Hu Jie, Zeng Jingyuan, Shi Yurou, Song Sen
School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.
Curr Zool. 2022 Feb 3;68(6):667-678. doi: 10.1093/cz/zoac005. eCollection 2022 Dec.
The behavioral video recordings of the gray-backed shrike revealed that parent birds eat the feces produced by their nestlings. "Parental nutrition hypothesis" attributes the origin of this behavior to nutrition-recovery and cost-saving, respectively. However, the presence of usable nutrients in the nestlings' feces is unknown because of traditional technology. In this study, we analyzed all the metabolites and the variations in the diversity and content of microbes in the feces of gray-backed shrike nestlings. We aimed to report the changes in microbes and metabolites with the age of nestlings and point out that the parent birds that eat the feces may gain potential nutrition benefits. The results showed that the relative abundances of Proteobacteria, Firmicutes, and Bacteroidota, changed significantly when the nestlings were 6 days old. The relative abundances of 6 probiotics, which are involved in digestion, metabolism, and immunity-related physiological functions, decreased in the nestlings' feces gradually with age; therefore, these probiotics may be obtained by parent birds upon ingestion of the feces of young nestlings. Among the metabolites that were detected, 20 were lipids and some had a role in anti-parasitic functions and wound healing; however, their relative contents decreased with age. These beneficial substances in the nestlings' feces may stimulate the parents to swallow the feces. Moreover, there were many aromatic metabolites in the newly hatched nestlings' feces, but the content of bitter metabolites increased as they grew up. Therefore, our results are in accordance with the nutritional hypothesis.
对灰背伯劳的行为视频记录显示，亲鸟会吃掉雏鸟产生的粪便。“亲代营养假说”分别将这种行为的起源归因于营养恢复和成本节约。然而，由于传统技术的原因，雏鸟粪便中是否存在可用营养物质尚不清楚。在本研究中，我们分析了灰背伯劳雏鸟粪便中的所有代谢物以及微生物多样性和含量的变化。我们旨在报告微生物和代谢物随雏鸟年龄的变化，并指出吃掉粪便的亲鸟可能获得潜在的营养益处。结果表明，当雏鸟6日龄时，变形菌门、厚壁菌门和拟杆菌门的相对丰度发生了显著变化。参与消化、代谢和免疫相关生理功能的6种益生菌的相对丰度在雏鸟粪便中随年龄逐渐降低；因此，这些益生菌可能会被亲鸟在摄入幼雏粪便时获得。在检测到的代谢物中，有20种是脂质，其中一些具有抗寄生虫功能和伤口愈合作用；然而，它们的相对含量随年龄下降。雏鸟粪便中的这些有益物质可能会刺激亲鸟吞食粪便。此外，新孵化雏鸟的粪便中有许多芳香族代谢物，但苦味代谢物的含量随着它们的成长而增加。因此，我们的结果与营养假说相符。
