The high doses of zinc oxide (ZnO) administered orally to piglets for the prevention of diarrhea and increase of growth rate can contaminate pig farms and the surrounding environment. Therefore, there is a need to find a replacement of high doses of dietary ZnO with an equally effective alternative. In the present study, the effect of two formulations of zinc phosphate-based nanoparticles (ZnA and ZnC NPs) on growth performance, intestinal microbiota, antioxidant status, and intestinal and liver morphology was evaluated. A total of 100 weaned piglets were randomly divided into 10 equal groups with the base diet (control) or the base diet supplemented with ZnA, ZnC, or ZnO at concentrations 500, 1000, and 2000 mg Zn per kilogram of diet. Supplements were given to animals for 10 days. Fecal samples were collected on day 0, 5, 10 and 20. At the end of the treatment (day 10), three piglets from each group were sacrificed and analyzed. Comparing to that of control, the significantly higher piglet weight gain was observed in all piglet groups fed with ZnA (P < 0.05). Differences in the total aerobic bacteria and coliform counts in piglet feces after NPs supplementation compared to that of control and ZnO groups were also found (P < 0.05). The majority of aerobic culturable bacteria from the feces represented Escherichia (28.57–47.62%), Enterococcus (3.85–35.71%), and Streptococcus (3.70–42.31%) spp. A total of 542 Escherichia coli isolates were screened for the virulence genes STa, STb, Stx2, F4, and F18. The substantial occurrence of E. coli virulence factors was found on day 5, mainly in fimbrillary antigen and thermostable toxins, except for piglets fed by ZnC. Zn treatment decreased Zn blood levels in piglets fed with ZnO and ZnA (500 mg/kg) and increased in ZnC (2000 mg/kg) compared to that of control (P < 0.05). The antioxidant status of piglets was affected only by ZnA. While some changes in the liver and the intestinal morphology of piglets with NPs were observed, none were serious as reflected by the normal health status and increased weigh gain performance. Our results indicate that ZnA NPs have a positive effect on the piglet growth performance even at the lowest concentration. The prevalence of E. coli virulence factors was lowest in pigs supplemented with ZnC. Zinc phosphate-based nanoparticles may be an effective alternative to ZnO.

中文翻译：

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磷酸锌纳米颗粒作为断奶仔猪日粮中氧化锌的替代品。

为了预防腹泻和提高生长速度而给仔猪口服高剂量氧化锌（ZnO）会污染养猪场和周围环境。因此，需要找到一种同等有效的替代品来替代高剂量的膳食氧化锌。在本研究中，评估了两种磷酸锌纳米颗粒（ZnA 和 ZnC NP）配方对生长性能、肠道微生物群、抗氧化状态以及肠道和肝脏形态的影响。将 100 头断奶仔猪随机分为 10 等组，分别采用基础日粮（对照）或基础日粮中添加 ZnA、ZnC 或 ZnO（锌浓度为每公斤日粮 500、1000 和 2000 mg）的基础日粮。给动物服用补充剂10天。在第0、5、10和20天收集粪便样本。在治疗结束时（第10天），处死每组的三头仔猪并进行分析。与对照组相比，饲喂 ZnA 的所有仔猪组的仔猪增重均显着升高（P < 0.05）。与对照组和ZnO组相比，添加NPs后仔猪粪便中需氧菌总数和大肠菌群计数也存在差异（P < 0.05）。粪便中的大多数需氧可培养细菌为埃希氏菌属（28.57-47.62%）、肠球菌属（3.85-35.71%）和链球菌属（3.70-42.31%）。共筛选了 542 株大肠杆菌分离株的毒力基因 STa、STb、Stx2、F4 和 F18。第5天发现大肠杆菌毒力因子大量出现，主要存在于纤丝抗原和耐热毒素中，除ZnC喂养的仔猪外。与对照组相比，锌处理降低了饲喂 ZnO 和 ZnA (500 mg/kg) 仔猪的血液中 Zn 水平，并增加了 ZnC (2000 mg/kg)（P < 0.05）。仔猪的抗氧化状态仅受 ZnA 影响。虽然观察到使用纳米颗粒的仔猪的肝脏和肠道形态发生了一些变化，但从正常的健康状况和增加的增重性能来看，这些变化并不严重。我们的结果表明，ZnA NPs 即使在最低浓度下也对仔猪生长性能产生积极影响。补充 ZnC 的猪中大肠杆菌毒力因子的流行率最低。磷酸锌纳米粒子可能是氧化锌的有效替代品。