High crude protein (CP; 21-26%) diets fed during the first 21 to 28 d post-weaning are viewed negatively because of a perceived increase in the incidence rates of diarrhea due to increased intestinal protein fermentation and/or augmented enteric pathogen burden. This is thought to antagonize nursery pig health and growth performance. Therefore, our objective was to evaluate the impact of low vs. high dietary CP on 21-day post-weaned pig intestinal function. Analyzed parameters included ex vivo intestinal barrier integrity (ileum and colon), ileal nutrient transport, tissue inflammation, and fecal DM. 120 Gilts and barrows (avg BW) were randomly assigned to one of two diets post-weaning. Diets were fed for 21 d, in 2 phases. Phase 1 diets: Low CP (17%) with a 1.4% standardized ileal digestible (SID) Lys (LCP), or high CP (24%) with a 1.4% SID Lysine (HCP). Phase 2: LCP (17%) and a 1.35% SID Lysine, or HCP (24%) formulated to a 1.35% SID Lysine. Pig growth rates, feed intakes, and fecal consistency did not differ (P>0.05) due to dietary treatment. Six animals per treatment were euthanized for additional analyses. There were no differences in colonic epithelial barrier function as measured by transepithelial electrical resistance (TER) and Fluorescein isothiocyanate (FITC)-dextran transport between treatments (P>0.05). Interleukins (IL)-1α, IL-1β, IL-1ra, IL-2 IL-4, IL-6 and IL-12 were not different between treatments (P>0.05). However, IL-8 and IL-18 were higher in HCP-vs. LCP-fed pigs (P<0.05). There were no differences in fecal DM (P>0.05) between treatments. In the ileum, there was a tendency (P=0.06) for TER to be higher in HCP-fed pigs, suggesting a more robust barrier. Interestingly, glucose and glutamine transport were decreased in HCP vs. LCP-fed pigs (P<0.05). FITC-dextran transport was not different between treatments (P>0.05). There were also no differences in ileal cytokine concentrations between diets (P>0.05). Taken together, the data show that low CP does not negatively impact colonic barrier function, fecal DM, or inflammation. In contrast, ileal barrier function and nutrient transport were altered, suggesting a regional effect of diet on overall intestinal function.

中文翻译：

---

日粮蛋白质水平对保育猪肠道功能和炎症的影响

断奶后 21 至 28 天期间饲喂的高粗蛋白（CP；21-26%）日粮被认为是负面的，因为肠道蛋白质发酵增加和/或肠道病原体负担增加导致腹泻发生率增加。这被认为会损害保育猪的健康和生长性能。因此，我们的目的是评估低与高日粮 CP 对断奶后 21 天猪肠道功能的影响。分析的参数包括离体肠屏障完整性（回肠和结肠）、回肠营养物运输、组织炎症和粪便DM。 120 头后备母猪和阉猪（平均体重）在断奶后被随机分配到两种饮食中的一种。饲料喂养21天，分2个阶段。第一阶段饮食：低 CP (17%) 含 1.4% 标准化回肠可消化 (SID) 赖氨酸 (LCP)，或高 CP (24%) 含 1.4% SID 赖氨酸 (HCP)。第 2 相：LCP (17%) 和 1.35% SID 赖氨酸，或配制为 1.35% SID 赖氨酸的 HCP (24%)。由于日粮处理，猪的生长速度、采食量和粪便稠度没有差异(P＞0.05)。每次治疗六只动物被安乐死以进行额外分析。通过跨上皮电阻(TER)和异硫氰酸荧光素(FITC)-葡聚糖转运测量，治疗之间的结肠上皮屏障功能没有差异(P＞0.05)。白细胞介素(IL)-1α、IL-1β、IL-1ra、IL-2、IL-4、IL-6和IL-12在治疗之间没有差异(P＞0.05)。然而，HCP 组的 IL-8 和 IL-18 高于对照组。 LCP饲喂的猪(P＜0.05)。治疗之间粪便DM没有差异(P＞0.05)。在回肠中，HCP 喂养的猪的 TER 有较高的趋势 (P=0.06)，表明屏障更坚固。有趣的是，与 LCP 喂养的猪相比，HCP 喂养的猪的葡萄糖和谷氨酰胺转运减少（P＜0.05）。 FITC-葡聚糖转运在处理之间没有差异(P＞0.05)。饮食之间的回肠细胞因子浓度也没有差异(P＞0.05)。综上所述，数据表明低 CP 不会对结肠屏障功能、粪便糖尿病或炎症产生负面影响。相反，回肠屏障功能和营养物质运输发生了改变，表明饮食对整体肠道功能的区域影响。