During early postnatal development, biomolecules are particularly exposed to the detrimental actions of unneutralized reactive oxygen species. These prooxidant molecules have been claimed to mediate the trade-off between growth and somatic maintenance. Vitamin E is a key exogenous antioxidant that plays an important role in protecting biological membranes against oxidative damage. However, evidence of the effect of vitamin E supplementation during early life on growth and oxidative status in wild populations is equivocal. We tested the effect of supplementing western bluebird nestlings (Sialia mexicana) with vitamin E on growth rate, antioxidant capacity, and oxidative damage to lipids. During the period of accelerated growth (5-8 d), bill growth rate was 21% higher in supplemented nestlings from nests with breeding helpers than in supplemented nestlings from unassisted nests. Vitamin E also boosted tarsus growth rate during the period of slow growth (11-18 d), and this effect was independent of the presence of breeding helpers. Differences in body size and mass, oxidative damage to lipids, and antioxidant capacity were not evident between supplemented and control nestlings at 18 d. Therefore, we conclude that vitamin E promoted faster bill and tarsus growth, but this transient effect disappeared as soon as the supplementation ceased. Our experimental study also supports the idea that tocopherols are rapidly metabolized, since we failed to detect any evident increase of vitamin E in supplemented nestlings at age 18 d. These results provide partial support for the hypothesis that growth rate is constrained by its costs in terms of increased susceptibility to oxidative stress.

中文翻译：

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补充维生素E是否可以在无氧化成本的情况下提高育种助手的生长效益？

在出生后早期发育期间，生物分子特别容易受到未中和的活性氧的有害作用。这些原抗氧化剂分子被认为可以介导生长与体细胞维持之间的权衡。维生素E是一种重要的外源抗氧化剂，在保护生物膜免受氧化损伤方面起着重要作用。然而，在生命早期补充维生素E对野生种群生长和氧化状态的影响的证据是模棱两可的。我们测试了用维生素E补充西部蓝bird雏鸟（Sialia mexicana）对生长速率，抗氧化能力和脂质氧化损伤的作用。在加速增长期间（5-8天），带有育种助手的巢中的雏鸟的账单增长率比非辅助巢中的雏鸟的账单增长率高21％。在生长缓慢的时期（11-18天），维生素E还可以提高体的生长速度，并且这种效果与育种助手的存在无关。18 d时补充和对照的雏鸟的体重和体重，脂质的氧化损伤和抗氧化能力的差异不明显。因此，我们得出结论，维生素E促进了较快的比尔和骨生长，但是这种暂时性作用在停止补充后就消失了。我们的实验研究也支持生育酚迅速代谢的想法，因为我们未能在18 d的补充雏鸟中检测到维生素E明显增加。