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M D Carro - One of the best experts on this subject based on the ideXlab platform.

  • effects of modifications to retain protozoa in continuous culture Fermenters on ruminal fermentation microbial populations and microbial biomass assessed by two different methods
    Animal Feed Science and Technology, 2018
    Co-Authors: I Cabezaluna, M D Carro, J Fernandezyepes, E Molinaalcaide
    Abstract:

    Abstract An important limitation of continuous-culture Fermenters is their inability of maintaining microbial populations similar to those observed in the rumen, especially protozoa numbers, which usually decrease markedly or even disappear. Two approaches (a polyurethane-sponge (SP) and a filter system (FIL) for additionally retaining protozoa were tested in continuous culture system already designed to retain protozoa ( Muetzel et al., 2009 ), and their effects on microbial populations, fermentation parameters and microbial biomass were assessed. Two 14-day incubation runs were carried out with 6 Fermenters, and in each run two Fermenters were randomly assigned to each of the experimental treatments (control, SP and FIL). Total protozoa numbers assessed by microscopic counting were 1.7 and 2.1 times greater in SP and FIL Fermenters than in control ones on day 14, although differences did not reach the significance level (P = 0.855). Protozoal DNA concentration on day 14 were 1.6 and 1.4 times greater in SP and FIL Fermenters, respectively, than in control ones, but differences were not significant (P = 0.524). Results from protozoal DNA concentrations determined in each fermenter on the different sampling days (n = 48) were positively correlated (P   0.05) fermentation parameters, which reached a steady-state after 6 days of incubation. Values of microbial biomass determined using purine bases as a microbial marker were significantly correlated with the amount of bacterial plus protozoal DNA (r = 0.794; P = 0.002; n = 12) in each fermenter. In conclusion, the two tested modifications increased the protozoa numbers in continuous-culture Fermenters, and the FIL allowed maintaining a proportion of holotrich protozoa similar to that in the ruminal fluid used as inoculum.

  • influence of increasing doses of a yeast hydrolyzate obtained from sugarcane processing on in vitro rumen fermentation of two different diets and bacterial diversity in batch cultures and rusitec Fermenters
    Animal Feed Science and Technology, 2017
    Co-Authors: A Diaz, Maria Jose Ranilla, Maria L Tejido, C Saro, M Perezquintana, M D Carro
    Abstract:

    Abstract Live yeast cultures and yeast hydrolyzates can be used as rumen fermentation modifiers, but their effects and mode of action are different. Whereas the effects of live yeast cultures on rumen fermentation are well documented, yeast hydrolyzates have received much less attention. The influence of a yeast hydrolyzate from Saccharomyces cerevisiae , obtained after ethanol production from sugarcane (YHS), on in vitro rumen fermentation was investigated using both batch cultures and Rusitec Fermenters inoculated with ruminal fluid from sheep. Batch cultures (300 mg dry matter (DM)) with two mixed diets (AHC, 0.5:0.5 alfalfa hay:concentrate; BSC, 0.15:0.85 barley straw:concentrate) as substrate were supplemented with increasing doses of YHS (0, 3.3, 6.7, 10.0 and 13.3 ml/l) and incubated for 16.5 h at 39 °C. Supplementation of increasing amounts of YHS to AHC-cultures increased ( P   0.05) linearly total volatile fatty acid (VFA) production and butyrate molar proportion, and decreased ( P   0.001) acetate proportion and acetate:propionate ratio. In contrast, only subtle effects of YHS on NH 3 -N concentrations and molar proportions of isovalerate and caproate were observed for the BSC diet. Longer-term effects of YHS supplementation on rumen fermentation of AHC diet were investigated using four Rusitec Fermenters in a cross-over experimental design with two 14-day incubation periods. Fermenters were given daily 30 g of diet DM, and in each period half of them were supplemented daily with 5 ml of YHS (10.0 ml/l) Supplementing with YHS did not affect ( P >  0.05) total VFA production, lactate concentrations, DM and aNDFom disappearance or enzymatic activities (amylase, xylanase and carboxymethylcellulase). Compared with the unsupplemented Fermenters, YHS treatment increased ( P   0.001) NH 3 -N concentrations and molar proportions of propionate and butyrate at the expense of acetate, and decreased ( P   0.001) acetate:propionate ratio. In addition, YHS supplementation tended ( P   0.07) to reduce CH 4 /total VFA ratio and to increase microbial growth in the liquid phase of the Fermenters. The automated ribosomal intergenic spacer analysis (ARISA) of samples taken on days 3, 8 and 14 of incubation from solid and liquid content of Fermenters revealed that YHS supplementation increased ( P   0.02) bacterial diversity in the liquid phase and tended to increase ( P   0.08) it in the solid phase. The results indicate that YHS at a dose of 10 ml/l may be a useful dietary additive for ruminants, because it promoted a shift in fermentation toward propionate production, reduced the CH 4 /total VFA ratio and increased microbial growth with a 50:50 alfalfa hay:concentrate diet.

  • shifts in microbial populations in rusitec Fermenters as affected by the type of diet and impact of the method for estimating microbial growth 15n v microbial dna
    Animal, 2017
    Co-Authors: I Mateos, C Saro, Maria Jose Ranilla, M D Carro
    Abstract:

    Rusitec Fermenters are in vitro systems widely used to study ruminal fermentation, but little is known about the microbial populations establishing in them. This study was designed to assess the time evolution of microbial populations in Fermenters fed medium- (MC; 50% alfalfa hay : concentrate) and high-concentrate diets (HC; 15 : 85 barley straw : concentrate). Samples from solid (SOL) and liquid (LIQ) content of Fermenters were taken immediately before feeding on days 3, 8 and 14 of incubation for quantitative polymerase chain reaction and automated ribosomal intergenic spacer analysis analyses. In SOL, total bacterial DNA concentration and relative abundance of Ruminococcus flavefaciens remained unchanged over the incubation period, but protozoal DNA concentration and abundance of Fibrobacter succinogenes , Ruminococcus albus and fungi decreased and abundance of methanogenic archaea increased. In LIQ, total bacterial DNA concentration increased with time, whereas concentration of protozoal DNA and abundance of methanogens and fungi decreased. Diet×time interactions were observed for bacterial and protozoal DNA and relative abundance of F. succinogenes and R. albus in SOL, as well as for protozoal DNA in LIQ. Bacterial diversity in SOL increased with time, but no changes were observed in LIQ. The incubated diet influenced all microbial populations, with the exception of total bacteria and fungi abundance in LIQ. Bacterial diversity was higher in MC-fed than in HC-fed Fermenters in SOL, but no differences were detected in LIQ. Values of pH, daily production of volatile fatty acids and CH 4 and isobutyrate proportions remained stable over the incubation period, but other fermentation parameters varied with time. The relationships among microbial populations and fermentation parameters were in well agreement with those previously reported in in vivo studies. Using 15 N as a microbial marker or quantifying total microbial DNA for estimating microbial protein synthesis offered similar results for diets comparison, but both methods presented contrasting results for microbial growth in SOL and LIQ phases. The study showed that fermentation parameters remained fairly stable over the commonly used sampling period (days 8 to 14), but shifts in microbial populations were detected. Moreover, microbial populations differed markedly from those in the inocula, which indicates the difficulty of directly transposing results on microbial populations developed in Rusitec Fermenters to in vivo conditions.

  • comparison of fermentation of diets of variable composition and microbial populations in the rumen of sheep and rusitec Fermenters ii protozoa population and diversity of bacterial communities
    Journal of Dairy Science, 2010
    Co-Authors: M D Carro, M E Martinez, Maria Jose Ranilla, Maria L Tejido, C Saro
    Abstract:

    Four ruminally and duodenally cannulated sheep and 8 Rusitec Fermenters were used to determine the effects of dietary characteristics on microbial populations and bacterial diversity. The purpose of the study was to assess how closely Fermenters can mimic the differences between diets found in vivo. The 4 experimental diets contained forage to concentrate (F:C) ratios of 70:30 (high forage; HF) or 30:70 (high concentrate; HC) with either alfalfa hay (A) or grass hay (G) as the forage. Total bacterial numbers were greater in the rumen of sheep fed HF diets compared with those fed HC diets, whereas the opposite was found in Fermenters. The numbers of cellulolytic bacteria were not affected by F:C ratio in any fermentation system, but cellulolytic numbers were 2.7 and 1.8 times greater in sheep than in Fermenters for HF and HC diets, respectively. Neither total bacterial nor cellulolytic numbers were affected by the type of forage in sheep or Fermenters. Decreasing F:C ratio increased total protozoa and Entodiniae numbers in sheep by about 29 and 25%, respectively, but it had no effect in Fermenters. Isotrichidae and Ophryoscolecinae numbers in sheep were not affected by changing F:C ratio, but both disappeared completely from Fermenters fed HC diets. Total protozoa and Entodiniae numbers were greater in sheep fed A diets than in those fed G diets, whereas the opposite was found in Fermenters. Results indicate that under the conditions of the present study, protozoa population in Rusitec Fermenters was not representative of that in the rumen of sheep fed the same diets. In addition, protozoa numbers in Fermenters were 121 and 226 times lower than those in the sheep rumen for HF and HC diets, respectively. The automated ribosomal intergenic spacer analysis of the 16S ribosomal DNA was used to analyze the diversity of liquid- and solid-associated bacteria in both systems. A total of 170 peaks were detected in the automated ribosomal intergenic spacer analysis electropherograms of bacterial pellets across the full set of 64 samples, from which 160 were detected in at least 1 individual from each system (sheep or fermenter). Diversity of liquid-associated bacterial pellets was greater with G diets in Fermenters but seemed to be unaffected by diet in sheep. Bacterial diversity in solid-associated bacteria pellets was greater for G diets compared with A diets in sheep and Fermenters. Different conditions in the Fermenters compared with sheep rumen might have caused a selection of some bacterial strains.

  • comparison of fermentation of diets of variable composition and microbial populations in the rumen of sheep and rusitec Fermenters i digestibility fermentation parameters and microbial growth
    Journal of Dairy Science, 2010
    Co-Authors: M E Martinez, M D Carro, Maria Jose Ranilla, Maria L Tejido, S Ramos
    Abstract:

    Abstract Four ruminally and duodenally cannulated sheep and 8 Rusitec Fermenters were used to determine the effects of forage to concentrate (F:C) ratio and type of forage in the diet on ruminal fermentation and microbial protein synthesis. The purpose of the study was to assess how closely Fermenters can mimic the dietary differences found in vivo. The 4 experimental diets contained F:C ratios of 70:30 or 30:70 with either alfalfa hay or grass hay as the forage. Microbial growth was determined in both systems using 15 N as a microbial marker. Rusitec Fermenters detected differences between diets similar to those observed in sheep by changing F:C ratio on pH; neutral detergent fiber digestibility; total volatile fatty acid concentrations; molar proportions of acetate, propionate, butyrate, isovalerate, and caproate; and amylase activity. In contrast, Rusitec Fermenters did not reproduce the dietary differences found in sheep for NH 3 -N and lactate concentrations, dry matter (DM) digestibility, proportions of isobutyrate and valerate, carboxymethylcellulase and xylanase activities, and microbial growth and its efficiency. Regarding the effect of the type of forage in the diet, Rusitec Fermenters detected differences between diets similar to those found in sheep for most determined parameters, with the exception of pH, DM digestibility, butyrate proportion, and carboxymethylcellulase activity. Minimum pH and maximal volatile fatty acid concentrations were reached at 2h and at 6 to 8h postfeeding in sheep and Fermenters, respectively, indicating that feed fermentation was slower in Fermenters compared with that in sheep. There were differences between systems in the magnitude of most determined parameters. In general, Fermenters showed lower lactate concentrations, neutral detergent fiber digestibility, acetate:propionate ratios, and enzymatic activities. On the contrary, Fermenters showed greater NH 3 -N concentrations, DM digestibility, and proportions of propionate, butyrate, isovalerate, valerate, and caproate. Values of efficiency of microbial growth were greater in Fermenters compared with sheep for 70:30 diets, but they were lower for 30:70 diets. Differences between fermentation in sheep and Fermenters can be mainly attributed to the lack of absorption in Fermenters, differences in solid retention time, and compartmentalization in the Rusitec system. In general, the Rusitec system simulated more closely the in vivo fermentation of high-forage diets compared with high-concentrate diets.

E Molinaalcaide - One of the best experts on this subject based on the ideXlab platform.

  • effects of modifications to retain protozoa in continuous culture Fermenters on ruminal fermentation microbial populations and microbial biomass assessed by two different methods
    Animal Feed Science and Technology, 2018
    Co-Authors: I Cabezaluna, M D Carro, J Fernandezyepes, E Molinaalcaide
    Abstract:

    Abstract An important limitation of continuous-culture Fermenters is their inability of maintaining microbial populations similar to those observed in the rumen, especially protozoa numbers, which usually decrease markedly or even disappear. Two approaches (a polyurethane-sponge (SP) and a filter system (FIL) for additionally retaining protozoa were tested in continuous culture system already designed to retain protozoa ( Muetzel et al., 2009 ), and their effects on microbial populations, fermentation parameters and microbial biomass were assessed. Two 14-day incubation runs were carried out with 6 Fermenters, and in each run two Fermenters were randomly assigned to each of the experimental treatments (control, SP and FIL). Total protozoa numbers assessed by microscopic counting were 1.7 and 2.1 times greater in SP and FIL Fermenters than in control ones on day 14, although differences did not reach the significance level (P = 0.855). Protozoal DNA concentration on day 14 were 1.6 and 1.4 times greater in SP and FIL Fermenters, respectively, than in control ones, but differences were not significant (P = 0.524). Results from protozoal DNA concentrations determined in each fermenter on the different sampling days (n = 48) were positively correlated (P   0.05) fermentation parameters, which reached a steady-state after 6 days of incubation. Values of microbial biomass determined using purine bases as a microbial marker were significantly correlated with the amount of bacterial plus protozoal DNA (r = 0.794; P = 0.002; n = 12) in each fermenter. In conclusion, the two tested modifications increased the protozoa numbers in continuous-culture Fermenters, and the FIL allowed maintaining a proportion of holotrich protozoa similar to that in the ruminal fluid used as inoculum.

  • garlic derived compounds modify ruminal fatty acid biohydrogenation and induce shifts in the butyrivibrio community in continuous culture Fermenters
    Animal Feed Science and Technology, 2013
    Co-Authors: E Ramosmorales, E Molinaalcaide, Gonzalo Martinezfernandez, L Abecia, A I Martingarcia, D R Yanezruiz
    Abstract:

    Abstract Garlic essential oil contains a variety of fat soluble organosulfur compounds with antibacterial activity. Nevertheless, only recent studies have evaluated garlic oil and its constituents as modulators of ruminal processes. The present study was undertaken to evaluate the potential of diallyl disulfide (DDS) and propyl propane thiosulfinate (PTS) to modulate rumen biohydrogenation in vitro . Six continuous-culture Fermenters, inoculated with rumen fluid from goats, were used in two replicated incubation runs of 12 days each. Two Fermenters per run received either a control diet (without additive) or the same diet with 80 μl/L of DDS or 200 μl/L of PTS daily. At the end of each incubation run, samples of fermenter contents were taken for fatty acid analysis. The DDS addition resulted in lower (P=0.012) total saturated fatty acids (SFA) and higher monounsaturated fatty acids (MUFA; P=0.001) and polyunsaturated fatty acids (PUFA; P=0.018) contents as compared to the control. Increases in trans -10, cis -12 CLA (P=0.065), trans -10 18:1 (P trans -11-18:1) (P=0.009) were also observed. Similar results were found for PTS addition, although significant differences with the control group were detected only for PUFA and trans -10 18:1 amounts. Additionally, 1 mL of the fermenter contents was incubated in vitro with 0.167 g/L of linoleic acid ( cis -9, cis -12 18:2; LA) for 0, 1, 3, 6, 9 and 24 h. Vaccenic acid and trans -10 18:1 accumulated to higher concentrations (P=0.054 at 9 h and P=0.021 at 3 h, respectively) when LA was incubated with the fermenter contents treated with DDS and PTS. Garlic derived compounds did not affect the amount of total bacteria (P=0.936) or abundances of Butyrivibrio proteoclasticus (P=0.693); although PTS increased the abundance of Butyrivibrio fibrisolvens (P=0.001), in comparison to the control and DDS treatments. Differences in the Butyrivibrio group structure were observed from the cluster analysis, which showed segregation for Fermenters with garlic derived compounds from those without additives. It was concluded that adding DDS and PTS to the diet of Fermenters modified the fatty acid of rumen contents, with potential health benefits of ruminant products. These changes in biohydrogenation appeared to be related to shifts within the Butyrivibrio bacterial community. In vivo studies are now required to confirm the potential of these compounds.

  • the effect of the feed to buffer ratio on bacterial diversity and ruminal fermentation in single flow continuous culture Fermenters
    Journal of Dairy Science, 2011
    Co-Authors: G Cantalapiedrahijar, D R Yanezruiz, C J Newbold, E Molinaalcaide
    Abstract:

    Abstract Eight single-flow continuous-culture Fermenters were used in a completely randomized block design with a 2 × 4 factorial arrangement of treatments to investigate the effects of the feed-to-buffer ratio (F/B) on ruminal fermentation, the diversity and community structure of bacteria, nutrient digestibility, and N metabolism. Four diets with forage-to-concentrate ratios of 70:30 or 30:70 with alfalfa or grass hay as forage were supplied to Fermenters twice per day at 2 different F/B (23.5 and 35 g of DM/L). The dilution rate was kept constant (5.3%) among all Fermenters by infusing the same volume of buffer. An increase in the total volatile fatty acid (VFA) concentration and a decrease in the average pH were observed with an increased F/B. In addition, the molar proportions of all individual VFA found in Fermenters differed, depending on the F/B. A terminal restriction fragment length polymorphism analysis showed that the community structure and diversity of bacteria were highly influenced by the F/B. Both diversity and the number of peaks in the electropherograms were lower in most Fermenters receiving diets at a high F/B, whereas the similarity percentage of the bacterial communities across diets was higher as the F/B increased. Moreover, the high reduction of neutral detergent fiber digestibility (15.3% ± 3.65) in Fermenters with high F/B suggested a pH-related decrease in the cellulolytic bacterial community as the F/B increased. The crude protein degradation found in Fermenters receiving diets with a high F/B was lower compared with that from Fermenters with a low F/B. The VFA concentration and purine bases flow response patterns to diets were similar to in vivo conditions only in the case of Fermenters with a low F/B. The results suggested that the community structure and diversity of bacteria, as well as the in vitro fermentation parameters, may be affected by the F/B that is used, most likely through a pH effect. In addition, several fermentation parameters showed different response patterns to diets according to the F/B used. Therefore, the amount of feed supplied to single-flow continuous-culture Fermenters in which pH is not under control should be carefully chosen according to the volume of buffer infused for the purpose of simulating ruminal fermentation.

  • effects of concentrate replacement by feed blocks on ruminal fermentation and microbial growth in goats and single flow continuous culture Fermenters
    Journal of Animal Science, 2009
    Co-Authors: E Molinaalcaide, M R Pascual, G Cantalapiedrahijar, E Y Moralesgarcia, A I Martingarcia
    Abstract:

    The effect of replacing concentrate with 2 different feed blocks (FB) on ruminal fermentation and microbial growth was evaluated in goats and in single-flow continuous-culture Fermenters. Diets consisted of alfalfa hay plus concentrate and alfalfa hay plus concentrate with 1 of the 2 studied FB. Three trials were carried out with 6 rumen-fistulated Granadina goats and 3 incubation runs in 6 single-flow continuous-culture Fermenters. Experimental treatments were assigned randomly within each run, with 2 repetitions for each diet. At the end of each in vivo trial, the rumen contents were obtained for inoculating the Fermenters. For each incubation run, the Fermenters were inoculated with ruminal fluid from goats fed the same diet supplied to the corresponding fermenter flask. The average pH values, total and individual VFA, and NH₃-N concentrations, and acetate:propionate ratios in the rumen of goats were not affected (P greater-than-or-equal 0.10) by diet, whereas the microbial N flow (MNF) and efficiency were affected (P [less-than or equal to] 0.001), with the greatest values observed for the diet without FB. In Fermenters, the diet affected pH (P < 0.001), propionate concentrations (P = 0.01), acetate:propionate ratio (P = 0.03), carbohydrate digestibility (P greater-than-or-equal 0.05), and total (P = 0.02), NH₃ (P = 0.005), and non-NH₃ (P = 0.02) N flows, whereas the efficiency of VFA production was not affected (P = 0.75). The effect of diet on MNF and efficiency depended on the bacterial pellet used as a reference. An effect (P < 0.05) of diet on the composition of solid- and liquid-associated bacteria was observed. The compositions of liquid-associated bacteria in the fermenter contents and effluent were similar (P = 0.05). Differences (P < 0.001) between in vivo and in vitro values for most fermentation variables and bacterial pellet compositions were found. Partial replacement of the concentrate with FB did not greatly compromise carbohydrate fermentation in unproductive goats. However, this was not the case for MNF and efficiency. Differences between the results obtained in vivo and in vitro indicate a need to identify conditions in Fermenters that allow better simulation of fermentation, microbial growth, and bacterial pellet composition in vivo. Reduced feeding cost could be achieved with the inclusion of FB in the diets of unproductive goats without altering rumen fermentation.

  • comparison of microbial fermentation of high and low forage diets in rusitec single flow continuous culture Fermenters and sheep rumen
    Animal, 2009
    Co-Authors: M D Carro, A I Martingarcia, Maria Jose Ranilla, E Molinaalcaide
    Abstract:

    Eight Rusitec and eight single-flow continuous-culture Fermenters (SFCCF) were used to compare the ruminal fermentation oftwo diets composed of alfalfa hay and concentrate in proportions of 80:20 (F80) and 20:80 (F20). Results were validated withthose obtained previously in sheep fed the same diets. Rusitec Fermenters were fed once daily and SFCCF twice, but liquiddilution rates were similar in both types of Fermenters. Mean values of pH over the 12h postfeeding were higher (P,0.001)in Rusitec than in SFCCF, with diet F80 showing higher values (P,0.001) in both types of Fermenters. Concentrations of totalvolatile fatty acids (VFA) were higher (P,0.001) in SFCCF than in Rusitec, and in both systems were higher (P50.002) fordiet F20 than for diet F80. There were significant differences between systems in the proportions of the main VFA, and afermentation system3diet interaction (P,0.001) was detected for all VFA with the exception of valerate. No differences(P50.145) between the two types of Fermenters were detected in dry matter (DM) digestibility, but NDF, microbial N flowand its efficiency were higher (P50.001) in SFCCF compared to Rusitec. Whereas pH values and VFA concentrations remainedfairly stable through the day in bothin vitro systems, pH dropped and VFA increased shortly after feeding in sheep rumenreaching the minimum and maximal values, respectively, about 4h after feeding. Bothin vitro systems detected differencesbetween diets similar to those found in sheep for liquid dilution rate, pH values, DM digestibility, microbial N flow and growthefficiency. In contrast, acetate/propionate ratios were lower for diet F20 than for F80 in sheep rumen (2.73 and 3.97) andSFCCF (3.07 and 4.80), but were higher for diet F20 compared to F80 (4.29 and 3.40) in Rusitec, with values considered tobe unphysiological for high-concentrate diets.In vivo NDF digestibility was affected (P50.017) by diet, but no differencesbetween diets (P.0.05) were found in anyin vitro system. A more precise control of pH in both types of Fermenters anda reduction of concentrate retention time in Rusitec could probably improve the simulation ofin vivo fermentation.

Maria Jose Ranilla - One of the best experts on this subject based on the ideXlab platform.

  • influence of increasing doses of a yeast hydrolyzate obtained from sugarcane processing on in vitro rumen fermentation of two different diets and bacterial diversity in batch cultures and rusitec Fermenters
    Animal Feed Science and Technology, 2017
    Co-Authors: A Diaz, Maria Jose Ranilla, Maria L Tejido, C Saro, M Perezquintana, M D Carro
    Abstract:

    Abstract Live yeast cultures and yeast hydrolyzates can be used as rumen fermentation modifiers, but their effects and mode of action are different. Whereas the effects of live yeast cultures on rumen fermentation are well documented, yeast hydrolyzates have received much less attention. The influence of a yeast hydrolyzate from Saccharomyces cerevisiae , obtained after ethanol production from sugarcane (YHS), on in vitro rumen fermentation was investigated using both batch cultures and Rusitec Fermenters inoculated with ruminal fluid from sheep. Batch cultures (300 mg dry matter (DM)) with two mixed diets (AHC, 0.5:0.5 alfalfa hay:concentrate; BSC, 0.15:0.85 barley straw:concentrate) as substrate were supplemented with increasing doses of YHS (0, 3.3, 6.7, 10.0 and 13.3 ml/l) and incubated for 16.5 h at 39 °C. Supplementation of increasing amounts of YHS to AHC-cultures increased ( P   0.05) linearly total volatile fatty acid (VFA) production and butyrate molar proportion, and decreased ( P   0.001) acetate proportion and acetate:propionate ratio. In contrast, only subtle effects of YHS on NH 3 -N concentrations and molar proportions of isovalerate and caproate were observed for the BSC diet. Longer-term effects of YHS supplementation on rumen fermentation of AHC diet were investigated using four Rusitec Fermenters in a cross-over experimental design with two 14-day incubation periods. Fermenters were given daily 30 g of diet DM, and in each period half of them were supplemented daily with 5 ml of YHS (10.0 ml/l) Supplementing with YHS did not affect ( P >  0.05) total VFA production, lactate concentrations, DM and aNDFom disappearance or enzymatic activities (amylase, xylanase and carboxymethylcellulase). Compared with the unsupplemented Fermenters, YHS treatment increased ( P   0.001) NH 3 -N concentrations and molar proportions of propionate and butyrate at the expense of acetate, and decreased ( P   0.001) acetate:propionate ratio. In addition, YHS supplementation tended ( P   0.07) to reduce CH 4 /total VFA ratio and to increase microbial growth in the liquid phase of the Fermenters. The automated ribosomal intergenic spacer analysis (ARISA) of samples taken on days 3, 8 and 14 of incubation from solid and liquid content of Fermenters revealed that YHS supplementation increased ( P   0.02) bacterial diversity in the liquid phase and tended to increase ( P   0.08) it in the solid phase. The results indicate that YHS at a dose of 10 ml/l may be a useful dietary additive for ruminants, because it promoted a shift in fermentation toward propionate production, reduced the CH 4 /total VFA ratio and increased microbial growth with a 50:50 alfalfa hay:concentrate diet.

  • shifts in microbial populations in rusitec Fermenters as affected by the type of diet and impact of the method for estimating microbial growth 15n v microbial dna
    Animal, 2017
    Co-Authors: I Mateos, C Saro, Maria Jose Ranilla, M D Carro
    Abstract:

    Rusitec Fermenters are in vitro systems widely used to study ruminal fermentation, but little is known about the microbial populations establishing in them. This study was designed to assess the time evolution of microbial populations in Fermenters fed medium- (MC; 50% alfalfa hay : concentrate) and high-concentrate diets (HC; 15 : 85 barley straw : concentrate). Samples from solid (SOL) and liquid (LIQ) content of Fermenters were taken immediately before feeding on days 3, 8 and 14 of incubation for quantitative polymerase chain reaction and automated ribosomal intergenic spacer analysis analyses. In SOL, total bacterial DNA concentration and relative abundance of Ruminococcus flavefaciens remained unchanged over the incubation period, but protozoal DNA concentration and abundance of Fibrobacter succinogenes , Ruminococcus albus and fungi decreased and abundance of methanogenic archaea increased. In LIQ, total bacterial DNA concentration increased with time, whereas concentration of protozoal DNA and abundance of methanogens and fungi decreased. Diet×time interactions were observed for bacterial and protozoal DNA and relative abundance of F. succinogenes and R. albus in SOL, as well as for protozoal DNA in LIQ. Bacterial diversity in SOL increased with time, but no changes were observed in LIQ. The incubated diet influenced all microbial populations, with the exception of total bacteria and fungi abundance in LIQ. Bacterial diversity was higher in MC-fed than in HC-fed Fermenters in SOL, but no differences were detected in LIQ. Values of pH, daily production of volatile fatty acids and CH 4 and isobutyrate proportions remained stable over the incubation period, but other fermentation parameters varied with time. The relationships among microbial populations and fermentation parameters were in well agreement with those previously reported in in vivo studies. Using 15 N as a microbial marker or quantifying total microbial DNA for estimating microbial protein synthesis offered similar results for diets comparison, but both methods presented contrasting results for microbial growth in SOL and LIQ phases. The study showed that fermentation parameters remained fairly stable over the commonly used sampling period (days 8 to 14), but shifts in microbial populations were detected. Moreover, microbial populations differed markedly from those in the inocula, which indicates the difficulty of directly transposing results on microbial populations developed in Rusitec Fermenters to in vivo conditions.

  • comparison of fermentation of diets of variable composition and microbial populations in the rumen of sheep and rusitec Fermenters ii protozoa population and diversity of bacterial communities
    Journal of Dairy Science, 2010
    Co-Authors: M D Carro, M E Martinez, Maria Jose Ranilla, Maria L Tejido, C Saro
    Abstract:

    Four ruminally and duodenally cannulated sheep and 8 Rusitec Fermenters were used to determine the effects of dietary characteristics on microbial populations and bacterial diversity. The purpose of the study was to assess how closely Fermenters can mimic the differences between diets found in vivo. The 4 experimental diets contained forage to concentrate (F:C) ratios of 70:30 (high forage; HF) or 30:70 (high concentrate; HC) with either alfalfa hay (A) or grass hay (G) as the forage. Total bacterial numbers were greater in the rumen of sheep fed HF diets compared with those fed HC diets, whereas the opposite was found in Fermenters. The numbers of cellulolytic bacteria were not affected by F:C ratio in any fermentation system, but cellulolytic numbers were 2.7 and 1.8 times greater in sheep than in Fermenters for HF and HC diets, respectively. Neither total bacterial nor cellulolytic numbers were affected by the type of forage in sheep or Fermenters. Decreasing F:C ratio increased total protozoa and Entodiniae numbers in sheep by about 29 and 25%, respectively, but it had no effect in Fermenters. Isotrichidae and Ophryoscolecinae numbers in sheep were not affected by changing F:C ratio, but both disappeared completely from Fermenters fed HC diets. Total protozoa and Entodiniae numbers were greater in sheep fed A diets than in those fed G diets, whereas the opposite was found in Fermenters. Results indicate that under the conditions of the present study, protozoa population in Rusitec Fermenters was not representative of that in the rumen of sheep fed the same diets. In addition, protozoa numbers in Fermenters were 121 and 226 times lower than those in the sheep rumen for HF and HC diets, respectively. The automated ribosomal intergenic spacer analysis of the 16S ribosomal DNA was used to analyze the diversity of liquid- and solid-associated bacteria in both systems. A total of 170 peaks were detected in the automated ribosomal intergenic spacer analysis electropherograms of bacterial pellets across the full set of 64 samples, from which 160 were detected in at least 1 individual from each system (sheep or fermenter). Diversity of liquid-associated bacterial pellets was greater with G diets in Fermenters but seemed to be unaffected by diet in sheep. Bacterial diversity in solid-associated bacteria pellets was greater for G diets compared with A diets in sheep and Fermenters. Different conditions in the Fermenters compared with sheep rumen might have caused a selection of some bacterial strains.

  • comparison of fermentation of diets of variable composition and microbial populations in the rumen of sheep and rusitec Fermenters i digestibility fermentation parameters and microbial growth
    Journal of Dairy Science, 2010
    Co-Authors: M E Martinez, M D Carro, Maria Jose Ranilla, Maria L Tejido, S Ramos
    Abstract:

    Abstract Four ruminally and duodenally cannulated sheep and 8 Rusitec Fermenters were used to determine the effects of forage to concentrate (F:C) ratio and type of forage in the diet on ruminal fermentation and microbial protein synthesis. The purpose of the study was to assess how closely Fermenters can mimic the dietary differences found in vivo. The 4 experimental diets contained F:C ratios of 70:30 or 30:70 with either alfalfa hay or grass hay as the forage. Microbial growth was determined in both systems using 15 N as a microbial marker. Rusitec Fermenters detected differences between diets similar to those observed in sheep by changing F:C ratio on pH; neutral detergent fiber digestibility; total volatile fatty acid concentrations; molar proportions of acetate, propionate, butyrate, isovalerate, and caproate; and amylase activity. In contrast, Rusitec Fermenters did not reproduce the dietary differences found in sheep for NH 3 -N and lactate concentrations, dry matter (DM) digestibility, proportions of isobutyrate and valerate, carboxymethylcellulase and xylanase activities, and microbial growth and its efficiency. Regarding the effect of the type of forage in the diet, Rusitec Fermenters detected differences between diets similar to those found in sheep for most determined parameters, with the exception of pH, DM digestibility, butyrate proportion, and carboxymethylcellulase activity. Minimum pH and maximal volatile fatty acid concentrations were reached at 2h and at 6 to 8h postfeeding in sheep and Fermenters, respectively, indicating that feed fermentation was slower in Fermenters compared with that in sheep. There were differences between systems in the magnitude of most determined parameters. In general, Fermenters showed lower lactate concentrations, neutral detergent fiber digestibility, acetate:propionate ratios, and enzymatic activities. On the contrary, Fermenters showed greater NH 3 -N concentrations, DM digestibility, and proportions of propionate, butyrate, isovalerate, valerate, and caproate. Values of efficiency of microbial growth were greater in Fermenters compared with sheep for 70:30 diets, but they were lower for 30:70 diets. Differences between fermentation in sheep and Fermenters can be mainly attributed to the lack of absorption in Fermenters, differences in solid retention time, and compartmentalization in the Rusitec system. In general, the Rusitec system simulated more closely the in vivo fermentation of high-forage diets compared with high-concentrate diets.

  • effects of dilution rate and retention time of concentrate on efficiency of microbial growth methane production and ruminal fermentation in rusitec Fermenters
    Journal of Dairy Science, 2009
    Co-Authors: M E Martinez, Maria Jose Ranilla, Maria L Tejido, S Ramos, M D Carro
    Abstract:

    The objective of this study was to investigate the effects of 2 dilution rates (DL) and 2 concentrate retention times (RT) on microbial growth, methane production, and fermentation of a 30:70 alfalfa hay:concentrate diet in Rusitec Fermenters maintained at similar pH. The DL were 3.78 (low DL, LDL) and 5.42%/h (high DL, HDL), and concentrate RT was either 24 h (T24) or 48 h (T48). Forage RT was 48 h in all Fermenters. Apparent disappearance of diet DM and NDF was greater in HDL Fermenters compared with LDL Fermenters, but there was a significant DL x concentrate RT interaction, showing that the effect of DL was more pronounced in T48 compared with T24 Fermenters. Methane production was not affected by DL, but was greater in T48 compared with T24 Fermenters, which was consistent with the increased fiber degradation in T48 Fermenters. Increasing DL augmented volatile fatty acid production and molar proportions of propionate, isovalerate, and valerate, and reduced those of caproate, but no effects were observed on acetate, butyrate, and isobutyrate proportions. Increasing concentrate RT resulted in greater volatile fatty acid production and proportions of acetate, butyrate, and caproate, but reduced those of propionate, valerate, and isovalerate. Ammonia-N production was not affected by concentrate RT, but was greater at HDL compared with LDL. Microbial growth was not affected by DL, but microbial growth efficiency was lower in HDL compared with LDL Fermenters. Concentrate RT affected microbial growth and its efficiency, with both being greater in T48 compared with T24 Fermenters. Carboxymetylcellulase and xylanase activities in ruminal fluid were greater in HDL compared with LDL Fermenters, but were not affected by concentrate RT. There were DL x concentrate RT interactions for diet apparent disappearance, molar proportions of propionate, butyrate, isovalerate, and caproate, and acetate:propionate ratio, indicating that effects of DL on these variables were influenced by concentrate RT. The results would indicate that using higher DL and shorter concentrate RT than those typically used in Rusitec Fermenters would contribute to improving the simulation of in vivo fermentation of high-concentrate diets.

Maria L Tejido - One of the best experts on this subject based on the ideXlab platform.

  • influence of increasing doses of a yeast hydrolyzate obtained from sugarcane processing on in vitro rumen fermentation of two different diets and bacterial diversity in batch cultures and rusitec Fermenters
    Animal Feed Science and Technology, 2017
    Co-Authors: A Diaz, Maria Jose Ranilla, Maria L Tejido, C Saro, M Perezquintana, M D Carro
    Abstract:

    Abstract Live yeast cultures and yeast hydrolyzates can be used as rumen fermentation modifiers, but their effects and mode of action are different. Whereas the effects of live yeast cultures on rumen fermentation are well documented, yeast hydrolyzates have received much less attention. The influence of a yeast hydrolyzate from Saccharomyces cerevisiae , obtained after ethanol production from sugarcane (YHS), on in vitro rumen fermentation was investigated using both batch cultures and Rusitec Fermenters inoculated with ruminal fluid from sheep. Batch cultures (300 mg dry matter (DM)) with two mixed diets (AHC, 0.5:0.5 alfalfa hay:concentrate; BSC, 0.15:0.85 barley straw:concentrate) as substrate were supplemented with increasing doses of YHS (0, 3.3, 6.7, 10.0 and 13.3 ml/l) and incubated for 16.5 h at 39 °C. Supplementation of increasing amounts of YHS to AHC-cultures increased ( P   0.05) linearly total volatile fatty acid (VFA) production and butyrate molar proportion, and decreased ( P   0.001) acetate proportion and acetate:propionate ratio. In contrast, only subtle effects of YHS on NH 3 -N concentrations and molar proportions of isovalerate and caproate were observed for the BSC diet. Longer-term effects of YHS supplementation on rumen fermentation of AHC diet were investigated using four Rusitec Fermenters in a cross-over experimental design with two 14-day incubation periods. Fermenters were given daily 30 g of diet DM, and in each period half of them were supplemented daily with 5 ml of YHS (10.0 ml/l) Supplementing with YHS did not affect ( P >  0.05) total VFA production, lactate concentrations, DM and aNDFom disappearance or enzymatic activities (amylase, xylanase and carboxymethylcellulase). Compared with the unsupplemented Fermenters, YHS treatment increased ( P   0.001) NH 3 -N concentrations and molar proportions of propionate and butyrate at the expense of acetate, and decreased ( P   0.001) acetate:propionate ratio. In addition, YHS supplementation tended ( P   0.07) to reduce CH 4 /total VFA ratio and to increase microbial growth in the liquid phase of the Fermenters. The automated ribosomal intergenic spacer analysis (ARISA) of samples taken on days 3, 8 and 14 of incubation from solid and liquid content of Fermenters revealed that YHS supplementation increased ( P   0.02) bacterial diversity in the liquid phase and tended to increase ( P   0.08) it in the solid phase. The results indicate that YHS at a dose of 10 ml/l may be a useful dietary additive for ruminants, because it promoted a shift in fermentation toward propionate production, reduced the CH 4 /total VFA ratio and increased microbial growth with a 50:50 alfalfa hay:concentrate diet.

  • comparison of fermentation of diets of variable composition and microbial populations in the rumen of sheep and rusitec Fermenters ii protozoa population and diversity of bacterial communities
    Journal of Dairy Science, 2010
    Co-Authors: M D Carro, M E Martinez, Maria Jose Ranilla, Maria L Tejido, C Saro
    Abstract:

    Four ruminally and duodenally cannulated sheep and 8 Rusitec Fermenters were used to determine the effects of dietary characteristics on microbial populations and bacterial diversity. The purpose of the study was to assess how closely Fermenters can mimic the differences between diets found in vivo. The 4 experimental diets contained forage to concentrate (F:C) ratios of 70:30 (high forage; HF) or 30:70 (high concentrate; HC) with either alfalfa hay (A) or grass hay (G) as the forage. Total bacterial numbers were greater in the rumen of sheep fed HF diets compared with those fed HC diets, whereas the opposite was found in Fermenters. The numbers of cellulolytic bacteria were not affected by F:C ratio in any fermentation system, but cellulolytic numbers were 2.7 and 1.8 times greater in sheep than in Fermenters for HF and HC diets, respectively. Neither total bacterial nor cellulolytic numbers were affected by the type of forage in sheep or Fermenters. Decreasing F:C ratio increased total protozoa and Entodiniae numbers in sheep by about 29 and 25%, respectively, but it had no effect in Fermenters. Isotrichidae and Ophryoscolecinae numbers in sheep were not affected by changing F:C ratio, but both disappeared completely from Fermenters fed HC diets. Total protozoa and Entodiniae numbers were greater in sheep fed A diets than in those fed G diets, whereas the opposite was found in Fermenters. Results indicate that under the conditions of the present study, protozoa population in Rusitec Fermenters was not representative of that in the rumen of sheep fed the same diets. In addition, protozoa numbers in Fermenters were 121 and 226 times lower than those in the sheep rumen for HF and HC diets, respectively. The automated ribosomal intergenic spacer analysis of the 16S ribosomal DNA was used to analyze the diversity of liquid- and solid-associated bacteria in both systems. A total of 170 peaks were detected in the automated ribosomal intergenic spacer analysis electropherograms of bacterial pellets across the full set of 64 samples, from which 160 were detected in at least 1 individual from each system (sheep or fermenter). Diversity of liquid-associated bacterial pellets was greater with G diets in Fermenters but seemed to be unaffected by diet in sheep. Bacterial diversity in solid-associated bacteria pellets was greater for G diets compared with A diets in sheep and Fermenters. Different conditions in the Fermenters compared with sheep rumen might have caused a selection of some bacterial strains.

  • comparison of fermentation of diets of variable composition and microbial populations in the rumen of sheep and rusitec Fermenters i digestibility fermentation parameters and microbial growth
    Journal of Dairy Science, 2010
    Co-Authors: M E Martinez, M D Carro, Maria Jose Ranilla, Maria L Tejido, S Ramos
    Abstract:

    Abstract Four ruminally and duodenally cannulated sheep and 8 Rusitec Fermenters were used to determine the effects of forage to concentrate (F:C) ratio and type of forage in the diet on ruminal fermentation and microbial protein synthesis. The purpose of the study was to assess how closely Fermenters can mimic the dietary differences found in vivo. The 4 experimental diets contained F:C ratios of 70:30 or 30:70 with either alfalfa hay or grass hay as the forage. Microbial growth was determined in both systems using 15 N as a microbial marker. Rusitec Fermenters detected differences between diets similar to those observed in sheep by changing F:C ratio on pH; neutral detergent fiber digestibility; total volatile fatty acid concentrations; molar proportions of acetate, propionate, butyrate, isovalerate, and caproate; and amylase activity. In contrast, Rusitec Fermenters did not reproduce the dietary differences found in sheep for NH 3 -N and lactate concentrations, dry matter (DM) digestibility, proportions of isobutyrate and valerate, carboxymethylcellulase and xylanase activities, and microbial growth and its efficiency. Regarding the effect of the type of forage in the diet, Rusitec Fermenters detected differences between diets similar to those found in sheep for most determined parameters, with the exception of pH, DM digestibility, butyrate proportion, and carboxymethylcellulase activity. Minimum pH and maximal volatile fatty acid concentrations were reached at 2h and at 6 to 8h postfeeding in sheep and Fermenters, respectively, indicating that feed fermentation was slower in Fermenters compared with that in sheep. There were differences between systems in the magnitude of most determined parameters. In general, Fermenters showed lower lactate concentrations, neutral detergent fiber digestibility, acetate:propionate ratios, and enzymatic activities. On the contrary, Fermenters showed greater NH 3 -N concentrations, DM digestibility, and proportions of propionate, butyrate, isovalerate, valerate, and caproate. Values of efficiency of microbial growth were greater in Fermenters compared with sheep for 70:30 diets, but they were lower for 30:70 diets. Differences between fermentation in sheep and Fermenters can be mainly attributed to the lack of absorption in Fermenters, differences in solid retention time, and compartmentalization in the Rusitec system. In general, the Rusitec system simulated more closely the in vivo fermentation of high-forage diets compared with high-concentrate diets.

  • effects of dilution rate and retention time of concentrate on efficiency of microbial growth methane production and ruminal fermentation in rusitec Fermenters
    Journal of Dairy Science, 2009
    Co-Authors: M E Martinez, Maria Jose Ranilla, Maria L Tejido, S Ramos, M D Carro
    Abstract:

    The objective of this study was to investigate the effects of 2 dilution rates (DL) and 2 concentrate retention times (RT) on microbial growth, methane production, and fermentation of a 30:70 alfalfa hay:concentrate diet in Rusitec Fermenters maintained at similar pH. The DL were 3.78 (low DL, LDL) and 5.42%/h (high DL, HDL), and concentrate RT was either 24 h (T24) or 48 h (T48). Forage RT was 48 h in all Fermenters. Apparent disappearance of diet DM and NDF was greater in HDL Fermenters compared with LDL Fermenters, but there was a significant DL x concentrate RT interaction, showing that the effect of DL was more pronounced in T48 compared with T24 Fermenters. Methane production was not affected by DL, but was greater in T48 compared with T24 Fermenters, which was consistent with the increased fiber degradation in T48 Fermenters. Increasing DL augmented volatile fatty acid production and molar proportions of propionate, isovalerate, and valerate, and reduced those of caproate, but no effects were observed on acetate, butyrate, and isobutyrate proportions. Increasing concentrate RT resulted in greater volatile fatty acid production and proportions of acetate, butyrate, and caproate, but reduced those of propionate, valerate, and isovalerate. Ammonia-N production was not affected by concentrate RT, but was greater at HDL compared with LDL. Microbial growth was not affected by DL, but microbial growth efficiency was lower in HDL compared with LDL Fermenters. Concentrate RT affected microbial growth and its efficiency, with both being greater in T48 compared with T24 Fermenters. Carboxymetylcellulase and xylanase activities in ruminal fluid were greater in HDL compared with LDL Fermenters, but were not affected by concentrate RT. There were DL x concentrate RT interactions for diet apparent disappearance, molar proportions of propionate, butyrate, isovalerate, and caproate, and acetate:propionate ratio, indicating that effects of DL on these variables were influenced by concentrate RT. The results would indicate that using higher DL and shorter concentrate RT than those typically used in Rusitec Fermenters would contribute to improving the simulation of in vivo fermentation of high-concentrate diets.

  • influence of exogenous fibrolytic enzymes and fumarate on methane production microbial growth and fermentation in rusitec Fermenters
    British Journal of Nutrition, 2007
    Co-Authors: L A Giraldo, Maria L Tejido, M J Ranilla, M D Carro
    Abstract:

    Two incubation runs were conducted with Rusitec Fermenters to investigate the effects of three additive treatments (mixed fibrolytic enzymes from Trichoderma longibrachiatum (FE), disodium fumarate (FUM) and both additives (MIX)) on rumen microbial growth and fermentation of a grass hay:concentrate (600:400g/kgDM) substrate. Each fermenter received daily 20g substrate DM. Application rate (per g substrate DM) was 34·3 endoglucanase, 0·57 exoglucanase, 24·7 xylanase and 5·51 amylase units for FE and 30mg fumarate for FUM. MIX Fermenters received both additives. Both FE and MIX increased (P,0·05) daily production of acetate, butyrate and methane, substrate DM and fibre disappearance at 6 and 48h incubation, daily flow of microbial-N, and the microbial colonisation of substrate at 6h incubation. Compared to FE, MIX treatment increased (P,0·05) propionate production by 28% and decreased (P,0·05) the acetate:propionate ratio, but no other differences between both treatments were found (P.0·05). Supplementing with FUM increased (P,0·05) volatile fatty acid production by 11% and decreased (P,0·05) the acetate:propionate ratio, but did not affect (P.0·05) any other variable, thus suggesting that observed effects were due to fermentation of FUM itself. The lack of effects of FUM and the absence of differences between FE and MIX on most of the measured variables would indicate that beneficial effects found in MIX Fermenters were mainly due to the action of FE. Combining FE and FUM as feed additives under the conditions of the present experiment did not further improve rumen fermentation, compared to FE alone. Fibrolytic enzymes: Fumarate: Rumen microbial growth: Rusitec

M E Martinez - One of the best experts on this subject based on the ideXlab platform.

  • comparison of fermentation of diets of variable composition and microbial populations in the rumen of sheep and rusitec Fermenters ii protozoa population and diversity of bacterial communities
    Journal of Dairy Science, 2010
    Co-Authors: M D Carro, M E Martinez, Maria Jose Ranilla, Maria L Tejido, C Saro
    Abstract:

    Four ruminally and duodenally cannulated sheep and 8 Rusitec Fermenters were used to determine the effects of dietary characteristics on microbial populations and bacterial diversity. The purpose of the study was to assess how closely Fermenters can mimic the differences between diets found in vivo. The 4 experimental diets contained forage to concentrate (F:C) ratios of 70:30 (high forage; HF) or 30:70 (high concentrate; HC) with either alfalfa hay (A) or grass hay (G) as the forage. Total bacterial numbers were greater in the rumen of sheep fed HF diets compared with those fed HC diets, whereas the opposite was found in Fermenters. The numbers of cellulolytic bacteria were not affected by F:C ratio in any fermentation system, but cellulolytic numbers were 2.7 and 1.8 times greater in sheep than in Fermenters for HF and HC diets, respectively. Neither total bacterial nor cellulolytic numbers were affected by the type of forage in sheep or Fermenters. Decreasing F:C ratio increased total protozoa and Entodiniae numbers in sheep by about 29 and 25%, respectively, but it had no effect in Fermenters. Isotrichidae and Ophryoscolecinae numbers in sheep were not affected by changing F:C ratio, but both disappeared completely from Fermenters fed HC diets. Total protozoa and Entodiniae numbers were greater in sheep fed A diets than in those fed G diets, whereas the opposite was found in Fermenters. Results indicate that under the conditions of the present study, protozoa population in Rusitec Fermenters was not representative of that in the rumen of sheep fed the same diets. In addition, protozoa numbers in Fermenters were 121 and 226 times lower than those in the sheep rumen for HF and HC diets, respectively. The automated ribosomal intergenic spacer analysis of the 16S ribosomal DNA was used to analyze the diversity of liquid- and solid-associated bacteria in both systems. A total of 170 peaks were detected in the automated ribosomal intergenic spacer analysis electropherograms of bacterial pellets across the full set of 64 samples, from which 160 were detected in at least 1 individual from each system (sheep or fermenter). Diversity of liquid-associated bacterial pellets was greater with G diets in Fermenters but seemed to be unaffected by diet in sheep. Bacterial diversity in solid-associated bacteria pellets was greater for G diets compared with A diets in sheep and Fermenters. Different conditions in the Fermenters compared with sheep rumen might have caused a selection of some bacterial strains.

  • comparison of fermentation of diets of variable composition and microbial populations in the rumen of sheep and rusitec Fermenters i digestibility fermentation parameters and microbial growth
    Journal of Dairy Science, 2010
    Co-Authors: M E Martinez, M D Carro, Maria Jose Ranilla, Maria L Tejido, S Ramos
    Abstract:

    Abstract Four ruminally and duodenally cannulated sheep and 8 Rusitec Fermenters were used to determine the effects of forage to concentrate (F:C) ratio and type of forage in the diet on ruminal fermentation and microbial protein synthesis. The purpose of the study was to assess how closely Fermenters can mimic the dietary differences found in vivo. The 4 experimental diets contained F:C ratios of 70:30 or 30:70 with either alfalfa hay or grass hay as the forage. Microbial growth was determined in both systems using 15 N as a microbial marker. Rusitec Fermenters detected differences between diets similar to those observed in sheep by changing F:C ratio on pH; neutral detergent fiber digestibility; total volatile fatty acid concentrations; molar proportions of acetate, propionate, butyrate, isovalerate, and caproate; and amylase activity. In contrast, Rusitec Fermenters did not reproduce the dietary differences found in sheep for NH 3 -N and lactate concentrations, dry matter (DM) digestibility, proportions of isobutyrate and valerate, carboxymethylcellulase and xylanase activities, and microbial growth and its efficiency. Regarding the effect of the type of forage in the diet, Rusitec Fermenters detected differences between diets similar to those found in sheep for most determined parameters, with the exception of pH, DM digestibility, butyrate proportion, and carboxymethylcellulase activity. Minimum pH and maximal volatile fatty acid concentrations were reached at 2h and at 6 to 8h postfeeding in sheep and Fermenters, respectively, indicating that feed fermentation was slower in Fermenters compared with that in sheep. There were differences between systems in the magnitude of most determined parameters. In general, Fermenters showed lower lactate concentrations, neutral detergent fiber digestibility, acetate:propionate ratios, and enzymatic activities. On the contrary, Fermenters showed greater NH 3 -N concentrations, DM digestibility, and proportions of propionate, butyrate, isovalerate, valerate, and caproate. Values of efficiency of microbial growth were greater in Fermenters compared with sheep for 70:30 diets, but they were lower for 30:70 diets. Differences between fermentation in sheep and Fermenters can be mainly attributed to the lack of absorption in Fermenters, differences in solid retention time, and compartmentalization in the Rusitec system. In general, the Rusitec system simulated more closely the in vivo fermentation of high-forage diets compared with high-concentrate diets.

  • effects of dilution rate and retention time of concentrate on efficiency of microbial growth methane production and ruminal fermentation in rusitec Fermenters
    Journal of Dairy Science, 2009
    Co-Authors: M E Martinez, Maria Jose Ranilla, Maria L Tejido, S Ramos, M D Carro
    Abstract:

    The objective of this study was to investigate the effects of 2 dilution rates (DL) and 2 concentrate retention times (RT) on microbial growth, methane production, and fermentation of a 30:70 alfalfa hay:concentrate diet in Rusitec Fermenters maintained at similar pH. The DL were 3.78 (low DL, LDL) and 5.42%/h (high DL, HDL), and concentrate RT was either 24 h (T24) or 48 h (T48). Forage RT was 48 h in all Fermenters. Apparent disappearance of diet DM and NDF was greater in HDL Fermenters compared with LDL Fermenters, but there was a significant DL x concentrate RT interaction, showing that the effect of DL was more pronounced in T48 compared with T24 Fermenters. Methane production was not affected by DL, but was greater in T48 compared with T24 Fermenters, which was consistent with the increased fiber degradation in T48 Fermenters. Increasing DL augmented volatile fatty acid production and molar proportions of propionate, isovalerate, and valerate, and reduced those of caproate, but no effects were observed on acetate, butyrate, and isobutyrate proportions. Increasing concentrate RT resulted in greater volatile fatty acid production and proportions of acetate, butyrate, and caproate, but reduced those of propionate, valerate, and isovalerate. Ammonia-N production was not affected by concentrate RT, but was greater at HDL compared with LDL. Microbial growth was not affected by DL, but microbial growth efficiency was lower in HDL compared with LDL Fermenters. Concentrate RT affected microbial growth and its efficiency, with both being greater in T48 compared with T24 Fermenters. Carboxymetylcellulase and xylanase activities in ruminal fluid were greater in HDL compared with LDL Fermenters, but were not affected by concentrate RT. There were DL x concentrate RT interactions for diet apparent disappearance, molar proportions of propionate, butyrate, isovalerate, and caproate, and acetate:propionate ratio, indicating that effects of DL on these variables were influenced by concentrate RT. The results would indicate that using higher DL and shorter concentrate RT than those typically used in Rusitec Fermenters would contribute to improving the simulation of in vivo fermentation of high-concentrate diets.