Low doses of microencapsulated zinc oxide improve performance and modulate the ileum architecture, inflammatory cytokines and tight junctions expression of weaned pigs

Abstract

The aim of this study was to compare low doses of microencapsulated v. pharmacological ZnO in the diet of piglets on growth performance, ileum health status and architecture. One hundred and forty-four piglets weaned at 28 days and divided in 36 pens (two males and two females per pen), received a basal diet (control, Zn at 50 mg/kg) or the basal diet with ZnO at 3000 mg/kg (pZnO), or with lipid microencapsulated ZnO at 150 or 400 mg/kg (mZnO-300 and mZnO-800, respectively). After 14 and 42 days, three pigs per sex per treatment were euthanized to collect the ileum mucosa for immunohistochemistry, histomorphology, inflammatory cytokines and tight junction components gene expression. Data were analyzed with one-way ANOVA. At 0 to 14 days, the pZnO and mZnO-800 groups had greater average daily gain compared with control ( P < 0.05). Gain to feed ratio (G : F) in the same time interval was higher in pZnO group compared with control thus resulting in higher BW ( P < 0.05). At day 14, ileum villi height in mZnO-800 pigs was 343 µm v. 309 and 317 µm in control and pZnO, respectively ( P < 0.01) and villi : crypts ratio (V : C), as well as cells positive to proliferating cell nuclear antigen (PCNA), were greater in all treated groups compared with control ( P < 0.01). In mZnO-800 group, interferon-γ mRNA was the lowest ( P = 0.02), and both pharmacological ZnO and mZnO reduced tumor necrosis factor-α protein level ( P < 0.0001). Compared with pZnO group, mZnO-800 increased occludin and zonula occludens-1 protein level (1.6-fold and 1.3-fold, respectively; P < 0.001). At day 42, both groups receiving microencapsulated ZnO had 1.7 kg greater BW than control and did not differ from pZnO group ( P = 0.01); ileum villi height and V : C ratio were the greatest for pZnO compared with the other groups, whereas PCNA-positive cells were the most numerous in mZnO-800 group ( P < 0.001).In conclusion, pigs receiving low doses of microencapsulated ZnO had G : F comparable with those receiving pharmacological level of ZnO in the overall post-weaning phase. Moreover, in the first 2 weeks post-weaning, microencapsulated ZnO effect on inflammatory status and ileum structure and integrity was comparable with pharmacological ZnO.

Towards Zero Zinc Oxide: Feeding Strategies to Manage Post-Weaning Diarrhea in Piglets

“…During in vitro infections of intestinal epithelial cells with E. coli F4, ZnO significantly reduced the expression of several pro-inflammatory cytokines and improved the transcription of the anti-inflammatory cytokine TGF-β [47], together with a significant downregulation of genes related to the innate immune response [49]. The same modulatory effect on intestinal inflammation was demonstrated by many in vivo studies, which reported lower IFN-γ, TNF-α, and IL-6 in ZnO-supplemented piglets [35,36,50].…”

“…Rather than the fulfilment of Zn daily nutritional requirements, the main mechanism of action of ZnO seems to be related to a substantial enhancement in nutrient absorption and intestinal morphology [34]. Indeed, further studies confirmed that the supplementation of pharmacological ZnO improves performance by ensuring higher villi:crypt ratio, greater occludin protein levels, and a considerable proliferative effect on enterocytes [35,36]. The increase in tight-junction expression is a clear marker of ZnO ability to reduce intestinal permeability in a very delicate phase for piglets [37], with a marked influence on the appearance of diarrheic symptoms.…”

Effects of dietary supplementation of lipid-coated zinc oxide on intestinal mucosal morphology and expression of the genes associated with growth and immune function in weanling pigs

“…Likewise, IL-6 expression is seemingly down-regulated by the increasing dose of SZ, as suggested by the negative regression of its mRNA level on the supplemental SZ concentration. Shen et al [ 15 ] and Grilli et al [ 30 ] have reported the effects for one of two other lipid-coated ZnO supplements, respectively, on jejunal expression of a number of cytokines [ 30 ] as well as growth factors and tight junction proteins [ 15 ], but comparison of their results with the present ones was precluded because of the unknown efficacies of the different Zn supplements as well as different ranges of dietary concentrations of them examined in these and present studies.…”

Encapsulation Methods and Use in Animal Nutrition

“…It has also been reported that the addition of encapsulated cinnamaldehyde and eugenol essential oil mixture increases the concentration of ruminal ammonia in dairy cattle (Tekippe et al 2013). The microencapsulated zinc oxide has shown positive effects on growth performance and intestinal structure in piglets and that microencapsulation may be beneficial to the environment by using lower levels of zinc oxide and less waste has been reported (Grilli et al 2015).…”