Effect of coconut oil and defaunation treatment on methanogenesis in sheep

The present study was conducted to evaluate in vivo the role of rumen ciliate protozoa with respect to the methane-suppressing effect of coconut oil. Three sheep were subjected to a 2 x 2 factorial design comprising two types of dietary lipids (50 g x kg(-1) coconut oil vs. 50 g x kg(-1) rumen-protected fat) and defaunation treatment (with vs. without). Due to the defaunation treatment, which reduced the rumen ciliate protozoa population by 94% on average, total tract fibre degradation was reduced but not the methane production. Feeding coconut oil significantly reduced daily methane release without negatively affecting the total tract nutrient digestion. Compared with the rumen-protected fat diet, coconut oil did not alter the energy retention of the animals. There was no interaction between coconut oil feeding and defaunation treatment in methane production. An interaction occurred in the concentration of methanogens in the rumen fluid, with the significantly highest values occurring when the animals received the coconut oil diet and were subjected to the defaunation treatment. Possible explanations for the apparent inconsistency between the amount of methane produced and the concentration of methane-producing microbes are discussed. Generally, the present data illustrate that a depression of the concentration of ciliate protozoa or methanogens in rumen fluid cannot be used as a reliable indicator for the success of a strategy to mitigate methane emission in vivo. The methane-suppressing effect of coconut oil seems to be mediated through a changed metabolic activity and/or composition of the rumen methanogenic population.     

Influence of ciliate protozoa on biochemical changes and hydrolytic enzyme profile in the rumen ecosystem

AIMS: To assess the effect of presence or absence of rumen protozoa on fermentation characteristics and enzyme profile in growing lambs. METHODS AND RESULTS: Weaner lambs (G1, G2, G3, G4, G5 and G6 groups) were defaunated by oral administration of sodium laurel sulphate (at 8 g 100 kg(-1) body weight). The lambs of G4, G5 and G6 groups were refaunated. The roughage and concentrate ratio in the diet of G1 and G4, G2 and G5, and G3 and G6 were 50:50 (R1), 65:35 (R2) and 80:20 (R3), respectively. Daily dry matter intake was similar in defaunated and faunated lambs. However, digestibility of organic matter (OM), cellulose and gross energy were lower in defaunated lambs while crude protein (CP) digestibility was similar in both defaunated and faunated lambs. The rumen pH and NH3-N were lower (P < 0.01) while TVFA, total-N and TCA-ppt-N were higher (P < 0.01), in defaunated lambs. Ruminal activity of carboxymethyl cellulase was lower (P < 0.01) in defaunated lambs and amylase, xylanase, protease and urease were similar in faunated and defaunated lambs. Nutrient utilization, rumen metabolites and ciliate protozoal count were higher, whereas digestibility of fibre fractions was lower in high rather than low concentrate fed lambs. The rumen protozoa present before defaunation were B-type and the protozoa which re-established on refaunation were also B-type. CONCLUSIONS: Absence of ciliate protozoa decreased nutrient digestibility and increased ruminal TVFA and total-N with lower NH3-N concentration, indicating better energy and protein utilization in defaunated lambs. SIGNIFICANCE AND IMPACT OF THE STUDY: Defaunation improved energy and protein utilization in lambs.     

Relationship Between Rumen Ammonia Levels and the Microbial Population and Volatile Fatty Acid Proportions in Faunated and Defaunated Sheep

Cheviot wethers were defaunated by using dioctyl sodium sulfosuccinate and were constantly infused with urea to provide 2.87% of the daily N intake. Defaunation resulted in higher rumen dry matter and lower rumen pH. The molar per cent propionate was higher in defaunated sheep, whereas the molar per cent butyrate and acetate was lower. Apparent nitrogen digestibility, nitrogen utilization, and nitrogen balance were higher in defaunated sheep when compared with faunated animals. Urea infusion resulted in lower apparent nitrogen digestibility, nitrogen utilization, and nitrogen balance in faunated sheep, but did not affect nitrogen metabolism in defaunated sheep. Rumen ammonia-N levels in defaunated sheep were lower than those observed for faunated animals, and urea infusion into faunated sheep increased rumen ammonia-N levels to a greater extent than did the urea infusion into defaunated animals. Significant correlations were demonstrated between rumen ammonia-N levels and C(2)/C(3), C(3)/C(4) and C(2)/C(4) volatile acid ratios. From this it was concluded that, as rumen ammonia-N levels increased, there was a shift from propionate to higher proportions of butyrate and acetate.     

Contribution of rumen protozoa to fibre degradation and cellulase activity in vitro

Abstract The contribution of ciliates to rumen fermentation was estimated by determination of overall fibre degradation and cellulase activities (determined as carboxymethylcellulase activity) in faunated and defaunated 'artificial rumen' cultures. Experiments performed at loading rates of 22.5 and 35 g per liter per day of a grass-grain substrate revealed that fibre degradation was significantly lower in the absence of ciliates only at the high loading rate. This effect of defaunation was smaller at dilution rates below 1.7 fermenter volume turnovers per day. Bacterial numbers were higher in all experiments after removal of ciliates. Fractionation studies demonstrated that ciliates accounted for 19–28% of the total cellulase activity in faunated cultures fed on filter paper cellulose.     

Methane production and substrate degradation by rumen microbial communities containing single protozoal species in vitro

AIMS: To assess the effect of protozoal species on rumen fermentation characteristics in vitro. METHODS AND RESULTS: Entodinium caudatum, Isotricha intestinalis, Metadinium medium, and Eudiplodinium maggii from monofaunated wethers and mixed protozoa from conventional wethers were obtained by centrifugation, re-suspended at their normal densities in rumen fluid supernatants from defaunated or conventional wethers and incubated in vitro. The presence of protozoa increased the concentration of ammonia and altered the volatile fatty acids balance with more acetate and butyrate produced at the expense of propionate. Differences among species were observed, notably in the production of methane, which increased with E. caudatum as compared to other ciliates and to defaunated and mixed protozoa treatments (P < 0.05). The increased methanogenesis was not correlated to protozoal biomass indicating that the metabolism of this protozoan and/or its influence on the microbial ecosystem was responsible for this effect. CONCLUSIONS: Entodinium caudatum stimulated the production of methane, a negative effect that was reinforced by a concomitant increase in protein degradation. SIGNIFICANCE AND IMPACT OF THE STUDY: Comparison of individual species of protozoa highlighted the particular influence of E. caudatum on rumen fermentation. Its elimination (targeted defaunation) from the rumen could reduce methane production without affecting feed degradation.     

Effects of defaunation on digestion of fresh Digitaria decumbens grass and growth of lambs

The effects of defaunation on growth and digestion were measured in sheep fed fresh Digitaria decumbens grass cut at four stages of regrowth 14, 28, 42, and 56 days, and with different protein to energy (P/E) ratios. Two completely randomized designs trials (growth and digestion) were conducted using faunated animals, defaunated rams and protozoa free lambs. The digestion trial: eight faunated and eight defaunated rams fitted with ruminal and duodenal cannulas were fed 4 diets (diets D1 to D4) to measure digestion parameters. The dietary P/E ratios were 120 (D1), 130 (D2), 130 (D3), and 140 (D4) g PDIN/UFL (Protein Digested in the small Intestine supplied by microbial protein from rumen-degraded protein/Feed Unit for Lactation) and the grass stages of regrowth were 56, 42, 28, and 14 days, respectively. Increasing the dietary P/E ratios increased dry matter intake (DMI) and the total tract digestibility of organic matter (OM), NDF and CP. Defaunation decreased DMI, except for rams fed D4 diet. Defaunation also decreased total tract digestibility of OM except for rams fed D1 diet and that of NDF except for rams fed D1 and D4 diets. Increasing the dietary P/E ratios also increased nitrogen intake and ammonia (NH3) concentration in the rumen, whereas defaunation decreased them. The dietary P/E ratio increased non-NH3 nitrogen and microbial nitrogen duodenal flows and microbial efficiency. Defaunation did not affect duodenal flows of neither non-NH3 nitrogen and microbial nitrogen or microbial efficiency. The growth trial: 20 faunated and 20 protozoa free lambs were fed four diets (diets D5 to D8) to measure their average daily gain (ADG). The dietary P/E ratios were 60 (D5), 70 (D6), 80 (D7) and 100 (D8) g PDIN/UFL and the stages of regrowth were 56, 42, 28, and 14 days, respectively. DMI of lambs increased with P/E ratio. Protozoa free lambs had greater DMI than faunated ones when fed D7 diet (80.8 v. 74.9 g/kg LW0.75, respectively). The ADG of the lambs increased with P/E ratio. Fed on the same D5 diet, protozoa free lambs had greater ADG than faunated lambs (29.8 v. 11.6 g/day, respectively). In conclusion, animal response to defaunation was modulated by the P/E ratio of the D. decumbens grass diets. Defaunation increased ADG of lambs fed forage with the lowest P/E ratio, while digestion and nitrogen duodenal flows of rams fed the lowest P/E ratio were not affected.     

Rumen enzyme profile and fermentation characteristics in sheep as affected by treatment with sodium lauryl sulfate as defaunating agent and presence of ciliate protozoa

The efficiency of sodium lauryl sulfate as a defaunating agent and effect of rumen protozoa on nutrient utilization, fermentation characteristics and enzyme profile were evaluated in adult sheep maintained on a mixed ration containing 65:35% Pala (Ziziphus numularia) leaf: concentrate. Twenty-one adult Malpura sheep divided into three equal groups (DF, RF and F) were either defaunated by oral administration of sodium lauryl sulfate at the rate of 8 g/100 kg body weight (DF), or defaunated and again refaunated (RF), or maintained faunated (F). Daily dry matter intake was similar in defaunated, refaunated and faunated sheep. However, digestibility of cell wall and cell wall contents (NDF, ADF and cellulose) were lower (P < 0.01) in defaunated than refaunated and faunated sheep. Irrespective of the presence or absence of rumen protozoa, daily intake of DCP and DE were similar in the three experimental groups. Even with similar DM, DCP and DE intake, N-retention, blood glucose level, ruminal concentration of total VFA and total-N were higher (P < 0.01), while rumen pH and NH₃-N concentration were lower (P < 0.01) in defaunated sheep. Ruminal activity of amylase, xylanase, protease and urease enzymes were not influenced by presence or absence of ciliate protozoa. However, carboxymethyl cellulase enzyme activity was lower (P < 0.01) in the rumen of defaunated sheep. The total and differential counts of rumen protozoa were similar in refaunated and faunated sheep indicating lack of residual toxic effect of sodium lauryl sulfate. It is concluded that absence of ciliate protozoa increased ruminal TVFA, total-N with lower NH₃-N concentration and fibre digestibility in sheep. Moreover, sodium lauryl sulfate was fully effective for complete removal of rumen ciliate protozoa and successfully defaunated the sheep.     

Protein-bound amino acid content of normally and abnormally faunated Formosan termites, Coptotermes formosanus

InCoptotermes formosanus workers containing all (normally faunated), none (completely defaunated), or all but one species (partially defaunated) of their symbiotic protozoa, protein-bound amino acid contents changed little in 1, 3, 5, or 8 weeks after defaunation. There were few differences in the amino acid contents of the three termite groups at any one time. Thus, the termites may be able to maintain their protein levels without protozoa, dead protozoa probably do not furnish needed nitrogen, and symbiotic protozoa gave no evidence of the ability to fix atmospheric nitrogen.     

Contribution of protozoa to lysine synthesis in the in vitro rumen microbial ecosystem

Isotopic tracer experiments were conducted in vitro to determine contribution of protozoa toward the biosynthesis of lysine in the rumen microbial ecosystem. The presence of protozoa in a rumen microbial suspension always increased lysine synthesis from aspartate. Rumen contents from a faunated goat produced a higher amount of lysine than did those from a defaunated one.     

Effect of the rumen ciliates Entodinium caudatum, Epidinium ecaudatum and Eudiplodinium maggii, and combinations thereof, on ruminal fermentation and total tract digestion in sheep

The quantitative importance of individual ciliate species and their interaction in the rumen is still unclear. The present study was performed to test whether there are species differences in the influence on ruminal fermentation in vivo and if combinations of ciliates act additive in that respect. Six adult wethers fed a hay-concentrate diet were defaunated, then refaunated either with Entodinium caudatum (EC), Epidinium ecaudatum (EE) or Eudiplodinium maggii (EM) alone, then progressively with all possible species combinations. Feed, faeces, urine, ruminal fluid and gas were sampled for eight days always after at least 21 days of adaptation. With a linear mixed model, accounting for the 2 x 2 x 2 full factorial study design, mean marginal effect sizes, i.e., the magnitude of change in variables as caused by the presence of each ciliate species or of combinations of them, were estimated. The apparent digestibility of organic matter and neutral detergent fibre remained unaffected. The apparent N digestibility increased by 0.054 with EM (0.716 with defaunation). Ruminal ammonia increased by 1.6, 4.0 and 8.7 mmol/l in the presence of EM, EC and EE, respectively, compared to defaunation (6.9 mmol/l). In the EM + EE combination, ruminal ammonia was lower than would have been expected from an additive effect. With EE, total short-chain fatty acids increased by 23 mmol/l (100 mmol/l with defaunation), but not when EE was combined with EM. The acetate-to-propionate ratio decreased by 0.73 units in the presence of EE (4.0 with defaunation), but only when EE was the sole ciliate species in the rumen. In the presence of any ciliate species, the 16S rDNA copies of total Bacteria and major fibrolytic species decreased to 0.52- and 0.22-fold values, respectively of that found without protozoa. Total Archaea were unaffected; however, Methanobacteriales copies increased 1.44-fold with EC. The CH4-to-CO2 ratio of ruminal gas decreased by 0.036 with EM and 0.051 with EE (0.454 with defaunation). In conclusion, individual ciliates affected ruminal fermentation differently and, when different species were combined, sometimes in a non-additive manner. From the ciliates investigated, EE affected ruminal fermentation most and might play a dominant role in mixed ciliate populations.     

Contribution of protozoa to lysine synthesis in the in vitro rumen microbial ecosystem.

Isotopic tracer experiments were conducted in vitro to determine contribution of protozoa toward the biosynthesis of lysine in the rumen microbial ecosystem. The presence of protozoa in a rumen microbial suspension always increased lysine synthesis from aspartate. Rumen contents from a faunated goat produced a higher amount of lysine than did those from a defaunated one.     

Effect of rumen ciliates on the digestive utilization of various carbohydrate-rich diets and on the end-products formed in the rumen. II. Utilization of inulin, saccharose and lactose

Three diets rich in inulin, saccharose and lactose, respectively, were given to 10 rumen-fistulated sheep. Two animals were defaunated, two were inoculated with either Polyplastron multivesibulatum or Entodinium sp., and two others were inoculated with both. The latter two were bred in conventional conditions. All animals ingested the same amounts of carbohydrates in the three diets (21-22 g/kg P0.75/day). Dietary nitrogen content was similar (table 1). The ciliate population was improved with the inulin diet (fig. 1; table 2). With a mixed population, the Entodinium improved with the inulin diet (fig 1; table 2). With a mixed population, the Entodinium sp. genus was always predominant. Holotrich protozoa (mainly Isotricha) in the rumen of the conventional sheep represented 15 to 30% of the total ciliate biomass, indicating that they were able to metabolize these soluble sugars. We also observed that P. multivesiculatum can ferment cellulose and all the soluble carbohydrates proposed in these diets. However, Entodinium sp. development occurred mainly in the presence of the sugard produced during carbohydrate hydrolysis by other ciliates or bacteria. The highest organic matter digestibility, noted in faunated animals (table 3) was confirmed by the VFA concentration in the rumen (table 4). This could be explained either by an activation of bacterial metabolism due to predation or by the direct effect of ciliates on fermentations, or both. Modifications in the VFA composition varied with ciliate inoculation, showing that ciliate metabolism may vary with the nature of the energy in the diet or that the observed results depended on various opposite effects in which the intensity of each component was influenced by the diet. In general, the acetic acid molar proportion increased and propionic acid decreased when there was a considerable Entodinium sp. population. The effect on butyric acid was low with these diets. Higher ammonia and lactic acid concentrations were observed in the rumen of faunated than defaunated sheep, irrespective of the ciliate inoculum.     

Effect of the rumen ciliates Entodinium caudatum,Epidinium ecaudatum and Eudiplodinium maggii,and combinations thereof,on ruminal fermentation and total tract digestion in sheep

The quantitative importance of individual ciliate species and their interaction in the rumen is still unclear. The present study was performed to test whether there are species differences in the influence on ruminal fermentation in vivo and if combinations of ciliates act additive in that respect. Six adult wethers fed a hay-concentrate diet were defaunated, then refaunated either with Entodinium caudatum (EC), Epidinium ecaudatum (EE) or Eudiplodinium maggii (EM) alone, then progressively with all possible species combinations. Feed, faeces, urine, ruminal fluid and gas were sampled for eight days always after at least 21 days of adaptation. With a linear mixed model, accounting for the 2 × 2 × 2 full factorial study design, mean marginal effect sizes, i.e., the magnitude of change in variables as caused by the presence of each ciliate species or of combinations of them, were estimated. The apparent digestibility of organic matter and neutral detergent fibre remained unaffected. The apparent N digestibility increased by 0.054 with EM (0.716 with defaunation). Ruminal ammonia increased by 1.6, 4.0 and 8.7 mmol/l in the presence of EM, EC and EE, respectively, compared to defaunation (6.9 mmol/l). In the EM + EE combination, ruminal ammonia was lower than would have been expected from an additive effect. With EE, total short-chain fatty acids increased by 23 mmol/l (100 mmol/l with defaunation), but not when EE was combined with EM. The acetate-to-propionate ratio decreased by 0.73 units in the presence of EE (4.0 with defaunation), but only when EE was the sole ciliate species in the rumen. In the presence of any ciliate species, the 16S rDNA copies of total Bacteria and major fibrolytic species decreased to 0.52- and 0.22-fold values, respectively of that found without protozoa. Total Archaea were unaffected; however, Methanobacteriales copies increased 1.44-fold with EC. The CH₄-to-CO₂ ratio of ruminal gas decreased by 0.036 with EM and 0.051 with EE (0.454 with defaunation). In conclusion, individual ciliates affected ruminal fermentation differently and, when different species were combined, sometimes in a non-additive manner. From the ciliates investigated, EE affected ruminal fermentation most and might play a dominant role in mixed ciliate populations.     

Seed survival and dispersal of an endemic Atlantic forest palm: the combined effects of defaunation and forest fragmentation

About 45 palm species occur in the Atlantic forest of Brazil, and most of them are affected by loss of seed dispersers resulting from forest fragmentation and hunting. Here we report the effects of habitat loss and defaunation on the seed dispersal system of an endemic palm, Astrocaryum aculeatissimum . We evaluated seed removal, insect and rodent seed predation, and scatter-hoarding in nine sites, ranging from 19 ha to 79 000 ha. We report the seedling, juvenile and adult palm densities in this range of sites. Endocarps remaining beneath the parent palm had a higher probability of being preyed upon by insects in small, mostly fragmented and more defaunated sites. The frequency of successful seed removal, scatter-hoarding and consumption by rodents increased in the larger, less defaunated sites. Successful removal and dispersal collapsed in small (< 1000 ha), highly defaunated sites and frequently resulted in low densities of both seedlings and juveniles. Our results indicate that a large fraction of Atlantic forest palms that rely on scatter-hoarding rodents may become regionally extinct due to forest fragmentation and defaunation. Current management practices including palm extraction and hunting pressure have a lasting effect on Atlantic forest palm regeneration by severely limiting successful recruitment of prereproductive individuals. © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 151 , 141–149.     

Effect of tea saponin on rumen fermentation in vitro

The present study was conducted to investigate the effect of tea saponins (TS) on ruminal fermentation in vitro using gas syringes as incubators. The TS were added at levels of 0, 2, 4, 6 and 8 mg against 200 mg mixture of corn meal and grass meal (1/1, w/w) in rumen fluid. In vitro gas production (GP) was recorded and methane concentration was determined at 3, 6, 9, 12 and 24 h incubation. After 24 h, the incubation was stopped and the inoculants were determined for pH, ammonia-N, volatile fatty acids (VFAs), protozoa counts and microbial protein yield. The GP was increased with the increasing level of TS except 8 mg at 24 h, which kept little change from that of the control. Methane concentration was decreased at all levels of TS at each incubation time. At 24 h incubation, inclusion with 2, 4, 6 and 8 mg of TS decreased methane concentration by 13, 22, 25 and 26%, respectively. The pH of ruminal fluid was slightly lower at 4 and 6 mg TS, but all values were in the normal range. Ammonia-N concentrations decreased significantly (P < 0.01) when the TS were included. Concentrations of individual and total VFAs were not significantly effected by TS addition. The TS significantly inhibited the protozoa growth in ruminal fluid (P < 0.01). At 24 h incubation, protozoa counts were reduced by 19, 25, 45 and 79%, respectively at levels of 2, 4, 6 and 8 mg of TS compared to that in control. The microbial protein was enhanced with the TS addition except 2 mg level, and reached 1.92, 2.36 and 2.61 mg/mL with addition of 4, 6 and 8 mg TS, compared to 1.50 mg/mL in control. It is suggested that TS could modify the rumen fermentation and inhibit the release of methane and ammonia, which may be beneficial for improving nutrient utilization and animal growth.     

The importance of methanogens associated with ciliate protozoa in ruminal methane production in vitro

The importance of methanogenic bacteria associated with ciliate protozoa was estimated either by removing protozoa from whole rumen fluid (using defaunated rumen fluid to correct for the effects of centrifugation on bacteria) or by isolating the protozoa. Rumen fluid was withdrawn from sheep inoculated with either Polyplastron multivesiculatum , a co-culture of Isotricha prostoma plus Entodinium spp. or a mixed type B fauna of Entodinium, Eudiplodinium and Epidinium spp. Methanogenesis was highest in rumen fluid containing a mixed protozoal population of the following genera: Entodinium, Eudiplodinium and Epidinium , was lower in defaunated rumen fluid and lowest in rumen fluid containing either I. prostoma plus Entodinium or P. multivesiculatum . Methanogenic bacteria associated with rumen ciliates were apparently responsible for between 9 and 25% of methanogenesis in rumen fluid.     

Effect of rumen ciliates on the digestion of different carbohydrates in sheep. I.--Utilization of cell wall carbohydrates (cellulose and hemicellulose) and of starch

Two diets rich in cell-wall carbohydrates or starch were given to 10 rumen-fistulated sheep; two sheep were defaunated and the others were inoculated with Polyplastron multivesiculatum (P) or Entodinium sp. (E), or both (P + E), or with conventional fauna. Ciliate biomass was greater when the animals were fed a high starch diet than when the diet was rich in cell-wall carbohydrates (table 2). With both diets, the Entodinium genus in the mixed fauna sampling predominated. We showed that Polyplastron was directly involved in cell-wall carbohydrate breakdown, while Entodinium capacity to digest cellulose remained low. We noted that with a diet rich in cellulose and hemicellulose, bacterial cellulolytic activity was improved by the presence of ciliates in the rumen but was decreased with the "starch" diet (table 3). The greater VFA concentration observed in the faunated animals expressed ciliate effect on the fermentations as well as activation of bacterial metabolism. With a high starch diet, the Entodinium sp. ciliates may have a buffering effect on the pH values in the rumen by limiting bacterial fermentation after food intake and by prolonging starch digestion during the day (table 4). The composition of the VFA mixture was modified by ciliate inoculation. The molar proportion of butyric acid always increased, while that of acetic and propionic acids evolved differently according to the diets and the ciliates (table 4). The higher ammonia concentration in the rumen liquor observed in faunated animals (table 4) could be explained either by the breakdown of both feed and bacterial proteins ingested by ciliates or by a lower ammonia nitrogen incorporation by fewer bacteria. Statistical analyses were used to explain the specific effect of P and E and also the interactions between them and between each of them and the diets.     

Response of polychaetes to oil spills in natural and defaunated subtropical mangrove sediments from Paranaguá bay (SE Brazil)

A short-term short-scale field manipulation experiment was designed to assess the effects of total or partial defaunation, by sediment drying or diesel oil respectively, on polychaete recolonization rates in mangrove sediments of Paranaguá Bay, SE Brazil. After replacement of defaunated cores in the field, disturbed and adjacent undisturbed control sites were subsequently sampled together with adjacent undisturbed control sites on different dates over a 64-day period. Analyses of variance were carried out to test for differences in polychaete populational densities among experimental treatments and sampling dates. Examination of cores impacted by oil showed that most polychaete species kept rather active, quickly reacting to mechanical or light stimuli or moving rapidly. Polychaete recolonization of local mangroves after small-scale disturbance by oil was a fast process, in contrast to that following total defaunation by sediment drying. Rapid recolonization was largely dependent upon the differing mobility of adults of individual species from unaffected areas nearby, epifaunal crawlers or infaunal predators exhibiting the most rapid recovery rates. Conversely, the slow-paced recolonization of completely defaunated areas was due to the modification of sediment properties by drying and to the absence of larvae or juveniles of local species during the experiment.     

Der Einfluß der Verfütterung von Silage aus frischem bzw. angewelktem Gras oder Heu auf die Futteraufnahme,Verdaulichkeit, Milchleistung und Blutzusammensetzung der Milchkühe

A survey is given of research results on ruminant lipid digestion obtained at the authors’ laboratory. Results are presented in terms of lipid changes occurring in the rumen and in terms of effects on nature, extent and site of digestion.

The rumen can be adapted to an extremely high capacity for triglyceride lipolysis, preferentially releasing polyunsaturated fatty acids that are then further hydrogenated with accumulation of oleic acid isomers in vitro only. Evidence was obtained for both microbial incorporation and synthesis of polyunsaturated acids. In vitro lipolysis is inhibited by pH values below 6.3 and by ionophores. Free fatty acids inhibit methanogenesis with associated increases in propionate production and decreases in acetate and butyrate productions; the latter being related to their defaunating effect. Both in the faunated and defaunated rumen, free fatty acids decrease fibre digestion, which is shifted to the hindgut, at least in sheep. Defaunation increases rumen microbial growth efficiency and may result in a higher duodenal flow of both feed and microbial protein, provided these increases are not overcome by a decreased apparent rumen OM digestibility. Considerable between animal variability exists for these effects, associated with variable effects on rumen particle and liquid volumes and outflow rates.     

Effects of protozoa on Methane production in rumen and hindgut of calves around time of weaning

Effects of the presence or absence of ciliate protozoa on methanogenesis in the rumen and hindgut were investigated in young calves during a 7-week period. Ten Holstein calves, aged 7 days, were divided in two groups (n = 5) and fed an increasing amount of a commercial milk replacer and small amounts of a calves starter. One group was inoculated with ciliate fauna on two occasions, week 5 and 6, while the second remained ciliate-free. The absence of protozoa in the rumen decreased rumen empty weight ( ? 23%, P < 0.01), and rumen pool size of N ( ? 36%, P < 0.01) and crude fat ( ? 37%, P < 0.05). Rumen bacteria of non-faunated calves contained a higher proportion of total amino acid-N per 16 g N ( + 3%, P < 0.01) and D-alanine-N per 16 g N ( + 13%, P < 0.05) compared to faunated calves. Further results contain a reference for a higher bacterial mass in the ciliate-free rumen with an increased number of bacteria adherent to rumen mucosa. The CH₄ production in the rumen increased exponentially with the increase in protozoa population size (R² = 0.68). In presence of 46 · 10⁴ protozoa per ml rumen fluid, the in vitro CH₄ production of rumen fluid per mol total VFA was about 34% higher in faunated than in non-faunated calves (P < 0.001). Hydrogen (2H) recovery of rumen fermentation was positively correlated (R² = 0.55) to the CH₄ production rate. Methanogens were attached on rumen mucosa. Methanogenesis, induced by rumen mucosa attached bacteria, was stimulated by ruminal protozoa. In the absence of protozoa in the rumen, the acetate - propionate ratio and butyrate proportion of VFA were reduced. In vivo in the absence of protozoa not only the whole animal CH₄ production ( ? 30%, P < 0.05) but also the digestibility of carbohydrates ( ? 4%, P < 0.05) was reduced. Thereby no difference was observed in the intake of ME per kg DM between the groups. In conclusion, the methanogenesis in the rumen, but not in hindgut, is associated with the development of the ruminal protozoa population. The level of methanogenesis (mol/mol VFA) in the hindgut amounts to 20% of the ruminal methanogenesis.