Institute of College of Life Science and Resources and Environment, Yichun University, Yi Chun, 336000, China.
Sichuan Academy of Grassland Sciences, Sichuan, 625014, Chengdu, China.
BMC Vet Res. 2022 Dec 6;18(1):425. doi: 10.1186/s12917-022-03483-2.
To our knowledge, carbon loaded with nano-ZnO (NZnOC) represents a new nutritional additive for the animal husbandry industry. However, the mechanism by which NZnOC mediates beef cattle growth and intestinal health is not fully understood. This study aimed to investigate the effects of carbon loaded with nano-ZnO (NZnOC) supplementation on growth performance, gut microbiota, bile acid (BAs) metabolism and intestinal immunity in fattening cattle. Twenty cattle (16 ± 0.95 months) were randomly assigned to two dietary groups: CON (control, without feed additive) and NZnOC (diet supplemented with 80 mg NZnOC/kg diet dry matter basic) for 60 d. The colon digesta microbiota composition and BAs concentration were determined by microbiota metagenomics and gas chromatography methods, respectively.
The results showed that the NZnOC-supplemented cattle had greater final weight, average daily gain and gain-to-feed ratio than those in the CON group. Cattle fed the NZnOC diet had a higher relative abundance of the secondary BAs synthesizing phyla Firmicutes, Tenericutes and Actinobacteria than those fed the CON diet. Dietary supplementation with NZnOC increased the relative abundance of the secondary BAs synthesis microbiota genera Clostridium, Ruminococcus, Eubacterium, and Brevibacillus in colon digesta. Cattle fed the NZnOC diet had increased activities of 3α-hydroxysteroid dehydrogenase (EC: 1.1.1.52) and bile acid-CoA ligase BaiB (EC: 6.2.1.7) in the colon digesta compared with those fed the CON diet. The primary BAs taurocholic acid, taurochenodeoxycholic acid and taurodeoxycholate acid were significantly decreased by dietary NZnOC supplementation, while the secondary BAs deoxycholic acid, taurolithocholic acid, beta-muricholic acid, 12-ketolithocholic acid and ursodeoxycholic acid were significantly increased. Dietary supplementation with NZnOC increased the mRNA abundance of G protein-coupled bile acid receptor 1, protein kinase cAMP-activated catalytic subunit alpha, cyclic-AMP response element binding protein 1 and interleukin (IL)-10 in the colon mucosa of cattle, while the mRNA abundance of tumor necrosis factor and IL-1β were significantly decreased.
In summary, dietary supplementation with NZnOC can facilitate the growth performance and intestinal immune function of cattle by improving BAs metabolism. NZnOC can be supplemented in the diet as a safe regulator of gut microbiota and as a feed additive in the ruminants industry.
据我们所知，负载纳米氧化锌的碳（NZnOC）代表了畜牧业的一种新型营养添加剂。然而，NZnOC 介导肉牛生长和肠道健康的机制尚不完全清楚。本研究旨在探讨负载纳米氧化锌的碳（NZnOC）对育肥牛生长性能、肠道微生物群、胆汁酸（BAs）代谢和肠道免疫的影响。将 20 头牛（16±0.95 月龄）随机分为两组：CON（对照组，无饲料添加剂）和 NZnOC（日粮添加 80mg NZnOC/kg 日粮干物质基础），试验期为 60d。通过微生物组学和气相色谱法分别测定结肠内容物微生物组成和 BAs 浓度。
结果表明，与 CON 组相比，添加 NZnOC 的牛的终重、平均日增重和增重/饲料比更高。与 CON 组相比，饲喂 NZnOC 日粮的牛次级 BAs 合成菌门厚壁菌门、无壁菌门和放线菌门的相对丰度更高。NZnOC 日粮添加增加了结肠内容物中次级 BAs 合成菌群梭菌属、真杆菌属、真杆菌属和短杆菌属的相对丰度。与 CON 组相比，NZnOC 日粮组牛结肠内容物中 3α-羟甾类脱氢酶（EC：1.1.1.52）和胆汁酸-CoA 连接酶 BaiB（EC：6.2.1.7）的活性增加。与 CON 组相比，日粮中添加 NZnOC 显著降低了初级 BAs 牛磺胆酸、牛磺鹅脱氧胆酸和牛磺脱氧胆酸的含量，而次级 BAs 脱氧胆酸、牛磺石胆酸、β-鼠胆酸、12-酮石胆酸和熊去氧胆酸的含量显著增加。NZnOC 日粮添加增加了牛结肠黏膜中 G 蛋白偶联胆汁酸受体 1、蛋白激酶 cAMP 激活的催化亚单位α、环磷酸腺苷反应元件结合蛋白 1 和白细胞介素（IL）-10 的 mRNA 丰度，而肿瘤坏死因子和 IL-1β 的 mRNA 丰度则显著降低。
综上所述，日粮添加 NZnOC 可通过改善 BAs 代谢促进牛的生长性能和肠道免疫功能。NZnOC 可作为肠道微生物群的安全调节剂和反刍动物饲料添加剂添加到饲料中。
