Effects of heat stress and depressed feed intake on the cecal and ileal microbiota of broiler chickens

Samples were obtained from cecal and ileal contents from 4 groups of broiler chickens: thermoneutral (TN, 23 deg C), chronic heat stress (CHS, 35 deg C for 8 h/day), pair-fed (PF, fed same amount of feed as CHS, 23 deg C), and acute heat stress (AHS, 35 deg C for 2 h on d 42 before sampling). The primary aim of the study was to distinguish between effects from CHS and effects solely from depressed feed intake through the PF group. Because CHS causes depressed feed intake, it is unclear how much of a role feed intake plays in microbiota diversity and composition compared to the direct effects of CHS. Additionally, the inclusion of the AHS group allows for comparison of microbiota after long-term CHS and a brief 2 hr period of AHS.

本研究的样本来源于4组肉鸡的盲肠与回肠内容物，分组情况如下：热中性环境组（thermoneutral, TN，23℃）、慢性热应激组（chronic heat stress, CHS，每日于35℃环境暴露8小时）、配对饲喂组（pair-fed, PF，日粮饲喂量与CHS组一致，环境温度为23℃）以及急性热应激组（acute heat stress, AHS，于采样前第42天在35℃环境暴露2小时）。本研究的核心目标是区分慢性热应激（CHS）本身的效应，与仅由采食量降低所介导的效应——该区分通过配对饲喂组（PF）完成。由于慢性热应激会导致肉鸡采食量下降，目前尚不明确相较于慢性热应激的直接作用，采食量在肠道微生物群的多样性与组成中发挥了多大的调控作用。此外，纳入急性热应激组（AHS）可用于对比长期慢性热应激与短暂2小时急性热应激后，肉鸡肠道微生物群的差异。