Zinc (Zn) is an essential trace element that has physiological and nutritional functions. However, excessive use of Zn can lead to waste of resources. In this study, we compared the effects of inorganic (ZnSO4) and organic Zn glycine chelate (Zn-Gly) on the growth performance, intestinal morphology, immune function, barrier integrity, and gut microbiome of Cherry Valley ducks. We randomly divided 180 one-day-old male meat ducks into three groups, each with six replicates of 10 birds: basal diet group (CON), basal diet with 70 mg Zn/kg from ZnSO4 (ZnSO4 group), and basal diet with 70 mg Zn/kg from Zn-Gly (Zn-Gly group). After 14 and 35 d of feeding, birds in the Zn groups had significantly increased body weight and average daily gain (ADG), decreased intestinal permeability indicator d-lactate, improved intestinal morphology and barrier function-related tight junction protein levels, and upregulated mucin 2 and secretory immunoglobulin A levels compared to the control (P < 0.05). Additionally, compared to the ZnSO4 group, we found that supplementation with Zn-Gly at 70 mg/kg Zn resulted in the significant increase of body weight at 35 d, 1 to 35 d ADG and average daily feed intake, villus height at 14 and 35 d, secretory immunoglobulin A and immunoglobulin G at 14 d, and mucin 2 mRNA level at 14 d (P < 0.05). Compared with the control group, dietary Zn had a significant effect on the gene expression of metallothionein at 14 and 35 d (P < 0.05). 16S rRNA sequencing showed that Zn significantly increased alpha diversity (P < 0.05), whereas no differences in beta diversity were observed among groups (P > 0.05). Dietary Zn significantly altered the cecal microbiota composition by increasing the abundances of Firmicutes, Blautia, Lactobacillus, Prevotellaceae NK3B31, and [Ruminococcus] torques group and reducing that of Bacteroides (P < 0.05). Spearman correlation analysis revealed that the changes in microbiota were highly correlated (P < 0.05) with growth performance, intestinal morphology, and immune function-related parameters. Taken together, our data show that, under the condition of adding 70 mg/kg Zn, supplementation with Zn-Gly promoted growth performance by regulating intestinal morphology, immune function, barrier integrity, and gut microbiota of Cherry Valley ducks compared with the use of ZnSO4 in feed.
Keywords: Cherry Valley ducks; Zn sources; growth performance; gut microbiome; intestinal barrier.
Zinc (Zn) is an essential trace element that is required for physiological and nutritional functions, but excessive use of Zn can lead to environmental pollution. Few studies have directly compared the impact of different Zn sources on growth performance and intestinal barrier function in Cherry Valley ducks. This study was conducted to investigate the effects of two sources of Zn (inorganic ZnSO4 or organic Zn glycine chelate, Zn-Gly) on growth performance, intestinal morphology, barrier function, and gut microbiome of ducks. Compared to the ZnSO4 group, we found that supplementation with Zn-Gly resulted in the significant increase of body weight at 35 d, 1 to 35 d average daily gain and average daily feed intake, villus height at 14 and 35 d, secretory immunoglobulin A and immunoglobulin G at 14 d, and mucin 2 mRNA level at 14 d. At the genus level, the relative abundance of Blautia was higher in the Zn-Gly group than that in the control and ZnSO4 group. Therefore, Zn-Gly supplementation at 70 mg/kg Zn had positive effects in promoting growth performance by regulating intestinal morphology, barrier function, and gut microbiota of ducks when compared with the same dosage use of ZnSO4 in feed.
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