Effects Of Different Months,seasons And Feeding Methods On Rumen Microorganisms Of Sunit Sheep

In order to better guide the transformation of feeding methods in pastoral areas,this thesis took Sunit sheep as the research object.Based on 16 S r DNA and ITS r DNA sequencing technology,the effects of different ages,seasons and feeding methods on rumen microorganisms of Sunit sheep were investigated from vertical,temporal and spatial perspectives,aiming to provide scientific reference for nutrient balance regulation technology of grazing sheep.This thesis is divided into three parts:1.Study on the difference of rumen microbial structure of Sunit sheep at different months of grazing age.Six healthy 3-month-old Sunit female lambs of similar weight and six healthy6-month-old Sunit female lambs of similar weight were selected to collect rumen fluid and determine the bacteria and fungi in them,which were recorded as group G3 and group G6,respectively.The results showed that the intake of solid feed and the change of feeding environment were the main factors leading to the change of rumen microbial structure of Sunit sheep.The richness and diversity of rumen bacteria increased with age.At the level of bacteria,Firmicutes and Bacteroidetes are the dominant bacteria of the two groups.At the level of genus,Ruminococcaceae＿unclassified and Ruminococcus are the dominant bacteria.In addition,the abundance of these two genera in G3 group is significantly higher than that in G6 group,while the abundance of Bifidobacterium is significantly higher than that in G6 group.With the increase of age,the diversity of rumen fungi did not change significantly,but the richness decreased.At the level of phyla,the abundance of Ascomycota in G3 group was significantly higher than that in G6 group.At the genus level,Simplicillium,Malassezia and Davidiella were gradually replaced by Preussia and Cyllamyces.2.Study on seasonal variation of rumen microorganisms of grazing Sunit sheep.Rumen fluid samples of 10 Sunit ewe grazing all year round were collected in winter(February),spring(May),summer(August)and autumn(October)for determination,and were denoted as M2,M5,M8 and M10,respectively.The experimental results showed that: For adult grazing sheep,the changes of rumen microbial structure were related to forage biomass and nutrient levels.The Alpha diversity of bacteria in M8 group was significantly higher than that in M2 group and M5 group,that is,the seasons had no significant effect on the rumen bacterial richness of grazing Sunit sheep,but the diversity in winter and spring was significantly higher than that in summer.At the level of bacteria,the richness of Firmicutes increases significantly in summer,while the richness of Bacteroidetes decreases significantly in summer.The effects of seasons on rumen archaea Alpha diversity of grazing Sunit sheep were not significant,and 99% of the archaea at the phylum level belonged to Eurycoarchaea,and Methanobrevibacter was the dominant genus at the genus level,and the abundance of this bacterium was higher in autumn and winter than in spring and summer.Methanomassiliicoccus,as a secondary dominant genus,had the opposite abundance change.The diversity of fungi in group M5 was significantly lower than that in other groups,and Ascomycota was the absolute dominant bacteria,and its dominant position remained unchanged.On the genus level,the richness of Preussia,Simplicillium and Cryptococcus is lower in spring and summer,but higher in winter and spring.3.Effects of different feeding methods on rumen microorganisms of Sunit sheep.Thirty Sunit ewes in late gestation were randomly divided into 3 groups with 10 ewes in each group.The control group(C)was grazed,group 1(S1)was grazed for 8h every day,and 250 g corn was supplemented after grazing,group 2(S2)was fed warm house feeding,and formulated diets according to the feeding standards of pregnant sheep.The experiment was conducted in winter and spring.The experiment lasted for 90 days,including the late gestation period and 30 days postpartum.Rumen fluid was collected on the day after the experiment,and bacteria and fungi were detected respectively.The results showed that the ratio of concentrate to forage and the change of temperature were the main factors causing the different rumen microbial structure under the three different feeding methods.Compared with group C,the bacterial diversity and richness in groups S1 and S2 were significantly decreased.The richness of Firmicutes was C>S1>S2 from large to small,and the difference is very significant.Bacteroidetes is the opposite of it.At the genus level,house feeding significantly increased the richness of Bacteroidetes＿unclassified and Prevotella related to carbohydrate degradation,while significantly decreased the richness of Ruminococcaceae＿unclassified involved in the degradation of fibrous substances.The Alpha diversity index of group S2 was significantly lower than that of group C.At gate level,the richness of Ascomycota in group C was significantly lower than that in the other two groups,whereas Basidiomycota was the opposite.At the genus level,house feeding significantly decreased the richness of Cryptococcus and Preussia,but significantly increased the richness of Davidiella and Alternaria.