Estimation, effectiveness and opportunities of long term genetic improvement in animals and maize

Genetic improvement in animals and plants for food consumption has been practised and realised since domestication. Intensive improvement, increasingly with incorporation of genetic principles, has been undertaken for a century or more. Much of this has been highly intensive and effective, notably in poultry. There are consequently concerns that genetic variation is being exhausted and continued gains cannot be expected. On the other hand, new technologies, in particular using molecular markers and, perhaps, transgenic methods, have become available, which in themselves provide the possibility of increasing responses by making better use of existing variability and indeed in generating new variability.