found for environmental sensitivity of milk protein yield, days open and length of productive life of dairy cattle it is possible to change environmental sensitivity of these traits with selection. Genetic evaluation of environmental sensitivity is possible using a reaction norm model. Response to mass selection of a trait affected by GxE was described using a linear reaction norm model combined with selection index theory. Prediction equations were derived for the genetic change in reaction norm coefficients and the average phenotypic value in any environment, depending on the environment in which the animals were evaluated and selected. A breeding program can be optimised by choosing the selection environment that gives the maximum genetic progress for a given breeding objective and environment where the animals are required to live. Equations were derived to predict this optimum selection environment.

Authors/Creators:Kolmodin, Rebecka
Title:Reaction norms for the study of genotype by environment interaction in animal breeding
Series Name/Journal:Acta Universitatis Agriculturae Sueciae. Agraria
Year of publishing :December 2003
Number of Pages:35
ALLI. Kolmodin, R., Strandberg, E., Madsen, P., Jensen, J. & Jorjani, H. 2002. Genotype by environment interaction in Nordic dairy cattle studied by use of reaction norms. Acta Agric. Scand., Section A, Anim. Sci.. 52, 11-24. II. Kolmodin, R., Strandberg, E., Danell, B. & Jorjani, H. 2003. Reaction norms of protein yield and days open in Swedish Red and White dairy cattle in relation to various environmental variables. Submitted. III. Petersson, K-J., Kolmodin, R. & Strandberg, E. Genotype by environment interaction for productive life in Swedish Red and White dairy cattle. Submitted. IV. Kolmodin, R., Strandberg, E., Jorjani, H. & Danell, B. 2003. Selection in the presence of a genotype by environment interaction: response in environmental sensitivity. Anim. Sci. 76, 375-385. V. Kolmodin, R. & Bijma, P. Response to mass selection when genotype by environment interaction is modelled as a linear reaction norm. Submitted.
Place of Publication:Uppsala
ISBN for printed version:91-576-6484-6
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:L Animal production > L10 Animal genetics and breeding
Subjects:Not in use, please see Agris categories
Agrovoc terms:dairy cattle, environmental factors, genetic correlation, milk protein, yields, models, selection responses, simulation
Keywords:dairy cattle, days open, environmental sensitivity, genetic correlation, milk protein yield, productive life, random regression model, selection response, simulation, variance component estimation
Permanent URL:
ID Code:419
Department:(NL, NJ) > Institutionen för husdjursgenetik (fr.o.m. 960101)
Deposited By: Rebecka Kolmodin
Deposited On:09 Dec 2003 00:00
Metadata Last Modified:02 Dec 2014 10:04

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