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.