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Optimal mass selection policies for schemes with overlapping generations and restricted inbreeding

Genetics Selection Evolution200032:339

Received: 22 October 1999

Accepted: 13 March 2000

Published: 15 July 2000


Optimum breeding schemes for maximising the rate of genetic progress with a restriction on the rate of inbreeding (per year or per generation) are investigated for populations with overlapping generations undergoing mass selection. The optimisation is for the numbers of males and females to be selected and for their distribution over age classes. Expected rates of genetic progress (ΔG) are combined with expected rates of inbreeding (ΔF) in a linear objective function (Φ = ΔG - λΔF) which is maximised. A simulated annealing algorithm is used to obtain the solutions. The restriction on inbreeding is achieved by increasing the number of parents and, in small schemes with severe restrictions, by increasing the generation interval. In the latter case the optimum strategy for obtaining the maximum genetic gain is far from truncation selection across age classes. In most situations, the optimum mating ratio is one but the differences in genetic gain obtained with different mating ratios are small. Optimisation of schemes when restricting the rate of inbreeding per generation leads to shorter generation intervals than optimisation when restricting the rate of inbreeding per year.


optimal selectionoverlapping generationsrestricted inbreedingmass selectiongenetic gain

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Authors’ Affiliations

Scottish Agricultural College, Edinburgh, UK
Animal Breeding and Genetics Group, Wageningen Institute of Animal Sciences, Wageningen Agricultural University, Wageningen, The Netherlands
Roslin Institute (Edinburgh), Roslin, Midlothian, UK


© INRA, EDP Sciences 2000