Dietary Supplementation of Ferrous Glycine Chelate Improves Growth Performance of Piglets by Enhancing Serum Immune Antioxidant Properties, Modulating Microbial Structure and Its Metabolic Function in the Early Stage

Abstract

The present research aimed to explore the effect of dietary ferrous glycine chelate supplementation on performance, serum immune-antioxidant parameters, fecal volatile fatty acids, and microbiota in weaned piglets. A total of 80 healthy piglets (weaned at 28 day with an initial weight of 7.43 ± 1.51 kg) were separated into two treatments with five replicates of eight pigs each following a completely randomized block design. The diet was a corn-soybean basal diet with 2,000 mg/kg ferrous glycine chelates (FGC) or not (Ctrl). The serum and fecal samples were collected on days 14 and 28 of the experiment. The results indicated that dietary FGC supplementation improved (p < 0.05) the average daily gain and average daily feed intake overall, alleviated (p < 0.05) the diarrhea rate of piglets at the early stage, enhanced (p < 0.05) the levels of superoxide dismutase and catalase on day 14 and lowered (p < 0.05) the MDA level overall. Similarly, the levels of growth hormone and serum iron were increased (p < 0.05) in the FGC group. Moreover, dietary FGC supplementation was capable of modulating the microbial community structure of piglets in the early period, increasing (p < 0.05) the abundance of short-chain fatty acid-producing bacteria Tezzerella, decreasing (p < 0.05) the abundance of potentially pathogenic bacteria Slackia, Olsenella, and Prevotella as well as stimulating (p < 0.05) the propanoate and butanoate metabolisms. Briefly, dietary supplemented FGC ameliorates the performance and alleviated the diarrhea of piglets by enhancing antioxidant properties, improving iron transport, up-regulating the growth hormone, modulating the fecal microbiota, and increasing the metabolism function. Therefore, FGC is effective for early iron supplementation and growth of piglets and may be more effective in neonatal piglets.

Keywords: antioxidative property; fecal microbiota; ferrous glycine chelate; growth performance; piglets.

Figure 1

Serum metabolites of 7d, 14d and 28d-piglets as affected by dietary ferrous glycine chelate supplementation. NEFA, non-esterified fatty acids; TC, total cholesterol; TG, total triglycerides; HDL, high density lipoprotein; LDL, low density lipoprotein; ALT, alanine aminotransferase; AST, aspartate aminotransferase; TP, total protein; AKP, alkaline phosphatase; BUN, blood urea nitrogen; D-LA, D-lactate; LDH, lactate dehydrogenase; UA, uric acid. Ctrl, corn-soybean basal diet; FGC, corn-soybean basal diet with 2,000 mg/kg ferrous glycine chelate. Data were shown as means ± SEM. *p < 0.05; **p < 0.01; ***p < 0.001. N = 10.

Figure 2

Serum antioxidant capacity of 7d, 14d and 28d-piglets as affected by dietary ferrous glycine chelate supplementation. GSH-Px, glutathione peroxidase; SOD, superoxide dismutase, T-AOC, total antioxidant capacity; XOD, xanthine oxidase; CAT, catalase; MDA, Malondialdehyde. Ctrl, corn-soybean basal diet; FGC, corn-soybean basal diet with 2,000 mg/kg ferrous glycine chelate. Data were shown as means ± SEM. *p < 0.05; **p < 0.01; ***p < 0.001. N = 10.

Figure 3

Serum hormones and iron-binding capacity of 7d, 14d and 28d-piglets as affected by dietary ferrous glycine chelate supplementation. ACTH, adrenocorticotropic hormone; TIBC, total iron binding capacity. Ctrl, corn-soybean basal diet; FGC, corn-soybean basal diet with 2,000 mg/kg ferrous glycine chelate. Data were shown as means ± SEM. *p < 0.05. N = 10.

Figure 4

Fecal microbial α-diversity and rarefaction curves at OTU level. (A) Sobs index. (B) Shannon index. (C) Simpson index. (D) Ace index. (E) Chao index. (F) phylogenetic diversity index. (G) Shannon curves at d 14. (H) Shannon curves at d 28. Ctrl, corn-soybean basal diet; FGC, corn-soybean basal diet with 2,000 mg/kg ferrous glycine chelate. Data were shown as means ± SEM. *p < 0.05. N = 5.

Figure 5

Overview of fecal microbial composition of 14d-piglets. (A) Venn diagram. (B) Heatmap at genus level. (C) Circos diagram at family level. (D) Barplot and pieplot at phylum level. (E) Barplot and pieplot diagram at family level. Ctrl, corn-soybean basal diet; FGC, corn-soybean basal diet with 2,000 mg/kg ferrous glycine chelate. N = 5.

Figure 6

Overview of fecal microbial composition of 28d-piglets. (A) Venn diagram. (B) Heatmap at genus level. (C) Circos diagram at family level. (D) Barplot and pieplot at phylum level. (E) Barplot and pieplot diagram at family level. Ctrl, corn-soybean basal diet; FGC, corn-soybean basal diet with 2,000 mg/kg ferrous glycine chelate. N = 5.

Figure 7

Fecal microbial β-diversity at OTU levels and LEfSe analysis from phylum to genus level of 14d and 28d-piglets. (A) PCoA of 14d-piglets 14. (B) PCoA of 28d-piglets. (C) Cladogram of 14d-piglets. (D) Cladogram of 28d-piglets. (E) LDA of 14d-piglets. (F) LDA of 28d-piglets. p < 0.05 and LDA score>3 were presented. LEfSe, linear discriminant analysis effect size; PCoA, principal co-ordinate analysis; LDA, linear discriminant analysis. Ctrl, corn-soybean basal diet; FGC, corn-soybean basal diet with 2,000 mg/kg ferrous glycine chelate. N = 5.

Figure 8

Histogram of fecal microbial community differences. (A–C) Differences in fecal microbiota of 14d-piglets at phylum, family, and genus levels. (D,E) Differences in the fecal microbiota of 28d-piglets at family and genus levels. Ctrl, corn-soybean basal diet; FGC, corn-soybean basal diet with 2,000 mg/kg ferrous glycine chelate. N = 5.

Figure 9

Correlation heatmap analysis among performance indices and significantly differential bacteria for (A) 14d-piglets and (B) 28d-piglets. ADG, average daily gain; ADFI, average daily feed intake; GE, gross energy; CP, crude protein; FCR, feed conversion ratio; EE, ether extract. Ctrl, corn-soybean basal diet; FGC, corn-soybean basal diet with 2,000 mg/kg ferrous glycine chelate. Red: positive correlation; blue, negative correlation. *p < 0.05; **p < 0.01; ***p < 0.001. N = 5.

Figure 10

Predictive functional analysis of fecal microbiota in 14d and 28d-piglets. (A) COG function classification of 14d-piglets (B) KEGG metabolic function of 14d-piglets at pathway level 2. (C) COG function classification of 28d-piglets (D) KEGG metabolic function of 28d-piglets at pathway level 2. COG, Clusters of Orthologous Groups; KEGG, Kyoto Encyclopedia of Genes and Genomes. Ctrl, corn-soybean basal diet; FGC, corn-soybean basal diet with 2,000 mg/kg ferrous glycine chelate. Data were shown as means ± SEM. **p < 0.01; ***p < 0.001. N = 5.

Figure 11

Fecal volatile fatty acid of piglets as affected by dietary FGC supplementation (mg/g). Ctrl, corn-soybean basal diet; FGC, corn-soybean basal diet with 2,000 mg/kg ferrous glycine chelate. Data were shown as means ± SEM. **p < 0.01; *p < 0.05. N = 5.