Genetic management of small populations: A review

The genetic management of small population is reviewed with the main objective of making the endangered breeds profitable, addressing the genetic improvement aspect. The discussed methods are: optimum contribution selection; maximum avoidance of inbreeding and factorial matings, making use of the genetics of other, related breeds, integrating life and cryoconservation schemes; rotational breeding scheme; and the introduction of novel traits from conserved populations into commercial breeding populations. The use of dense marker genotyping reduces the necessity of pedigree recording, which is problematic in many conservation schemes. For the choice of breeds in across breed conservation schemes, the following selection criteria were considered: (i) Weitzman's diversity; (ii) gene diversity/expected heterozygosity; (iii) maximum total genetic variance; and (iv) a criterion that puts five times as much weight on between breed compared to within breed diversity. For several reasons, criterion (iii) was considered the criterion of choice.