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Main page > Research and Trials > Ruminants > Trials with rumen simulation methods and with fistulated cows
The effect of hydrolysed brewery yeast on rumen fermentationObjective The aim of the trials was to study the effects of hydrolysed brewery yeast product Progut on rumen fermentation parameters in vitro and in vivo. Rumen simulation studies at Alimetrics Ltd. The effect of Progut® on rumen fermentation was investigated in a series of rumen simulation studies in vitro by Alimetrics Ltd. in Finland in 2006. Total gas production, pH and short chain fatty acid production (SCFA) was measured and the total number of microbes was determined by flow cytometry. Progut enhanced rumen fermentation rate Progut significantly enhanced rumen fermentation rate, the effect being independent from the basic feed raw materials tested (figure 1). The fermentation rate is calculated from microbial gas production and presented as maximum enhancement percentage compared with the control. The tested diets were: Diet 1 - 50 % grass silage and 50 % compound feed A, Diet 2 - 50 % maize silage, 25 % barley meal and 25 % soy meal and Diet 3 - 50 % grass silage and 50 % compound feed B. The effect of Progut on rumen fermentation was also tested in comparison with a competitive live yeast product (1 x 10E8 cells per gram) and with an inactivated yeast culture product. The results presented in figure 2 show that Progut had at least similar efficacy than the live yeast product and superior efficacy in comparison with the inactivated yeast culture product at the same dose levels in the simulation. Figure 1. The effect of Progut® on microbial gas production with different diets
Figure 2. The effect of different yeast products on microbial gas production
Progut increased the energy and protein supply Progut increased both the production of energy and protein by increasing the number of rumen microbes and by increasing short chain fatty acid production (figure 3). When converting these effects to microbial protein and energy, it was seen that the addition of Progut increased the protein and energy supply of ruminants (figure 4) remarkably. Figure 3. The effect of Progut® on rumen fermentation parameters
Figure 4. The effect of Progut® on the protein and energy supply of ruminants (calculated from the effects on rumen fermentation parameters presented in above)
Progut had positive effects on all rumen fermentation parameters studied (table 1). The effects of the competitive products were less significant. 1. The effects of different yeast products on the rumen fermentation parameters in vitro
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Rumen simulation studies at Hannover Veterinary UniversityIn the studies at Hannover Veterinary University 2006, the rumen simulation technique (Rusitec) was used. Standard Progut® and less hydrolyzed brewery yeast of the same raw material were tested. The roughage to concentrate ratio in the trials was 55:45. The results in figure 5 are presented as a % from the control. Progut® with both inclusion rates tested increased the production of total SCFA, acetic acid and propionate. The effect of the less hydrolyzed brewery yeast on rumen microbial metabolism was negligible. This indicates that the degree of hydrolysis is important for the efficacy of this type of yeast in the rumen. Figure 5. The effects of Progut® and less hydrolyzed brewery yeast on in vitro rumen microbial metabolism. Hannover Veterinary University 2006
The effects of Progut on rumen fermentation measured with fistulated cowA rumen fistulated cow received (6am and 3pm) 1 kg dose of compound feed twice a day. Grass silage and water was available for the cow ab libitum. Progut, at a level of 15 grams per day, was mixed to the 6am compound feed diet. The sampling was done by aspiring rumen fluid with a vacuum pump. The feeding protocol for Progut was as follows: • Day 0 No Progut, a control sample • Day 1-7 Progut 15g per day • Day 8-14 No Progut, a washout period The best statistically significant fit was reached with a mathematical model that assumes a linear increase for four days after the start of Progut feeding, a steady state until four days after Progut feeding was stopped and linear decrease after that. All rumen parameters were thereafter modelled by using the assumptions described above. Results: Progut increased all the studied rumen fermentation parameters compared with the control sample. The number of rumen microbes showed and increasing trend, but the high variation prevented the accurate modeling of the data. All the measured rumen fermentation parameters followed a similar pattern. A linear increase during the first four days of Progut® feeding, a steady state until four days after Progut® feeding was stopped and a linear decrease after that. For example, the volatile fatty acid (VFA) concentration increased from the control level during the first four days of Progut feeding, then stabilized and started to decrease after the feeding of Progut was stopped (figure 6). Figure 6. The effect of Progut® on the concentration of VFA with fistulated cow (r² = 0,54, p < 0.0001)
The effect of hydrolysed brewery yeast Progut on rumen fermentation with different silage-to-compound feed ratiosObjective The aim of the study was to investigate the effect of hydrolysed brewery yeast Progut on rumen microbial fermentation and microbial community structure with different silage-to–compound feed ratios. Materials and methods The effect of Progut on rumen microbial fermentation was investigated in a rumen simulation study by Alimetrics Ltd. in Finland in 2007. Total gas production, pH, short chain fatty acid production (SCFA) and volatile fatty acid (VFA) production were measured and the total number of microbes was determined by flow cytometry. The microbial community structure was analysed by sequencing of the 16S rDNA gene. There were three basic diets in the trial. 1) 75 % compound feed and 25 % grass silage 2) 50 % compound feed and 50 % grass silage 3) 25 % compound feed and 75 % grass silage Results The effect of Progut on rumen microbial fermentation Addition of the hydrolysed brewery yeast (Progut) increased rumen fermentation rate with all three silage-to-compound feed ratios (figure 1). Similarly, it increased the production of microbial biomass with all three diets (figure 2) during the first six hours of the simulation. In the end of the simulation (24 h) Progut® increased microbial biomass with all basic diets but the difference to control was statistically significant only with the highest compound feed diet. The results from the microbial community structure analysis show that the increase in the microbial biomass in different stages of fermentation was caused by different microbial groups. Figure 1. Cumulative gas production
Figure 2. The total number of microbes at 6 hours of simulation
Progut® significantly increased SCFA production after 6 hours of simulation with the two highest compound feed ratios and at 24 hours with all three diets (table 1). Increase in the VFA production at later stage of fermentation was mainly due to increased propionate production. Lactic acid is the main SCFA at early stage of rumen fermentation and it’s later converted to propionate by normal rumen microbes. Results from this study indicate that Progut® improved the conversion of lactic acid to propionate. Table 1. The effect of Progut® on the production of SCFA with different basic diets
+ increase by 0-5 % * 0.05 > p- value > 0.01 ++ increase by 5-10 % ** 0.01 > p.value > 0.001 +++ increase by > 10 % *** 0.001 > p-value > 0.0001 **** p-value < 0.0001
Progut stimulated metabolically active microbes in rumenProgut® had clearest effect on the number of lactate degrading Selenomonas spp. group bacteria. It tended to increase the amount of this bacteria group at 12 hours with the two highest compound feed diets and significantly increased its amount at 24 hours with the high silage diet (figure 3). Figure 3. The effect of Progut® on lactate degrading Selenomonas spp.
The stimulatory effect of Progut® on the cellulolytic + amylolytic microbes was statistically significantly detected for the high silage treatment at 24 hour time point (p = 0.004). At this time point Progut increased the proportion of cellulolytic + amylolytic bacteria from < 20 % up to > 45 % with the high silage diet but didn’t have an effect with the other diets (figure 4). Overall, the results suggest that Progut always stimulates those microbes that are metabolically most active. Figure 4. The effect of Progut® on cellulolytic+amylolytic microbial groups
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