Revealing the Potential Advantages of Plectasin Through In Vitro Rumen Fermentation Analysis
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Plectasin, a novel antimicrobial peptide, has the potential to disrupt bacterial cell walls and alter the rumen fermentation mode, making it a superior alternative to antibiotics. However, there is limited research on the effects of plectasin on rumen microbiota. This study aimed to evaluate the effects of plectasin (0.057 μmol/L) on in vitro rumen fermentation characteristics and select groups of rumen bacterial communities in comparison with monensin (5 μmol/L), one of the most commonly used ionophores in ruminants, and as a control treatment with the basal substrate. Unlike monensin, plectasin was found to increase the molar proportions of butyrate and acetate/propionate ratio (p < 0.001) while decreasing pH and the molar proportions of propionate (p < 0.05). Principal component analysis of bacterial 16S rRNA gene amplicons clearly showed a separation between the bacteria shaped by plectasin and monensin. Comparative analysis also revealed differences in the relative abundance of certain bacteria in different taxa between plectasin and monensin. The divergent effects of plectasin and monensin on bacterial communities are likely responsible for the differences in their ability to alter rumen fermentation. Plectasin may have advantages over monensin in modulating ruminal bacterial communities and increasing the butyrate and the acetate/propionate ratio. Therefore, it may be considered as a potential additive for ruminant feed.The aim of this study was to test the effect of different yeast fermented liquid on the rumen fermentation in vitro. The eight different yeast fermented liquid were added to the rumen fluid of dairy goats with substrate. And the group only contained the substrate was as control. The effects of 8 yeast fermented liquid on the rumen fermentation were analyzed by measuring the p H of culture fluid, concentration of NH3-N, BCP and VFA in vitro. The results showed that XR4, SC18 and YJ2 reduced the concentration of NH3-N(P0.05) and SC18, YN7 and YJ2 increased the rumen BCP concentrations significantly(P 0.05). YJ2 and YL5 increased the total content of VFA significantly and stabilized the p H of culture fluid. In conclusion SC18, YJ2 and YN7 may promote the rumen fermentation significantly.
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Effect of Rumen Fluid-buffer Ratio on Gas Production and pH in Short-term Rumen Simulation Technique
The short-term rumen simulation technique inoculated with different rumen fluid level was used to study effect of rumen fluid(rumen micro-organism) level on gas production and pH in the artificial rumen.Ten treatments,i.e.,artificial saliva: rumen fluid by 1∶1,2∶1,3∶1,4∶1,5∶1,6∶1,7∶1,8∶1,9∶1,10∶1 were used.Each treatment had 2 replicates and 2 blanks.Gas production was recorded after 2,4,8,12,24 and 48 h of fermentation,respectively,and pH was measured at the end.Results showed that gas production in the first 12 h had significant correlations with the rumen fluid level,especially that within the beginning 4 h,while gas production over 12 h and pH are irrelative to rumen fluid level.
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The purpose of this study was to obtain data on the characteristics of rumen fluids, type and the number of microbes in Java and Ongole Grade (OG) bulls rumen. The material used in the study were 12 samples of the rumen fluids (6 of Java bulls and 6 of OG bulls) collected from the slaughter house in Brebes, Central Java. The rumen fluids were analyzed for the pH, NH3, volatile fatty acids (VFA) and microbes content which could be divided into: protozoa, bacteria and fungi. The data were analyzed descriptively. The results showed that the value of pH rumen fluid of Java bulls (6.83) was slightly higher than those in the OG bulls (6.67), but both were still in normal condition. NH3 concentration of Java bulls’ rumen fluid (8.75 mg N/100ml) was higher than those of the OG bulls (7.49 mg N/100ml). Concentration of acetate and butyrate of Java bulls’ rumen fluid was lower than those of the OG bulls, but the propionate concentration was higher. The acetate-propionate ratio of Java bulls’ rumen fluid was lower than those of the OG bulls. Number of protozoa in Java bulls’ rumen fluid (64.12 per µl of rumen fluid) was lower than those in the OG bulls (76.33 per µl of rumen fluid). The number of Java rumen fluid bacteria (2.7 x 10 7 cfu/g) was lower than those in the OG (2.3 x 10 8 cfu/g), but the amount of Java rumen fluid fungi (9.3 x 10 4 cfu/g) was higher than those of the OG (1.9 x 10 3 cfu/g). It was concluded that the pH of rumen fluid in either bulls were neutral, but the NH3 concentration, propionate acid and the number of fungi in the rumen fluid of Java was higher than those of the OG, so that the acetatepropionate ratio was lower in Java which showed that Java cattle has the potential to produce higher weight gain.
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Original rumen digesta, rumen liquid and solid fractions have been frequently used to assess the rumen bacterial community. However, bacterial profiles in rumen original digesta, liquid and solid fractions vary from each other and need to be better established.To compare bacterial profiles in each fraction, samples of rumen digesta from six cows fed either a high fiber diet (HFD) or a high energy diet (HED) were collected via rumen fistulas. Rumen digesta was then squeezed through four layers of cheesecloth to separate liquid and solid fractions. The bacterial profiles of rumen original digesta, liquid and solid fractions were analyzed with High-throughput sequencing technique.Rumen bacterial diversity was mainly affected by diet and individual cow (P > 0.05) rather than rumen fraction. Bias distributed bacteria were observed in solid and liquid fractions of rumen content using Venn diagram and LEfSe analysis. Fifteen out of 16 detected biomarkers (using LEfSe analysis) were found in liquid fraction, and these 15 biomarkers contributed the most to the bacterial differences among rumen content fractions.Similar results were found when using samples of original rumen digesta, rumen liquid or solid fractions to assess diversity of rumen bacteria; however, more attention should be draw onto bias distributed bacteria in different ruminal fractions, especially when liquid fraction has been used as a representative sample for rumen bacterial study.
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Seven in vivo experiments are reported in which the effects of diverting alkaline mixed saliva from the actively fermenting contents of the rumen of anaesthetized and conscious sheep fed on a standard ration were studied for periods up to 6 hr. The absence of various quantities of saliva (225–1349 ml) was associated with profound alterations in the rumen environment: rumen liquor volatile fatty acid (V.F.A.) levels were consistently and substantially elevated, and rumen pH levels depressed. These changes in the rumen environment began about 40–60 min after saliva diversion commenced, and were sustained long after such values for the control animals had inflected towards fasting levels. Rumen movements were recorded in two experiments. Rumen movement was reduced, but not entirely suppressed, some 60 min after the minimal pH values obtained. It is suggested that this reduction in rumen movement was a consequence of depressed pH values. The rumen pH-rumen V.F.A. relationship was, in six such cases, altered but the strength of this relationship was not significantly changed. It was concluded that these effects on rumen pH-V.F.A. levels and relationship were due, directly or indirectly, to the changed buffering or osmotic regime, or both, of the saliva-depleted rumen liquor. Implications of these findings are discussed in the light of rumen physiology and the field use of oesophageally fistulated sheep.
Volatile fatty acids
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The criteria used in comparing the utilization of grass silage by reindeer and sheep were rumen pH, ammonia, volatile fatty acids (VFA) and microbes. Rumen samples were taken before feeding, and 2 ½ and 5 ½ hours after the beginning of feeding. Rumen fermentation was lower in the reindeer than in the sheep and differed less between the three sampling times. In the reindeer/the pH of the rumen fluid averaged 6.94 and in the sheep 6.61. The average amounts of NH3—N were 17.0 and 24.2 mg/100 ml rumen fluid and those of total VFA 8.46 and 10.90 mmoles/100ml rumen fluid, respectively. The proportion of acetic acid in the VFA in the reindeer was 75.3 molar % and in the sheep 66.0 molar %, the corresponding values for propionic acid being 18.5 and 22.0 molar % and for butytic acid 4.2 and 8.8 molar %. The number of rumen ciliates in the reindeer averaged 87/mm3 rumen contents and in the sheep 314/ mm3. The numbers of bacteria were 16.0 X 106/mm3, respectively. The proportion of the total microbe mass in the reindeer rumen contents was 1.8 % and in the sheep 2.4 %. The proportions of bacteria in this mass were 87 % and 70 %, respectively. The differences between the reindeer and sheep in the rumen fermentation results and in the numbers of rumen microbiota were nearly all statistically significant (P
Silage
Volatile fatty acids
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The suggestion that homologous rumen fluid in culture media results in better growth of rumen bacteria than that obtained with heterologous fluid was tested with samples of rumen material from cows and sheep, with the use of rumen fluid from cows and sheep, and two agar culture media. It is shown that the suggestion cannot be taken as applying in general. With rumen material from the cow, the use of either type of rumen fluid gave the same growth, whereas with rumen material from the sheep, growth was depressed by use of sheep rumen fluid.
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In experiments on six sheep fed on a low nitrogen diet (3.7 g N/day), urease (EC 3.5.1.5) activity (nkat X mg-1 bacterial dry weight) 3 h after feeding was found to be highest in the bacteria adhering to the rumen wall (13.25 +/- 2.10), lower in the rumen fluid bacteria (8.96 +/- 1.35) and lowest in the bacteria adhering to feed particles in the rumen (5.69 +/- 2.13). The urease activity of bacteria adhering to the rumen wall and of the rumen fluid bacteria of six sheep fed on a high nitrogen diet (21 g N/day) was significantly lower than in sheep with a low N intake and in both cases was roughly the same (3.81 +/- 1.37 and 3.76 +/- 1.02 respectively); it was lowest in bacteria adhering to feed particles in the rumen (1.92 +/- 0.90). It is concluded from the results that the urease activity of rumen fluid bacteria and of bacteria adhering to the rumen wall and to feed particles in the rumen is different and that it falls significantly in the presence of a high nitrogen intake. From the relatively high ureolytic activity of bacteria adhering to the rumen wall in the presence of a low nitrogen intake it is assumed that this is one of the partial mechanisms of the hydrolysis of blood urea entering the rumen across the rumen wall and of its reutilization in the rumen-liver nitrogen cycle in ruminants.
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Streptococcus bovis and Butyrivibrio sp. were labeled with thymidine-methyl- 3 H, washed, and resuspended in rumen fluid or rumen fluid fractions obtained from Holstein and Jersey cows fed alfalfa hay once daily. Factors affecting the lytic activity found in untreated rumen fluid were examined. Day to day variation and differences before and after feeding were observed for the same cow. There were also differences between cows on the same day. For a given rumen fluid, the rate of release of label was roughly proportional to the number of labeled cells present over a 100-fold range in concentration. Removal of protozoa largely abolished the lytic action of fresh rumen fluid for S. bovis , but some soluble lytic activity remained. Mixed rumen protozoa added to media containing labeled S. bovis caused label to appear in solution. In a sample of rumen fluid containing 4.3 × 10 4 protozoa/ml 5.2% of the S. bovis population were destroyed by protozoa per hr. The mean rate of destruction for 12 runs on whole rumen fluid was 8.7% per hr with a standard deviation of 6.05. Parallel experiments with Butyrivibrio indicated that soluble lytic factors were more important for this organism. They could be destroyed by autoclaving and were generated when viable rumen bacteria were resuspended in autoclaved rumen fluid. The lysis of S. bovis and Butyrivibrio , at equal cell densities, by mixed rumen protozoa was compared in 30% rumen fluid media, and Butyrivibrio appeared to be more readily lysed than S. bovis .
Streptococcus bovis
Lytic cycle
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