Richards M P, Proszkowiec-Weglarz M
USDA, ARS, Growth Biology Laboratory, Beltsville, MD 20705-2350, USA.
Poult Sci. 2007 Jul;86(7):1478-90. doi: 10.1093/ps/86.7.1478.
To achieve energy balance and maintain a constant BW, changes in feed intake and energy expenditure must be coordinated and tightly regulated. This may not hold true for some poultry species intensively selected for such economically important traits as growth and meat production. For example, the modern commercial broiler breeder does not adequately control voluntary feed intake to meet its energy requirements and maintain energy balance. As a consequence, feeding must be limited in these birds to avoid overconsumption and excessive fattening during production. It is important to determine a genetic basis to help explain this situation and to offer potential strategies for producing more efficient poultry. This review summarizes what is currently known about the control of feed intake and energy expenditure at the gene level in birds. Highly integrated regulatory systems have been identified that link the control of feeding with the sensing of energy status. How such systems function in poultry is currently being explored. One example recently identified in chickens is the adenosine monophosphate-activated protein kinase pathway that links energy sensing with modulation of metabolic activity to maintain energy homeostasis at the cellular level. In the hypothalamus, this same pathway may also play an important role in regulating feed intake and energy expenditure commensurate with perceived whole body energy needs. Genes encoding key regulatory factors such as hormones, neuropeptides, receptors, enzymes, and transcription factors produce the molecular components that make up intricate and interconnected neural, endocrine, and metabolic pathway networks linking peripheral tissues with the central nervous system. Moreover, coordinate expression of specific gene groups can establish functional pathways that respond to and are regulated by such factors as hormones, nutrients, and metabolites. Thus, with a better understanding of the genetic and molecular basis for regulating feed intake and energy expenditure in birds important progress can be made in developing, evaluating, and managing more efficient commercial poultry lines.
为实现能量平衡并维持恒定体重，采食量和能量消耗的变化必须相互协调并受到严格调控。对于一些为生长和产肉等经济重要性状而经过高强度选育的家禽品种而言，情况可能并非如此。例如，现代商业肉鸡育种鸡不能充分控制自主采食量以满足其能量需求并维持能量平衡。因此，必须限制这些鸡的采食量，以避免在生产过程中过度采食和过度育肥。确定遗传基础有助于解释这种情况，并为培育更高效的家禽提供潜在策略，这一点很重要。本综述总结了目前关于鸟类基因水平上采食量和能量消耗控制的已知情况。已确定了高度整合的调节系统，该系统将采食控制与能量状态感知联系起来。目前正在探索此类系统在禽类中的功能。最近在鸡中发现的一个例子是腺苷单磷酸激活的蛋白激酶途径，该途径将能量感知与代谢活动调节联系起来，以在细胞水平维持能量稳态。在下丘脑中，同样的途径可能在根据感知到的全身能量需求调节采食量和能量消耗方面也发挥重要作用。编码关键调节因子（如激素、神经肽、受体、酶和转录因子）的基因产生构成复杂且相互连接的神经、内分泌和代谢途径网络的分子成分，这些网络将外周组织与中枢神经系统连接起来。此外，特定基因组的协同表达可以建立对激素、营养物质和代谢产物等因素作出反应并受其调节的功能途径。因此，通过更好地理解鸟类采食量和能量消耗调节的遗传和分子基础，可以在培育、评估和管理更高效的商业家禽品系方面取得重要进展。
