Effects Of Dietary Supplementation With Lignocellulose On Intestinal Structure And Function,Intestinal Microflora And Growth Performance Of Cherry Valley Ducks

In the past,antibiotics were often used as feed additives for the prevention and control of diseases and promotion of growth in animal production.However,it has caused a widespread antibiotic resistance and the emergence of super-strong strains of bacteria in human and animal medicines.With the prohibition on dietary antibiotics,the livestock and poultry raisers urgently need an alternative to ensure that production efficiency is not affected.Lignocellulose is an insoluble fiber of natural origin.Previous studies have shown that the appropriate addition of lignocellulose to diet is beneficial to the improvement of growth performance,intestinal immunity and faeces quality of livestock and poultry.However,the related research in meat ducks hasnot been reported yet.The purpose of this study was to investigate the effects of adding lignocellulose to diets on growth performance,digestion performance,immune performance and intestinal microflora in meat ducks.One hundred eighty 1-day-old healthy male Cherry Valley ducklings were selected with similar body weight,and randomly divided into 3 groups(named as CNTL group,LIGNI group,and LIGN2 group),with 6 replicates per group and 10 ducks per replicate.The CNTL group was the control group and fed with a basal diet,the LING1 group(the constant supplementation group)was fed basal diet supplemented with 0.6%lignocellulose during whole period of experiment,and the LING2 group(the gradient addition group)was fed basal diet supplemented with 0.3%lignocellulose for 1-21 days and 0.6%lignocellulose for 22-42 days.During the experiment,the body weight at birth,weekly feed intake and weekly body weight were measured to evaluate the growth performance of meat ducks.On the 43 rd day of age,the ducks were euthanized.The length and weight of each intestinal segment(duodenum,jejunum,ileum and cecum)were measured.Intestinal sections made in paraffin were used to determine the villi height,crypt depth and the ratio of the two(villus/crypt ratio for short term)of the intestine.The mucosa of the jejunum and ileum was collected to determine antioxidative indexes.The ileal content was collect to determine the activity of digestive enzymes.The faeces was pictured and collected to determine water content,and score the shapes of faeces.The mRNA expression of inflammation,tight junction and the Toll-like receptor pathway-related genes in jejunum,ileum and cecum was determined.In addition,the contents were collected from the jejunum,ileum and cecum for 16s rDNA sequencing analysis to evaluate the effects of lignocellulose supplementation on the intestinal microflora.The main results are as follows:(1)During the whole experimental period,the average daily gains for the CNTL,LIGN1 and LIGNs groups were 63.94 g,67.24 g and 66.29 g,respectively.Compared with the CNTL group,the LIGN1 group had a significant increase in the average daily weight gain(P<0.05).There was no significant difference in average daily feed intake and feed-to-meat ratio between the groups.(2)In regard to intestinal development,lignocellulose supplementation increased the lengths of duodenum and ileum and the absolute weights of ileum and cecum(P<0.05),but decreased the absolute weights of jejunum.In regard to intestinal structure and morphology,the supplementation of lignocellulose increased the crypt depth of duodenum and the villus height of ileum(P<0.05).The ratio of the villus height to crypt depth(C/V)of ileum was increased by the constant supplementation of lignocellulose(P<0.05).(3)The supplementation of lignocellulose decreased the content of malondialdehyde(MDA)and increased total antioxidative capacity(T-AOC)in jejunum(P<0.05),and increased glutathione S-transferase(GST)activity and total antioxidative capacity(T-AOC)in ileum(P<0.05).(4)The activities of amylase,maltase and sucrase in ileal contents were increased by lignocellulose supplementation(P<0.05),but the activity of chymotrypsin was decreased(P<0.05).Gradient supplementation of lignocellulosic only decreased the activity of sucrase in ileal contents(P<0.05),and had no significant adverse effects on the activities of other digestive enzymes.(5)The supplementation of lignocellulose reduced the content of bound water in duck faeces(P<0.05),the gradient supplementation of lignocellulose reduced the total water content in faeces(P<0.05),and the whole supplementation of lignocellulose improved the shape of faeces(P<0.05).(6)The supplementation of lignocellulose increased the mRNA expression of IL-8 in ileum,NF-κB in jejunum and cecum(P<0.05).The constant supplementation of lignocellulose increased the mRNA expression of TNF-α in jejunum(P<0.05),and decreased the mRNA expression of TNF-α in ileum(P<0.05).Gradient supplementation of lignocellulose increased the mRNA expression of TNF-α in cecum(P<0.05).(7)The results from 16s rDNA analysis of intestinal micro flora showed that there were significant differences in microbial composition of different intestinal segments at phylum level.The dominant phylum of bacteria in jejunum,ileum and cecum were Proteobacteria,Firmicutes and Bacteroidota,respectively.The dominant genera of bacteria in ileum were Candidatus Arthromitus and Romboutsia,and the dominant genear of bacteria in cecum were Bacteroides.In addition,lignocellulose supplementation increased the diversity and homogeneity of microbial species in cecum(P<0.05).At phylum level,lignocellulose supplementation mainly increased the relative abundance of Firmicutes in different intestinal segments.At genus level,lignocellulose supplementation reduced the relative abundance of Bacteroides in different intestinal segments,increased the relative abundance of Candidatus Arthromitus(17.09%)and Romboutsia(19.40%)in jejunum,and increased the relative abundance of Romboutsia(30.65%)and reduced the relative abundance of Helicobacter in ileum.The functional annotation for KEGG pathway analysis showed that,at the first tier,lignocellulose supplementation enhanced the microbial function related to Genetic information processing in jejunum and cecum,as well as the microbial function related to Human disease and Environmental information processing in ileum.At the secondary tier,lignocellulose supplementation enhanced the microbial function related to Nucleotide metabolism and Genetic information processing in jejunum,and decreased the microbial function related to Lipid metabolism,Amino acid metabolism,Cellular processes and signaling.In ileum,lignocellulose supplementation enhanced the microbial function related to Metabolism,Genetic information processing and the weakening of Immune system,Cellular processes and signaling.In cecum,lignocellulose supplementation enhanced the microbial function related to Nucleotide metabolism.Amino acid metabolism,Translation and other functions,and weakened the microbial function related to Lipid metabolism and Enzyme families.At the third tier,lignocellulosic supplementation enhanced the microbial function related to Quorum sensing,Peptidases and weakened the microbial function related to DNA replication proteins and Aminoacyl tRNA biosynthesis in jejunum.In ileum,lignocellulosic supplementation enhanced the microbial function related to Transcription factors and Peptidases,and weakened the microbial function related to Chromosomes and associated proteins,Bacterial motility proteins and DNA replication proteins.In cecum,lignocellulosic supplementation enhanced the microbial function related to Mitochondrial biogenesis,Amino acid-related enzymes and DNA replication proteins,and weakened the microbial function related to Galactose metabolism and Amino and nucleotide sugar metabolism.In conclusion,compared with the CNTL group,constant or gradient supplementation of lignocellulose increased the average daily gain of ducks(there are significant differences between the LIGN1 and CNTL groups),but did not significantly affect the average daily feed intake and the feed-to-meat ratio.The length and weight of intestinal tract and the hight of intestinal villi were increased,and the crypt depth was decreased.The antioxidative capacity of jejunum and ileum mucosa and the activities of some digestive enzymes in ileum were increased.The water content in duck faeces was reduced,and the shape of the faeces was improved.The mRAN expression of intestinal IL-8 and TNF-α was increased.The.biodiversity of cecal microflora was increased,the relative abundance of Firmicutes in each different intestinal segment was increased,and the relative abundance of Bacteroidetes was decreased.These findings suggest that lignocellulose supplementation to the diet is generally beneficial to meat duck,but the beneficial effect is influenced by the amount of supplemented lignocellulose and the manner of supplementation.So,the conditions where lignocellulose is supplemented should be appropriately taken into account in production practice to achieve the best results.