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ORIGINAL RESEARCH article

Front. Physiol.

Sec. Avian Physiology

Intestinal Gene Expression in Heat-Stressed Broilers Selected for High Water Efficiency

Provisionally accepted
Kentu  LassiterKentu LassiterLoujain  AlouiLoujain AlouiElizabeth  S GreeneElizabeth S GreeneMarciela  MaqaedaMarciela MaqaedaTravis  TaberTravis TaberRobert  F WidemanRobert F WidemanSara  OrlowskiSara OrlowskiSami  DridiSami DridiWalter  Gay BottjeWalter Gay Bottje*
  • University of Arkansas, Fayetteville, United States

The final, formatted version of the article will be published soon.

Background: The major goal of this study was to compare mRNA expression associated with water homeostasis in intestines of high water efficient (HWE) broilers to expression in unselected Modern Random Bred (MRB) broilers under thermoneutral (TN) and heat stress (HS) environments. Methods: A 2 x 2 factorial study was conducted with 2 lines (MRB and HWE) and environments (TN and HS). Males were raised in environmental chambers and maintained in TN conditions from 0 to 4 wk. From 4 to 7 wk, broilers were maintained under TN conditions (25 oC) or exposed to cyclic HS conditions (35 oC, 8 h/d). At 7 wk, upper and lower duodenum, and cecum samples were obtained. mRNA was determined by RT-PCR for; 1) heat shock proteins (HSP70, HSP90), 2) the arginine vasotocin (AVT), mesotocin (MT) and receptors (VR2, VR1a, VR1b, MTR), 3) the renin angiotensin system (RAS): angiotensinogen (AGT), angiotensin receptors, (AT1, AT2), renin (REN), AGT converting enzyme (ACE), and Na+/+ATPase (ATP1B1), 4) aquaporins (AQP1-5 and 11), and 5) tight junction proteins occludin (OCLN), and claudins (CLDN2, CLDN15). Results: A main effect of HS was observed for HSP70 and HSP90 expression in all 3 intestinal-segments. In lower duodenum, HS-induced up-regulation of AVT was accompanied by elevations in VR2, VR1a, VRb, AT1, AQPs (1, 3, 11) OCLN, and CLND2, CLDN15. Main effects of broiler line were observed with HWE exhibiting increased mRNA expression of VR2, VR1a, VR1b, AQP1, AQP3 and AQP5 and CLDN2 in the upper duodenum. There was also higher VR2, MT and AQP5 and lower expression of CLDN15 in the lower duodenum but there were no differences in gene expression between MRB and HWE lines in the cecum. Heat stress up-regulated AVT, VR1a, MTR, AVT/MT ratio, AQP1, and AQP3 but downregulated ACE in the upper duodenum. Heat stress also upregulated AVT, VR2, VR1a, VR1b, MTR, AT1, AT2 AQP3, ACP5, OCLN, CLDN2, CLDN15 in the lower duodenum and cecum. Conclusion: The results provide insight into mechanisms responsible for water efficiency in HWE broilers and provide new information in gene expression in the gastrointestinal tract of broilers exposed to chronic cyclic heat stress conditions.

Keywords: broilers, Gene Expression, Heat stress, Intestines, Water use efficiency

Received: 09 Apr 2025; Accepted: 05 Dec 2025.

Copyright: © 2025 Lassiter, Aloui, Greene, Maqaeda, Taber, Wideman, Orlowski, Dridi and Bottje. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Walter Gay Bottje

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