Department of Basic Medical Veterinary Sciences, Faculty of Veterinary Medicine, Jordan University of Science and Technology, Irbid 22110, Jordan.
Department of Applied Biological Sciences, Faculty of Science and Art, Jordan University of Science and Technology, Irbid 22110, Jordan.
Poult Sci. 2019 Sep 1;98(9):4113-4122. doi: 10.3382/ps/pez249.
Heat stress has a serious impact on nutrient digestion and absorption in broiler chickens. This study aimed to investigate the effects of chronic heat stress (CHS) on the mRNA expression of digestive enzymes and nutrient transporter genes in thermally manipulated (TM) broiler chickens. The evaluated genes encompassed pancreatic lipase, trypsin, amylase, maltase, and alkaline phosphatase as well as certain glucose transporter (GLUT2, SGLT1), amino acid transporter (y+LAT1, CAT1), and fatty acid transporter (FABP1, CD36) genes in the jejunal mucosa. Thermal manipulation was carried out at 39°C and 65% relative humidity for 18 h daily from embryonic days (ED) 10-18, while CHS was induced by raising the temperature to 35°C for 7 D throughout post-hatch days 28 to 35. After 0, 1, 3, 5, and 7 D of CHS, the pancreas and jejunal mucosa were collected from the control and TM groups to evaluate the mRNA expression by relative-quantitative real-time qRT-qPCR. Thermal manipulation significantly decreased the cloacal temperature (Tc) and the hatchling weight, and improved weight gain in broilers during post-hatch life and CHS. In addition, TM decreased the mortality rate during CHS. During CHS, the mRNA expression levels of SGLT1, GLUT2, FABP1, and trypsin were significantly decreased after 1 D in control chickens, and this lower expression persisted until day 7, after which it further decreased. In contrast, in TM chickens, SGLT1, GLUT2, and FABP1 expression decreased after 3, 5, and 7 D of CHS, respectively, while no significant change in trypsin expression was observed throughout the CHS period. Moreover, it was found that TM significantly modulated the mRNA expression dynamics of CD36, alkaline phosphatase, y+LAT1, CAT1, lipase, amylase, and maltase during CHS exposure. The findings of this study suggest that, in broiler chickens, TM has a long-lasting impact on nutrient digestion and absorption capabilities as well as Tc, mortality rates, and BW during CHS.
热应激对肉鸡的营养消化和吸收有严重影响。本研究旨在探讨慢性热应激（CHS）对热调控（TM）肉鸡肠道消化酶和营养转运体基因 mRNA 表达的影响。评估的基因包括胰腺脂肪酶、胰蛋白酶、淀粉酶、麦芽糖酶和碱性磷酸酶，以及某些葡萄糖转运体（GLUT2、SGLT1）、氨基酸转运体（y+LAT1、CAT1）和脂肪酸转运体（FABP1、CD36）在空肠黏膜中的基因。从胚胎第 10 天到第 18 天，每天进行 18 小时的 39°C 和 65%相对湿度的热调控，而在孵化后第 28 天到第 35 天，通过将温度升高到 35°C 诱导 CHS。在 CHS 后 0、1、3、5 和 7 天，从对照组和 TM 组收集胰腺和空肠黏膜，通过相对定量实时 qRT-PCR 评估 mRNA 表达。热调控显著降低了肉鸡的泄殖腔温度（Tc）和出雏体重，提高了出雏后和 CHS 期间的体重增加。此外，TM 降低了 CHS 期间的死亡率。在 CHS 期间，对照组鸡的 SGLT1、GLUT2、FABP1 和胰蛋白酶的 mRNA 表达水平在第 1 天显著降低，这种低表达一直持续到第 7 天，之后进一步降低。相比之下，在 TM 鸡中，SGLT1、GLUT2 和 FABP1 的表达分别在 CHS 后 3、5 和 7 天降低，而胰蛋白酶的表达在整个 CHS 期间没有明显变化。此外，研究发现，TM 显著调节了 CD36、碱性磷酸酶、y+LAT1、CAT1、脂肪酶、淀粉酶和麦芽糖酶在 CHS 暴露期间的 mRNA 表达动态。本研究结果表明，在肉鸡中，TM 对营养消化和吸收能力以及 CHS 期间的 Tc、死亡率和 BW 有持久影响。
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