| China’s animal husbandry is developed,and feed resources are an important factor affecting animal husbandry.Forage is an essential component of ruminant feed and an important source of nutrients and energy.However,the yield of high-quality forage is low and cannot meet the needs of animal growth and production in China.China imports a large amount of alfalfa for ruminant production every year.At the same time,the annual straw yield is very high in China.Due to its low nutritional value,the utilization rate in ruminant production is not high.Therefore,to study the digestion and metabolism of straw in ruminants,to propose targeted measures to improve the utilization of straw on ruminants,it is of great significance to balance feed utilization structure and reduce feeding costs.In this experiment,wheat straw and alfalfa hay were used as roughage to study the effects of feeding wheat straw on morphology,microbial flora structure and metabolism of gastrointestinal tract of Hu sheep,aiming to clarify the digestive and metabolic characteristics of straw in the digestive tract of Hu sheep and provide basic data for rational use of straw in ruminants.1 Effect of feeding wheat straw on the weight and pH value of gastrointestinal tract of Hu sheepThe aim of this study was to investigate the effect of wheat straw on the development of the digestive tract of Hu sheep.The experiment selected 12 Hu sheep with 40±2 kg.After 30 days of pre-feeding,they were randomly divided into two groups,namely alfalfa hay and wheat straw as roughage.Four weeks,all animals were weighed on the d 0 and 28 before morning feeding of the formal experiment,respectively.During experiment period,the amount of remaining feed(concentrate and forage)on the day before was weighed before morning feeding,and the feed intake was recorded.Before the morning feeding on the 28th day,all Hu sheep were slaughtered,the intestines of the gastrointestinal tract were separated and weighed separately,and the length,weight and pH value of the contents of the digestive tract were determined.The results showed that feeding wheat straw significantly reduced feed intake,daily feed intake,concentrate intake,forage intake,body weight gain,daily weight gain,and feed efficiency compared with feeding alfalfa hay(P<0.05).Feeding wheat straw significantly increased rumen wet weight of Hu sheep(P<0.05)and significantly reduced the wet weight of the rectum(P<0.05);feeding wheat straw significantly reduced the pH valves of omasum and ileum contents(P<0.05),the pH valves of the cecal and colon contents significantly decreased(P=0.060;P=0.070);feeding wheat straw had no significant effect on the length of each intestine(P>0.1).The results showed that feeding wheat straw reduced the growth performance of the sheep,the pH value of the intestinal contents and the rectal weight,and increased the weight of the rumen.2 Effect of feeding wheat straw on the microbial flora and metabolism of the gastrointestinal tract of Hu sheepThe purpose of this experiment was to study the effect of feeding wheat straw on the structure and metabolism of microbial flora in gastrointestinal tract of Hu sheep.The animal experiment was the same as the first chapter.The samples of rumen,jejunum and colon content were collected during slaughter and used to determine the composition of microbial flora and the concentration of metabolites.The 16S rRNA gene high-throughput sequencing technology was used to analyze the microbial flora structure in each intestinal tract,and the concentration of microbial metabolites in the content of each intestine was analyzed by gas chromatography.The results showed that Firmicutes and Bacteroidetes are the two dominant phyla in the rumen and colon of Hu sheep,while the dominant phylum in the jejunum are Firmicutes.Feeding wheat straw significantly increased the bacterial diversity in the rumen and colon of Hu sheep(P<0.05).At the genus level,feeding wheat straw significantly increased the relative abundance of unclassified Christensenellaceae in the rumen,jejunum and colon(P<0.05),significantly increased the relative abundance of Treponema,Desulfovibrio,SHD-231,Unclassified Ruminococcaceae and Unclassified F16 in either of the gastrointestinal sections(P<0.05),significantly reduced Butyrivibrio,Selenomonas,Bulleidia,Unclassified Lachnospiraceae,and Unclassified Rikenellaceae in either of the gastrointestinal sections in either of the gastrointestinal sections(P<0.05).The results of metabolite analysis showed that the feeding of wheat straw significantly reduced the concentration of ammonia nitrogen and microbial protein in the rumen,the concentration of ammonia nitrogen in the jejunum and the concentration of microbial protein in the colon(P<0.05).Feeding wheat straw had no significant effect of volatile fatty acids(including acetate,propionate,butyrate,isobutyrate,valerate,isovalerate)and lactate concentrations and the ratio of acetate to propionate of three intestines(P>0.05).The results showed that feeding wheat straw increased the diversity of microbial flora in the gastrointestinal tract of Hu sheep and reduced the concentration of ammonia nitrogen and microbial protein in the gastrointestinal tract of Hu sheep.3 Effect of feeding wheat straw on the morphology of gastrointestinal tract epithelium of Hu sheepThe purpose of this study was to understand the effect of feeding wheat straw on the morphology of the gastrointestinal tract epithelium of Hu sheep.The animal experiment was the same as the first chapter.All sheep were slaughtered before morning feeding,the rumen,jejunum and colon epithelial tissues were collected and the epithelial morphology was observed.Then they were fixed with 4%paraformaldehyde immediately,embedded in paraffin,stained with hematoxylin and eosin,and made into 6 mm thick sections.The rumen papillae,jejunual villus height and crypt depth,colonic epithelium were observed with an optical microscope.The results showed that compared with alfalfa hay,feeding wheat straw significantly reduced rumen papillae height,papillae unit area and total papillae area(P<0.05),and papillae width had a tendency to decrease(P=0.052),there was no significant effects on papillae density;feeding wheat Straw had no significant effect on thickness of the rumen epithelial stratum corneum,granular layer,spine base layer and total thickness(P>0.1);feeding wheat straw significantly reduced jejunal crypt depth(P<0.05),the ratio of villus and crypt tended to increase(P=0.095),and had no significant effect on villus height(P>0.1).Feeding wheat straw increased the gap between colonic epithelial cells.Therefore,feeding wheat straw changed the morphology of the gastrointestinal tract epithelium of the Hu sheep,reduced the rumen papillae area,and reduced the jejunal crypt depth. |
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