Effects Of Rosemary Extract On Nutrient Digestion,rumen Fermentation And Rumen Microorganism Of Dairy Goats

This experiment was conducted to investigate the effects of dietary rosemary extract on nutrient digestion,rumen fermentation and rumen microorganisms of dairy goats,and to provide theoretical basis for the application of rosemary extract in dairy goat production.Twenty four healthy Xinong Saanen dairy goats with similar parity,lactation age,milk yield and body weight were selected as experimental animals.They were randomly divided into 2 groups with 12 heads in each group.The control group was fed with total mixed diet,and the experimental group was fed with total mixed diet supplemented with2.14 g/kg rosemary extract.The experiment lasted for 52 days,including 10 days of pre feeding and 42 days of formal experiment.The results show that:(1)Compared with the control group,dietary rosemary extract had no significant effects on nutrient apparent digestibility of dairy goats(P>0.05).(2)Compared with the control group,the acetate/propionate in rumen fluid of rosemary extract group was significantly increased(P<0.05),and had a tendency to increase the content of acetic acid in rumen fluid(P=0.063).There were no significant differences in other rumen fermentation parameters between the two groups(P>0.05).(3)Compared with the control group,the ACE index,Chao index and Shannon index in rosemary extract group were significantly increased(P<0.05),and the Simpson index had a tendency to decrease(P=0.082).The coverage index between the two groups was higher than 98%,which indicated that the sequencing results could truly reflect the composition of rumen bacteria in dairy goats.(4)Based on 16 S rRNA high-throughput sequencing technology,21 phyla and 307 genera of rumen bacteria were obtained.At the phylum level,Firmicutes,Bacteroidota and Patescibacteria were the most abundant bacteria in the two groups,which accounts for94.66% of all bacteria.Compared with the control group,the relative abundance of WPS-2in rosemary extract group was significantly increased(P<0.05),and the relative abundance of Desulfobacterita tended to increase(P=0.073).There was no significant difference in relative abundance of other phyla between the two groups(P>0.05).At the genus level,compared with the control group,the relative abundance of norank＿f＿＿Eubacterium＿coprostanoligenes＿group in rosemary extract group was significantly decreased(P<0.05),the relative abundance of Succiniclasticum was significantly increased(P<0.05).The relative abundance of norank＿f＿＿norank＿o＿＿Clostridia＿UCG-014 in rosemary extract group tended to increase(P=0.091),and the relative abundance of Ruminococcus tended to decrease(P=0.075).There was no significant difference in the relative abundance of other genera between the two groups(P>0.05).(5)The correlation between rumen bacteria and rumen fermentation parameters were analyzed.The results showed that the acetic acid was positively correlated with norank＿f＿＿Muribaculaceae(r=0.643,P=0.024)and norank＿f＿＿norank＿o＿＿Clostridia＿UCG-014(r=0.615,P=0.033).The total volatile fatty acids was positively correlated with the norank＿f＿＿Muribaculaceae(r=0.622,P=0.031)and the norank＿f＿＿norank＿o＿＿Clostridia＿UCG-014(r=0.594,P=0.042).Succiniclasticum was positively correlated with the acetate/propionate in rumen fluid(r=0.609,P=0.035),and the norank＿f＿＿Eubacterium＿coprostanoligenes＿group was negatively correlated with the acetate/propionate in rumen fluid(r=0-762,P=0.004).(6)Tax4Fun was used to predict the potential function of rumen bacterial flora.The results showed that at KEGG pathway level 1,the rumen microflora mainly focused on metabolic function.At KEGG pathway level 2,a total of 40 metabolic functions were identified,and carbohydrate metabolism were the most abundant in the control group and rosemary extract group.Compared with the control group,the abundance of membrane transport function in rosemary extract group was significantly increased(P<0.05),the abundance of signal transduction function was significantly decreased(P<0.05),and the abundance of nucleotide metabolism had a tendency to be increased(P=0.053).In conclusion,under the conditions of this experiment,dietary rosemary extract can change the rumen fermentation type,improve the diversity and richness of rumen microflora,and affect the composition of rumen bacteria at phylum and genus levels of dairy goats.