Author
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Richards, Mark |
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Submitted to: National Breeders Roundtable Proceedings
Publication Type: Proceedings Publication Acceptance Date: 5/4/2004 Publication Date: 5/6/2004 Citation: Richards, M.P. 2004. Mechanisms regulating appetite and energy balance in poultry. Proceedings of the Fifty-third Annual National Breeders Roundtable. pp. 15-59. Interpretive Summary: One of the primary goals of poultry producers today is to improve the efficiency and profitability of meat production. To continue to meet this goal, poultry breeders have placed a major emphasis on the selection of lines of chickens and turkeys that grow faster and produce more meat than previous generations. Unfortunately, along with improvements in these economically important traits have come some unwanted changes in feed intake and body composition. Commercial lines of broiler chickens and turkeys tend to overeat when given free access to feed. This can lead to an excessive accumulation of fat and a variety of health-related problems if their access to feed is not strictly limited throughout their entire lifecycle. Abdominal fat is now regarded as a main source of waste by poultry processors and thus a major contributor to decreased production profitability. In order to improve this situation, it is important to first understand the underlying genetics of the mechanisms that regulate appetite and energy balance in poultry. This manuscript discusses what we currently know about the regulation of feed intake, energy balance, and body weight in poultry. A better understanding of the genes associated with controlling appetite and energy balance and how their expression is regulated by nutritional and hormonal stimuli will offer new insights into current poultry breeding and management practices. This information is intended for use by researchers studying the control of appetite and body weight in avian species, as well as, poultry producers in formulating new genetic selection and feeding strategies for commercial poultry flocks. Technical Abstract: Intensive selection by poultry breeders for economically important production traits such as growth rate and meat production has led to significant changes in correlated responses such as feed intake and energy metabolism. For example, the modern commercial broiler, selected for rapid growth and enhanced breast meat yield, does not adequately regulate voluntary feed intake to achieve energy balance and a constant body weight. When provided unrestricted access to feed, broilers will tend to over eat leading to an excessive accumulation of energy (fat) stores and a variety of health-related problems. A series of highly integrated regulatory mechanisms exists for control of appetite and energy balance involving complex interactions between peripheral tissues and the central nervous system. Within the central nervous system, the brainstem and the hypothalamus play critical roles in the regulation of feed intake and energy balance. Genes encoding key regulatory factors such as hormones, neuropeptides, receptors, enzymes, transport proteins, and transcription factors constitute the molecular basis for regulatory systems that derive from integrated sensing, signaling, and metabolic pathways. We do not yet have a complete understanding of the genetic basis for this regulation in poultry. A better understanding of the genes associated with controlling feed intake and energy balance and how their expression is regulated by nutritional and hormonal stimuli will offer new insights into current poultry breeding and management practices. |
