Background To our knowledge, carbon loaded with nano-ZnO (NZnOC) represents a new nutritional additive for the animal husbandry industry. However, the mechanism by which NZnOC mediates beef cattle growth and intestinal health is not fully understood. This study aimed to investigate the effects of carbon loaded with nano-ZnO (NZnOC) supplementation on growth performance, gut microbiota, bile acid (BAs) metabolism and intestinal immunity in fattening cattle. Twenty cattle (16 ± 0.95 months) were randomly assigned to two dietary groups: CON (control, without feed additive) and NZnOC (diet supplemented with 80 mg NZnOC/kg diet dry matter basic) for 60 d. The colon digesta microbiota composition and BAs concentration were determined by microbiota metagenomics and gas chromatography methods, respectively. Results The results showed that the NZnOC-supplemented cattle had greater final weight, average daily gain and gain-to-feed ratio than those in the CON group. Cattle fed the NZnOC diet had a higher relative abundance of the secondary BAs synthesizing phyla Firmicutes, Tenericutes and Actinobacteria than those fed the CON diet. Dietary supplementation with NZnOC increased the relative abundance of the secondary BAs synthesis microbiota genera Clostridium, Ruminococcus, Eubacterium, and Brevibacillus in colon digesta. Cattle fed the NZnOC diet had increased activities of 3α-hydroxysteroid dehydrogenase (EC: 1.1.1.52) and bile acid-CoA ligase BaiB (EC: 6.2.1.7) in the colon digesta compared with those fed the CON diet. The primary BAs taurocholic acid, taurochenodeoxycholic acid and taurodeoxycholate acid were significantly decreased by dietary NZnOC supplementation, while the secondary BAs deoxycholic acid, taurolithocholic acid, beta-muricholic acid, 12-ketolithocholic acid and ursodeoxycholic acid were significantly increased. Dietary supplementation with NZnOC increased the mRNA abundance of G protein-coupled bile acid receptor 1, protein kinase cAMP-activated catalytic subunit alpha, cyclic-AMP response element binding protein 1 and interleukin (IL)-10 in the colon mucosa of cattle, while the mRNA abundance of tumor necrosis factor and IL-1β were significantly decreased. Conclusions In summary, dietary supplementation with NZnOC can facilitate the growth performance and intestinal immune function of cattle by improving BAs metabolism. NZnOC can be supplemented in the diet as a safe regulator of gut microbiota and as a feed additive in the ruminants industry.

Background: To our knowledge, carbon loaded with nano-ZnO (NZnOC) represent a new nutritional additive for the food and animal husbandry industry. However, the mechanism by which NZnOC mediates cattle growth and intestinal health are not fully understood. This study aimed to investigate the effects of carbon loaded with nano-ZnO (NZnOC) supplementation on gut microbiota, BA metabolism and intestinal immunity in fattening cattle. Twenty cattle were randomly assigned to two dietary groups: control diet (CON) without Zn supplement and CON diet supplemented with NZnOC. The trial lasted for 60 d. Results: The results showed that the NZnOC-supplemented cattle had greater final weight, average daily gain and lower feed conversion ratio than those in the CON group. Cattle fed the NZnOC diet had significantly higher relative abundance of secondary BA synthesizing phyla Firmicutes, Tenericutes and Actinobacteria than those fed the CON diet. Dietary supplementation with NZnOC significantly increased the relative abundance of secondary BA synthesis microbiota genus Clostridium, Ruminococcus, Eubacterium, Lachnospira, Collinsella, Fusobacterium and Brevibacillus in colon digesta. Cattle fed the NZnOC diet had markedly increased the activities of 3α-hydroxysteroid dehydrogenase (EC:1.1.1.52) and bile acid-CoA ligase BaiB (EC:6.2.1.7) in the colon digesta compared with those fed the CON diet. The primary BA of taurocholic acid, taurochenodeoxycholic acid and taurodeoxycholate acid were significantly decreased by dietary NZnOC supplementation, while secondary BA of deoxycholic acid, taurolithocholic acid, beta-muricholic acid, 12-ketolithocholic acid and ursodeoxycholic acid were significantly increased. Dietary supplementation of NZnOC increased the mRNA abundance of Takeda G-protein-coupled receptor 5, phosphorylation of protein kinase A, cyclic-AMP response element binding protein and interleukin (IL)-10 in the colon mucosa of cattle, while the mRNA abundance of nuclear factor kappa-B, tumor necrosis factor-α (TNF-α) and IL-1β were significantly decreased. Compared with the CON group, cattle in the NZnOC group had higher mucosal IL-10 content and lower TNF-α and IL-1β contents. Conclusions: These results not only suggest a beneficial effect of NZnOC on growth performance and intestinal immune function, but provides insight into potential mechanisms underlying NZnOC-facilitated intestinal secondary BA synthesis microbiota growth and secondary BA synthesis in cattle.

Background To our knowledge, graphene oxide loaded with nano-ZnO (NZnOGO) represent a new nutritional additive for the food and animal husbandry industry. However, the mechanism by which NZnOGO mediates cattle growth and intestinal health are not fully understood. This study was conducted to evaluate the effects of NZnOGO on gut microbiota, bile acid (BA) concentration and intestinal immunity in fattening cattle. Results Twenty Simmental × Chinese Yellow Cattle were assigned to 2 dietary groups: control diet (CON) without Zn supplement and CON diet supplemented with NZnOGO. The trial lasted 60 d. The gut microbiota composition and BA concentration in the colon chyme samples were determined by microbiota metagenomics and gas chromatography methods, respectively. Colon mucosa immune factors and gene expression analysis were determined by ELISA and RT-PCR, respectively. The results showed that dietary NZnOGO supplementation significantly increased average daily gain (P < 0.05), and significantly decreased feed conversion ratio (P < 0.05). The relative abundance of the secondary BA synthesis microbiota genera Clostridium, Ruminococcus, Eubacterium, Enterococcus, Collinsella, Fusobacterium, Eggerthella, Brevibacillus and Peptostreptococcus in the NZnOGO group had significantly higher than the CON group (P < 0.05). At the secondary BA synthesis pathway, NZnOGO group had significantly higher 7α-hydroxysteroid dehydrogenase (EC:1.1.1.159) and bile acid-CoA ligase BaiB (EC:6.2.1.7) than the CON group (P < 0.05). Dietary NZnOGO supplementation significantly decreased primary BA (taurocholic acid, taurochenodeoxycholic acid and taurodeoxycholate acid) (P < 0.05), and significantly increased secondary BA (deoxycholic acid, beta-Muricholic acid, 12-ketolithocholic acid, hyodeoxycholic acid, lithocholic acid, isolithocholic acid, ursodeoxycholic acid and apocholic acid) (P < 0.05). The NZnOGO group significantly increased the abundance of gene expression at metabolism and higher defense mechanisms (P < 0.05). The expression of Takeda G-protein-coupled receptor 5, protein kinase A, cyclic-AMP response element binding protein, toll-like receptor 4 and interleukin-10 (IL-10) genes were increased by dietary NZnOGO supplementation (P < 0.05), while the expression of nuclear factor kappa-B (NF-κB), tumor necrosis factor-α (TNF-α) and IL-1β genes were significantly decreased (P < 0.05). IL-10 concentration was increased by dietary NZnOGO supplementation (P < 0.05), whereas TNF-α and IL-1β contents were significantly decreased (P < 0.05). Conclusions Taken together, dietary NZnOGO supplementation improved the growth performance and intestinal immune function of the fattening cattle, compared to the diet free of Zn supplement, which was associated with enhancing secondary BA synthesis microbiota growth and promoting secondary BA synthesis.

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