Plasma metabolite concentrations can be used to understand nutritional status and foraging behavior across ecological contexts including prehibernation fattening, migration refueling, and variation in foraging habitat quality. Generally, high plasma concentrations of the ketone β-hydroxybutyrate, a product of fat catabolism, indicate fasting, while triglycerides indicate recent feeding and fat accumulation. In recent studies of insectivorous bats, triglyceride concentration increased after feeding as expected, but β-hydroxybutyrate also unexpectedly increased rather than decreased. An aerial-hawking foraging strategy is energetically demanding, and thus it has been hypothesized that foraging by insectivorous bats requires catabolism of stored fat. We tested this hypothesis by quantifying plasma β-hydroxybutyrate and triglyceride concentration following feeding in little brown bats (Myotis lucifugus) that were temporarily housed in individual cages to prevent flight. We provided a fixed amount of food and collected blood samples at different intervals after feeding to produce variation in plasma metabolite concentrations. Plasma triglyceride concentration responded as predicted, but similar to previous studies and contrary to our prediction, when flight was eliminated plasma β-hydroxybutyrate concentration responded similarly to triglyceride. Thus, it is unlikely that the unexpected plasma β-hydroxybutyrate patterns observed in previous studies were related to flight. The mechanism underlying this unexpected pattern remains unknown, but the response has been consistent in all studies to date. Thus, plasma metabolite analysis provides an effective tool for studies of nutritional status, although more work is needed to understand why insectivorous bats respond differently than other taxa.

中文翻译：

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测试“觅食时进食”假设：最近进食对小棕蝙蝠（Myotis lucifugus）血浆代谢产物浓度的影响。

血浆代谢物浓度可用于了解整个生态环境中的营养状况和觅食行为，包括冬眠前育肥，迁移加油以及觅食栖息地质量的变化。通常，血浆脂肪分解代谢产物β-羟基丁酸酯的血浆浓度高，表明禁食，而甘油三酸酯则表明最近进食和脂肪堆积。在最近的食虫蝙蝠研究中，进食后甘油三酸酯的浓度如预期的那样增加，但是β-羟基丁酸酯也出人意料地增加而不是减少。空中鹰猎的觅食策略在能量上是需要的，因此，据推测，食虫蝙蝠觅食需要分解所储存的脂肪。我们通过定量喂食临时放置在各个笼子中以防止飞行的小棕蝙蝠（Myotis lucifugus）后，通过定量血浆β-羟基丁酸酯和甘油三酸酯浓度来检验该假设。喂食后，我们提供了固定量的食物并在不同的时间间隔采集了血样，以产生血浆​​代谢物浓度的变化。血浆甘油三酸酯浓度响应如预期，但与先前的研究相似，并且与我们的预测相反，当消除飞行时，血浆β-羟基丁酸酯浓度的响应与甘油三酸酯相似。因此，先前研究中观察到的意外血浆β-羟基丁酸酯模式与飞行无关。这种意外模式的潜在机制仍然未知，但迄今为止，所有研究的反应都是一致的。因此，血浆代谢物分析为研究营养状况提供了有效的工具，尽管需要更多的工作来理解为什么食虫蝙蝠与其他类群反应不同的原因。