Pearce S C, Sanz Fernandez M-V, Torrison J, Wilson M E, Baumgard L H, Gabler N K
J Anim Sci. 2015 Oct;93(10):4702-13. doi: 10.2527/jas.2015-9018.
Dietary zinc (inorganic and organic or zinc AA complex forms) is essential for normal intestinal barrier function and regeneration of intestinal epithelium. Given that heat stress (HS) exposure can negatively affect intestinal integrity and caloric intake, possible nutritional mitigation strategies are needed to improve health, performance, and well-being. Therefore, our objective was to evaluate 2 dietary zinc sources and reduced caloric intake on intestinal integrity in growing pigs subjected to 12 h of HS. A total of 36 pigs were fed 1 of 2 diets: 1) a control diet (CON; 120 mg/kg of zinc from zinc sulfate) or 2) 60 mg/kg from zinc sulfate and 60 mg/kg from zinc AA complex (ZnAA). After 17 d, the CON pigs were then exposed to thermal neutral (TN) conditions with ad libitum intake (TN-CON), HS (37°C) with ad libitum intake (HS-CON), or pair-fed to HS intake under TN conditions (PFTN); the ZnAA pigs were exposed to only HS (HS-ZnAA). All pigs were sacrificed after 12 h of environmental exposure, and blood and tissue bioenergetics stress markers and ex vivo ileum and colon integrity were assessed. Compared with TN-CON, HS significantly ( < 0.05) increased rectal temperatures and respiration rates. Ileum villus and crypt morphology was reduced by both pair-feeding and HS. Both PFTN and HS-CON pigs also had reduced ileum integrity (dextran flux and transepithelial resistance) compared with the TN-CON pigs. However, ZnAA tended to mitigate the HS-induced changes in ileum integrity. Ileum mucin 2 protein abundance was increased due to HS and pair-feeding. Colonic integrity did not differ due to HS or PFTN treatments. Compared with the HS-CON, HS-ZnAA pigs tended to have reduced blood endotoxin concentrations. In conclusion, HS and reduced feed intake compromised intestinal integrity in pigs, and zinc AA complex source mitigates some of these negative effects.
膳食锌（无机锌、有机锌或锌氨基酸复合物形式）对于正常的肠道屏障功能和肠上皮细胞再生至关重要。鉴于热应激（HS）会对肠道完整性和热量摄入产生负面影响，因此需要采取可能的营养缓解策略来改善健康、性能和幸福感。因此，我们的目标是评估两种膳食锌源以及减少热量摄入对遭受12小时热应激的生长猪肠道完整性的影响。总共36头猪被喂食两种日粮中的一种：1）对照日粮（CON；硫酸锌提供的锌含量为120毫克/千克）或2）硫酸锌提供的锌含量为60毫克/千克，锌氨基酸复合物（ZnAA）提供的锌含量为60毫克/千克。17天后，CON组的猪随后暴露于热中性（TN）条件下自由采食（TN-CON）、热应激（37°C）条件下自由采食（HS-CON）或在TN条件下按热应激组的采食量进行配对饲喂（PFTN）；ZnAA组的猪仅暴露于热应激条件下（HS-ZnAA）。在环境暴露12小时后，所有猪被宰杀，并评估血液和组织生物能量应激标志物以及离体回肠和结肠的完整性。与TN-CON组相比，热应激显著（<0.05）提高了直肠温度和呼吸频率。配对饲喂和热应激均降低了回肠绒毛和隐窝形态。与TN-CON组相比，PFTN组和HS-CON组的猪回肠完整性（葡聚糖通量和跨上皮电阻）也有所降低。然而，锌氨基酸复合物倾向于减轻热应激引起的回肠完整性变化。热应激和配对饲喂导致回肠粘蛋白2蛋白丰度增加。结肠完整性在热应激或PFTN处理后没有差异。与HS-CON组相比，HS-ZnAA组的猪血液内毒素浓度有降低的趋势。总之，热应激和采食量减少损害了猪的肠道完整性，而锌氨基酸复合物来源减轻了其中一些负面影响。
