Nutritional limitations on growth and development in poultry

Geneticists have been highly successful in improving potential growth of broilers over the past 50 years, and it is likely that more genetic progress is possible. However, in order to maximise this potential it will be necessary for nutritionists to review the way in which these fast-growing strains are fed. Unless changes are made to the composition of broiler feeds in the future, constraints are likely to occur immediately after hatching, when gut capacity will not allow the consumption of sufficient of a conventional starter feed to enable the chick to grow at its potential, and towards the end of the growing period, when heat production is so high that it may be impossible for a broiler to lose sufficient heat to the environment to enable it to grow at its potential. Issues discussed are those concerning the constraining effect of the egg on embryonic development, early feeding of the embryo and chick, problems associated with meeting the amino acid requirements immediately post-hatch, and various nutritional interventions that have been suggested as methods of reducing the heat load on broilers. It is suggested that with some manipulation of feed nutrient contents nutritionists will be able to keep up with the genetic changes taking place into the near future, but that the constraining effect on growth of global warming is a challenge that will need to be addressed by biologists and engineers in poultry research. (C) 2010 Elsevier B.V. All rights reserved.