BACKGROUND Nutrition plays a crucial role in regulating reproductive hormones and follicular development in cattle. This is visible particularly during the time of negative energy balance at the onset of milk production after calving. Here, elongated periods of anovulation have been observed, resulting from alterations in luteinizing hormone concentrations, likely caused by lower glucose and insulin concentrations in the blood. The mechanisms that result in a reduced fertility are not completely understood, although a close relationship to the glucose-insulin metabolism is widely supported. RESULTS Following this idea, we developed a mathematical model of the hormonal network combining reproductive hormones and hormones that are coupled to the glucose compartments within the body of the cow. The model is built on ordinary differential equations and relies on previously introduced models on the bovine estrous cycle and the glucose-insulin dynamics. Necessary modifications and coupling mechanisms are thoroughly discussed. Depending on the composition and the amount of feed, in particular the glucose content in the dry matter, the model quantifies reproductive hormones and follicular development over time. Simulation results for different nutritional regimes in lactating and non-lactating dairy cows are examined and compared with experimental studies. The simulations describe realistically the effects of nutritional glucose supply on the ovulatory cycle of dairy cattle. CONCLUSIONS The mathematical model enables the user to explore the relationship between nutrition and reproduction by running simulations and performing parameter studies. Regarding its applicability, this work is an early attempt towards developing in silico feeding strategies and may eventually help to refine and reduce animal experiments. REVIEWERS This article was reviewed by John McNamara and Tin Pang (nominated by Martin Lercher).

中文翻译：

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基于模型的葡萄糖代谢对奶牛动情周期动态影响的探索。


背景技术营养在调节牛的生殖激素和卵泡发育中起着至关重要的作用。这在产犊后开始产奶时能量负平衡期间尤其明显。在这里，观察到无排卵期延长，这是由于黄体生成素浓度的变化造成的，这可能是由于血液中葡萄糖和胰岛素浓度降低所致。尽管广泛支持与葡萄糖-胰岛素代谢的密切关系，但导致生育力降低的机制尚未完全了解。结果按照这个想法，我们开发了一个激素网络的数学模型，结合了生殖激素和与牛体内葡萄糖区室耦合的激素。该模型建立在常微分方程的基础上，并依赖于先前引入的牛动情周期和葡萄糖-胰岛素动力学模型。必要的修改和耦合机制进行了深入讨论。根据饲料的成分和数量，特别是干物质中的葡萄糖含量，该模型可以量化生殖激素和卵泡发育随时间的变化。对泌乳和非泌乳奶牛不同营养方案的模拟结果进行了检查，并与实验研究进行了比较。该模拟真实地描述了营养葡萄糖供应对奶牛排卵周期的影响。结论 数学模型使用户能够通过运行模拟和执行参数研究来探索营养与繁殖之间的关系。 就其适用性而言，这项工作是开发计算机喂养策略的早期尝试，最终可能有助于完善和减少动物实验。审稿人 本文由 John McNamara 和 Tin Pang（由 Martin Lercher 提名）审阅。