| The purpose of this paper was to study the morphological structure of gastrointestinal tract,digestive enzyme activity,microbial flora diversity and cecal liquid in vitro fermentation performance of 3-4 year old Guanzhong donkey.In order to provide theoretical basis for nutritional regulation and feed preparation of donkeys.The trial consists of three parts:Test 1:Study on the gastrointestinal morphology and function of donkey.Four adult Guanzhong donkeys with the same body weight?average body weight,192.85+8.87 kg?were selected,After slaughter,the stomach,duodenum,jejunum,ileum,cecum,colon and rectum were quickly separated according to anatomical features,and the weight,relative weight?%live weight and%total gastrointestinal mass?,content weight and relative weight?%live weight and%total gastrointestinal content weight?were measured respectively.The tissue morphology was observed,and the activity of digestive enzyme and the fermentation parameters were determined.The results showed that:?1?Morphological structure of gastrointestinal tract:The weight,relative weight,content weight and content relative weight of donkey cecum were significantly higher than those of stomach and other intestinal segments?P<0.05?.The relative weight of the duodenum was significantly lower than that of the jejunum and ileum?P<0.05?,and the content weight and content relative weight of colon were significantly higher than those of rectum?P<0.05?.The histomorphology of gastrointestinal tract in donkeys,the height of jejunum villus were significantly lower than that of duodenum and ileum?P>0.05?.There was no significant difference in the width of villi between different parts?P>0.05?.The depth of crypt was significantly lower in jejunum and ileum than that in duodenum?P<0.05?.The value of villus height/crypt depth?V/C?was significantly higher in ileum than that in duodenum and jejunum?P<0.05?.Ileum mucosal thickness was significantly higher than that of other intestinal segments?P<0.05?,colon and rectum was significantly lower than that of other parts?P<0.05?,While stomach mucosal muscle thickness was significantly higher than that of intestinal segments?P<0.05?.?2?The activities of digestive enzymes in stomach and small intestine:Ileum trypsin was significantly lower than duodenum and jejunum?P<0.05?,chymotrypsin in duodenum was significantly higher than that in jejunum and ileum?P<0.05?,amylase in jejunum was significantly higher than that in duodenum?P<0.05?,and lipase in jejunum was significantly higher than that in stomach?P<0.05?;Cellulose degrading enzymes in the cecum of donkeys were the highest and significantly higher than that in cecum Colon and rectum?P<0.05?,colon xylanase and carboxymethyl cellulase were significantly higher than rectum?P<0.05?.?3?Fermentation parameters:Except for colon,the pH of intestinal contents of donkey increased gradually along the posterior edge of intestine,with no significant difference?P>0.05?,but the pH of intestinal segments was significantly higher than that of the stomach?P<0.05?;acetic acid,propionic acid,butyric acid and TVFA were the highest in colon,and each segment of large intestine were significantly higher than those of stomach and small intestine?P<0.05?.It can be seen that the digestion of protein in donkey diet is mainly completed in the anterior part of small intestine,starch and fat are mainly digested in jejunum,and nutrient absorption capacity of ileum may be higher than that of stomach,duodenum and jejunum;cellulose and other carbohydrates are mainly digested in cecum and colon.Test 2:Study on microbial composition and diversity in different parts of donkey gastrointestinal tract.Illumina MiSeq high throughput sequencing technique was used to detect microflora of donkey gastrointestinal tract contents.The results were as follow:A total of 1152881 effective sequences were obtained,and the average number of effective sequences per sample was 42,699,with an average length of 419 bp.A total of 927 OTUs were obtained,and were annotated with 16 gates,29 classes,47 orders,95 families,and 233 genera.At the phylum level,donkey gastrointestinal bacteria come from 15 phylums,Firmicutes is the first dominant phylum in each gastrointestinal tract segment,The second dominant phylum of the stomach and small intestine is Proteobacteria,while that in large intestine is Bacteroidetes.ACE and Chao1 of colon and rectum were significantly higher than those of stomach and small intestinal segments?P<0.05?.There was no significant difference between Simpson and Shannon that the diversity index of microbial among stomach and small intestine?P>0.05?.Simpson index of large intestine segments were significantly lower than those of stomach and small intestine segments?P<0.05?,while Shannon index of the large intestine segments were significantly higher than those of the stomach and small intestine?P<0.05?.According to PCoA and UPGMA analysis,the donkey gastrointestinal bacteria can be clustered into two clusters,the stomach and small intestine are a cluster,and the large intestine is a cluster.There were 39 KEGG functional clusters in donkey gastrointestinal tract microorganisms at the level of secondary functional classification.The dominant functions include carbohydrate metabolism,global and overview maps,amino acid metabolism,membrane transport,energy metabolism and other genes related to metabolism and regulation.Test 3:Study on in vitro fermentation performance of donkey cecum.The purpose of this experiment was to study the effects of different ratios of oat hay and alfalfa on in vitro fermentation of donkey cecum,and to provide theoretical basis for scientific utilization of roughage in donkey breeding.Oat hay and alfalfa were divided into groups I,?,? and IV according to dry matter ratio of 80:20,60:40,40:60 and 20:80,and cultured for 2,4,8,12 and24 hours by in vitro gas production method and Artificial Continuous Fermentation Device in Vitro.After termination of fermentation,fermentation parameters and nutrient degradation rate of forage were determined.The combined effects of forage were calculated by weighted estimation of fermentation parameters at 24 hours.The results showed that:?1?Different ratios of oat hay and alfalfa affected the nutrient degradation rate,and with the increase of Alfalfa ratio,the degradation rate of dry matter?DM?and acid detergent fiber?ADF?increased,and the degradation rate of group IV was significantly higher than that of group I?P<0.05?,and there was no significant difference in the degradation rate of neutral detergent fiber?NDF?among groups?P>0.05?.?2?With the increase of Alfalfa proportion,the pH gradually increased,and that of group IV was significantly higher than that of group I?P<0.05?,the gas production?GP?at each time point of group ? were significantly higher than that of the other three groups?P<0.05?,and the IV group was significantly higher than the I and ? groups at24 h?P<0.05?.From 12 hours of fermentation,the concentration of NH3-N in group ? and IV was significantly higher than that in group I and ??P<0.05?.At 24 hours,the concentration of microbial protein?MCP?in group ? was significantly higher than that in group ??P<0.05?,but there was no significant difference between group I,? and IV?P>0.05?.The volatile fatty acids?VFA?were significantly affected by the ratio of oat hay and alfalfa.At 24 hours,the propionic acid concentration in group I and IV was significantly higher than that in group ? and ??P<0.05?,while the total VFA?TVFA?content in group I and ? was significantly higher than that in group ? and IV?P<0.05?.?3?After 24 hours of fermentation,positive combination effects were observed in groups I,? and IV,and the maximum effect was found in group IV,while negative combination effects were observed in group ?.To sum up,the degradation rates of DM,NDF and ADF were higher than those of other ratios when the oat hay and alfalfa were combined at 20:80,and the effect values of multiple combinations were higher,that is,the best in vitro fermentation of cecal cecum was achieved when oat and alfalfa were combined at 20:80. |
PDF Full Text Request