Abstract
The present study was carried out to determine whether low dose of zinc oxide nanoparticles (Nano-ZnO) could serve as a potential substitute of pharmacological dose of traditional ZnO in weaned piglets. 180 crossbred weaning piglets were randomly assigned to 3 treatments. Experimental animals were fed basal diet supplemented with 0 mg Zn/kg (Control), 600 mg Zn/kg (Nano-ZnO) and 2000 mg Zn/kg (ZnO) for 14 days. On day 14 after weaning, the piglets fed Nano-ZnO did not differ from those fed traditional ZnO in growth performance and jejunal morphology, while Nano-ZnO treatment could significantly alleviate the incidence of diarrhea (P < 0.05). In jejunum, the mRNA expressions of intestinal antioxidant enzymes and tight junction proteins were increased (P < 0.05) in Nano-ZnO treatment. In ileum, the expression levels of IFN-γ, IL-1β, TNF-α and NF-κB were decreased (P < 0.05). Gene sequencing analysis of 16S rRNA revealed that dietary Nano-ZnO increased the bacterial richness and diversity in ileum, while decreased both of them in cecum and colon. Specifically, the relative abundances of Streptococcus in ileum, Lactobacillus in colon were increased, while the relative abundances of Lactobacillus in ileum, Oscillospira and Prevotella in colon were decreased (P < 0.05). In conclusion, our data reveal that low dose of Nano-ZnO (600 mg Zn/kg) can effectively reduce piglet diarrhea incidence, similar to high dose of traditional ZnO (2000 mg Zn/kg), which may be mediated by improving intestinal microbiota and inflammation response in piglets, and help to reduce zinc environmental pollution.
Highlights
Weaning is commonly associated with oxidative stress, barrier dysfunction and the perturbation of gut microbiota especially in weaned piglets, which is responsible for the growth retardation, villus atrophy and diarrhea [1, 2]
Incidence of diarrhea was alleviated by the addition of Nano-ZnO and traditional ZnO when compared with the control group (P < 0.01), while piglets in Nano-ZnO treatment had higher diarrhea incidence than piglets in traditional ZnO group (P < 0.05)
Jejunal villus height and the ratio of villus height to crypt depth of weaning piglets fed traditional ZnO were significantly higher than piglets in the control group (P < 0.05), but showed no significant difference when compared with Nano-ZnO treatment (P > 0.05) (Figure 1A)
Summary
Weaning is commonly associated with oxidative stress, barrier dysfunction and the perturbation of gut microbiota especially in weaned piglets, which is responsible for the growth retardation, villus atrophy and diarrhea [1, 2]. In current animal husbandry industry, pharmacological dose of dietary ZnO (2000-3000 mg Zn/kg) has been widely used due to its efficient function on promoting growth and relieving diarrhea of weaned piglets. These functions may be accomplished by improving barrier function, regulating oxidation state, modulating immune response and altering microbiota [3]. Studies about Nano-ZnO application mainly focused on the hazards or toxicity in a dose- and time-dependent manner, which was probably caused by reactive oxygen species, oxidant injury or excitation of inflammation [9]. It has been demonstrated that Nano-ZnO moderated the antioxidant activity and revealed an excellent antiinflammatory property by suppressing the expression of inflammatory cytokines in a dose-dependent manner. An enhancing immune response of cows was found [12]
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