| Two strains of the anaerobic bacteria were isolated and screened from rumen fluid of health dairy cows by Actinomyces ruminicola selective medium using the isolated and identified way of anaerobic bacterium. According to the morphological observation, the biochemical trial and homology analysis of 16S rRNA gene sequence, both of them were identified as Actinomyces ruminicola, and named NY1 and NY2, respectively.To understand produce acid characteristics of the two strains of Actinomyces ruminicola, the trial in vitro was administrated in control group (added no strain in diet) and treatment groups including. Results showed that pH of rumen fluid pH of rumen fluid in NY2 group was lower than NY1 group and control group (P <0.05); the concentrations of acetic acid, propanoic acid, butanoic acid, and total VFA of NY2 group were higher than NY1 group and control group (P <0.05), and concentration of lactic acid in NY2 group were lower than NY1 group and control group (P <0.05). Therefore, the strain of NY2 has the more strong capacity of producing acid.To determine fermentation characteristics of the strain of NY2 in vitro in rumen fluid from diets with different ratio of forage to concentrate. Control group was took orally by equivalent physiological saline;rumen fluid obtained in health sheep was added by NY2 and 2.0 g substrate from diets of different ratio of forage to concentrate (60:40 for T1; 50:50 for T2, and 40:60 for T3). Culture fluids were collected to analyze pH, acetic acid, propanoic acid, butanoic acid, and lactic acid at 0, 2, 4, 6, 8, 10, 12, 24, 36, and 48h after initiation of fermentation. Results showed that compared to control group, T1 and T2 ; in T3 concentration of acetic acid, propanoic acid, butanoic acid and total VFA increased significantly (P <0.05 ), concentration of lactic acid decreased significantly (P <0.05).To clarify fermentation characteristics of the strain of NY2 in rumen from diets with different ratio of forage to concentrate ratio diets, six sheep were divided two groups, three sheep each group. control group was took orally by equivalent physiological saline ;treatment group was administrated orally by the strain of NY2culture fluid, control group was took orally by equivalent physiological saline. Rumen fluid were collected to determine level of pH, acetic acid, propanoic acid, butanoic acid, total VFA and lactic acid at 0, 2, 4, 8, 10, 12 and 24 h after administration. Results showed that compared to control group, T1and T2; in T3 concentrations of acetic acid, butanoic acid, and total VFA increased significantly (P <0.05); and concentration of lactic acid in NY2 group were lower than all groups (P <0.05). Terefore, The strain of NY2 had the more strong capacity of producing acid in rumen fluid from diet with ratio of forage to concentrate (40:60).To develop the microecologic preparation and understand the fermentation characteristics of microecologic preparation in vitro in rumen fluid added by different mixed ratio of the strain of NY2 to propionibacterium acnes. rumen fluid was collect from health sheep and divided into control groups and treatment groups. According to different ratio of the strain of NY2 (Actinomyces ruminicola, Ar) to Propionibacterium acnes (Pa), treatment groups including M1 group (Ar/Pa=40:80), M2 group (Ar/Pa=60:60), and M3 group (Ar/Pa=80:40). Culture fluids were collected to determine level of pH, acetic acid, propanoic acid, butanoic acid, and lactic acid at 0, 2, 4, 6, 8, 10, 12, 24, 36 and 48h after incubation. Results showed that tendency of pH in all groups first decreased, and then increased, in M2 group was lower than M1 group, M3 group and control group (P <0.05); concentrations of acetic acid, propanoic acid, butanoic acid, and total VFA in M2 group were higher than M1 group, M3 group and control group (P <0.05), concentration of lactic acid in M2 group was lower than M1 group, M3 group and control group (P <0.05).To develop the microecologic preparation and understand the fermentation characteristics of microecologic preparation in rumen administrated by gastric fistula in the different mixed ratio of the NY2 strain to propionibacterium acnes, six healthy sheep were divided into two groups, and control group and treatment contained, three sheep each group. Control group was took orally by equivalent physiological saline and treatment group added mixed preparations of diffrent mixed ratio of the strain of NY2 to propionibacterium acnes. Rumen fluid were collected to determine level of pH, acetic acid, propanoic acid, butanoic acid, total VFA, and lactic acid at 0, 2, 4, 8, 10, 12 and 24 h after administration. Results showed that tendency of pH in all groups first decreased, and then increased, in M2 group was lower than M1 group, M3 group and control group (P <0.05); concentrations of acetic acid, propanoic acid, butanoic acid, and total VFA in M2 group were higher than M1 group, M3 group and control group (P <0.05), concentration of lactic acid in M2 group was lower than M1 group, M3 group and control group (P <0.05).Conclusion obtained from above-mentioned results showed that the strain NY2 had the strong producing acid capacity in diet with a 40:60 ratio of forage to concentrate. When a ratio of the strain of NY2 to propionibacterium acnes is 60:60 in preparation, pH was in 6.0~7.0, and was beneficial to ruminal microbes fermentation, concentration of volatile fatty acid (acetic acid, propionic acid etc) increased, and lactic acid decreased. It is a basis of development of rumen microecologic preparations in future.
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