| Oats are a cereal with a long history of cultivation and are becoming increasingly popular because of their wide range of health benefits.Oats are rich in oat β-glucan,and further studies on oat β-glucan have revealed that it could influence intestinal mucosal morphology,improving intestinal flora,and relieving inflammation,and is considered to be an ideal prebiotic.Currently,most of these studies are based on rats and mice,and there are few studies on the nutritional health of oat β-glucan in weaned New Zealand white rabbits,which intestines are easily damaged due to weaning stress and intestinal flora not fully stabilized,and then causing diarrhea,usually they are treated with antibiotics in farming.In the current context of comprehensive antibiotic restriction in farming,it is important to explore possible antibiotic alternatives such as prebiotics for rabbit farming.Twenty-four 3-week-old female New Zealand weaned rabbits with similar body weight were selected and randomly divided into two groups after adaptive feeding for a week,BG group(β-Glucan group)and CT group(Control group).From the 1st day of the experiment,oat β-glucan(200 mg/kg BW,dissolved into 20 m L of water,and fresh water was added after finished drinking every day.)was added to the drinking water of BG group,while CT group was not added.On the 28 th day,all rabbits were euthanized,and the colon tissues and colon contents were collected for colon histomorphology detection,intestinal microbiota analysis by 16 s r DNA high-throughput sequencing technology,and metabolite levels of intestinal contents were analyzed by LC-MS untargeted metabolomics technology.The main findings are as follows:1.In terms of colonic histomorphology,the villus height,crypt depth,the ratio of villus height to crypt depth(V/C)and the thickness of colonic muscularis in BG group were higher than those in CT group,but the differences were not significant(P > 0.05).The goblet cell area of BG group was lower than that of CT group,but the difference was not significant(P > 0.05).In conclusion,oat β-glucan supplementation was conducive to increase the villus height,muscularis thickness and the V/C of colon in New Zealand white rabbits,and may promote the absorption of nutrients in the colon.2.In terms of intestinal flora,oat β-glucan had a significant effect on the relative abundance of intestinal flora at the level of colonic phylum in weaned New Zealand white rabbits,and the relative abundance of Proteobacteria and Thermotogae in BG group was extremely significantly higher than that in CT group(P < 0.01);Oat β-glucan significantly affected the relative abundance of colonic flora at the genus level,and the relative abundance of Acinetobacter,Bacillus,Prevotellaceae＿UCG-001,Lactobacillus,Mesotoga,Pediococcus,Ruminococcaceae＿UCG-007,Enterobacteriaceae,Mitochondria and Chloroplastin in BG group was extremely significantly higher than that in CT group(P <0.01),and the abundances of Ruminiclostridium＿5 in BG group is significantly higher than that in CT group(P < 0.05).The results showed that the addition of oat β-glucan could significantly increase the abundance of beneficial bacteria such as Ruminiclostridium＿5,Pediococcus,Bacillus,and Lactobacillus in the colon,and improve the colonic microbiota structure of weaned New Zealand white rabbits.3.The metabonomic analysis of colon contents found that a total of 86 differential metabolites were screened out,among which 13 were significantly up-regulated and 73 were significantly decreased in BG compared with CT.The differential metabolites were enriched in 7 metabolic pathways,among which citrate cycle(TCA cycle),pyruvate metabolism,glycolysis or gluconeogenesis are host metabolism;Riboflavin metabolism,lysine degradation,porphyrin and chlorophyll metabolism pathways are microbial metabolism;Glycerophospholipid metabolism pathway is co-metabolism of microbiota and host.Among the selected differential metabolites,organoheterocyclic compounds(e.g.,Artonol B),Organic acids and derivatives(e.g.,Trp-His),lipids and lipid-like molecules(e.g.,S-Acetyldihydrolipoamide-E,1-Acyl-sn-glycero-3-phosphocholine)accounted for a relatively large number,accounting for 63% of the total screened differential metabolites.It was shown that addition of oat β-glucan can significantly affect the metabolism of colon contents of weaned New Zealand white rabbits,and has a greater impact on the metabolism of organoheterocyclic compounds,organic acids and derivativesin,lipids and lipid molecules,and on the metabolic pathway of host citrate cycle,microbiota riboflavin metabolism and co-metabolism glycerophospholipid metabolism.In conclusion,the supplementation of oat β-glucan was conducive to increase the villus height,muscularis thickness and the V/C of colon in New Zealand white rabbits;it can significantly increase the abundance of Ruminiclostridium＿5,Pediococcus,Bacillus,and Lactobacillus and other beneficial bacteria in the colon,and improve the colonic microbiota structure of weaned New Zealand white rabbits;it can significantly affect colon content metabolism of weaned New Zealand white rabbits,and the organicheterocyclic compounds,organic acids and derivatives,lipids and lipid molecules in colon contents of weaned New Zealand white rabbits was significantly affected,the influence of metabolic pathway of host citrate cycle and microbiota riboflavin metabolism and co-metabolism glycerophospholipid metabolism were significant. |
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