Boumans Iris J M M, de Boer Imke J M, Hofstede Gert Jan, la Fleur Susanne E, Bokkers Eddie A M
Animal Production Systems Group, Wageningen University, Wageningen, The Netherlands.
Animal Production Systems Group, Wageningen University, Wageningen, The Netherlands.
Horm Behav. 2017 Jul;93:82-93. doi: 10.1016/j.yhbeh.2017.05.003. Epub 2017 May 19.
The interaction between hormonal circadian rhythms and feeding behaviour is not well understood. This study aimed to deepen our understanding of mechanisms underlying circadian feeding behaviour in animals, using pigs, Sus scrofa, as a case study. Pigs show an alternans feeding pattern, that is, a small peak of feed intake at the beginning of the day and a larger peak at the end of the day. We simulated the feeding behaviour of pigs over a 24h period. The simulation model contained mechanisms that regulate feeding behaviour of animals, including: processing of feed in the gastrointestinal tract, fluctuation in energy balance, circadian rhythms of melatonin and cortisol and motivational decision-making. From the interactions between these various processes, feeding patterns (e.g. feed intake, meal frequency, feeding rate) emerge. These feeding patterns, as well as patterns for the underlying mechanisms (e.g. energy expenditure), fitted empirical data well, indicating that our model contains relevant mechanisms. The circadian rhythms of cortisol and melatonin explained the alternans pattern of feeding in pigs. Additionally, the timing and amplitude of cortisol peaks affected the diurnal and nocturnal peaks in feed intake. Furthermore, our results suggest that circadian rhythms of other hormones, such as leptin and ghrelin, are less important in circadian regulation of feeding behaviour than previously thought. These results are relevant to animal species with a metabolic and endocrine system similar to that of pigs, such as humans. Moreover, the modelling approach to understand feeding behaviour can be applied to other animal species.
激素昼夜节律与摄食行为之间的相互作用尚未得到充分理解。本研究旨在以猪（Sus scrofa）为例，加深我们对动物昼夜摄食行为潜在机制的理解。猪表现出交替摄食模式，即在一天开始时摄食量有一个小高峰，而在一天结束时有一个较大的高峰。我们模拟了猪在24小时内的摄食行为。该模拟模型包含调节动物摄食行为的机制，包括：胃肠道内饲料的处理、能量平衡的波动、褪黑素和皮质醇的昼夜节律以及动机决策。从这些不同过程之间的相互作用中，出现了摄食模式（如采食量、进餐频率、采食速率）。这些摄食模式以及潜在机制的模式（如能量消耗）与实证数据拟合良好，表明我们的模型包含了相关机制。皮质醇和褪黑素的昼夜节律解释了猪的交替摄食模式。此外，皮质醇峰值的时间和幅度影响了采食量的昼夜高峰。此外，我们的结果表明，其他激素如瘦素和胃饥饿素的昼夜节律在摄食行为的昼夜调节中不如先前认为的那么重要。这些结果与具有与猪相似的代谢和内分泌系统的动物物种（如人类）相关。此外，理解摄食行为的建模方法可应用于其他动物物种。
