Effect of an organic acid blend as an antibiotic alternative on growth performance, antioxidant capacity, intestinal barrier function, and fecal microbiota in weaned piglets

Abstract

This study was conducted to evaluate the effects of dietary organic acid blend on growth performance, antioxidant capacity, intestinal barrier function, and fecal microbiota in weaned piglets compared with antibiotic growth promoters (AGPs). A total of 90 weaned crossbred barrows (24 ± 1 d of age) with an initial body weight of 7.40 kg were allocated into three experimental treatments. Each treatment consisted of six replicate pens, with five piglets housed in each pen. The dietary treatments included the basal diet (NC), the basal diet supplemented with antibiotics (PC), and the basal diet supplemented with organic acid blend (OA). On day 42, one piglet per pen was randomly selected for plasma and small intestinal sample collection. The results showed that dietary AGP significantly improved growth performance and reduced diarrhea incidence compared to the NC group (P < 0.05). Dietary OA tended to increase body weight on day 42 (P = 0.07) and average daily gain from days 0 to 42 (P = 0.06) and reduce diarrhea incidence (P = 0.05). Dietary OA significantly increased plasma catalase (CAT) activity and decreased the plasma concentration of malondialdehyde (MDA), tumor necrosis factor-α (TNF-α), interleukin (IL)-8, and IL-6, which were accompanied by upregulated the relative mRNA abundance of superoxide dismutase 1 (SOD1), glutathione peroxidase 1 (GPX1), and nuclear factor erythroid 2-related factor 2 (NRF2) in comparison to that in the NC group (P < 0.05). Moreover, pigs fed the OA diet significantly increased the ratio of villus height to crypt depth and upregulated the relative expression of zonula occludens-1 (ZO-1) and Claudin1 gene in the jejunum compared to the NC group (P < 0.05). Interestingly, dietary AGP or OA did not affect the fecal microbiota structure or volatile fatty acid content (P > 0.05). In conclusion, our results suggested that dietary OA supplementation could improve growth performance and antioxidant capacity and protect the intestinal barrier of weaned piglets, therefore, it has the potential to be considered as an alternative to AGP in the pig industry.

Keywords: antioxidant capacity; barrier function; growth performance; organic acid; postweaning diarrhea; weaned piglets.

Figure 1.

Effects of organic acid on the antioxidant and inflammatory cytokines indices in plasma of weaned piglets. The activity of CAT (A) and SOD (B). The content of MDA (C), H₂O₂ (D), TNF-α (D), IL-8 (D), and IL-6 (D). NC = basal diet without additive; PC = basal diet + 0.04 g/kg surmax + 0.1 g/kg olaquindox; OA = basal diet + 2 g/kg organic acid blend. ^a,b The values with different superscripts are significantly different (P < 0.05).

Figure 2.

Effects of organic acid on jejunal Nrf2 signaling pathway genes expression in weaned piglets. The relative expression of CAT (A), SOD1 (B), GPX1 (C), HO-1 (D), NQO-1 (E), and Nrf2 (F). NC = basal diet without additive; PC = basal diet + 0.04 g/kg surmax + 0.1 g/kg olaquindox; OA = basal diet + 2 g/kg organic acid blend. ^a,b The values with different superscripts are significantly different (P < 0.05).

Figure 3.

Effects of organic acid on jejunal barrier function genes expression in weaned piglets. The relative expression of ZO-1 (A), Occludin (B), Claudin1 (C), and MUC2 (D) in the jejunum. NC = basal diet without additive; PC = basal diet + 0.04 g/kg surmax + 0.1 g/kg olaquindox; OA = basal diet + 2 g/kg organic acid blend. ^a,b The values with different superscripts are significantly different (P < 0.05).

Figure 4.

Effects of organic acid on the fecal bacterial community of weaned piglets. (A-C) α-diversity index. (D) Ven diagram of OTU. (E) Principal component analysis. The relative abundance of microbiota at phylum (F) and genus (G) levels. A = basal diet without additive; B = basal diet + 0.04 g/kg surmax + 0.1 g/kg olaquindox; C = basal diet + 2 g/kg organic acid blend.