Effects Of Mulberry Leaf DNJ On Production Performance,Digestive Physiology,Intestinal Flora And Liver Transcriptome In Rabbits

The aim of this study was to investigate the effects of mulberry leaf DNJ supplementation in different proportions on production performance,digestive physiology,intestinal flora and liver transcriptomeof rabbits,and to provide a reference for the development and application of mulberry leaf feed resources.Thirty-six75-day-old fattening rabbits with an average body weight of(1.57 ± 0.11)kg were randomly divided into 2 experimental groups and 1 control group,with 12 rabbits in each group.The experimental groups were L-DNJ group(0.4g mulberry leaf DNJ per kg basal diet)and H-DNJ group(2.0g mulberry leaf DNJ per kg basal diet),respectively.The pre-trial period was 1 week,and the trial period was 6 weeks.The growth performance,nutrient digestibility,blood biochemical indexes,slaughter performance,meat quality,inestinal flora and liver tanscriptome of rabbits were statistically analyzed.The results showed that the final body weight,feed intake,daily gain,dry matter and crude fat digestibility,serum urea nitrogen and uric acid contents of rabbits in L-DNJ and H-DNJ groups were significantly lower than those in the control group(P < 0.05),the brightness of flesh color was significantly increased(P < 0.05).The crude protein digestibility of rabbits in H-DNJ group was significantly higher than that in control group(P < 0.05).There were no significant differences in feed/gain,crude fiber and mineral digestibility,serum transaminase,creatinine,blood glucose,blood lipid,slaughter rate and muscle physical and chemical characteristics among groups(P > 0.05).In the analysis of rabbits intestinal flora,the difference analysis of the first 6 dominant flora at the phylum level showed that feeding mulberry leaf DNJ significantly affected the relative abundance of Bacteroidetes cecum,Firmicutes,Proteobacteria,Firmicutes and Cyanobacteria in rabbits(P < 0.05),but had no significant effect on the relative abundance of Verrucobacteria(P > 0.05).At the genus level,the relative abundance of cecal microorganisms in rabbits was analyzed.It was found that there were a total of 37 species with significant differences among the three groups,and 43 genera with relative abundance above 0.1 %.A total of 1280 differentially expressed genes were screened by liver transcriptome sequencing,including 829 up-regulated genes and 451 down-regulated genes.The GO annotation analysis and KEGG enrichment analysis of the differentially expressed genes among the three groups showed that the differential genes were mainly concentrated in signal transduction,human diseases,biological systems,cell conduction processes,metabolism and other pathways.The expression levels of genes related to riboflavin metabolism and bile secretion,Metrnl and FGF19 genes in experimental group were significantly higher than those in the control group,indicating that the addition of DNJ may have a certain promotion effect on glucose and lipid metabolism,intestinal health,inhibition of diarrhea,and improvement of immunity in rabbits.In summary,DNJ may be one of the factors important affecting the usage of mulberry leaves in animal feed.Mulberry leaf DNJ has no adverse effects on the blood biochemical indexes and meat quality of rabbits,but inhibit the growth performance and the digestion and utilization of organic matter.Large consumption of mulberry leaves may not conducive to rapid fattening of animals.