Although the chicken was domesticated during the Neolithic period, the development of the modern broiler is a recent event that has occurred within the past 100 years. The chicken's adaptability has allowed it to be grown globally under a range of husbandry conditions. That is, the same genetic stock may be found in a range of environments, where it is noted for rapid growth to market weight and efficiency of feed use, which has increased dramatically, mainly through genetic selection. Under good husbandry and a high-energy diet, at 35 days of age a 1.40-kg broiler required 3.22 kg of feed in 1985. Twenty-five years later, we have a 2.44-kg broiler produced on 3.66 kg of feed. This review attempts to address the history of factors contributing to these changes, obstacles that have had to be overcome, and future limitations.
Keywords: breeding; chickens; genetics; heterosis; selection.