Research On The Gastrointestinal Microecology And Health Performance Of Sheep Fed Silage Dietary

With the improvement of people's living standard,there is an increasing demand for meat sheep product.It provides a good opportunity for the development of sheep industry,which makes the sheep industry develop rapidly,so it has higher requirements for forage grass,which leads to the variety of forage grass and the diversification of the utilization mode.There has not been a coordinated development between the grass industry and the traditional breeding industry,and some new kinds of forage grass and products have not been perfected in the feeding theory and supporting technology in the process of livestock production.It is a good source of high quality fodder for the low nutrient loss of silage,good adaptability of animals and long-term preservation.It is of great significance to study its effect on the health and microecology of gastrointestinal tract.The purpose of this experiment is to explore the influence of silage on microecology and health of gastrointestinal tract and provide technical support for the development and utilization of new feed resources.So this thesis designs the following four aspects:(1)study on the rumen microecology of different month aged mutton sheep fed by silage feeding;(2)study on the rumen microbial adaptability of the fed silage of sheep;(3)the microecology and microstructure of the gastrointestinal tract of fattening sheep with silage;(4)the blood physiological and biochemical indexes of silage fed feeding sheep.The results are as follows:(1)16S rDNA high-throughput sequencing technology was used to study the rumen microflora of 3-month-old and 15-month-old dorper sheep in the feeding of sweet sorghum silage and determination of rumen microbial metabolic parameters.The results showed that,the 3-month-old microbial diversity of dorper sheep was significantly higher than in the 15-month-old group(P<0.05);the bacterial composition in the rumen at the phylum level,the dominant bacteria in the 3-month-old group were Bacteroidetes,Firmicutes and Verrucomicrobia accounted for 61.13%,28.82% and 2.83%,respectively;while the dominant bacteria in the 15-month-old group were Bacteroidetes,Firmicutes and Proteobacteria,which accounted for 52.89%,34.46% and 3.67%,respectively;At the genus level,Prevotella 1,Christensenell R-7 group,and Rikenellaceae RC9 gut group were predominant in the 3-month-old group,accounting for 27.31%,3.54%,and 2.06%,respectively;while Prevotella,Lachnospiraceae XPB1014 group and Rikenellaceae RC9 gut group was dominant in the 15-month-old group,accounted for 23.64%,3.78%,and 2.59% of total bacteria,respectively;relative expression levels of Ruminococcus1,Ruminococcaceae UCG-014,and Lachnospiraceae NK4A136 groups in the rumen of two different ages,the 3-month-old group was significantly higher than that of the 15-month-old group(P<0.05).There was no significant difference in the volatile fatty acids,ammonia nitrogen,and pH of the rumen at different months(P>0.05).Sweet sorghum silage as mutton sheep fattening feed,although the rumen microflora was different at different ages,it had no significant effect on the rumen parameters.It shows that sorghum silage can be used for growing meat sheep fattening feed.(2)To study the changes of ruminal microflora during the adaptation of different silage diets,and to collect rumen fluid from different breeds of sheep before the morning feeding at 0,7 and 30 days for silage,and using 16 S rDNA high-throughput sequencing technology to study rumen microflora.The results showed that the changes in the rumen microflora had significant effects on mutton sheep breeds,silage types,and feeding stages.At the phylum level,Firmicutes and Proteobacteria had the same change trend(highest at 30 days)at different stages of dorper sheep,but the trend of small tail han sheep was different(the highest in the corn silage group at 30 days,and the sweet sorghum silage group was highest at 7 days).At the genera level,the expression level of Prevotella in the corn silage group was significantly higher than that in the sweet sorghum silage group at 7 days.The expression of rumen RC9_gut_group was significantly decreased with the extension of the adaptation period,while the expression level of Succiniclasticum increased of small tail han sheep,but there was no significant change in the dorper sheep.The relative expression levels of Butyrivibrio in the corn silage group(small tail han sheep and dorper sheep)increased with the extension of adaptation period,while the expression of Ruminococcus showed different changes with the extension of the adaptation period(when feeding sweet sorghum silage,the expression level increased first and then decreased,while when feeding corn silage,the expression level increased).In summary,compared with sweet sorghum silage,corn silage significantly affects rumen homeostasis of mutton sheep,and duper sheep has strong adaptability.(3)To study the effects of sweet sorghum silage and corn silage fed on the gastrointestinal microflora,metabolic parameters and gastrointestinal tract tissue structure of fatting sheep for 90 days.The results showed that the sweet sorghum silage has a higher proportion of fibrous carbohydrates,which is more suitable the growth of fibrinolytic bacteria(Fibrobacter succinogenes and Rumincoccus flavefaciens).The contents of total volatile fatty acids in the rumen and reticulum of the sweet sorghum silage group were higher than those in the corn silage group,but in the cecum,the results were opposite.Sweet sorghum silage group had lighter color on the front stomach,larger width of rumen papilla,thicker duodenum and cecum muscle layer,and the ratio of villi length to crypt depth of duodenum and jejunum of small tail han sheep(V/C)significantly larger than dorper sheep.In conclusion,the long-term feeding of sweet sorghum and corn silage did not have a significant negative effect on the gastrointestinal tract morphology and internal environment parameters of the mutton sheep,and the sweet sorghum silage group had a low degree of keratinization of the forestomach,indicating that it is more conducive to the health of mutton sheep.(4)In order to study the safety of sheep fed on different silage diets,the changes in physiological and biochemical indices of blood and antioxidants were measured at 30,60 and 90 days after blood tests.The results showed that T-CHO content of each group was higher at the end of the experiment,and there was a significant time effect in the durber sheep corn silage group;the BHAH content were significant effect by the treatment at the 90 th day of the experiment,the sorghum silage group was significantly lower than the corn silage group(P<0.05).The GOT activity of the sweet sorghum silage group was significantly lower than that of the corn silage group,and the sweet sorghum silage group of the small tail han sheep had the tendency of increasing first and then decreasing at the three experimental time points,small tail han sheep corn silage group was significantly higher than the previous period;serum AKP activity in each group showed a linear increase trend with the feeding time,and small tail han sheep corn silage group test was significantly higher than the previous period;Sweet sorghum silage serum SOD The activity increased significantly with the feeding time,but there was no significant change in the corn silage group,and the serum T-AOC in the dorper sweet sorghum silage group also had the same tendency.In summary,there is a safety risk for the long-term feeding of sheep with silage diet.Compared with corn silage,the sweet sorghum silage is beneficial to the health of the sheep and reduces the safety risk.In summary,sweet sorghum silage was fed to meat sheep of different ages,although the ruminal microbial is different,but its fermentation parameters have no significant effect.The adaptability of different varieties of mutton sheep to silage diets is different,and dorper sheep is more resistant to roughage.There was no significant negative effect on gastrointestinal morphology and internal environmental parameters of mutton sheep in the long-term feeding of sweet sorghum and corn silage,and the keratinization of the forestomach of sweet sorghum silage group was lower.Compared with corn silage,sweet sorghum silage is beneficial to the health of mutton sheep and reduce the safety risk.