Effects Of Mulberry Leaf DNJ On The Production Performance And Intestinal Digestive Function Of New Zealand White Rabbits

Mulberry leaves have high nutritional value and can be used as a new feed resource.1-deoxynojirimycin（DNJ）is a highly enriched plant secondary metabolite in mulberry leaves,and has a strong regulatory effect on glucose and lipid metabolism in animals.However,the mechanism of its effect on intestinal digestive function and nutrient utilization in animals is still unclear.The New Zealand white rabbits were chosen as the research object to analyze the metabolic dynamic process,production performance,meat quality,intestinal morphology,and digestive function of mulberry leaf DNJ,providing a certain theoretical basis for the feed application of mulberry leaf resources.The main research findings are as follows:1.Metabolic kinetics analysis of mulberry leaf DNJ in rabbitsNew Zealand rabbits were orally intragastriced with 110 mg/kg.bw mulberry leaf DNJ.Blood samples,liver,kidney,small intestine,and muscle tissue samples were collected after0 min,30 min,1 h,2 h,4 h,5 h,12 h,and 24 h of intragastric administration,respectively,and the DNJ content was measured.The results showed that（1）DNJ content was the highest in plasma,small intestine,liver,and kidney after 30 minutes of gavage.（2）The DNJ content in the small intestine decreased to trace levels after 4 hours.（3）The DNJ content in the liver and kidneys decreased to trace levels after 5 hours.（4）After gavage,the DNJ content in rabbit muscles fluctuated,stabilized after 12 hours,and remained after 24 hours.In summary,DNJ has a faster metabolic rate in rabbits.After 30 minutes of gavage,the content of DNJ in plasma,small intestine,liver,kidneys,and intestines decreased,and decreased to a trace level within5 hours.After 24 hours,only muscle remained.2.The effect of mulberry leaf DNJ extract on rabbit production performance and meat qualityThirty six New Zealand white rabbits with similar body weight were randomly divided into 3 groups and fed with diets containing 0 g/kg（T₀）,0.14 g/kg（T₁）,and 0.28 g/kg（T₂）of mulberry leaf DNJ,respectively.Production performance,physiological and biochemical indicators,slaughter performance,and meat quality indicators were measured.The results showed that（1）the ADG in T₂ group was significantly lower than T₀（P<0.05）,there was no significant difference between T₂ group and T₀ group（P>0.05）;（2）Plasma TG levels in treated group was significantly lower than T₀ group,while ADP level was higher（P<0.05）;（3）The redness of rabbit meat a^*was significantly higher and crude fat content was significantly lower in the treated group（P<0.05）,and the brightness of rabbit meat L^*was significantly lower in the T₂ group（P<0.05）;（4）Meat glutathione peroxidase（GSH-Px）activity was significantly increased（P<0.05）in the treated rabbits,and total antioxidant capacity（T-AOC）was significantly increased（P<0.05）in the T₂ group;（5）The highest palmitic acid（16:0）and linoleic acid（C18:2n6c）contents,followed by oleic acid（18:1n9）and stearic acid（18:0）were found in rabbit meat of all groups,and the saturated fatty acid（SFA）content was significantly lower（P<0.01）and polyunsaturated fatty acid（PUFA）content was significantly higher in rabbit meat of the T₂ group（P<0.05）.In conclusion,moderate addition of Mulberry leaf DNJ（0.28 g/kg）could improve the quality of rabbit meat,increased the PUFA content and antioxidant capacity in rabbit meat.3.Effects of mulberry leaf DNJ extract on intestinal morphology and digestive function in rabbitsIn the third week of the experiment,6 rabbits of similar weight were randomly selected from each group for digestion and metabolism tests.At the end of experiment,all rabbits were slaughtered for measuring the morphology,inflammatory factors,barrier function of jejunum,short chain fatty acids（SCFA）and microbiota of caecum.The results showed that（1）the apparent digestibility of dry matter and crude fat in the T₂ group was significantly lower than that in the T₀ group,while the apparent digestibility of crude protein in the T₂ group was significantly higher than that in the T₀ group（P<0.05）;（2）Mulberry leaf DNJ significantly reduced the ratio of jejunum villi height/crypt depth of jejunum（P<0.05）;（3）Mulberry leaf DNJ significantly reduced the content of tumor necrosis factor a（TNF-a）,interleukin-6（IL-6）,and C-reactive protein（CRP）in jejunum（P<0.05）;（4）Mulberry leaf DNJ significantly reduced the content of valeric acid in the caecum of rabbits（P<0.05）,the content of acetic acid and propionic acid in cecum of T₂ group decreased compared with that in the T₁ group（P<0.05）;（5）The relative abundance of Ralstonia and Lactobacillus in the caecum of T₂group rabbits was significantly reduced compared with that in T₀group（P<0.05）;（6）Mulberry leaf DNJ significantly increased the expression levels of jejunum barrier genes of JAM2,JAM3,mucin4,and mucin6（P<0.05）.In summary,adding mulberry leaf DNJ to the diet can affect the apparent digestibility of nutrients,intestinal villus height,reduce the content of intestinal inflammatory factors,regulate the content and composition of SCFA in the cecum,optimize the gut microbiota,and improve the intestinal barrier function of rabbits.4.Proteomics analysis of mulberry leaf DNJ on small intestinal epithelial cells in vitroSmall intestinal epithelial cells IEC-6 cell line was chosen and divided into WT group（control）,OD group（25μM DNJ）,OG group（25 m M glucose）,and DG group（25μM DNJ+25 m M glucose）.The total protein was extracted after the cells were incubated for 2hours,and proteomics was analyzed by TMT isotope labeling.The results showed that:（1）compared with the WT group,73 differential proteins were upregulated and 141 were downregulated in OD group;（2）Compared with the OD group,11 proteins in DG group were upregulated and 18 proteins were down regulated,DNJ affecting proteins of glucose metabolism in small intestinal epithelial cells were mainly focus on signal pathway referring to anti-virus,（3）Subcellular localization analysis showed that DNJ treated differential proteins were mainly distributed in the cytoplasm,cell membrane,mitochondria,endoplasmic reticulum.In summary,DNJ may exert regulatory effects on various proteins in small intestinal epithelial cells,thereby affecting their biological functions.