Rudolf Preisinger Lohmann Tierzucht, Cuxhaven, Germany The breeding of agricultural livestock is aimed at efficient food production and thus makes a major contribution towards feeding the world's population. Against the background of rapid population growth, with a current rate of increase of four people every second, or 345 600 per day, and a decline in the amount of arable land available for the production of animal feed and foodstuffs, the term "sustainability" encompasses a multitude of issues of increasing significance which need to be addressed both in the breeding and management of farm livestock. The paper proposes examination of efforts to increase the efficiency of feed conversion in commercial laying hen production with a view to reducing environmental pollution, the sustainability of breeding programmes and the preservation of the genetic diversity of the existing chicken populations.