The genus Allium, belonging to the family Amaryllidaceae has been known since ancient times for their therapeutic potentials. As the number of multi-drug resistant infections has increased due to in-feed antibiotic usage in poultry, the relevance of alliums as feed additives has been critically assessed. Garlic and the other Allium species, such as onions, leek, shallot, scallion, and chives, have been characterized to contain a plethora of bioactive compounds such as organosulfur compounds, polyphenols, saponins, fructans, and fructo-oligosaccharides. Consequently, alliums have been validated to confer antioxidant, antibacterial, antiviral, immunostimulatory, gut homeostasis, and lipid- as well as cholesterol-lowering properties in poultry. This review intends to summarize recent progress on the use of edible alliums as poultry feed additives, their beneficial effects, and the underlying mechanisms of their involvement in poultry nutrition. Perspectives for future research and limitations are also briefly discussed.

The nicotinamide adenine dinucleotide (NAD⁺) level shows a temporal decrease during the aging process, which has been deemed as an aging hallmark. Nicotinamide mononucleotide (NMN), a key NAD⁺ precursor, shows the potential to retard the age-associated functional decline in organs. In the current study, to explore whether NMN has an impact on the intestine during the aging process, the effects of NMN supplementation on the intestinal morphology, microbiota, and NAD⁺ content, as well as its anti-inflammatory, anti-oxidative and barrier functions were investigated in aging mice and D-galactose (D-gal) induced senescent IPEC-J2 cells. The results showed that 4 months of NMN administration had little impact on the colonic microbiota and NAD⁺ content in aging mice, while it significantly increased the jejunal NAD⁺ content and improved the jejunal structure including increasing the villus length and shortening the crypt. Moreover, NMN supplementation significantly up-regulated the mRNA expression of SIRT3, SIRT6, nuclear factor E2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), the catalytic subunit of glutamate-cysteine ligase (GCLC), superoxide dismutase 2 (SOD2), occludin, and claudin-1, but down-regulated the mRNA expression of tumor necrosis factor alpha (TNF-α). Specifically, in the D-gal induced senescent IPEC-J2 cells, 500 μM NMN restored the increased mRNA expression of interleukin 6 (IL6ST), IL-1A, nuclear factor (NF-κB1), and claudin-1 to normal levels to some extent. Furthermore, NMN treatment significantly affected the mRNA expression of antioxidant enzymes including NQO1, GCLC, SOD 2 and 3, and GSH-PX1, 3 and 4. In addition, 200 μM NMN enhanced the cell viability and total antioxidant capacity and lowered the reactive oxygen species level of senescent IPEC-J2 cells. Notably, NMN restored the down-regulated protein expression of occludin and claudin-1 induced by D-gal. The above data demonstrated the potential of NMN in ameliorating the structural and functional decline in the intestine during aging.

More attention has been paid in recent times to the application of Broussonetia papyrifera (BP) silage in ruminants, owing to its nutritional value. This study aimed to characterize the functionality of fermented BP and preliminarily explore its dietary effects on the gut health of laying hens. In this study, we characterized the antioxidant and antibacterial activities, bioactive compound profile, and bacterial community in Lactobacillus plantarum-fermented BP (FBP), as well as its dietary effects on intestinal morphology, microbiota and gene expression of laying hens. Improved contents of protein, total polyphenol and flavonoids as well as antioxidant and antibacterial activities were found after fermentation of BP. Untargeted metabolomics displayed more abundant apigenin, luteolin, diosmetin, and quercetin within the FBP, which may contribute to its functionality. Microbiome demonstrated increased abundance of Firmicutes at the expense of Cyanobacteria phylum, accompanied with raised levels of Lactobacillus genus. The results of a feeding trial showed dietary FBP supplementation increased the serum superoxide dismutase, but down-regulated gene expression of aryl hydrocarbon receptor (AhR), mucin2, and ZO-2, without obviously affecting the intestinal morphology and colonic microbiota. These findings suggest that FBP warrants further investigation as it may serve as a functional dietary supplement in laying hen feed.

Recently, the hybrid Broussonetia papyrifera (BP) has been extensively cultivated and predominantly utilized in ruminants because of its high protein and bioactive compound content. In the present study, the effects of an ethanolic extract of BP leaves (BPE, 200 mg/kg) on mitigating 2% dextran sodium sulfate (DSS)-induced intestinal inflammation in mice were evaluated. BPE is rich in flavonoids, polyphenols, and polysaccharides, and displays potent antioxidant and antibacterial activities against pathogenic strains such as Clostridium perfringens, Salmonella Typhimurium, and Salmonella enterica subsp. enterica in vitro. In a mouse study, oral administration of DSS resulted in weight loss, incidence of diarrhea, enlargement of the liver and spleen, impaired colonic morphology, downregulation of both gene and protein expression related to intestinal antioxidant (Nrf2) and barrier function (ZO-1), decreased diversity of colonic microbiota, and 218 differentially altered colonic metabolites; however, co-treatment with BPE did not restore these modified aspects except for the liver index and colonic bacterial diversity. The singular treatment with BPE did not manifest evident side effects in normal mice but induced a mild occurrence of diarrhea and a notable alteration in the colonic metabolite profile. Moreover, a single BPE administration augmented the abundance of the commensal beneficial bacteria Faecalibaculum and Akkermansia genera. Overall, the extract of BP leaves did not demonstrate the anticipated effectiveness in alleviating DSS-induced intestinal inflammation.

Ramie (Boehmeria nivea, BN) is used as livestock forage through suitable silage fermentation owing to its nutritional value. To date, relatively few studies have investigated the effects of dietary fermented BN (FBN) on gut health in finishing pigs. The aim of the present study was to investigate the effects of dietary supplementation with 20% FBN on intestinal morphology, gene expression, and the functional response of the gut microbiota in finishing pigs. We found that FBN did not significantly affect serum antioxidant enzyme activities, ileal morphology, or the expression of genes encoding antioxidant enzymes, inflammatory cytokines, or tight junction proteins in the liver of the pigs. However, the gene expression levels of aryl hydrocarbon receptor (AHR) and interleukin 6 (IL6) were significantly downregulated in the ileum. A metagenomic analysis demonstrated that, compared with that seen in the control group, the cecal microbiota of pigs in the FBN treatment group was more closely clustered and contained a greater number of unique microbes. Bacteria were the predominant kingdom in the cecal microbiota, while Firmicutes, Bacteroidetes, and Proteobacteria were the dominant phyla, and Streptococcus, Lactobacillus, and Prevotella were the dominant genera. Dietary FBN significantly increased the abundance of the probiotic bacterium Roseburia inulinivorans (p < 0.05). Functional analysis of the cecal microbiota showed that ABC transporter levels and glycolysis/gluconeogenesis-associated functions were diminished in FBN-fed pigs. Meanwhile, CAZyme analysis revealed that dietary FBN significantly downregulated the contents of carbohydrate-active enzymes, such as GT2, GH1, GH25, and GH13_31. In addition, cytochrome P450 analysis revealed that the abundance of CYP51 and CYP512 decreased with FBN treatment. An assessment of antibiotic resistance based on the Comprehensive Antibiotic Resistance Database (CARD) annotation indicated that the cecal microbes from pigs in the FBN treatment group had increased resistance to lincosamide, streptogramin, and chloramphenicol and reduced resistance to amikacin, isepamicin, neomycin, lividomycin, gentamicin, paromomycin, ribostamycin, and butirosin. Finally, virulence factor-related analysis showed that putative hemolysin-associated functions were decreased, whereas fibronectin-binding protein, flagella, and alginate-associated functions were increased. Taken together, our data showed that FBN supplementation exerted only minor effects on intestinal morphology and microbial community composition, suggesting that it is potentially safe for use as a supplement in the diets of finishing pigs. However, more studies are needed to validate its functionality.

Bile acids (BAs) are crucial for maintaining intestinal epithelial homeostasis. However, the metabolic changes in BAs and the communication between intestinal epithelial cells (IECs) in infants after birth remain unclear. This study aims to elucidate the BA profiles of newborn piglets (NPs) and suckling piglets (SPs), and to investigate their regulatory effects on IEC proliferation and barrier integrity, as well as the potential underlying mechanisms. In this study, compared with NPs, there were significant increases in serum triglycerides, total cholesterol, glucose, and albumin levels for SPs. The total serum BA content in SPs exhibited an obvious increase. Moreover, the expression of BA synthase cytochrome P450 27A1 (CYP27A1) was increased, and the ileal BA receptor Takeda G-coupled protein receptor 5 (TGR5) and proliferation marker Ki-67 were upregulated and showed a strong positive correlation through a Spearman correlation analysis, whereas the expression of farnesoid X receptor (FXR) and occludin was markedly downregulated in SPs and also revealed a strong positive correlation. These findings indicate that the increased synthesis and metabolism of BAs may upregulate TGR5 and downregulate FXR to promote IEC proliferation and influence barrier function; this offers a fresh perspective and evidence for the role of BAs and BA receptors in regulating intestinal development in neonatal pigs.